HTTPbis Working Group R. Peon Internet-Draft Google, Inc Intended status: Informational H. Ruellan Expires:April 24,June 7, 2014 Canon CRFOctober 21,December 4, 2013 HPACK - Header Compression for HTTP/2.0draft-ietf-httpbis-header-compression-04draft-ietf-httpbis-header-compression-05 Abstract This document describes HPACK, a format adapted to efficiently represent HTTP header fields in the context of HTTP/2.0. Editorial Note (To be removed by RFC Editor) Discussion of this draft takes place on the HTTPBIS working group mailing list (ietf-http-wg@w3.org), which is archived at <http://lists.w3.org/Archives/Public/ietf-http-wg/>. Working Group information and related documents can be found at <http://tools.ietf.org/wg/httpbis/> (Wiki) and <https://github.com/http2/http2-spec> (source code and issues tracker). The changes in this draft are summarized in Appendix A.1. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire onApril 24,June 7, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Outline . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Header Field Encoding . . . . . . . . . . . . . . . . . . . . 5 3.1. Encoding Concepts . . . . . . . . . . . . . . . . . . . . 5 3.1.1. Encoding Context . . . . . . . . . . . . . . . . . . . 5 3.1.2. Header Table . . . . . . . . . . . . . . . . . . . . . 6 3.1.3. Reference Set . . . . . . . . . . . . . . . . . . . . 6 3.1.4. Header Field Representation . . . . . . . . . . . . . 7 3.1.5. Header Field Emission . . . . . . . . . . . . . . . . 8 3.2. Header Block Decoding . . . . . . . . . . . . . . . . . . 8 3.2.1. Header Field Representation Processing . . . . . . . . 8 3.2.2. Reference Set Emission . . . . . . . . . . . . . . . .910 3.2.3. Header Set Completion . . . . . . . . . . . . . . . .910 3.3. Header Table Management . . . . . . . . . . . . . . . . .910 3.3.1. Maximum Table Size . . . . . . . . . . . . . . . . . .910 3.3.2. Entry Eviction When Header Table Size Changes . . . . 10 3.3.3. Entry Eviction when Adding New Entries . . . . . . . .1011 4. Detailed Format . . . . . . . . . . . . . . . . . . . . . . .1011 4.1. Low-level representations . . . . . . . . . . . . . . . .1011 4.1.1. Integer representation . . . . . . . . . . . . . . . . 11 4.1.2. String Literal Representation . . . . . . . . . . . . 13 4.2. Indexed Header Field Representation . . . . . . . . . . .1415 4.3. Literal Header Field Representation . . . . . . . . . . . 15 4.3.1. Literal Header Field without Indexing . . . . . . . . 15 4.3.2. Literal Header Field with Incremental Indexing . . . . 16 5. Security Considerations . . . . . . . . . . . . . . . . . . .1718 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6.1. Normative References . . . . . . . . . . . . . . . . . . . 18 6.2. Informative References . . . . . . . . . . . . . . . . . .1819 Appendix A. Change Log (to be removed by RFC Editor before publication . . . . . . . . . . . . . . . . . . . . . 19 A.1. Sincedraft-ietf-httpbis-header-compression-03draft-ietf-httpbis-header-compression-04 . . . . . . 19 A.2. Sincedraft-ietf-httpbis-header-compression-02draft-ietf-httpbis-header-compression-03 . . . . . .1920 A.3. Sincedraft-ietf-httpbis-header-compression-01draft-ietf-httpbis-header-compression-02 . . . . . .1920 A.4. Since draft-ietf-httpbis-header-compression-01 . . . . . .1920 A.5. Since draft-ietf-httpbis-header-compression-01 . . . . . . 21 Appendix B. Static Table . . . . . . . . . . . . . . . . . . . .2021 Appendix C. Huffman Codes For Requests . . . . . . . . . . . . .2223 Appendix D. Huffman Codes for Responses . . . . . . . . . . . . .2829 Appendix E. Examples . . . . . . . . . . . . . . . . . . . . . .3334 E.1.Request Decoding Example With HuffmanHeader Field Representation Examples . . . . . . . . . .33. 34 E.1.1. Literal Header Field with Indexing . . . . . . . . . . 34 E.1.2. Literal Header Field without Indexing . . . . . . . . 35 E.1.3. Indexed Header Field . . . . . . . . . . . . . . . . . 36 E.1.4. Indexed Header Field from Static Table . . . . . . . . 37 E.2. RequestDecoding Example WithoutExamples without Huffman . . . . . . . . . . . . . 37 E.2.1. First request . . . . . . . . . . . . . . . . . . . . 37 E.2.2. Second request . . . . . . . . . . . . . . . . . . . . 38 E.2.3. Third request . . . . . . . . . . . . . . . . . . . . 40 E.3.Response Decoding Example WithRequest Examples with Huffman . . . . . . . . . .43 E.4. Response Decoding Example Without Huffman. . . . 42 E.3.1. First request . . . .51 1. Introduction This document describes HPACK, a format adapted to efficiently represent HTTP header fields in the context of HTTP/2.0 (see [HTTP2]). 2. Overview In HTTP/1.X (see [HTTP-p1]), header fields are sent without any form of compression. As web pages have grown to include dozens. . . . . . . . . . . . . . . . 42 E.3.2. Second request . . . . . . . . . . . . . . . . . . . . 43 E.3.3. Third request . . . . . . . . . . . . . . . . . . . . 44 E.4. Response Examples without Huffman . . . . . . . . . . . . 46 E.4.1. First response . . . . . . . . . . . . . . . . . . . . 46 E.4.2. Second response . . . . . . . . . . . . . . . . . . . 48 E.4.3. Third response . . . . . . . . . . . . . . . . . . . . 49 E.5. Response Examples with Huffman . . . . . . . . . . . . . . 51 E.5.1. First response . . . . . . . . . . . . . . . . . . . . 51 E.5.2. Second response . . . . . . . . . . . . . . . . . . . 53 E.5.3. Third response . . . . . . . . . . . . . . . . . . . . 54 1. Introduction This document describes HPACK, a format adapted tohundreds of requests, the redundantefficiently represent HTTP header fields inthese requests nowthe context of HTTP/2.0 (see [HTTP2]). 2. Overview In HTTP (see [HTTP-p1]), header fields are sent without any form of compression. As web pages have grown to include dozens to hundreds of requests, the redundant header fields in these requests now pose a problem of measurable latency and unnecessary bandwidth (see [PERF1] and [PERF2]). SPDY [SPDY] initially addressed this redundancy by compressing header fields with Deflate, which proved very effective at eliminating the redundant header fields. However, thataproachapproach exposed a security risk as demonstrated by the CRIME [CRIME].In this document, we proposeThis document describes HPACK, a new compressor for header fields which eliminates redundant header fields, is not vulnerable toCRIME styleknown security attacks, and which also has a bounded memory cost for use in constrained environments. 2.1. Outline The HTTP header field encoding described in this document is based on a header table that map(name, value)name-value pairs to index values. Header tables are incrementally updated during the HTTP/2.0 session. The encoder is responsible for deciding which header fields to insert as new entries in the header table. The decoder then does exactly what the encoder prescribes, ending in a state that exactly matches the encoder's state. This enables decoders to remain simple and understand a wide variety of encoders. As two consecutive sets of header fields often have header fields in common, each set of header fields is coded as a difference from the previous set of header fields. The goal is to only encode the changes (header fields present in one of the set and not in the other) between the two sets of header fields. HTTP header field compression treats a set of header fields as an unordered collection of name-value pairs. Names and values are opaque sequences of octets. The order of header fields is not guaranteed to be preserved after being compression and decompression. Examples illustrating the use of these different mechanisms to represent header fields are available in Appendix E. 3. Header Field Encoding 3.1. Encoding Concepts The encoding and decoding of header fields relies on some components and concepts: Header Field: Akey, valuename-value pair.HPACK allows a header field value to be either aBoth name and valueas specified by HTTP/1.X (see [HTTP-p1]), or a NULL-separated ordered listare sequences ofHTTP/1.X values.octets. Header Table: The header table (see Section 3.1.2) is a component used to associate stored header fields to index values. The data stored in this table is in first-in, first-out order. Static Table: The static table (see Appendix B) is a component used to associate static header fields to index values. This data is ordered, read-only, always accessible, and may be shared amongst all encoding contexts. Reference Set: The reference set (see Section 3.1.3) is a component containing an unordered set of references to entries in the headertable or statictable. This is used for the differential encoding of a new header set. Header Set: A header set is a potentially ordered group of header fields that are encoded jointly. A complete set of key-value pairs contained in a HTTP request or response is a header set. Header Field Representation: A header field can be represented in encoded form either as a literal or as an index (see Section 3.1.4). Header Block: The entire set of encoded header field representations which, when decoded, yield a complete header set. Header Field Emission: When decoding a set of header field representations, some operations emit a header field (see Section 3.1.5). Emittedheadersheader fields can be safely passed to the upper processing layers as part of the current Header Set. 3.1.1. Encoding Context The set of mutable structures used within an encoding context include a header table and a reference set. Everything else is either immutable or conceptual. Using HTTP, messages are exchanged between a client and a server in both direction. To keep the encoding of header fields in each direction independent from the other direction, there is one encoding context for each direction. The header fields contained in a PUSH_PROMISE frame sent by a server to a client are encoded within the same context as the header fields contained in the HEADERS frame corresponding to a response sent from the server to the client. 3.1.2. Header Table A header table consists of a list of header fields maintained in first-in, first-out order. The first and newest entry in a header table is always at index0,1, and the oldest entry of a header table is at the index len(headertable)-1.table). The header table is initially empty. There is typically no need for the header table to contain duplicate entries. However, duplicate entries MUST NOT be treated as an error by a decoder. The encoder decides how to update the header table and as such can control how much memory is used by the header table. To limit the memory requirements on the decoder side, the header table size is strictly bounded (see Section 3.3.1). The header table is updated during the processing of a set of header field representations (see header field representation processing (Section3.2.1).3.2.1)). 3.1.3. Reference Set A reference set is an unordered set of references to entrieseither withinof the headertable or the statictable. The reference set is initially empty. The reference set is updated during the processing of a set of header field representations (see header field representation processing (Section3.2.1).3.2.1)). The reference set enables differential encoding, whereby only differences between the previous header set and the current header set need to be encoded. The use of differential encoding is optional for any header set. When an entry is evicted from the header table, if it was referenced from the reference set, its reference is removed from the reference set. To limit the memory requirements on the decoder side for handling the reference set, only entries within the header table can be contained in the reference set. To still allow entries from the static table to take advantage of the differential encoding, when a header field is represented as a reference to an entry of the static table, this entry is inserted into the header table ((see Section 3.2.1). 3.1.4. Header Field Representation An encoded header field can be represented either as a literal or as an index. Literal Representation: A literal representation defines a new header field. The header field name is represented either literally or as a reference to an entry of the header table. The header field value is represented literally. Two different literal representations are provided: * A literal representation that does not add the header field to the header table (see Section 4.3.1). * A literal representation that adds the header field as a new entry at the beginning of the header table (see Section 4.3.2). Indexed Representation: The indexed representation defines a header field as a reference to an entry in either the header table or the static table(see Section 4.2). <---------- Index Address Space ----------> <-- Header Table --> <-- Static Table --> +---+-----------+---+ +---+-----------+---+ |01 | ... | k | |k+1| ... | n | +---+-----------+---+ +---+-----------+---+ ^ | | V Insertion Point Drop Point Index Address Space Indices between01 and len(headertable)-1,table), inclusive, refer to elements in the header table, with index01 referring to the beginning of the table. Indices between len(headertable)table)+1 and len(header table)+ len(statictable)-1,table), inclusive, refer to elements in the static table, where the index len(headertable)table)+1 refers to the first entry in the static table. Index 0 signals that the reference set MUST be emptied. Any other indices MUST be treated as erroneous, and the compression context considered corrupt and unusable. 3.1.5. Header Field Emission The emission of a header field is the process ofpassing thatmarking a header field as belonging to theapplication, so that the application can process and react tocurrent headerfield data. By emittingset. Once a headerfields instead of emittinghas been emitted, it cannot be removed from the current headersets,set. On thedecoderdecoding side, an emitted header field can be safely passed to the upper processing layer as part of the current header set. The decoder MAY pass the emitted header fields to the upper processing layer in any order. By emitting header fields instead of emitting header sets, the decoder can be implemented in a streaming way, and as suchmusthas only to keep in memory the header table and the reference set. This bounds the amount of memory used by the decoder, even in presence of a very large set of header fields. The management of memory for handling very large sets of header fields can therefore be deferred to theapplication. When a header field is a NULL-separated list of values, each value within the list MAY be emitted separately, with the same header field name, and the order of emission MUST be the order of appearance in the list.upper processing layers. 3.2. Header Block Decoding The processing of a header block to obtain a header set is defined in this section. To ensure that the decoding will successfully produce a header set, a decoder MUST obey the following rules. 3.2.1. Header Field Representation Processing All the header field representations contained in a header block are processed in the order in which they are presented, as specified below. An _indexed representation_ with an index value of 0 entails the following actions: o The reference set is emptied. An _indexed representation_ corresponding to an entry _present_ in the reference set entails the following actions: o Thereference to theentry is removed from the reference set. An _indexed representation_ corresponding to an entry _not present_ in the reference set entails the following actions: o If referencing an element of the static table: * The header field corresponding to the referenced entry is emitted. * The referenced static entry isadded toinserted at the beginning of the header table. *If the new entry fits within the header table, aA reference tothethis new header table entry is added to the referenceset.set (except if this new entry didn't fit in the header table). o If referencing an element of the header table: * The header field corresponding to the referenced entry is emitted. * The referenced header table entry is added to theheader table.reference set. A _literal representation_ that is _not added_ to the header table entails the following action: o The header field is emitted. A _literal representation_ that is _added_ to the header table entails the following actions: o The header field is emitted. o The header field is inserted at the beginning of the header table. o A reference to the new entry is added to the referenceset. o Theset (except if this new entry didn't fit in the headerfield is emitted.table). 3.2.2. Reference Set Emission Once all the representations contained in a header block have been processed, the header fields referenced in the reference set which have not previously been emitted during this processing are emitted. 3.2.3. Header Set Completion Once all of the header field representations have been processed, and the remaining items in the reference set have been emitted, the header set is complete. 3.3. Header Table Management 3.3.1. Maximum Table Size To limit the memory requirements on the decoder side, the size of thetheheader table is bounded. The size of the header table MUST stay lower than or equal to the value of the HTTP/2.0 setting SETTINGS_HEADER_TABLE_SIZE (see [HTTP2]). The size of thetheheader table is the sum of the size of its entries. The size of an entry is the sum of its name's length inbytesoctets (as defined in Section 4.1.2), of its value's length inbytesoctets (Section 4.1.2) and of 32bytes.octets. The lengths are measured on the non-encoded entry name and entry value (for the case when a Huffman encoding is used to transmit string values). The 32bytesoctets are an accounting for the entry structure overhead. For example, an entry structure using two 64-bits pointers to reference the name and the value and the entry, and two 64-bits integer for counting the number of references to these name and value would use 32bytes.octets. 3.3.2. Entry Eviction When Header Table Size Changes Whenever an entry is evicted from the header table, any reference to that entry contained by the reference set is removed. Whenever SETTINGS_HEADER_TABLE_SIZE is made smaller, entries are evicted from the end of the header table until the size of the header table is less than or equal to SETTINGS_HEADER_TABLE_SIZE. The eviction of an entry from the header table causes the index of the entries in the static table to be reduced by one. 3.3.3. Entry Eviction when Adding New Entries Whenever a new entry is to be added to the table, any name referenced by the representation of this new entry is cached, and then entries are evicted from the end of the header table until the size of the header table is less than or equal to SETTINGS_HEADER_TABLE_SIZE - new entry size, or until the table is empty. If the size of the new entry is less than or equal to SETTINGS_HEADER_TABLE_SIZE, that entry is added to the table. It is not an error to attempt to add an entry that is larger than SETTINGS_HEADER_TABLE_SIZE. 4. Detailed Format 4.1. Low-level representations 4.1.1. Integer representation Integers are used to represent name indexes, pair indexes or string lengths. To allow for optimized processing, an integer representation always finishes at the end ofa byte.an octet. An integer is represented in two parts: a prefix that fills the currentbyteoctet and an optional list ofbytesoctets that are used if the integer value does not fit within the prefix. The number of bits of the prefix (called N) is a parameter of the integer representation. The N-bit prefix allows filling the currentbyte.octet. If the value is small enough (strictly less than 2^N-1), it is encoded within the N-bit prefix. Otherwise all the bits of the prefix are set to 1 and the value is encoded using an unsigned variable length integer [1] representation. N is always between 1 and 8 bits. An integer starting ata byte-boundaryan octet-boundary will have an 8-bit prefix. The algorithm to represent an integer I is as follows: If I < 2^N - 1, encode I on N bits Else encode 2^N - 1 on N bits I = I - (2^N - 1) While I >= 128 Encode (I % 128 + 128) on 8 bits I = I / 128 encode (I) on 8 bits This integer representation allows for values of indefinite size. It is also possible for an encoder to send a large number of zero values, which can wastebytesoctets and could be used to overflow integer values. Excessively large integer encodings - in value or octet length - MUST be treated as a decoding error. Different limits can be set for each of the different uses of integers, based on implementation constraints. 4.1.1.1. Example 1: Encoding 10 using a 5-bit prefix The value 10 is to be encoded with a 5-bit prefix. o 10 is less than 31 (= 2^5 - 1) and is represented using the 5-bit prefix. 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | X | X | X | 0 | 1 | 0 | 1 | 0 | 10 stored on 5 bits +---+---+---+---+---+---+---+---+ 4.1.1.2. Example 2: Encoding 1337 using a 5-bit prefix The value I=1337 is to be encoded with a 5-bit prefix. 1337 is greater than 31 (= 2^5 - 1). The 5-bit prefix is filled with its max value (31). I = 1337 - (2^5 - 1) = 1306. I (1306) is greater than or equal to 128, the while loop body executes: I % 128 == 26 26 + 128 == 154 154 is encoded in 8 bits as: 10011010 I is set to 10 (1306 / 128 == 10) I is no longer greater than or equal to 128, the while loop terminates. I, now 10, is encoded on 8 bits as: 00001010 The process ends. 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | X | X | X | 1 | 1 | 1 | 1 | 1 | Prefix = 31, I = 1306 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 1306>=128, encode(154), I=1306/128 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 10<128, encode(10), done +---+---+---+---+---+---+---+---+ 4.1.1.3. Example 3: Encoding 42 starting at an octet-boundary The value 42 is to be encoded starting at an octet-boundary. This implies that a 8-bit prefix is used. o 42 is less than 255 (= 2^8 - 1) and is represented using the 8-bit prefix. 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | 0 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 42 stored on 8 bits +---+---+---+---+---+---+---+---+ 4.1.2. String Literal Representation Header field names and header field values are encoded as sequences ofbytes.octets. A header field name or a header field value is encoded in three parts: 1. One bit, H, indicating whether or not thebytesoctets arehuffmanHuffman encoded. 2. The number ofbytesoctets required to hold the result of the next step, represented as a variable-length-quantity (Section 4.1.1), starting with a 7-bit prefix immediately following the first bit. 3. The encoded data of the string: 1. If H is true, then thetheencoded string data is the bitwise concatenation of the canonical[CANON]huffman[CANON]Huffman code [HUFF] corresponding to eachcharacteroctet of the data, followed by between 0-7 bits of padding. 2. If H is false, then the encoded string is thebytesoctets of the field value without modification. Padding is necessary when doinghuffmanHuffman encoding to ensure that the remaining bits between the actual end of the data and the nextbyteoctet boundary are not misinterpreted as part of the input data. When padding forhuffmanHuffman encoding, use the bits from the EOS (end-of- string) entry in the Huffman table, starting with theMSB.MSB (most significant bit). This entry is guaranteed to be at least 8 bits long. String literals sent in the client to server direction which usehuffmanHuffman encoding are encoded with the codes within the requesthuffmanHuffman code table (Appendix C) (see RequestDecodingExamples With HuffmanExample(Appendix E.3)). String literals sent in the server to client direction which usehuffmanHuffman encoding are encoded with the codes within the responsehuffmanHuffman code table (Appendix D) (see ResponseDecodingExamples With HuffmanExample(AppendixE.3)).E.5)). The EOS symbol is represented with value 256, and is used solely to signal the end of thehuffman-encodedHuffman-encoded key data or the end of thehuffman-encodedHuffman-encoded value data. Given that only between 0-7 bits of the EOS symbol is included in anyhuffman-encodedHuffman-encoded string, and given that the EOS symbol is at least 8 bits long, it is expected that it should never be successfully decoded. 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | 1 | Value Length Prefix (7) | +---+---+---+---+---+---+---+---+ | Value Length (0-Nbytes)octets) | +---+---+---+---+---+---+---+---+ ... +---+---+---+---+---+---+---+---+ | Huffman Encoded Data |Padding| +---+---+---+---+---+---+---+---+ String Literal With Huffman Encoding 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | 0 | Value Length Prefix (7) | +---+---+---+---+---+---+---+---+ | Value Length (0-Nbytes)octets) | +---+---+---+---+---+---+---+---+ ... +---+---+---+---+---+---+---+---+ | Field Bytes Without Encoding | +---+---+---+---+---+---+---+---+ String Literal Without Huffman Encoding 4.2. Indexed Header Field Representation An indexed header field representation either identifies an entry in the header table or static table. Thespecified entry is emitted and a reference to that entry is added to the reference set if it is not currently in the reference set. If itprocessing of an indexed header field representation ispresentdescribed inthe reference set then the reference is removed and the entry is not emitted.Section 3.2.1. 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | 1 | Index (7+) | +---+---------------------------+ Indexed Header Field This representation starts with the '1' 1-bit pattern, followed by the index of the matching pair, represented as an integer with a 7-bit prefix. The index value of 0 is reserved for signalling that the reference set is emptied. 4.3. Literal Header Field Representation Literal header field representations contain a literal header field value. Header field names are either provided as a literal or by reference to an existing header table or static table entry. Literal representations all result in the emission of a header field when decoded. 4.3.1. Literal Header Field without Indexing A literal header field without indexing causes the emission of a header field without altering the header table. 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | 0 | 1 | Index (6+) | +---+---+---+-------------------+ | Value Length (8+) | +-------------------------------+ | Value String (Length octets) | +-------------------------------+ Literal Header Field without Indexing - Indexed Name 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | 0 | 1 | 0 | +---+---+---+-------------------+ | Name Length (8+) | +-------------------------------+ | Name String (Length octets) | +-------------------------------+ | Value Length (8+) | +-------------------------------+ | Value String (Length octets) | +-------------------------------+ Literal Header Field without Indexing - New Name This representation starts with the '01' 2-bit pattern. If the header field name matches the header field name of a (name, value) pair stored in the Header Table or Static Table, the header field name can be represented using the index of that entry. In this case, the index of the entry,increased by one (index + 1),index (which is strictly greater than 0), is represented as an integer with a 6-bitprefix. Note that if the index is strictly below 63, only one byte is used for this representation. Ifprefix (see Section 4.1.1). Otherwise, the header field namedoes not matchis represented as aheader field name entry, theliteral. The value 0 is represented on 6 bits followed by the header field name(Section(see Section 4.1.2). The header field name representation is followed by the header field value represented as a literal string as described in Section 4.1.2. 4.3.2. Literal Header Field with Incremental Indexing A literal header field with incremental indexing adds a new entry to the header table. 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | 0 | 0 | Index (6+) | +---+---+---+-------------------+ | Value Length (8+) | +-------------------------------+ | Value String (Length octets) | +-------------------------------+ Literal Header Field with Incremental Indexing - Indexed Name 0 1 2 3 4 5 6 7 +---+---+---+---+---+---+---+---+ | 0 | 0 | 0 | +---+---+---+-------------------+ | Name Length (8+) | +-------------------------------+ | Name String (Length octets) | +-------------------------------+ | Value Length (8+) | +-------------------------------+ | Value String (Length octets) | +-------------------------------+ Literal Header Field with Incremental Indexing - New Name This representation starts with the '00' 2-bit pattern. If the header field name matches the header field name of a (name, value) pair stored in theheader tableHeader Table orstatic table,Static Table, the header field name can be represented using the index of that entry. In this case, thepair increased by one (index + 1)index of the entry, index (which is strictly greater than 0), is represented as an integer with a 6-bitprefix. Ifprefix (see Section 4.1.1). Otherwise, the header field namedoes not matchis represented as aheader field name entry, theliteral. The value 0 is represented on 6 bits followed by the header field name(Section(see Section 4.1.2). The header field name representation is followed by the header field value represented as a literal string as described in Section 4.1.2. 5. Security Considerations This compressor exists to solve security issues present in stream compressors such as DEFLATE whereby the compression context can be efficiently probed to reveal secrets. A conformant implementation of this specification should be fairly safe against that kind of attack, as the reaping of any information from the compression context requires more work than guessing and verifying theplaintextplain text data directly with the server. As with any secret, however, the longer the length of the secret, the more difficult the secret is to guess. It is inadvisable to have short cookies that are relied upon to remain secret for any duration of time. A proper security-conscious implementation will also need to prevent timing attacks by ensuring that the amount of time it takes to do string comparisons is always a function of the total length of the strings, and not a function of the number of matched characters. A decoder needs to ensure that larger values or encodings of integers do not permit exploitation. Decoders MUST limit the size of integers, both in value and encoded length, that it accepts (see Section 4.1.1). Another common security problem is when the remote endpoint successfully causes the local endpoint to exhaust its memory. This compressor attempts to deal with the most obvious ways that this could occur by limiting both the peak and the steady-state amount of memory consumed in the compressor state, by providing ways for the application to consume/flush the emitted header fields in small chunks, and by considering overhead in the state size calculation. Implementors must still be careful in the creation of APIs to an implementation of this compressor by ensuring that header field keys and values are either emitted as a stream, or that the compression implementation have a limit on the maximum size of a key or value. Failure to implement these kinds of safeguards may still result in a scenario where the local endpoint exhausts its memory. 6. References 6.1. Normative References [HTTP-p1] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing",draft-ietf-httpbis-p1-messaging-24draft-ietf-httpbis-p1-messaging-25 (work in progress),SeptemberNovember 2013. [HTTP2] Belshe, M., Peon, R., Thomson, M., Ed., and A. Melnikov, Ed., "Hypertext Transfer Protocol version 2.0",draft-ietf-httpbis-http2-06draft-ietf-httpbis-http2-08 (work in progress),AugustNovember 2013. 6.2. Informative References [CANON] Schwartz, E. and B. Kallick, "Generating a canonical prefix encoding", Communications of the ACM Volume 7 Issue 3, pp. 166-169, March 1964, <http://dl.acm.org/citation.cfm?id=363991>. [CRIME] Rizzo, J. and T. Duong, "The Crime Attack", September 2012, <https://docs.google.com/a/twist.com/ presentation/d/ 11eBmGiHbYcHR9gL5nDyZChu_-lCa2GizeuOfaLU2HOU/ edit#slide=id.g1eb6c1b5_3_6>. [HUFF] Huffman, D., "A Method for the Construction ofMinimimMinimum Redundancy Codes", Proceedings of the Institute of Radio Engineers Volume 40, Number 9, pp. 1098-1101, September 1952, <http://ieeexplore.ieee.org/xpl/ articleDetails.jsp?arnumber=4051119>. [PERF1] Belshe, M., "IETF83: SPDY and What to Consider for HTTP/2.0", March 2012, <http://www.ietf.org/proceedings/ 83/slides/slides-83-httpbis-3>. [PERF2] McManus, P., "SPDY: What I Like About You", September 2011, <http://bitsup.blogspot.com/2011/09/ spdy-what-i-like-about-you.html>. [SPDY] Belshe, M. and R. Peon, "SPDY Protocol", draft-mbelshe-httpbis-spdy-00 (work in progress), February 2012. URIs [1] <http://en.wikipedia.org/wiki/Variable-length_quantity> Appendix A. Change Log (to be removed by RFC Editor before publication A.1. Since draft-ietf-httpbis-header-compression-04 o Updated examples: take into account changes in the spec, and show more features. o Use 'octet' everywhere instead of having both 'byte' and 'octet'. o Added reference set emptying. o Editorial changes and clarifications. o Added "host" header to the static table. o Ordering for list of values (either NULL- or comma-separated). A.2. Since draft-ietf-httpbis-header-compression-03 o A large number of editorial changes; changed the description of evicting/adding new entries. o Removed substitution indexing o Changed 'initial headers' to 'static headers', as per issue #258 o Merged 'request' and 'response' static headers, as per issue #259 o Changed text to indicate that new headers are added at index 0 and expire from the largest index, as per issue #233A.2.A.3. Since draft-ietf-httpbis-header-compression-02 o Corrected error in integer encoding pseudocode.A.3.A.4. Since draft-ietf-httpbis-header-compression-01 o Refactored of Header Encoding Section: split definitions and processing rule. o Backward incompatible change: Updated reference set management as per issue #214. This changes how the interaction between the reference set and eviction works. This also changes the working of the reference set in some specific cases. o Backward incompatible change: modified initial header list, as per issue #188. o Added example of 32bytesoctets entry structure (issue #191). o Added Header Set Completion section. Reflowed some text. Clarified some writing which was akward. Added text about duplicate header entry encoding. Clarified some language w.r.t Header Set. Changed x-my-header to mynewheader. Added text in the HeaderEmission section indicating that the application may also be able to free up memory more quickly. Added information in Security Considerations section.A.4.A.5. Since draft-ietf-httpbis-header-compression-01 Fixed bug/omission in integer representation algorithm. Changed the document title. Header matching text rewritten. Changed the definition of header emission. Changed the name of the setting which dictates how much memory the compression context should use. Removed "specific use cases" section Corrected erroneous statement about what index can be contained in onebyteoctet Added descriptions of opcodes Removed security claims from introduction. Appendix B. Static Table The static table consists of anunchangableunchangeable ordered list of (name, value) pairs. The first entry in the table is always represented by the index len(headertable),table)+1, and the last entry in the table is represented by the index len(header table)+len(statictable)-1.table). [[anchor9: The ordering of these tables is currently arbitrary. The tables in this section should be updated and ordered such that the table entries with the smallest indices are those which, based on a statistical analysis of the frequency of use weighted by size, achieve the largest decrease inbytesoctets transmitted subject to HTTP 2.0 header field rules (like removal of some header fields). This set of header fields is currently very likely incomplete, and should be made complete.]] The following table lists the pre-defined header fields that make-up the static header table. +-------+-----------------------------+--------------+ | Index | Header Name | Header Value | +-------+-----------------------------+--------------+ |01 | :authority | | |12 | :method | GET | |23 | :method | POST | |34 | :path | / | |45 | :path | /index.html | |56 | :scheme | http | |67 | :scheme | https | |78 | :status | 200 | |89 | :status | 500 | |910 | :status | 404 | |1011 | :status | 403 | |1112 | :status | 400 | |1213 | :status | 401 | |1314 | accept-charset | | |1415 | accept-encoding | | |1516 | accept-language | | |1617 | accept-ranges | | |1718 | accept | | |1819 | access-control-allow-origin | | |1920 | age | | |2021 | allow | | |2122 | authorization | | |2223 | cache-control | | |2324 | content-disposition | | |2425 | content-encoding | | |2526 | content-language | | |2627 | content-length | | |2728 | content-location | | |2829 | content-range | | |2930 | content-type | | |3031 | cookie | | |3132 | date | | |3233 | etag | | |3334 | expect | | |3435 | expires | | |3536 | from | | |3637 | host | | | 38 | if-match | | |3739 | if-modified-since | | |3840 | if-none-match | | |3941 | if-range | | |4042 | if-unmodified-since | | |4143 | last-modified | | |4244 | link | | |4345 | location | | |4446 | max-forwards | | |4547 | proxy-authenticate | | |4648 | proxy-authorization | | |4749 | range | | |4850 | referer | | |4951 | refresh | | |5052 | retry-after | | |5153 | server | | |5254 | set-cookie | | |5355 | strict-transport-security | | |5456 | transfer-encoding | | |5557 | user-agent | | |5658 | vary | | |5759 | via | | |5860 | www-authenticate | | +-------+-----------------------------+--------------+ Table 1: Static Table Entries The table give the index of each entry in the static table. The full index of each entry, to be used for encoding a reference to this entry, is computed by adding the number of entries in the header table to this index. Appendix C. Huffman Codes For Requests The following Huffman codes are used when encoding string literals in the client to server direction. [[anchor10: This tableis out of date and needs updating. In particular, EOS needsmay need to beat least 7-bits long and currently is not.]]regenerated.]] aligned aligned to len to len MSB in LSB in sym as bits bits as hex bits ( 0) |11111111|11111111|11110111|010 [27] 7ffffba [27] ( 1) |11111111|11111111|11110111|011 [27] 7ffffbb [27] ( 2) |11111111|11111111|11110111|100 [27] 7ffffbc [27] ( 3) |11111111|11111111|11110111|101 [27] 7ffffbd [27] ( 4) |11111111|11111111|11110111|110 [27] 7ffffbe [27] ( 5) |11111111|11111111|11110111|111 [27] 7ffffbf [27] ( 6) |11111111|11111111|11111000|000 [27] 7ffffc0 [27] ( 7) |11111111|11111111|11111000|001 [27] 7ffffc1 [27] ( 8) |11111111|11111111|11111000|010 [27] 7ffffc2 [27] ( 9) |11111111|11111111|11111000|011 [27] 7ffffc3 [27] ( 10) |11111111|11111111|11111000|100 [27] 7ffffc4 [27] ( 11) |11111111|11111111|11111000|101 [27] 7ffffc5 [27] ( 12) |11111111|11111111|11111000|110 [27] 7ffffc6 [27] ( 13) |11111111|11111111|11111000|111 [27] 7ffffc7 [27] ( 14) |11111111|11111111|11111001|000 [27] 7ffffc8 [27] ( 15) |11111111|11111111|11111001|001 [27] 7ffffc9 [27] ( 16) |11111111|11111111|11111001|010 [27] 7ffffca [27] ( 17) |11111111|11111111|11111001|011 [27] 7ffffcb [27] ( 18) |11111111|11111111|11111001|100 [27] 7ffffcc [27] ( 19) |11111111|11111111|11111001|101 [27] 7ffffcd [27] ( 20) |11111111|11111111|11111001|110 [27] 7ffffce [27] ( 21) |11111111|11111111|11111001|111 [27] 7ffffcf [27] ( 22) |11111111|11111111|11111010|000 [27] 7ffffd0 [27] ( 23) |11111111|11111111|11111010|001 [27] 7ffffd1 [27] ( 24) |11111111|11111111|11111010|010 [27] 7ffffd2 [27] ( 25) |11111111|11111111|11111010|011 [27] 7ffffd3 [27] ( 26) |11111111|11111111|11111010|100 [27] 7ffffd4 [27] ( 27) |11111111|11111111|11111010|101 [27] 7ffffd5 [27] ( 28) |11111111|11111111|11111010|110 [27] 7ffffd6 [27] ( 29) |11111111|11111111|11111010|111 [27] 7ffffd7 [27] ( 30) |11111111|11111111|11111011|000 [27] 7ffffd8 [27] ( 31) |11111111|11111111|11111011|001 [27] 7ffffd9 [27] ' ' ( 32) |11101000| [8] e8 [8] '!' ( 33) |11111111|1100 [12] ffc [12] '"' ( 34) |11111111|111010 [14] 3ffa [14] '#' ( 35) |11111111|1111100 [15] 7ffc [15] '$' ( 36) |11111111|1111101 [15] 7ffd [15] '%' ( 37) |100100 [6] 24 [6] '&' ( 38) |1101110 [7] 6e [7] ''' ( 39) |11111111|1111110 [15] 7ffe [15] '(' ( 40) |11111111|010 [11] 7fa [11] ')' ( 41) |11111111|011 [11] 7fb [11] '*' ( 42) |11111110|10 [10] 3fa [10] '+' ( 43) |11111111|100 [11] 7fc [11] ',' ( 44) |11101001| [8] e9 [8] '-' ( 45) |100101 [6] 25 [6] '.' ( 46) |00100 [5] 4 [5] '/' ( 47) |0000 [4] 0 [4] '0' ( 48) |00101 [5] 5 [5] '1' ( 49) |00110 [5] 6 [5] '2' ( 50) |00111 [5] 7 [5] '3' ( 51) |100110 [6] 26 [6] '4' ( 52) |100111 [6] 27 [6] '5' ( 53) |101000 [6] 28 [6] '6' ( 54) |101001 [6] 29 [6] '7' ( 55) |101010 [6] 2a [6] '8' ( 56) |101011 [6] 2b [6] '9' ( 57) |101100 [6] 2c [6] ':' ( 58) |11110110|0 [9] 1ec [9] ';' ( 59) |11101010| [8] ea [8] '<' ( 60) |11111111|11111111|10 [18] 3fffe [18] '=' ( 61) |101101 [6] 2d [6] '>' ( 62) |11111111|11111110|0 [17] 1fffc [17] '?' ( 63) |11110110|1 [9] 1ed [9] '@' ( 64) |11111111|111011 [14] 3ffb [14] 'A' ( 65) |1101111 [7] 6f [7] 'B' ( 66) |11101011| [8] eb [8] 'C' ( 67) |11101100| [8] ec [8] 'D' ( 68) |11101101| [8] ed [8] 'E' ( 69) |11101110| [8] ee [8] 'F' ( 70) |1110000 [7] 70 [7] 'G' ( 71) |11110111|0 [9] 1ee [9] 'H' ( 72) |11110111|1 [9] 1ef [9] 'I' ( 73) |11111000|0 [9] 1f0 [9] 'J' ( 74) |11111000|1 [9] 1f1 [9] 'K' ( 75) |11111110|11 [10] 3fb [10] 'L' ( 76) |11111001|0 [9] 1f2 [9] 'M' ( 77) |11101111| [8] ef [8] 'N' ( 78) |11111001|1 [9] 1f3 [9] 'O' ( 79) |11111010|0 [9] 1f4 [9] 'P' ( 80) |11111010|1 [9] 1f5 [9] 'Q' ( 81) |11111011|0 [9] 1f6 [9] 'R' ( 82) |11111011|1 [9] 1f7 [9] 'S' ( 83) |11110000| [8] f0 [8] 'T' ( 84) |11110001| [8] f1 [8] 'U' ( 85) |11111100|0 [9] 1f8 [9] 'V' ( 86) |11111100|1 [9] 1f9 [9] 'W' ( 87) |11111101|0 [9] 1fa [9] 'X' ( 88) |11111101|1 [9] 1fb [9] 'Y' ( 89) |11111110|0 [9] 1fc [9] 'Z' ( 90) |11111111|00 [10] 3fc [10] '[' ( 91) |11111111|111100 [14] 3ffc [14] '\' ( 92) |11111111|11111111|11111011|010 [27] 7ffffda [27] ']' ( 93) |11111111|11100 [13] 1ffc [13] '^' ( 94) |11111111|111101 [14] 3ffd [14] '_' ( 95) |101110 [6] 2e [6] '`' ( 96) |11111111|11111111|110 [19] 7fffe [19] 'a' ( 97) |01000 [5] 8 [5] 'b' ( 98) |101111 [6] 2f [6] 'c' ( 99) |01001 [5] 9 [5] 'd' (100) |110000 [6] 30 [6] 'e' (101) |0001 [4] 1 [4] 'f' (102) |110001 [6] 31 [6] 'g' (103) |110010 [6] 32 [6] 'h' (104) |110011 [6] 33 [6] 'i' (105) |01010 [5] a [5] 'j' (106) |1110001 [7] 71 [7] 'k' (107) |1110010 [7] 72 [7] 'l' (108) |01011 [5] b [5] 'm' (109) |110100 [6] 34 [6] 'n' (110) |01100 [5] c [5] 'o' (111) |01101 [5] d [5] 'p' (112) |01110 [5] e [5] 'q' (113) |11110010| [8] f2 [8] 'r' (114) |01111 [5] f [5] 's' (115) |10000 [5] 10 [5] 't' (116) |10001 [5] 11 [5] 'u' (117) |110101 [6] 35 [6] 'v' (118) |1110011 [7] 73 [7] 'w' (119) |110110 [6] 36 [6] 'x' (120) |11110011| [8] f3 [8] 'y' (121) |11110100| [8] f4 [8] 'z' (122) |11110101| [8] f5 [8] '{' (123) |11111111|11111110|1 [17] 1fffd [17] '|' (124) |11111111|101 [11] 7fd [11] '}' (125) |11111111|11111111|0 [17] 1fffe [17] '~' (126) |11111111|1101 [12] ffd [12] (127) |11111111|11111111|11111011|011 [27] 7ffffdb [27] (128) |11111111|11111111|11111011|100 [27] 7ffffdc [27] (129) |11111111|11111111|11111011|101 [27] 7ffffdd [27] (130) |11111111|11111111|11111011|110 [27] 7ffffde [27] (131) |11111111|11111111|11111011|111 [27] 7ffffdf [27] (132) |11111111|11111111|11111100|000 [27] 7ffffe0 [27] (133) |11111111|11111111|11111100|001 [27] 7ffffe1 [27] (134) |11111111|11111111|11111100|010 [27] 7ffffe2 [27] (135) |11111111|11111111|11111100|011 [27] 7ffffe3 [27] (136) |11111111|11111111|11111100|100 [27] 7ffffe4 [27] (137) |11111111|11111111|11111100|101 [27] 7ffffe5 [27] (138) |11111111|11111111|11111100|110 [27] 7ffffe6 [27] (139) |11111111|11111111|11111100|111 [27] 7ffffe7 [27] (140) |11111111|11111111|11111101|000 [27] 7ffffe8 [27] (141) |11111111|11111111|11111101|001 [27] 7ffffe9 [27] (142) |11111111|11111111|11111101|010 [27] 7ffffea [27] (143) |11111111|11111111|11111101|011 [27] 7ffffeb [27] (144) |11111111|11111111|11111101|100 [27] 7ffffec [27] (145) |11111111|11111111|11111101|101 [27] 7ffffed [27] (146) |11111111|11111111|11111101|110 [27] 7ffffee [27] (147) |11111111|11111111|11111101|111 [27] 7ffffef [27] (148) |11111111|11111111|11111110|000 [27] 7fffff0 [27] (149) |11111111|11111111|11111110|001 [27] 7fffff1 [27] (150) |11111111|11111111|11111110|010 [27] 7fffff2 [27] (151) |11111111|11111111|11111110|011 [27] 7fffff3 [27] (152) |11111111|11111111|11111110|100 [27] 7fffff4 [27] (153) |11111111|11111111|11111110|101 [27] 7fffff5 [27] (154) |11111111|11111111|11111110|110 [27] 7fffff6 [27] (155) |11111111|11111111|11111110|111 [27] 7fffff7 [27] (156) |11111111|11111111|11111111|000 [27] 7fffff8 [27] (157) |11111111|11111111|11111111|001 [27] 7fffff9 [27] (158) |11111111|11111111|11111111|010 [27] 7fffffa [27] (159) |11111111|11111111|11111111|011 [27] 7fffffb [27] (160) |11111111|11111111|11111111|100 [27] 7fffffc [27] (161) |11111111|11111111|11111111|101 [27] 7fffffd [27] (162) |11111111|11111111|11111111|110 [27] 7fffffe [27] (163) |11111111|11111111|11111111|111 [27] 7ffffff [27] (164) |11111111|11111111|11100000|00 [26] 3ffff80 [26] (165) |11111111|11111111|11100000|01 [26] 3ffff81 [26] (166) |11111111|11111111|11100000|10 [26] 3ffff82 [26] (167) |11111111|11111111|11100000|11 [26] 3ffff83 [26] (168) |11111111|11111111|11100001|00 [26] 3ffff84 [26] (169) |11111111|11111111|11100001|01 [26] 3ffff85 [26] (170) |11111111|11111111|11100001|10 [26] 3ffff86 [26] (171) |11111111|11111111|11100001|11 [26] 3ffff87 [26] (172) |11111111|11111111|11100010|00 [26] 3ffff88 [26] (173) |11111111|11111111|11100010|01 [26] 3ffff89 [26] (174) |11111111|11111111|11100010|10 [26] 3ffff8a [26] (175) |11111111|11111111|11100010|11 [26] 3ffff8b [26] (176) |11111111|11111111|11100011|00 [26] 3ffff8c [26] (177) |11111111|11111111|11100011|01 [26] 3ffff8d [26] (178) |11111111|11111111|11100011|10 [26] 3ffff8e [26] (179) |11111111|11111111|11100011|11 [26] 3ffff8f [26] (180) |11111111|11111111|11100100|00 [26] 3ffff90 [26] (181) |11111111|11111111|11100100|01 [26] 3ffff91 [26] (182) |11111111|11111111|11100100|10 [26] 3ffff92 [26] (183) |11111111|11111111|11100100|11 [26] 3ffff93 [26] (184) |11111111|11111111|11100101|00 [26] 3ffff94 [26] (185) |11111111|11111111|11100101|01 [26] 3ffff95 [26] (186) |11111111|11111111|11100101|10 [26] 3ffff96 [26] (187) |11111111|11111111|11100101|11 [26] 3ffff97 [26] (188) |11111111|11111111|11100110|00 [26] 3ffff98 [26] (189) |11111111|11111111|11100110|01 [26] 3ffff99 [26] (190) |11111111|11111111|11100110|10 [26] 3ffff9a [26] (191) |11111111|11111111|11100110|11 [26] 3ffff9b [26] (192) |11111111|11111111|11100111|00 [26] 3ffff9c [26] (193) |11111111|11111111|11100111|01 [26] 3ffff9d [26] (194) |11111111|11111111|11100111|10 [26] 3ffff9e [26] (195) |11111111|11111111|11100111|11 [26] 3ffff9f [26] (196) |11111111|11111111|11101000|00 [26] 3ffffa0 [26] (197) |11111111|11111111|11101000|01 [26] 3ffffa1 [26] (198) |11111111|11111111|11101000|10 [26] 3ffffa2 [26] (199) |11111111|11111111|11101000|11 [26] 3ffffa3 [26] (200) |11111111|11111111|11101001|00 [26] 3ffffa4 [26] (201) |11111111|11111111|11101001|01 [26] 3ffffa5 [26] (202) |11111111|11111111|11101001|10 [26] 3ffffa6 [26] (203) |11111111|11111111|11101001|11 [26] 3ffffa7 [26] (204) |11111111|11111111|11101010|00 [26] 3ffffa8 [26] (205) |11111111|11111111|11101010|01 [26] 3ffffa9 [26] (206) |11111111|11111111|11101010|10 [26] 3ffffaa [26] (207) |11111111|11111111|11101010|11 [26] 3ffffab [26] (208) |11111111|11111111|11101011|00 [26] 3ffffac [26] (209) |11111111|11111111|11101011|01 [26] 3ffffad [26] (210) |11111111|11111111|11101011|10 [26] 3ffffae [26] (211) |11111111|11111111|11101011|11 [26] 3ffffaf [26] (212) |11111111|11111111|11101100|00 [26] 3ffffb0 [26] (213) |11111111|11111111|11101100|01 [26] 3ffffb1 [26] (214) |11111111|11111111|11101100|10 [26] 3ffffb2 [26] (215) |11111111|11111111|11101100|11 [26] 3ffffb3 [26] (216) |11111111|11111111|11101101|00 [26] 3ffffb4 [26] (217) |11111111|11111111|11101101|01 [26] 3ffffb5 [26] (218) |11111111|11111111|11101101|10 [26] 3ffffb6 [26] (219) |11111111|11111111|11101101|11 [26] 3ffffb7 [26] (220) |11111111|11111111|11101110|00 [26] 3ffffb8 [26] (221) |11111111|11111111|11101110|01 [26] 3ffffb9 [26] (222) |11111111|11111111|11101110|10 [26] 3ffffba [26] (223) |11111111|11111111|11101110|11 [26] 3ffffbb [26] (224) |11111111|11111111|11101111|00 [26] 3ffffbc [26] (225) |11111111|11111111|11101111|01 [26] 3ffffbd [26] (226) |11111111|11111111|11101111|10 [26] 3ffffbe [26] (227) |11111111|11111111|11101111|11 [26] 3ffffbf [26] (228) |11111111|11111111|11110000|00 [26] 3ffffc0 [26] (229) |11111111|11111111|11110000|01 [26] 3ffffc1 [26] (230) |11111111|11111111|11110000|10 [26] 3ffffc2 [26] (231) |11111111|11111111|11110000|11 [26] 3ffffc3 [26] (232) |11111111|11111111|11110001|00 [26] 3ffffc4 [26] (233) |11111111|11111111|11110001|01 [26] 3ffffc5 [26] (234) |11111111|11111111|11110001|10 [26] 3ffffc6 [26] (235) |11111111|11111111|11110001|11 [26] 3ffffc7 [26] (236) |11111111|11111111|11110010|00 [26] 3ffffc8 [26] (237) |11111111|11111111|11110010|01 [26] 3ffffc9 [26] (238) |11111111|11111111|11110010|10 [26] 3ffffca [26] (239) |11111111|11111111|11110010|11 [26] 3ffffcb [26] (240) |11111111|11111111|11110011|00 [26] 3ffffcc [26] (241) |11111111|11111111|11110011|01 [26] 3ffffcd [26] (242) |11111111|11111111|11110011|10 [26] 3ffffce [26] (243) |11111111|11111111|11110011|11 [26] 3ffffcf [26] (244) |11111111|11111111|11110100|00 [26] 3ffffd0 [26] (245) |11111111|11111111|11110100|01 [26] 3ffffd1 [26] (246) |11111111|11111111|11110100|10 [26] 3ffffd2 [26] (247) |11111111|11111111|11110100|11 [26] 3ffffd3 [26] (248) |11111111|11111111|11110101|00 [26] 3ffffd4 [26] (249) |11111111|11111111|11110101|01 [26] 3ffffd5 [26] (250) |11111111|11111111|11110101|10 [26] 3ffffd6 [26] (251) |11111111|11111111|11110101|11 [26] 3ffffd7 [26] (252) |11111111|11111111|11110110|00 [26] 3ffffd8 [26] (253) |11111111|11111111|11110110|01 [26] 3ffffd9 [26] (254) |11111111|11111111|11110110|10 [26] 3ffffda [26] (255) |11111111|11111111|11110110|11 [26] 3ffffdb [26] EOS (256) |11111111|11111111|11110111|00 [26] 3ffffdc [26] Appendix D. Huffman Codes for Responses The following Huffman codes are used when encoding string literals in the server to client direction. These codes apply for both responses to client requests and for push-promises. [[anchor11: This tableis out of date and needs updating. In particular, EOS needsmay need to beat least 7-bits long and currently is not.]]regenerated.]] aligned aligned to len to len MSB in LSB in sym as bits bits as hex bits ( 0) |11111111|11111111|11011110|0 [25] 1ffffbc [25] ( 1) |11111111|11111111|11011110|1 [25] 1ffffbd [25] ( 2) |11111111|11111111|11011111|0 [25] 1ffffbe [25] ( 3) |11111111|11111111|11011111|1 [25] 1ffffbf [25] ( 4) |11111111|11111111|11100000|0 [25] 1ffffc0 [25] ( 5) |11111111|11111111|11100000|1 [25] 1ffffc1 [25] ( 6) |11111111|11111111|11100001|0 [25] 1ffffc2 [25] ( 7) |11111111|11111111|11100001|1 [25] 1ffffc3 [25] ( 8) |11111111|11111111|11100010|0 [25] 1ffffc4 [25] ( 9) |11111111|11111111|11100010|1 [25] 1ffffc5 [25] ( 10) |11111111|11111111|11100011|0 [25] 1ffffc6 [25] ( 11) |11111111|11111111|11100011|1 [25] 1ffffc7 [25] ( 12) |11111111|11111111|11100100|0 [25] 1ffffc8 [25] ( 13) |11111111|11111111|11100100|1 [25] 1ffffc9 [25] ( 14) |11111111|11111111|11100101|0 [25] 1ffffca [25] ( 15) |11111111|11111111|11100101|1 [25] 1ffffcb [25] ( 16) |11111111|11111111|11100110|0 [25] 1ffffcc [25] ( 17) |11111111|11111111|11100110|1 [25] 1ffffcd [25] ( 18) |11111111|11111111|11100111|0 [25] 1ffffce [25] ( 19) |11111111|11111111|11100111|1 [25] 1ffffcf [25] ( 20) |11111111|11111111|11101000|0 [25] 1ffffd0 [25] ( 21) |11111111|11111111|11101000|1 [25] 1ffffd1 [25] ( 22) |11111111|11111111|11101001|0 [25] 1ffffd2 [25] ( 23) |11111111|11111111|11101001|1 [25] 1ffffd3 [25] ( 24) |11111111|11111111|11101010|0 [25] 1ffffd4 [25] ( 25) |11111111|11111111|11101010|1 [25] 1ffffd5 [25] ( 26) |11111111|11111111|11101011|0 [25] 1ffffd6 [25] ( 27) |11111111|11111111|11101011|1 [25] 1ffffd7 [25] ( 28) |11111111|11111111|11101100|0 [25] 1ffffd8 [25] ( 29) |11111111|11111111|11101100|1 [25] 1ffffd9 [25] ( 30) |11111111|11111111|11101101|0 [25] 1ffffda [25] ( 31) |11111111|11111111|11101101|1 [25] 1ffffdb [25] ' ' ( 32) |0000 [4] 0 [4] '!' ( 33) |11111111|1010 [12] ffa [12] '"' ( 34) |1101010 [7] 6a [7] '#' ( 35) |11111111|11010 [13] 1ffa [13] '$' ( 36) |11111111|111100 [14] 3ffc [14] '%' ( 37) |11110110|0 [9] 1ec [9] '&' ( 38) |11111110|00 [10] 3f8 [10] ''' ( 39) |11111111|11011 [13] 1ffb [13] '(' ( 40) |11110110|1 [9] 1ed [9] ')' ( 41) |11110111|0 [9] 1ee [9] '*' ( 42) |11111111|1011 [12] ffb [12] '+' ( 43) |11111111|010 [11] 7fa [11] ',' ( 44) |100010 [6] 22 [6] '-' ( 45) |100011 [6] 23 [6] '.' ( 46) |100100 [6] 24 [6] '/' ( 47) |1101011 [7] 6b [7] '0' ( 48) |0001 [4] 1 [4] '1' ( 49) |0010 [4] 2 [4] '2' ( 50) |0011 [4] 3 [4] '3' ( 51) |01000 [5] 8 [5] '4' ( 52) |01001 [5] 9 [5] '5' ( 53) |01010 [5] a [5] '6' ( 54) |100101 [6] 25 [6] '7' ( 55) |100110 [6] 26 [6] '8' ( 56) |01011 [5] b [5] '9' ( 57) |01100 [5] c [5] ':' ( 58) |01101 [5] d [5] ';' ( 59) |11110111|1 [9] 1ef [9] '<' ( 60) |11111111|11111010| [16] fffa [16] '=' ( 61) |1101100 [7] 6c [7] '>' ( 62) |11111111|11100 [13] 1ffc [13] '?' ( 63) |11111111|1100 [12] ffc [12] '@' ( 64) |11111111|11111011| [16] fffb [16] 'A' ( 65) |1101101 [7] 6d [7] 'B' ( 66) |11101010| [8] ea [8] 'C' ( 67) |11101011| [8] eb [8] 'D' ( 68) |11101100| [8] ec [8] 'E' ( 69) |11101101| [8] ed [8] 'F' ( 70) |11101110| [8] ee [8] 'G' ( 71) |100111 [6] 27 [6] 'H' ( 72) |11111000|0 [9] 1f0 [9] 'I' ( 73) |11101111| [8] ef [8] 'J' ( 74) |11110000| [8] f0 [8] 'K' ( 75) |11111110|01 [10] 3f9 [10] 'L' ( 76) |11111000|1 [9] 1f1 [9] 'M' ( 77) |101000 [6] 28 [6] 'N' ( 78) |11110001| [8] f1 [8] 'O' ( 79) |11110010| [8] f2 [8] 'P' ( 80) |11111001|0 [9] 1f2 [9] 'Q' ( 81) |11111110|10 [10] 3fa [10] 'R' ( 82) |11111001|1 [9] 1f3 [9] 'S' ( 83) |101001 [6] 29 [6] 'T' ( 84) |01110 [5] e [5] 'U' ( 85) |11111010|0 [9] 1f4 [9] 'V' ( 86) |11111010|1 [9] 1f5 [9] 'W' ( 87) |11110011| [8] f3 [8] 'X' ( 88) |11111110|11 [10] 3fb [10] 'Y' ( 89) |11111011|0 [9] 1f6 [9] 'Z' ( 90) |11111111|00 [10] 3fc [10] '[' ( 91) |11111111|011 [11] 7fb [11] '\' ( 92) |11111111|11101 [13] 1ffd [13] ']' ( 93) |11111111|100 [11] 7fc [11] '^' ( 94) |11111111|1111100 [15] 7ffc [15] '_' ( 95) |11111011|1 [9] 1f7 [9] '`' ( 96) |11111111|11111111|0 [17] 1fffe [17] 'a' ( 97) |01111 [5] f [5] 'b' ( 98) |1101110 [7] 6e [7] 'c' ( 99) |101010 [6] 2a [6] 'd' (100) |101011 [6] 2b [6] 'e' (101) |10000 [5] 10 [5] 'f' (102) |1101111 [7] 6f [7] 'g' (103) |1110000 [7] 70 [7] 'h' (104) |1110001 [7] 71 [7] 'i' (105) |101100 [6] 2c [6] 'j' (106) |11111100|0 [9] 1f8 [9] 'k' (107) |11111100|1 [9] 1f9 [9] 'l' (108) |1110010 [7] 72 [7] 'm' (109) |101101 [6] 2d [6] 'n' (110) |101110 [6] 2e [6] 'o' (111) |101111 [6] 2f [6] 'p' (112) |110000 [6] 30 [6] 'q' (113) |11111101|0 [9] 1fa [9] 'r' (114) |110001 [6] 31 [6] 's' (115) |110010 [6] 32 [6] 't' (116) |110011 [6] 33 [6] 'u' (117) |110100 [6] 34 [6] 'v' (118) |1110011 [7] 73 [7] 'w' (119) |11110100| [8] f4 [8] 'x' (120) |1110100 [7] 74 [7] 'y' (121) |11110101| [8] f5 [8] 'z' (122) |11111101|1 [9] 1fb [9] '{' (123) |11111111|11111100| [16] fffc [16] '|' (124) |11111111|111101 [14] 3ffd [14] '}' (125) |11111111|11111101| [16] fffd [16] '~' (126) |11111111|11111110| [16] fffe [16] (127) |11111111|11111111|11101110|0 [25] 1ffffdc [25] (128) |11111111|11111111|11101110|1 [25] 1ffffdd [25] (129) |11111111|11111111|11101111|0 [25] 1ffffde [25] (130) |11111111|11111111|11101111|1 [25] 1ffffdf [25] (131) |11111111|11111111|11110000|0 [25] 1ffffe0 [25] (132) |11111111|11111111|11110000|1 [25] 1ffffe1 [25] (133) |11111111|11111111|11110001|0 [25] 1ffffe2 [25] (134) |11111111|11111111|11110001|1 [25] 1ffffe3 [25] (135) |11111111|11111111|11110010|0 [25] 1ffffe4 [25] (136) |11111111|11111111|11110010|1 [25] 1ffffe5 [25] (137) |11111111|11111111|11110011|0 [25] 1ffffe6 [25] (138) |11111111|11111111|11110011|1 [25] 1ffffe7 [25] (139) |11111111|11111111|11110100|0 [25] 1ffffe8 [25] (140) |11111111|11111111|11110100|1 [25] 1ffffe9 [25] (141) |11111111|11111111|11110101|0 [25] 1ffffea [25] (142) |11111111|11111111|11110101|1 [25] 1ffffeb [25] (143) |11111111|11111111|11110110|0 [25] 1ffffec [25] (144) |11111111|11111111|11110110|1 [25] 1ffffed [25] (145) |11111111|11111111|11110111|0 [25] 1ffffee [25] (146) |11111111|11111111|11110111|1 [25] 1ffffef [25] (147) |11111111|11111111|11111000|0 [25] 1fffff0 [25] (148) |11111111|11111111|11111000|1 [25] 1fffff1 [25] (149) |11111111|11111111|11111001|0 [25] 1fffff2 [25] (150) |11111111|11111111|11111001|1 [25] 1fffff3 [25] (151) |11111111|11111111|11111010|0 [25] 1fffff4 [25] (152) |11111111|11111111|11111010|1 [25] 1fffff5 [25] (153) |11111111|11111111|11111011|0 [25] 1fffff6 [25] (154) |11111111|11111111|11111011|1 [25] 1fffff7 [25] (155) |11111111|11111111|11111100|0 [25] 1fffff8 [25] (156) |11111111|11111111|11111100|1 [25] 1fffff9 [25] (157) |11111111|11111111|11111101|0 [25] 1fffffa [25] (158) |11111111|11111111|11111101|1 [25] 1fffffb [25] (159) |11111111|11111111|11111110|0 [25] 1fffffc [25] (160) |11111111|11111111|11111110|1 [25] 1fffffd [25] (161) |11111111|11111111|11111111|0 [25] 1fffffe [25] (162) |11111111|11111111|11111111|1 [25] 1ffffff [25] (163) |11111111|11111111|10000000| [24] ffff80 [24] (164) |11111111|11111111|10000001| [24] ffff81 [24] (165) |11111111|11111111|10000010| [24] ffff82 [24] (166) |11111111|11111111|10000011| [24] ffff83 [24] (167) |11111111|11111111|10000100| [24] ffff84 [24] (168) |11111111|11111111|10000101| [24] ffff85 [24] (169) |11111111|11111111|10000110| [24] ffff86 [24] (170) |11111111|11111111|10000111| [24] ffff87 [24] (171) |11111111|11111111|10001000| [24] ffff88 [24] (172) |11111111|11111111|10001001| [24] ffff89 [24] (173) |11111111|11111111|10001010| [24] ffff8a [24] (174) |11111111|11111111|10001011| [24] ffff8b [24] (175) |11111111|11111111|10001100| [24] ffff8c [24] (176) |11111111|11111111|10001101| [24] ffff8d [24] (177) |11111111|11111111|10001110| [24] ffff8e [24] (178) |11111111|11111111|10001111| [24] ffff8f [24] (179) |11111111|11111111|10010000| [24] ffff90 [24] (180) |11111111|11111111|10010001| [24] ffff91 [24] (181) |11111111|11111111|10010010| [24] ffff92 [24] (182) |11111111|11111111|10010011| [24] ffff93 [24] (183) |11111111|11111111|10010100| [24] ffff94 [24] (184) |11111111|11111111|10010101| [24] ffff95 [24] (185) |11111111|11111111|10010110| [24] ffff96 [24] (186) |11111111|11111111|10010111| [24] ffff97 [24] (187) |11111111|11111111|10011000| [24] ffff98 [24] (188) |11111111|11111111|10011001| [24] ffff99 [24] (189) |11111111|11111111|10011010| [24] ffff9a [24] (190) |11111111|11111111|10011011| [24] ffff9b [24] (191) |11111111|11111111|10011100| [24] ffff9c [24] (192) |11111111|11111111|10011101| [24] ffff9d [24] (193) |11111111|11111111|10011110| [24] ffff9e [24] (194) |11111111|11111111|10011111| [24] ffff9f [24] (195) |11111111|11111111|10100000| [24] ffffa0 [24] (196) |11111111|11111111|10100001| [24] ffffa1 [24] (197) |11111111|11111111|10100010| [24] ffffa2 [24] (198) |11111111|11111111|10100011| [24] ffffa3 [24] (199) |11111111|11111111|10100100| [24] ffffa4 [24] (200) |11111111|11111111|10100101| [24] ffffa5 [24] (201) |11111111|11111111|10100110| [24] ffffa6 [24] (202) |11111111|11111111|10100111| [24] ffffa7 [24] (203) |11111111|11111111|10101000| [24] ffffa8 [24] (204) |11111111|11111111|10101001| [24] ffffa9 [24] (205) |11111111|11111111|10101010| [24] ffffaa [24] (206) |11111111|11111111|10101011| [24] ffffab [24] (207) |11111111|11111111|10101100| [24] ffffac [24] (208) |11111111|11111111|10101101| [24] ffffad [24] (209) |11111111|11111111|10101110| [24] ffffae [24] (210) |11111111|11111111|10101111| [24] ffffaf [24] (211) |11111111|11111111|10110000| [24] ffffb0 [24] (212) |11111111|11111111|10110001| [24] ffffb1 [24] (213) |11111111|11111111|10110010| [24] ffffb2 [24] (214) |11111111|11111111|10110011| [24] ffffb3 [24] (215) |11111111|11111111|10110100| [24] ffffb4 [24] (216) |11111111|11111111|10110101| [24] ffffb5 [24] (217) |11111111|11111111|10110110| [24] ffffb6 [24] (218) |11111111|11111111|10110111| [24] ffffb7 [24] (219) |11111111|11111111|10111000| [24] ffffb8 [24] (220) |11111111|11111111|10111001| [24] ffffb9 [24] (221) |11111111|11111111|10111010| [24] ffffba [24] (222) |11111111|11111111|10111011| [24] ffffbb [24] (223) |11111111|11111111|10111100| [24] ffffbc [24] (224) |11111111|11111111|10111101| [24] ffffbd [24] (225) |11111111|11111111|10111110| [24] ffffbe [24] (226) |11111111|11111111|10111111| [24] ffffbf [24] (227) |11111111|11111111|11000000| [24] ffffc0 [24] (228) |11111111|11111111|11000001| [24] ffffc1 [24] (229) |11111111|11111111|11000010| [24] ffffc2 [24] (230) |11111111|11111111|11000011| [24] ffffc3 [24] (231) |11111111|11111111|11000100| [24] ffffc4 [24] (232) |11111111|11111111|11000101| [24] ffffc5 [24] (233) |11111111|11111111|11000110| [24] ffffc6 [24] (234) |11111111|11111111|11000111| [24] ffffc7 [24] (235) |11111111|11111111|11001000| [24] ffffc8 [24] (236) |11111111|11111111|11001001| [24] ffffc9 [24] (237) |11111111|11111111|11001010| [24] ffffca [24] (238) |11111111|11111111|11001011| [24] ffffcb [24] (239) |11111111|11111111|11001100| [24] ffffcc [24] (240) |11111111|11111111|11001101| [24] ffffcd [24] (241) |11111111|11111111|11001110| [24] ffffce [24] (242) |11111111|11111111|11001111| [24] ffffcf [24] (243) |11111111|11111111|11010000| [24] ffffd0 [24] (244) |11111111|11111111|11010001| [24] ffffd1 [24] (245) |11111111|11111111|11010010| [24] ffffd2 [24] (246) |11111111|11111111|11010011| [24] ffffd3 [24] (247) |11111111|11111111|11010100| [24] ffffd4 [24] (248) |11111111|11111111|11010101| [24] ffffd5 [24] (249) |11111111|11111111|11010110| [24] ffffd6 [24] (250) |11111111|11111111|11010111| [24] ffffd7 [24] (251) |11111111|11111111|11011000| [24] ffffd8 [24] (252) |11111111|11111111|11011001| [24] ffffd9 [24] (253) |11111111|11111111|11011010| [24] ffffda [24] (254) |11111111|11111111|11011011| [24] ffffdb [24] (255) |11111111|11111111|11011100| [24] ffffdc [24] EOS (256) |11111111|11111111|11011101| [24] ffffdd [24] Appendix E. ExamplesA number of examples are worked through here, for both requests and responses, and with andA number of examples are worked through here, for both requests and responses, and with and without Huffman coding. E.1. Header Field Representation Examples This section show several independent representation examples. E.1.1. Literal Header Field with Indexing The header field representation uses a literal name and a literal value. Header set to encode: custom-key: custom-header Reference set: empty. Hex dump of encoded data: 000a 6375 7374 6f6d 2d6b 6579 0d63 7573 | ..custom-key.cus 746f 6d2d 6865 6164 6572 | tom-header Decoding process: 00 | == Literal indexed == 0a | Literal name (len = 10) 6375 7374 6f6d 2d6b 6579 | custom-key 0d | Literal value (len = 13) 6375 7374 6f6d 2d68 6561 6465 72 | custom-header | -> custom-key: custom-head\ | er Header Table (after decoding): [ 1] (s = 55) custom-key: custom-header Table size: 55 Decoded header set: custom-key: custom-header E.1.2. Literal Header Field without Indexing The header field representation uses an indexed name and a literal value. Header set to encode: :path: /sample/path Reference set: empty. Hex dump of encoded data: 440c 2f73 616d 706c 652f 7061 7468 | D./sample/path Decoding process: 44 | == Literal not indexed == | Indexed name (idx = 4) | :path 0c | Literal value (len = 12) 2f73 616d 706c 652f 7061 7468 | /sample/path | -> :path: /sample/path Header table (after decoding): empty. Decoded header set: :path: /sample/path E.1.3. Indexed Header Field The header field representation uses an indexed header field, from the static table. Upon using it, the static table entry is copied into the header table. Header set to encode: :method: GET Reference set: empty. Hex dump of encoded data: 82 | . Decoding process: 82 | == Indexed - Add == | idx = 2 | -> :method: GET Header Table (after decoding): [ 1] (s = 42) :method: GET Table size: 42 Decoded header set: :method: GET E.1.4. Indexed Header Field from Static Table The header field representation uses an indexed header field, from the static table. In this example, the SETTINGS_HEADER_TABLE_SIZE is set to 0, therefore, the entry is not copied into the header table. Header set to encode: :method: GET Reference set: empty. Hex dump of encoded data: 82 | . Decoding process: 82 | == Indexed - Add == | idx = 2 | -> :method: GET Header table (after decoding): empty. Decoded header set: :method: GET E.2. Request Examples withouthuffman coding. E.1. Request Decoding Example WithHuffman#This section shows several consecutive header sets, corresponding to HTTP requests, on the same connection. E.2.1. First request Header set tobe encodedencode: :method: GET :scheme: http :path: / :authority:www.foo.com # Hexdumpwww.example.com Reference set: empty. Hex dump of encodeddata which will be decoded 02 84 f7 77 78 ff 07 83 ce 31 77 06 81 0f 04 88data: 8287 8604 0f77 7777 2e65 7861 6d70 6c65 | .....www.example 2e63 6f6d |...wx....1w..... db 6d 89 8b 5a 44 b7 4f.com Decoding process: 82 |.m..ZD.O # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '02' name_index: encoded: "02" decoded: 2 value_data_length: encoded: "84" decoded: 4 value_data: is_huffman_encoded: 1 encoded: "f77778ff" decoded: "GET" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits:== Indexed - Add == | idx = 2discoveredFromPeekingAtByte: '07' name_index: encoded: "07" decoded:| -> :method: GET 87 | == Indexed - Add == | idx = 7value_data_length: encoded: "83" decoded: 3 value_data: is_huffman_encoded: 1 encoded: "ce3177" decoded: "http" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '06' name_index: encoded: "06" decoded:| -> :scheme: http 86 | == Indexed - Add == | idx = 6value_data_length: encoded: "81" decoded: 1 value_data: is_huffman_encoded: 1 encoded: "0f" decoded: "/" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '04' name_index: encoded: "04" decoded: 4 value_data_length: encoded: "88" decoded: 8 value_data: is_huffman_encoded: 1 encoded: "db6d898b5a44b74f" decoded: "www.foo.com" #| -> :path: / 04 | == Literal indexed == | Indexed name (idx = 4) | :authority 0f | Literal value (len = 15) 7777 772e 6578 616d 706c 652e 636f 6d | www.example.com | -> :authority: www.example\ | .com Header Table (after decoding): [ 1] (s = 57) :authority: www.example.com [ 2] (s = 38) :path: / [ 3] (s = 43) :scheme: http [ 4] (s = 42) :method: GET Table size: 180 Decoded header set: :method: GET :scheme: http :path: / :authority: www.example.com E.2.2. Second request This request takes advantage of the differential encoding of header sets. Header set to encode: :method: GET :scheme: http :path: / :authority: www.example.com cache-control: no-cache Reference set: [ 1] :authority: www.example.com [ 2] :path: / [ 3] :scheme: http [ 4] :method: GET Hex dump of encoded data: 1b08 6e6f 2d63 6163 6865 | ..no-cache Decoding process: 1b | == Literal indexed == | Indexed name (idx = 27) | cache-control 08 | Literal value (len = 8) 6e6f 2d63 6163 6865 | no-cache | -> cache-control: no-cache Header Table (after decoding): [ 1] (s = 53) cache-control: no-cache [ 2] (s = 57) :authority: www.example.com [ 3] (s = 38) :path: / [ 4] (s = 43) :scheme: http [ 5] (s = 42) :method: GET Table size: 233 Decoded headersetset: cache-control: no-cache :authority:www.foo.com :method: GETwww.example.com :path: / :scheme: http######################### #:method: GET E.2.3. Third request This request has not enough headers in common with the previous request to take advantage of the differential encoding. Therefore, the reference set is emptied before encoding the header fields. Header set tobe encodedencode: :method: GET :scheme: https :path://index.html :authority:www.bar.comwww.example.com custom-key: custom-value Reference set: [ 1] cache-control: no-cache# Hexdump[ 2] :authority: www.example.com [ 3] :path: / [ 4] :scheme: http [ 5] :method: GET Hex dump of encodeddata which will be decoded 03 84 ce 31 74 3f 02 88 db 6d 89 7a 1e 44 b7 4fdata: 8085 8c8b 8400 0a63 7573 746f 6d2d 6b65 | .......custom-ke 790c 6375 7374 6f6d 2d76 616c 7565 |...1t?...m.z.D.O 1d 86 63 65 4a 13 98 ff 83y.custom-value Decoding process: 80 | == Empty reference set == | idx = 0 85 |..ceJ..... # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '03' name_index: encoded: "03" decoded: 3 value_data_length: encoded: "84" decoded: 4 value_data: is_huffman_encoded: 1 encoded: "ce31743f" decoded: "https" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '02' name_index: encoded: "02" decoded: 2 value_data_length: encoded: "88" decoded: 8 value_data: is_huffman_encoded: 1 encoded: "db6d897a1e44b74f" decoded: "www.bar.com" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '1d' name_index: encoded: "1d" decoded: 29 value_data_length: encoded: "86" decoded: 6 value_data: is_huffman_encoded: 1 encoded: "63654a1398ff" decoded: "no-cache" INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '83' entry_index: encoded: "83" decoded: 3 INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '85' entry_index: encoded: "85" decoded:== Indexed - Add == | idx = 5# Decoded header set :authority: www.bar.com| -> :method: GET 8c | == Indexed - Add == | idx = 12 | -> :scheme: https 8b | == Indexed - Add == | idx = 11 | -> :path://index.html 84 | == Indexed - Add == | idx = 4 | -> :authority: www.example\ | .com 00 | == Literal indexed == 0a | Literal name (len = 10) 6375 7374 6f6d 2d6b 6579 | custom-key 0c | Literal value (len = 12) 6375 7374 6f6d 2d76 616c 7565 | custom-value | -> custom-key: custom-valu\ | e Header Table (after decoding): [ 1] (s = 54) custom-key: custom-value [ 2] (s = 48) :path: /index.html [ 3] (s = 44) :scheme: https [ 4] (s = 53) cache-control: no-cache######################### #[ 5] (s = 57) :authority: www.example.com [ 6] (s = 38) :path: / [ 7] (s = 43) :scheme: http [ 8] (s = 42) :method: GET Table size: 379 Decoded header set: :method: GET :scheme: https :path: /index.html :authority: www.example.com custom-key: custom-value E.3. Request Examples with Huffman This section shows the same examples as the previous section, but using Huffman encoding for the literal values. E.3.1. First request Header set tobeencode: :method: GET :scheme: http :path: / :authority: www.example.com Reference set: empty. Hex dump of encoded data: 8287 8604 8bdb 6d88 3e68 d1cb 1225 ba7f | ......m..h...%.. Decoding process: 82 | == Indexed - Add == | idx = 2 | -> :method: GET 87 | == Indexed - Add == | idx = 7 | -> :scheme:httpshttp 86 | == Indexed - Add == | idx = 6 | -> :path:/custom-path.css :authority: www.bar.com custom-key: custom-value # Hexdump of encoded data which will be decoded 05 8b/ 04eb 08 b7 49 5c 88 e6 44 c2 1f 00 88 4e|......I\..D....N b0 8b 74 97 90 fa 7f 89 4e b0== Literal indexed == | Indexed name (idx = 4) | :authority 8b74 97 9a 17 a8|..t.....N..t.... ff 82 86Literal value (len = 15) |... # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '05' name_index: encoded: "05" decoded: 5 value_data_length: encoded: "8b" decoded: 11 value_data: is_huffman_encoded: 1 encoded: "04eb08b7495c88e644c21f" decoded: "/custom-path.css" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '00' name_index: encoded: "00" decoded: 0 name_data_length: encoded: "88" decoded: 8 name_data: is_huffman_encoded: 1 encoded: "4eb08b749790fa7f" decoded: "custom-key" value_data_length: encoded: "89" decoded: 9 value_data: is_huffman_encoded: 1 encoded: "4eb08b74979a17a8ff" decoded: "custom-value" INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '82' entry_index: encoded: "82" decoded: 2 INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '86' entry_index:Huffman encoded:"86" decoded: 6 #db6d 883e 68d1 cb12 25ba 7f | .m..h...%.. | Decoded: | www.example.com | -> :authority: www.example\ | .com Header Table (after decoding): [ 1] (s = 57) :authority: www.example.com [ 2] (s = 38) :path: / [ 3] (s = 43) :scheme: http [ 4] (s = 42) :method: GET Table size: 180 Decoded headerset :authority: www.bar.comset: :method: GET:path: /custom-path.css:scheme:https custom-key: custom-value ######################### E.2. Request Decoding Example Without Huffman #http :path: / :authority: www.example.com E.3.2. Second request This request takes advantage of the differential encoding of header sets. Header set tobe encodedencode: :method: GET :scheme: http :path: / :authority:www.foo.com # Hexdumpwww.example.com cache-control: no-cache Reference set: [ 1] :authority: www.example.com [ 2] :path: / [ 3] :scheme: http [ 4] :method: GET Hex dump of encodeddata which will be decoded 02 03 47 45 54 07 04 68 74 74 70 06 01 2f 04 0bdata: 1b86 6365 4a13 98ff |..GET..http../.. 77 77 77 2e 66 6f 6f 2e 63 6f 6d..ceJ... Decoding process: 1b |www.foo.com # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '02' name_index: encoded: "02" decoded: 2 value_data_length: encoded: "03" decoded: 3 value_data: is_huffman_encoded: 0 encoded: "474554" decoded: "GET" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '07' name_index: encoded: "07" decoded: 7 value_data_length: encoded: "04" decoded: 4 value_data: is_huffman_encoded: 0 encoded: "68747470" decoded: "http" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '06' name_index: encoded: "06" decoded: 6 value_data_length: encoded: "01" decoded: 1 value_data: is_huffman_encoded: 0 encoded: "2f" decoded: "/" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '04' name_index: encoded: "04" decoded: 4 value_data_length: encoded: "0b" decoded: 11 value_data: is_huffman_encoded: 0== Literal indexed == | Indexed name (idx = 27) | cache-control 86 | Literal value (len = 8) | Huffman encoded:"7777772e666f6f2e636f6d" decoded: "www.foo.com" #6365 4a13 98ff | ceJ... | Decoded: | no-cache | -> cache-control: no-cache Header Table (after decoding): [ 1] (s = 53) cache-control: no-cache [ 2] (s = 57) :authority: www.example.com [ 3] (s = 38) :path: / [ 4] (s = 43) :scheme: http [ 5] (s = 42) :method: GET Table size: 233 Decoded headersetset: cache-control: no-cache :authority:www.foo.com :method: GETwww.example.com :path: / :scheme: http######################### #:method: GET E.3.3. Third request This request has not enough headers in common with the previous request to take advantage of the differential encoding. Therefore, the reference set is emptied before encoding the header fields. Header set tobe encodedencode: :method: GET :scheme: https :path://index.html :authority:www.bar.comwww.example.com custom-key: custom-value Reference set: [ 1] cache-control: no-cache# Hexdump[ 2] :authority: www.example.com [ 3] :path: / [ 4] :scheme: http [ 5] :method: GET Hex dump of encodeddata which will be decoded 03 05 68 74 74 70 73 02 0b 77 77 77 2e 62 61 72data: 8085 8c8b 8400 884e b08b 7497 90fa 7f89 | .......N..t..... 4eb0 8b74 979a 17a8 ff |..https..www.bar 2e 63 6f 6d 1d 08 6e 6f 2d 63 61 63 68 65 83 85N..t..... Decoding process: 80 |.com..no-cache.. # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '03' name_index: encoded: "03" decoded: 3 value_data_length: encoded: "05" decoded: 5 value_data: is_huffman_encoded: 0 encoded: "6874747073" decoded: "https" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '02' name_index: encoded: "02" decoded: 2 value_data_length: encoded: "0b" decoded: 11 value_data: is_huffman_encoded: 0 encoded: "7777772e6261722e636f6d" decoded: "www.bar.com" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '1d' name_index: encoded: "1d" decoded: 29 value_data_length: encoded: "08" decoded: 8 value_data: is_huffman_encoded:== Empty reference set == | idx = 0encoded: "6e6f2d6361636865" decoded: "no-cache" INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '83' entry_index: encoded: "83" decoded: 3 INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '85' entry_index: encoded: "85" decoded:85 | == Indexed - Add == | idx = 5# Decoded header set :authority: www.bar.com :method: GET :path: / :scheme: https cache-control: no-cache ######################### # Header set to be encoded| -> :method: GET 8c | == Indexed - Add == | idx = 12 | -> :scheme: https 8b | == Indexed - Add == | idx = 11 | -> :path:/custom-path.css/index.html 84 | == Indexed - Add == | idx = 4 | -> :authority:www.bar.com custom-key: custom-value # Hexdump of encoded data which will be decoded 05 10 2f 63 75 73 74 6f 6d 2d 70 61 74 68 2e 63www.example\ |../custom-path.c 73 73.com 000a 63 75 73 74 6f 6d 2d 6b 65 79 0c 63|ss..custom-key.c 75 73 74 6f 6d 2d 76 61 6c 75 65 82 86== Literal indexed == 88 |ustom-value.. # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '05' name_index: encoded: "05" decoded: 5 value_data_length: encoded: "10" decoded: 16 value_data: is_huffman_encoded: 0 encoded: "2f637573746f6d2d706174682e637373" decoded: "/custom-path.css" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '00' name_index: encoded: "00" decoded: 0 name_data_length: encoded: "0a" decoded: 10 name_data: is_huffman_encoded: 0 encoded: "637573746f6d2d6b6579" decoded: "custom-key" value_data_length: encoded: "0c" decoded: 12 value_data: is_huffman_encoded: 0 encoded: "637573746f6d2d76616c7565" decoded: "custom-value" INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '82' entry_index:Literal name (len = 10) | Huffman encoded:"82" decoded: 2 INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '86' entry_index:4eb0 8b74 9790 fa7f | N..t.... | Decoded: | custom-key 89 | Literal value (len = 12) | Huffman encoded:"86" decoded: 6 #4eb0 8b74 979a 17a8 ff | N..t..... | Decoded: | custom-value | -> custom-key: custom-valu\ | e Header Table (after decoding): [ 1] (s = 54) custom-key: custom-value [ 2] (s = 48) :path: /index.html [ 3] (s = 44) :scheme: https [ 4] (s = 53) cache-control: no-cache [ 5] (s = 57) :authority: www.example.com [ 6] (s = 38) :path: / [ 7] (s = 43) :scheme: http [ 8] (s = 42) :method: GET Table size: 379 Decoded headerset :authority: www.bar.comset: :method: GET:path: /custom-path.css:scheme: https :path: /index.html :authority: www.example.com custom-key: custom-value######################### E.3.E.4. ResponseDecoding Example WithExamples without Huffman#This section shows several consecutive header sets, corresponding to HTTP responses, on the same connection. SETTINGS_HEADER_TABLE_SIZE is set to the value of 256 octets, causing some evictions to occur. E.4.1. First response Header set tobe encodedencode: :status: 302 cache-control: private date: Mon, 21OCtOct 2013 20:13:21 GMT location:: https://www.bar.com # Hexdumphttps://www.example.com Reference set: empty. Hex dump of encodeddata which will be decodeddata: 0803 3330 3218 0770 7269 7661 7465 221d | ..302..private". 4d6f 6e2c 2032 3120 4f63 7420 3230 3133 | Mon, 21 Oct 2013 2032 303a 3133 3a32 3120 474d 5430 1768 | 20:13:21 GMT0.h 7474 7073 3a2f 2f77 7777 2e65 7861 6d70 | ttps://www.examp 6c65 2e63 6f6d | le.com Decoding process: 0882 40 9f 18 86 c3 1b 39 bf 38 7f 22 92 a2 fb|..@.....9.8."... a2== Literal indexed == | Indexed name (idx = 8) | :status 0320 f2 eb cc 0c 49 00 62 d2 43 4c 82 7a 1d|.. ....I.b.CL.z. 2f 91 68 71 cf 3c 32 6e bd 7e 9e 9e 92 6e 7eLiteral value (len = 3) 3330 32 |/.hq.<2n.~...n~2 55 7d bf302 |U}. # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '08' name_index: encoded: "08" decoded: 8 value_data_length: encoded: "82" decoded: 2 value_data: is_huffman_encoded: 1 encoded: "409f" decoded: "302" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '18' name_index: encoded: "18" decoded: 24 value_data_length: encoded: "86" decoded: 6 value_data: is_huffman_encoded: 1 encoded: "c31b39bf387f" decoded: "private" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '22' name_index: encoded: "22" decoded: 34 value_data_length: encoded: "92" decoded:-> :status: 302 18value_data: is_huffman_encoded: 1 encoded: "a2fba20320f2ebcc0c490062d2434c827a1d" decoded: "Mon,| == Literal indexed == | Indexed name (idx = 24) | cache-control 07 | Literal value (len = 7) 7072 6976 6174 65 | private | -> cache-control: private 22 | == Literal indexed == | Indexed name (idx = 34) | date 1d | Literal value (len = 29) 4d6f 6e2c 2032 3120 4f63 7420 3230 3133 | Mon, 21 Oct 2013 2032 303a 3133 3a32 3120 474d 54 | 20:13:21 GMT | -> date: Mon, 21 Oct 2013 \ | 20:13:21 GMT 30 | == Literal indexed == | Indexed name (idx = 48) | location 17 | Literal value (len = 23) 6874 7470 733a 2f2f 7777 772e 6578 616d | https://www.exam 706c 652e 636f 6d | ple.com | -> location: https://www.e\ | xample.com Header Table (after decoding): [ 1] (s = 63) location: https://www.example.com [ 2] (s = 65) date: Mon, 21OCtOct 2013 20:13:21GMT" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '2f' name_index: encoded: "2f" decoded: 47 value_data_length: encoded: "91" decoded: 17 value_data: is_huffman_encoded: 1 encoded: "6871cf3c326ebd7e9e9e926e7e32557dbf" decoded: ": https://www.bar.com" #GMT [ 3] (s = 52) cache-control: private [ 4] (s = 42) :status: 302 Table size: 222 Decoded headersetset: :status: 302 cache-control: private date: Mon, 21OCtOct 2013 20:13:21 GMT location:: https://www.bar.com ######################### #https://www.example.com E.4.2. Second response The (":status", "302") header field is evicted from the header table to free space to allow adding the (":status", "200") header field to be copied from the static table into the header table. Header set tobe encodedencode: :status: 200 cache-control: private date: Mon, 21OCtOct 201320:13:2220:13:21 GMT location:https://www.bar.com content-encoding: gzip set-cookie: foo=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAALASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUAXLQEU\ AXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUA\ XLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQW\ EOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEI\ UALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ1234 max-age=3600; version=1 # Hexdumphttps://www.example.com Reference set: [ 1] location: https://www.example.com [ 2] date: Mon, 21 Oct 2013 20:13:21 GMT [ 3] cache-control: private [ 4] :status: 302 Hex dump of encodeddata which will be decoded 04 82 31 1f 03 92 a2 fb a2 03 20 f2 eb cc 0c 49data: 848c |..1....... ....I 00 62 d2 43 4c c2 7a 1d 03 90 e3 9e 78 64 dd 7a | .b.CL.z.....xd.z fd 3d 3d 24 dc fc 64 aa fb 7f 20.. Decoding process: 84e1 fb b3 0f | .==$..d... ..... 3d ff ee 02 df 7d fb 36 ed db b7 6e dd bb 76 ed | =....}.6...n..v. db b7 6e dd bb 76 ed db b7 6e dd bb 76 ed db b7 | ..n..v...n..v... 6e dd bb 76 ed db b7 6e dd bb 76 ed db b7 6e dd | n..v...n..v...n. bb 76 ed db b7 6e dd bb 76 ed db b7 6e dd bb 76 | .v...n..v...n..v ed db b7 6e dd bb 7e 3b 69 ec f0 fe 7e 1f d7 f3|...n..~;i...~... d5 fe 7f 7e 5f d7 9f 6f 97 cb bf e9 b7 fb fe bc | ...~_..o........ fb 7c bb fe 9b 7f bf 8f 87 f3 f0 fe bc fc bb 7b | .|.............{ fe 9b 7e 3f d7 9f 6f 97 7f d3 6f f7 f1 fe bb 7e== Indexed - Remove == |..~?..o...o....~ 9b 7f bf 8f c7 f9 f0 db 4f 67 f5 e7 db e5 f4 efidx = 4 |........Og...... db fd f8 91 a1 3f 1d b4 f6 78 7f 3f 0f eb f9 ea-> :status: 302 8c |.....?...x.?.... ff 3f bf 2f eb cf b7 cb e5 df f4 db fd ff 5e 7d== Indexed - Add == |.?./..........^} be 5d ff 4d bf df c7 c3 f9 f8 7f 5e 7e 5d bd ffidx = 12 |.].M.......^~].. 4d bf 1f eb cf b7 cb bf e9 b7 fb f8 ff 5d bf 4d | M............].M bf df c7 e3 fc f8 6d a7 b3 fa f3 ed f2 fa 77 ed- evict: :status: 302 |......m.......w. fe fc 48 d0 9f 8e da 7b 3c 3f 9f 87 f5 fc f5 7f-> :status: 200 Header Table (after decoding): [ 1] (s = 42) :status: 200 [ 2] (s = 63) location: https://www.example.com [ 3] (s = 65) date: Mon, 21 Oct 2013 20:13:21 GMT [ 4] (s = 52) cache-control: private Table size: 222 Decoded header set: :status: 200 location: https://www.example.com date: Mon, 21 Oct 2013 20:13:21 GMT cache-control: private E.4.3. Third response Several header fields are evicted from the header table during the processing of this header set. Before evicting a header belonging to the reference set, it is emitted, by coding it twice as an Indexed Representation. The first representation removes the header field from the reference set, the second one adds it again to the reference set, also emitting it. Header set to encode: :status: 200 cache-control: private date: Mon, 21 Oct 2013 20:13:22 GMT location: https://www.example.com content-encoding: gzip set-cookie: foo=ASDJKHQKBZXOQWEOPIUAXQWEOIU; max-age=3600; version=1 Reference set: [ 1] :status: 200 [ 2] location: https://www.example.com [ 3] date: Mon, 21 Oct 2013 20:13:21 GMT [ 4] cache-control: private Hex dump of encoded data: 8384 8403 1d4d 6f6e 2c20 3231 204f 6374 |..H....{<?...... 9f df 97 f5 e7 db e5 f2 ef fa 6d fe ff af 3e df.....Mon, 21 Oct 2032 3031 3320 3230 3a31 333a 3232 2047 |..........m...>. 2e ff a6 df ef e3 e1 fc fc 3f af 3f 2e de ff a62013 20:13:22 G 4d54 1d04 677a 6970 8484 8383 3a38 666f | MT..gzip....:8fo 6f3d 4153 444a 4b48 514b 425a 584f 5157 | o=ASDJKHQKBZXOQW 454f 5049 5541 5851 5745 4f49 553b 206d | EOPIUAXQWEOIU; m 6178 2d61 6765 3d33 3630 303b 2076 6572 | ax-age=3600; ver 7369 6f6e 3d31 |.........?.?.... df 8f f5 e7 db e5 df f4 db fd fc 7f ae df a6 dfsion=1 Decoding process: 83 |................ ef e3 f1 fe 7c 36 d3 d9 fd 79 f6 f9 7d 3b f6 ff== Indexed - Remove == |....|6...y..};.. 7e 24 68 4f c7 6d 3d 9e 1f cf c3 fa fe 7a bf cfidx = 3 |~$hO.m=......z.. ef cb fa f3 ed f2 f9 77 fd 36 ff 7f d7 9f 6f 97-> date: Mon, 21 Oct 2013 \ |.......w.6....o. 7f d3 6f f7 f1 f0 fe 7e 1f d7 9f 97 6f 7f d3 6f20:13:21 GMT 84 |..o....~....o..o c7 fa f3 ed f2 ef fa 6d fe fe 3f d7 6f d3 6f f7== Indexed - Remove == |.......m..?.o.o. f1 f8 ff 3e 1b 69 ec fe bc fb 7c be 9d fb 7f bfidx = 4 |...>.i....|..... 12 34 27 fc ff 3f cf f3 fc ff 3f cf f3 fc ff 3f-> cache-control: private 84 |.4'..?....?....? cf f3 fc ff 3f cf f3 fc ff 3f cf f3 fc ff 3f cf== Indexed - Add == |....?....?....?. f3 fc ff 3f cf f3 fc ff 3f cf f3 fc ff 3f cf f3idx = 4 |...?....?....?.. fc ff 3f cf f3 fc ff 3f cf f3 fc ff 3f cf f3 fc-> cache-control: private 03 |..?....?....?... ff 3f cf f3 fc ff 3f cf f3 fc ff 3f cf f3 fc ff== Literal indexed == |.?....?....?.... 3f cf f3 fc ff 3f cf f3 fc ff 3f cf f0 8d 09 0b | ?....?....?..... 5f d2 37 f0 86 c4 4a 23 ef 0e 70 c7 2b 2f bb 61Indexed name (idx = 3) |_.7...J#..p.+/.a 7f 85 86 88date 1d | Literal value (len = 29) 4d6f 6e2c 2032 3120 4f63 7420 3230 3133 |.... # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '04' name_index: encoded: "04" decoded: 4 value_data_length: encoded: "82" decoded: 2 value_data: is_huffman_encoded: 1 encoded: "311f" decoded: "200" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '03' name_index: encoded: "03" decoded: 3 value_data_length: encoded: "92" decoded: 18 value_data: is_huffman_encoded: 1 encoded: "a2fba20320f2ebcc0c490062d2434cc27a1d" decoded: "Mon, 21 OCt 2013 20:13:22 GMT" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '03' name_index: encoded: "03" decoded: 3 value_data_length: encoded: "90" decoded: 16 value_data: is_huffman_encoded: 1 encoded: "e39e7864dd7afd3d3d24dcfc64aafb7f" decoded: "https://www.bar.com" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '20' name_index: encoded: "20" decoded: 32 value_data_length: encoded: "84" decoded: 4 value_data: is_huffman_encoded: 1 encoded: "e1fbb30f" decoded: "gzip" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '3d' name_index: encoded: "3d" decoded: 61 value_data_length: encoded: "ffee02" decoded: 493 value_data: is_huffman_encoded: 1 encoded: "df7dfb36eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76edd\ bb76eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76eddb\ b76eddbb7e3b69ecf0fe7e1fd7f3d5fe7f7e5fd79f6f97cbbfe9b7fbfebcfb7cbbfe9b7\ fbf8f87f3f0febcfcbb7bfe9b7e3fd79f6f977fd36ff7f1febb7e9b7fbf8fc7f9f0db4f\ 67f5e7dbe5f4efdbfdf891a13f1db4f6787f3f0febf9eaff3fbf2febcfb7cbe5dff4dbf\ dff5e7dbe5dff4dbfdfc7c3f9f87f5e7e5dbdff4dbf1febcfb7cbbfe9b7fbf8ff5dbf4d\ bfdfc7e3fcf86da7b3faf3edf2fa77edfefc48d09f8eda7b3c3f9f87f5fcf57f9fdf97f\ 5e7dbe5f2effa6dfeffaf3edf2effa6dfefe3e1fcfc3faf3f2edeffa6df8ff5e7dbe5df\ f4dbfdfc7faedfa6dfefe3f1fe7c36d3d9fd79f6f97d3bf6ff7e24684fc76d3d9e1fcfc\ 3fafe7abfcfefcbfaf3edf2f977fd36ff7fd79f6f977fd36ff7f1f0fe7e1fd79f976f7f\ d36fc7faf3edf2effa6dfefe3fd76fd36ff7f1f8ff3e1b69ecfebcfb7cbe9dfb7fbf123\ 427fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcf\ f3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff\ 3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff08d090b5fd237f086c44a23ef0e70c7\ 2b2fbb617f" decoded: "foo=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAAAAAAAALASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIU\ AXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQ\ WEOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOE\ IUALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJK\ HQWOEIUALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234ZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ1234max-age=3600; version=1\ " INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '85' entry_index: encoded: "85" decoded: 5 INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '86' entry_index: encoded: "86" decoded: 6 INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '88' entry_index: encoded: "88" decoded: 8 # Decoded header set :status: 200 cache-control: private content-encoding: gzip date:Mon, 21OCtOct 2013 2032 303a 3133 3a32 3220 474d 54 | 20:13:22 GMTlocation: https://www.bar.com set-cookie: foo=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAALASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUAXLQEU\ AXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUA\ XLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQW\ EOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEI\ UALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ1234 max-age=3600; version=1 ######################### # Header set to be encoded :status: 200| - evict: cache-control:privatepr\ | ivate | -> date: Mon, 21OCtOct 2013 \ | 20:13:22 GMTlocation: https://www.bar.com content-encoding: gzip set-cookie: foo=ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZLASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUAXLQEU\ AXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUA\ XLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQW\ EOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEI\ UALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA1234 max-age=3600; version=1 # Hexdump of encoded data which will be decoded 01 ff ee 02 df 7d fb 3f cf f3 fc ff 3f cf f3 fc1d |.....}.?....?... ff 3f cf f3 fc ff 3f cf f3 fc ff 3f cf f3 fc ff== Literal indexed == |.?....?....?.... 3f cf f3 fc ff 3f cf f3 fc ff 3f cf f3 fc ff 3fIndexed name (idx = 29) |?....?....?....? cf f3 fc ff 3f cf f3 fc ff 3f cf f3 fc ff 3f cfcontent-encoding 04 |....?....?....?. f3 fc ff 3f cf f3 fc ff 3f cf f3 fc ff 3f cf f3Literal value (len = 4) 677a 6970 |...?....?....?.. fc ff 3f cf f3 fc ff 3f cf f3 fc ff 3f cf f3 fcgzip |..?....?....?... ff 3e 3b 69 ec f0 fe 7e 1f d7 f3 d5 fe 7f 7e 5f- evict: date: Mon, 21 Oct\ |.>;i...~......~_ d7 9f 6f 97 cb bf e9 b7 fb fe bc fb 7c bb fe 9b2013 20:13:21 GMT |..o.........|... 7f bf 8f 87 f3 f0 fe bc fc bb 7b fe 9b 7e 3f d7-> content-encoding: gzip 84 |..........{..~?. 9f 6f 97 7f d3 6f f7 f1 fe bb 7e 9b 7f bf 8f c7== Indexed - Remove == |.o...o....~..... f9 f0 db 4f 67 f5 e7 db e5 f4 ef db fd f8 91 a1idx = 4 |...Og........... 3f 1d b4 f6 78 7f 3f 0f eb f9 ea ff 3f bf 2f eb-> location: https://www.e\ |?...x.?.....?./. cf b7 cb e5 df f4 db fd ff 5e 7d be 5d ff 4d bfxample.com 84 |.........^}.].M. df c7 c3 f9 f8 7f 5e 7e 5d bd ff 4d bf 1f eb cf== Indexed - Add == |......^~]..M.... b7 cb bf e9 b7 fb f8 ff 5d bf 4d bf df c7 e3 fcidx = 4 |........].M..... f8 6d a7 b3 fa f3 ed f2 fa 77 ed fe fc 48 d0 9f-> location: https://www.e\ |.m.......w...H.. 8e da 7b 3c 3f 9f 87 f5 fc f5 7f 9f df 97 f5 e7xample.com 83 |..{<?........... db e5 f2 ef fa 6d fe ff af 3e df 2e ff a6 df ef== Indexed - Remove == |.....m...>...... e3 e1 fc fc 3f af 3f 2e de ff a6 df 8f f5 e7 dbidx = 3 |....?.?......... e5 df f4 db fd fc 7f ae df a6 df ef e3 f1 fe 7c-> :status: 200 83 |...............| 36 d3 d9 fd 79 f6 f9 7d 3b f6 ff 7e 24 68 4f c7== Indexed - Add == |6...y..};..~$hO. 6d 3d 9e 1f cf c3 fa fe 7a bf cf ef cb fa f3 edidx = 3 |m=......z....... f2 f9 77 fd 36 ff 7f d7 9f 6f 97 7f d3 6f f7 f1-> :status: 200 3a |..w.6....o...o.. f0 fe 7e 1f d7 9f 97 6f 7f d3 6f c7 fa f3 ed f2== Literal indexed == |..~....o..o..... ef fa 6d fe fe 3f d7 6f d3 6f f7 f1 f8 ff 3e 1bIndexed name (idx = 58) |..m..?.o.o....>. 69 ec fe bc fb 7c be 9d fb 7f bf 12 34 27 6e ddset-cookie 38 |i....|......4'n. bb 76 ed db b7 6e dd bb 76 ed db b7 6e dd bb 76Literal value (len = 56) 666f 6f3d 4153 444a 4b48 514b 425a 584f | foo=ASDJKHQKBZXO 5157 454f 5049 5541 5851 5745 4f49 553b | QWEOPIUAXQWEOIU; 206d 6178 2d61 6765 3d33 3630 303b 2076 |.v...n..v...n..v ed db b7 6e dd bb 76 ed db b7 6e dd bb 76 ed dbmax-age=3600; v 6572 7369 6f6e 3d31 | ersion=1 | - evict: location: https:/\ |...n..v...n..v.. b7 6e dd bb 76 ed db b7 6e dd bb 76 ed db b7 6e/www.example.com |.n..v...n..v...n dd bb 76 ed db b7 6e dd bb 76 ed db b4 8d 09 0b | ..v...n..v...... 5f d2 37 f0 86 c4 4a 23 ef 0e 70 c7 2b 2f bb 61- evict: :status: 200 |_.7...J#..p.+/.a 7f 81-> set-cookie: foo=ASDJKHQ\ |.. # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '01' name_index: encoded: "01" decoded: 1 value_data_length: encoded: "ffee02" decoded: 493 value_data: is_huffman_encoded: 1 encoded: "df7dfb3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3f\ cff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fc\ ff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3fcff3e3b69ecf\ 0fe7e1fd7f3d5fe7f7e5fd79f6f97cbbfe9b7fbfebcfb7cbbfe9b7fbf8f87f3f0febcfc\ bb7bfe9b7e3fd79f6f977fd36ff7f1febb7e9b7fbf8fc7f9f0db4f67f5e7dbe5f4efdbf\ df891a13f1db4f6787f3f0febf9eaff3fbf2febcfb7cbe5dff4dbfdff5e7dbe5dff4dbf\ dfc7c3f9f87f5e7e5dbdff4dbf1febcfb7cbbfe9b7fbf8ff5dbf4dbfdfc7e3fcf86da7b\ 3faf3edf2fa77edfefc48d09f8eda7b3c3f9f87f5fcf57f9fdf97f5e7dbe5f2effa6dfe\ ffaf3edf2effa6dfefe3e1fcfc3faf3f2edeffa6df8ff5e7dbe5dff4dbfdfc7faedfa6d\ fefe3f1fe7c36d3d9fd79f6f97d3bf6ff7e24684fc76d3d9e1fcfc3fafe7abfcfefcbfa\ f3edf2f977fd36ff7fd79f6f977fd36ff7f1f0fe7e1fd79f976f7fd36fc7faf3edf2eff\ a6dfefe3fd76fd36ff7f1f8ff3e1b69ecfebcfb7cbe9dfb7fbf1234276eddbb76eddbb7\ 6eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76eddbb76\ eddbb76eddbb76eddbb76eddbb76eddbb76eddbb48d090b5fd237f086c44a23ef0e70c7\ 2b2fbb617f" decoded: "foo=ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZZZZZZZLASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIU\ AXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQ\ WEOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOE\ IUALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJK\ HQWOEIUALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234AAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA1234max-age=3600; version=1\ " INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '81' entry_index: encoded: "81" decoded: 1 #KBZXOQWEOPIUAXQWEOIU; ma\ | x-age=3600; version=1 Header Table (after decoding): [ 1] (s = 98) set-cookie: foo=ASDJKHQKBZXOQWEOPIUAXQWEOIU; max-age\ =3600; version=1 [ 2] (s = 52) content-encoding: gzip [ 3] (s = 65) date: Mon, 21 Oct 2013 20:13:22 GMT Table size: 215 Decoded headerset :status: 200set: cache-control: privatecontent-encoding: gzipdate: Mon, 21OCtOct 2013 20:13:22 GMT content-encoding: gzip location:https://www.bar.comhttps://www.example.com :status: 200 set-cookie:foo=ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZLASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUAXLQEU\ AXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUA\ XLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQW\ EOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEI\ UALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA1234foo=ASDJKHQKBZXOQWEOPIUAXQWEOIU; max-age=3600; version=1######################### E.4.E.5. ResponseDecoding Example WithoutExamples with Huffman This section shows the same examples as the previous section, but using Huffman#encoding for the literal values. The eviction mechanism uses the length of the decoded literal values, so the same evictions occurs as in the previous section. E.5.1. First response Header set tobe encodedencode: :status: 302 cache-control: private date: Mon, 21OCtOct 2013 20:13:21 GMT location:: https://www.bar.com # Hexdumphttps://www.example.com Reference set: empty. Hex dump of encodeddata which will be decodeddata: 0882 409f 1886 c31b 39bf 387f 2292 a2fb | ..@.....9.8."... a203 20f2 ab30 3124 018b 490d 3209 e877 | .. ..01$..I.2..w 3093 e39e 7864 dd7a fd3d 3d24 8747 db87 | 0...xd.z.==$.G.. 2849 55f6 ff | (IU.. Decoding process: 0803 33 30 32 18 07 70 72 69 76 61 74 65 22 1d|..302..private". 4d 6f 6e 2c 20 32 31 20 4f 43 74 20 32 30 31 33== Literal indexed == |Mon, 21 OCt 2013 20 32 30 3a 31 33 3a 32 31 20 47 4d 54 2f 15 3aIndexed name (idx = 8) |20:13:21 GMT/.: 20 68 74 74 70 73 3a 2f 2f 77 77 77 2e 62 61 72:status 82 |https://www.bar 2e 63 6f 6dLiteral value (len = 3) |.com # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '08' name_index: encoded: "08" decoded: 8 value_data_length: encoded: "03" decoded: 3 value_data: is_huffman_encoded: 0 encoded: "333032" decoded: "302" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '18' name_index: encoded: "18" decoded: 24 value_data_length: encoded: "07" decoded: 7 value_data: is_huffman_encoded: 0 encoded: "70726976617465" decoded: "private" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '22' name_index: encoded: "22" decoded: 34 value_data_length: encoded: "1d" decoded: 29 value_data: is_huffman_encoded: 0 encoded: "4d6f6e2c203231204f437420323031332032303a31333a3231204\ 74d54" decoded: "Mon, 21 OCt 2013 20:13:21 GMT" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '2f' name_index: encoded: "2f" decoded: 47 value_data_length: encoded: "15" decoded: 21 value_data: is_huffman_encoded: 0Huffman encoded:"3a2068747470733a2f2f7777772e6261722e636f6d" decoded: ": https://www.bar.com" # Decoded header set409f | @. | Decoded: | 302 | -> :status: 302 18 | == Literal indexed == | Indexed name (idx = 24) | cache-control 86 | Literal value (len = 7) | Huffman encoded: c31b 39bf 387f | ..9.8. | Decoded: | private | -> cache-control: privatedate:22 | == Literal indexed == | Indexed name (idx = 34) | date 92 | Literal value (len = 29) | Huffman encoded: a2fb a203 20f2 ab30 3124 018b 490d 3209 | .... ..01$..I.2. e877 | .w | Decoded: | Mon, 21OCtOct 2013 20:13:21 \ | GMTlocation: : https://www.bar.com ######################### # Header set to be encoded :status: 200 cache-control: private| -> date: Mon, 21OCtOct 201320:13:22\ | 20:13:21 GMTlocation: https://www.bar.com content-encoding: gzip set-cookie: foo=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAALASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUAXLQEU\ AXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUA\ XLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQW\ EOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEI\ UALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ1234 max-age=3600; version=1 # Hexdump of encoded data which will be decoded 04 03 32 303003 1d 4d 6f 6e 2c 20 32 31 20 4f|..200..Mon, 21 O 43 74 20 32 30 31 33 20 32 30 3a 31 33 3a 32 32== Literal indexed == |Ct 2013 20:13:22 20 47 4d 54 03 13 68 74 74 70 73 3a 2f 2f 77 77Indexed name (idx = 48) |GMT..https://ww 77 2e 62 61 72 2e 63 6f 6d 20 04 67 7a 69 70 3dlocation 93 |w.bar.com .gzip= 7f e1 02 66 6f 6f 3d 41 41 41 41 41 41 41 41 41Literal value (len = 23) |...foo=AAAAAAAAA 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41Huffman encoded: e39e 7864 dd7a fd3d 3d24 8747 db87 2849 |AAAAAAAAAAAAAAAA 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41..xd.z.==$.G..(I 55f6 ff |AAAAAAAAAAAAAAAA 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41U.. |AAAAAAAAAAAAAAAA 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 4cDecoded: |AAAAAAAAAAAAAAAL 41 53 44 4a 4b 48 51 4b 42 5a 58 4f 51 57 45 4fhttps://www.example.com |ASDJKHQKBZXOQWEO 50 49 55 41 58 51 57 45 4f 49 55 41 58 4c 4a 4b-> location: https://www.e\ | xample.com Header Table (after decoding): [ 1] (s = 63) location: https://www.example.com [ 2] (s = 65) date: Mon, 21 Oct 2013 20:13:21 GMT [ 3] (s = 52) cache-control: private [ 4] (s = 42) :status: 302 Table size: 222 Decoded header set: :status: 302 cache-control: private date: Mon, 21 Oct 2013 20:13:21 GMT location: https://www.example.com E.5.2. Second response The (":status", "302") header field is evicted from the header table to free space to allow adding the (":status", "200") header field to be copied from the static table into the header table. Header set to encode: :status: 200 cache-control: private date: Mon, 21 Oct 2013 20:13:21 GMT location: https://www.example.com Reference set: [ 1] location: https://www.example.com [ 2] date: Mon, 21 Oct 2013 20:13:21 GMT [ 3] cache-control: private [ 4] :status: 302 Hex dump of encoded data: 848c |PIUAXQWEOIUAXLJK 48 51 57 4f 45 49 55 41 4c 51 57 45 4f 49 55 41.. Decoding process: 84 |HQWOEIUALQWEOIUA 58 4c 51 45 55 41 58 4c 4c 4b 4a 41 53 44 51 57== Indexed - Remove == |XLQEUAXLLKJASDQW 45 4f 55 49 41 58 4e 31 32 33 34 4c 41 53 44 4aidx = 4 |EOUIAXN1234LASDJ 4b 48 51 4b 42 5a 58 4f 51 57 45 4f 50 49 55 41-> :status: 302 8c |KHQKBZXOQWEOPIUA 58 51 57 45 4f 49 55 41 58 4c 4a 4b 48 51 57 4f== Indexed - Add == |XQWEOIUAXLJKHQWO 45 49 55 41 4c 51 57 45 4f 49 55 41 58 4c 51 45idx = 12 |EIUALQWEOIUAXLQE 55 41 58 4c 4c 4b 4a 41 53 44 51 57 45 4f 55 49- evict: :status: 302 |UAXLLKJASDQWEOUI 41 58 4e 31 32 33 34 4c 41 53 44 4a 4b 48 51 4b-> :status: 200 Header Table (after decoding): [ 1] (s = 42) :status: 200 [ 2] (s = 63) location: https://www.example.com [ 3] (s = 65) date: Mon, 21 Oct 2013 20:13:21 GMT [ 4] (s = 52) cache-control: private Table size: 222 Decoded header set: :status: 200 location: https://www.example.com date: Mon, 21 Oct 2013 20:13:21 GMT cache-control: private E.5.3. Third response Several header fields are evicted from the header table during the processing of this header set. Before evicting a header belonging to the reference set, it is emitted, by coding it twice as an Indexed Representation. The first representation removes the header field from the reference set, the second one adds it again to the reference set, also emitting it. Header set to encode: :status: 200 cache-control: private date: Mon, 21 Oct 2013 20:13:22 GMT location: https://www.example.com content-encoding: gzip set-cookie: foo=ASDJKHQKBZXOQWEOPIUAXQWEOIU; max-age=3600; version=1 Reference set: [ 1] :status: 200 [ 2] location: https://www.example.com [ 3] date: Mon, 21 Oct 2013 20:13:21 GMT [ 4] cache-control: private Hex dump of encoded data: 8384 8403 92a2 fba2 0320 f2ab 3031 2401 | ......... ..01$. 8b49 0d33 09e8 771d 84e1 fbb3 0f84 8483 | .I.3..w......... 833a b3df 7dfb 36d3 d9e1 fcfc 3faf e7ab | .:..}.6.....?... fcfe fcbf af3e df2f 977f d36f f7fd 79f6 | ......./...o..y. f977 fd3d e16b fa46 fe10 d889 447d e1ce | .w.=.k.F....D}.. 18e5 65f7 6c2f |AXN1234LASDJKHQK 42 5a 58 4f 51 57 45 4f 50 49 55 41 58 51 57 45..e.l/ Decoding process: 83 |BZXOQWEOPIUAXQWE 4f 49 55 41 58 4c 4a 4b 48 51 57 4f 45 49 55 41== Indexed - Remove == |OIUAXLJKHQWOEIUA 4c 51 57 45 4f 49 55 41 58 4c 51 45 55 41 58 4cidx = 3 |LQWEOIUAXLQEUAXL 4c 4b 4a 41 53 44 51 57 45 4f 55 49 41 58 4e 31-> date: Mon, 21 Oct 2013 \ |LKJASDQWEOUIAXN1 32 33 34 4c 41 53 44 4a 4b 48 51 4b 42 5a 58 4f20:13:21 GMT 84 |234LASDJKHQKBZXO 51 57 45 4f 50 49 55 41 58 51 57 45 4f 49 55 41== Indexed - Remove == |QWEOPIUAXQWEOIUA 58 4c 4a 4b 48 51 57 4f 45 49 55 41 4c 51 57 45idx = 4 |XLJKHQWOEIUALQWE 4f 49 55 41 58 4c 51 45 55 41 58 4c 4c 4b 4a 41-> cache-control: private 84 |OIUAXLQEUAXLLKJA 53 44 51 57 45 4f 55 49 41 58 4e 31 32 33 34 5a== Indexed - Add == |SDQWEOUIAXN1234Z 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a | ZZZZZZZZZZZZZZZZ 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a | ZZZZZZZZZZZZZZZZ 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a | ZZZZZZZZZZZZZZZZ 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a | ZZZZZZZZZZZZZZZZ 5a 5a 5a 5a 5a 5a 5a 31 32 33 34 20 6d 61 78 2didx = 4 |ZZZZZZZ1234 max- 61 67 65 3d 33 36 30 30 3b 20 76 65 72 73 69 6f-> cache-control: private 03 |age=3600; versio 6e 3d 31 85 86 88== Literal indexed == |n=1... # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '04' name_index: encoded: "04" decoded: 4 value_data_length: encoded: "03" decoded: 3 value_data: is_huffman_encoded: 0 encoded: "323030" decoded: "200" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '03' name_index: encoded: "03" decoded: 3 value_data_length: encoded: "1d" decoded: 29 value_data: is_huffman_encoded: 0 encoded: "4d6f6e2c203231204f437420323031332032303a31333a3232204\ 74d54" decoded: "Mon, 21 OCt 2013 20:13:22 GMT" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '03' name_index: encoded: "03" decoded: 3 value_data_length: encoded: "13" decoded: 19 value_data: is_huffman_encoded: 0 encoded: "68747470733a2f2f7777772e6261722e636f6d" decoded: "https://www.bar.com" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '20' name_index: encoded: "20" decoded: 32 value_data_length: encoded: "04" decoded: 4 value_data: is_huffman_encoded: 0 encoded: "677a6970" decoded: "gzip" LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '3d' name_index: encoded: "3d" decoded: 61 value_data_length: encoded: "7fe102" decoded: 480 value_data: is_huffman_encoded: 0 encoded: "666f6f3d414141414141414141414141414141414141414141414\ 14141414141414141414141414141414141414141414141414141414141414141414141\ 41414141414141414141414141414c4153444a4b48514b425a584f5157454f504955415\ 85157454f495541584c4a4b4851574f454955414c5157454f495541584c51455541584c\ 4c4b4a4153445157454f554941584e313233344c4153444a4b48514b425a584f5157454\ f50495541585157454f495541584c4a4b4851574f454955414c5157454f495541584c51\ 455541584c4c4b4a4153445157454f554941584e313233344c4153444a4b48514b425a5\ 84f5157454f50495541585157454f495541584c4a4b4851574f454955414c5157454f49\ 5541584c51455541584c4c4b4a4153445157454f554941584e313233344c4153444a4b4\ 8514b425a584f5157454f50495541585157454f495541584c4a4b4851574f454955414c\ 5157454f495541584c51455541584c4c4b4a4153445157454f554941584e313233345a5\ a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a\ 5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a3\ 1323334206d61782d6167653d333630303b2076657273696f6e3d31" decoded: "foo=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAAAAAAAALASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIU\ AXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQ\ WEOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOE\ IUALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJK\ HQWOEIUALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234ZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ1234max-age=3600; version=1\ " INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '85' entry_index: encoded: "85" decoded: 5 INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '86' entry_index: encoded: "86" decoded: 6 INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '88' entry_index:Indexed name (idx = 3) | date 92 | Literal value (len = 29) | Huffman encoded:"88" decoded: 8 # Decoded header set :status: 200 cache-control: private content-encoding: gzip date:a2fb a203 20f2 ab30 3124 018b 490d 3309 | .... ..01$..I.3. e877 | .w | Decoded: | Mon, 21OCtOct 2013 20:13:22 \ | GMTlocation: https://www.bar.com set-cookie: foo=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAALASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUAXLQEU\ AXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUA\ XLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQW\ EOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEI\ UALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ1234 max-age=3600; version=1 ######################### # Header set to be encoded :status: 200| - evict: cache-control:privatepr\ | ivate | -> date: Mon, 21OCtOct 2013 \ | 20:13:22 GMTlocation: https://www.bar.com1d | == Literal indexed == | Indexed name (idx = 29) | content-encoding 84 | Literal value (len = 4) | Huffman encoded: e1fb b30f | .... | Decoded: | gzip | - evict: date: Mon, 21 Oct\ | 2013 20:13:21 GMT | -> content-encoding: gzipset-cookie: foo=ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZLASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUAXLQEU\ AXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUA\ XLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQW\ EOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEI\ UALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA1234 max-age=3600; version=1 # Hexdump of encoded data which will be decoded 01 7f e1 02 66 6f 6f 3d 5a 5a 5a 5a 5a 5a 5a 5a | ....foo=ZZZZZZZZ 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a | ZZZZZZZZZZZZZZZZ 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a | ZZZZZZZZZZZZZZZZ 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a | ZZZZZZZZZZZZZZZZ 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a84 |ZZZZZZZZZZZZZZZZ 4c 41 53 44 4a 4b 48 51 4b 42 5a 58 4f 51 57 45== Indexed - Remove == |LASDJKHQKBZXOQWE 4f 50 49 55 41 58 51 57 45 4f 49 55 41 58 4c 4aidx = 4 |OPIUAXQWEOIUAXLJ 4b 48 51 57 4f 45 49 55 41 4c 51 57 45 4f 49 55-> location: https://www.e\ |KHQWOEIUALQWEOIU 41 58 4c 51 45 55 41 58 4c 4c 4b 4a 41 53 44 51xample.com 84 |AXLQEUAXLLKJASDQ 57 45 4f 55 49 41 58 4e 31 32 33 34 4c 41 53 44== Indexed - Add == |WEOUIAXN1234LASD 4a 4b 48 51 4b 42 5a 58 4f 51 57 45 4f 50 49 55idx = 4 |JKHQKBZXOQWEOPIU 41 58 51 57 45 4f 49 55 41 58 4c 4a 4b 48 51 57-> location: https://www.e\ |AXQWEOIUAXLJKHQW 4f 45 49 55 41 4c 51 57 45 4f 49 55 41 58 4c 51xample.com 83 |OEIUALQWEOIUAXLQ 45 55 41 58 4c 4c 4b 4a 41 53 44 51 57 45 4f 55== Indexed - Remove == |EUAXLLKJASDQWEOU 49 41 58 4e 31 32 33 34 4c 41 53 44 4a 4b 48 51idx = 3 |IAXN1234LASDJKHQ 4b 42 5a 58 4f 51 57 45 4f 50 49 55 41 58 51 57-> :status: 200 83 | == Indexed - Add == | idx = 3 |KBZXOQWEOPIUAXQW 45 4f 49 55 41 58 4c 4a 4b 48 51 57 4f 45 49 55-> :status: 200 3a |EOIUAXLJKHQWOEIU 41 4c 51 57 45 4f 49 55 41 58 4c 51 45 55 41 58== Literal indexed == |ALQWEOIUAXLQEUAX 4c 4c 4b 4a 41 53 44 51 57 45 4f 55 49 41 58 4eIndexed name (idx = 58) |LLKJASDQWEOUIAXN 31 32 33 34 4c 41 53 44 4a 4b 48 51 4b 42 5a 58set-cookie b3 |1234LASDJKHQKBZX 4f 51 57 45 4f 50 49 55 41 58 51 57 45 4f 49 55Literal value (len = 56) |OQWEOPIUAXQWEOIU 41 58 4c 4a 4b 48 51 57 4f 45 49 55 41 4c 51 57Huffman encoded: df7d fb36 d3d9 e1fc fc3f afe7 abfc fefc | .}.6.....?...... bfaf 3edf 2f97 7fd3 6ff7 fd79 f6f9 77fd | ..../...o..y..w. 3de1 6bfa 46fe 10d8 8944 7de1 ce18 e565 |AXLJKHQWOEIUALQW 45 4f 49 55 41 58 4c 51 45 55 41 58 4c 4c 4b 4a=.k.F....D}....e f76c 2f |EOIUAXLQEUAXLLKJ 41 53 44 51 57 45 4f 55 49 41 58 4e 31 32 33 34.l/ |ASDQWEOUIAXN1234 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41Decoded: |AAAAAAAAAAAAAAAA 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41foo=ASDJKHQKBZXOQWEOPIUAXQ\ |AAAAAAAAAAAAAAAA 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41WEOIU; max-age=3600; versi\ |AAAAAAAAAAAAAAAA 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41on=1 |AAAAAAAAAAAAAAAA 41 41 41 41 41 41 41 41 31 32 33 34 20 6d 61 78- evict: location: https:/\ |AAAAAAAA1234 max 2d 61 67 65 3d 33 36 30 30 3b 20 76 65 72 73 69/www.example.com |-age=3600; versi 6f 6e 3d 31 81- evict: :status: 200 |on=1. # Decoded opcodes LITERAL_INCREMENTAL_OPCODE: opcodeLengthInBits: 2 discoveredFromPeekingAtByte: '01' name_index: encoded: "01" decoded: 1 value_data_length: encoded: "7fe102" decoded: 480 value_data: is_huffman_encoded: 0 encoded: "666f6f3d5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5\ a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a5a\ 5a5a5a5a5a5a5a5a5a5a5a5a5a5a4c4153444a4b48514b425a584f5157454f504955415\ 85157454f495541584c4a4b4851574f454955414c5157454f495541584c51455541584c\ 4c4b4a4153445157454f554941584e313233344c4153444a4b48514b425a584f5157454\ f50495541585157454f495541584c4a4b4851574f454955414c5157454f495541584c51\ 455541584c4c4b4a4153445157454f554941584e313233344c4153444a4b48514b425a5\ 84f5157454f50495541585157454f495541584c4a4b4851574f454955414c5157454f49\ 5541584c51455541584c4c4b4a4153445157454f554941584e313233344c4153444a4b4\ 8514b425a584f5157454f50495541585157454f495541584c4a4b4851574f454955414c\ 5157454f495541584c51455541584c4c4b4a4153445157454f554941584e31323334414\ 14141414141414141414141414141414141414141414141414141414141414141414141\ 41414141414141414141414141414141414141414141414141414141414141414141413\ 1323334206d61782d6167653d333630303b2076657273696f6e3d31" decoded: "foo=ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZZZZZZZLASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIU\ AXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQ\ WEOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOE\ IUALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJK\ HQWOEIUALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234AAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA1234max-age=3600; version=1\ " INDEX_OPCODE: opcodeLengthInBits: 1 discoveredFromPeekingAtByte: '81' entry_index: encoded: "81" decoded: 1 #-> set-cookie: foo=ASDJKHQ\ | KBZXOQWEOPIUAXQWEOIU; ma\ | x-age=3600; version=1 Header Table (after decoding): [ 1] (s = 98) set-cookie: foo=ASDJKHQKBZXOQWEOPIUAXQWEOIU; max-age\ =3600; version=1 [ 2] (s = 52) content-encoding: gzip [ 3] (s = 65) date: Mon, 21 Oct 2013 20:13:22 GMT Table size: 215 Decoded headerset :status: 200set: cache-control: privatecontent-encoding: gzipdate: Mon, 21OCtOct 2013 20:13:22 GMT content-encoding: gzip location:https://www.bar.comhttps://www.example.com :status: 200 set-cookie:foo=ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ\ ZZZZZZZZZZZZZZZZZLASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUAXLQEU\ AXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQWEOIUA\ XLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEIUALQW\ EOIUAXLQEUAXLLKJASDQWEOUIAXN1234LASDJKHQKBZXOQWEOPIUAXQWEOIUAXLJKHQWOEI\ UALQWEOIUAXLQEUAXLLKJASDQWEOUIAXN1234AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA1234foo=ASDJKHQKBZXOQWEOPIUAXQWEOIU; max-age=3600; version=1#########################Authors' Addresses Roberto Peon Google, Inc EMail: fenix@google.com Herve Ruellan Canon CRF EMail: herve.ruellan@crf.canon.fr