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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 RFC 5323

Network Working Group                                    J. Reschke, Ed.
Internet-Draft                                                greenbytes
Expires: April 9, 2004                                          S. Reddy
                                                                  Oracle
                                                                J. Davis
                                                     Intelligent Markets
                                                               A. Babich
                                                                 Filenet
                                                        October 10, 2003


                             WebDAV SEARCH
                     draft-reschke-webdav-search-05

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
   groups may also distribute working documents as Internet-Drafts.

   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."

   The list of current Internet-Drafts can be accessed at http://
   www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on April 9, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

   This document specifies a set of methods, headers, properties and
   content-types composing WebDAV SEARCH, an application of the HTTP/1.1
   protocol to efficiently search for DAV resources based upon a set of
   client-supplied criteria.

   Distribution of this document is unlimited. Please send comments to
   the Distributed Authoring and Versioning (WebDAV) DASL mailing list



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   at www-webdav-dasl@w3.org [1], which may be joined by sending a
   message with subject "subscribe" to www-webdav-dasl-request@w3.org
   [2]. Discussions of the WebDAV DASL mailing list are archived at URL:
   http://www.w3.org/pub/WWW/Archives/Public/www-webdav-dasl/.

Table of Contents

   1.     Introduction . . . . . . . . . . . . . . . . . . . . . . .   5
   1.1    DASL . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   1.2    Relationship to DAV  . . . . . . . . . . . . . . . . . . .   5
   1.3    Terms  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   1.4    Notational Conventions . . . . . . . . . . . . . . . . . .   7
   1.5    Editorial note on usage of 'DAV:' namespace  . . . . . . .   7
   1.6    An Overview of DASL at Work  . . . . . . . . . . . . . . .   8
   2.     The SEARCH Method  . . . . . . . . . . . . . . . . . . . .   9
   2.1    Overview . . . . . . . . . . . . . . . . . . . . . . . . .   9
   2.2    The Request  . . . . . . . . . . . . . . . . . . . . . . .   9
   2.2.1  The Request-URI  . . . . . . . . . . . . . . . . . . . . .   9
   2.2.2  The Request Body . . . . . . . . . . . . . . . . . . . . .   9
   2.3    The Successful 207 (Multistatus) Response  . . . . . . . .  10
   2.3.1  Extending the PROPFIND Response  . . . . . . . . . . . . .  10
   2.3.2  Example: A Simple Request and Response . . . . . . . . . .  10
   2.3.3  Example: Result Set Truncation . . . . . . . . . . . . . .  11
   2.4    Unsuccessful Responses . . . . . . . . . . . . . . . . . .  13
   2.4.1  Example of an Invalid Scope  . . . . . . . . . . . . . . .  13
   3.     Discovery of Supported Query Grammars  . . . . . . . . . .  14
   3.1    The OPTIONS Method . . . . . . . . . . . . . . . . . . . .  14
   3.2    The DASL Response Header . . . . . . . . . . . . . . . . .  14
   3.3    DAV:supported-query-grammar-set (protected)  . . . . . . .  15
   3.4    Example: Grammar Discovery . . . . . . . . . . . . . . . .  15
   4.     Query Schema Discovery: QSD  . . . . . . . . . . . . . . .  18
   4.1    Additional SEARCH semantics  . . . . . . . . . . . . . . .  18
   4.1.1  Example of query schema discovery  . . . . . . . . . . . .  19
   5.     The DAV:basicsearch Grammar  . . . . . . . . . . . . . . .  21
   5.1    Introduction . . . . . . . . . . . . . . . . . . . . . . .  21
   5.2    The DAV:basicsearch DTD  . . . . . . . . . . . . . . . . .  21
   5.2.1  Example Query  . . . . . . . . . . . . . . . . . . . . . .  22
   5.3    DAV:select . . . . . . . . . . . . . . . . . . . . . . . .  23
   5.4    DAV:from . . . . . . . . . . . . . . . . . . . . . . . . .  23
   5.4.1  Relationship to the Request-URI  . . . . . . . . . . . . .  24
   5.4.2  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . .  24
   5.5    DAV:where  . . . . . . . . . . . . . . . . . . . . . . . .  24
   5.5.1  Use of Three-Valued Logic in Queries . . . . . . . . . . .  24
   5.5.2  Handling Optional operators  . . . . . . . . . . . . . . .  24
   5.5.3  Treatment of NULL Values . . . . . . . . . . . . . . . . .  24
   5.5.4  Treatment of properties with mixed/element content . . . .  25
   5.5.5  Example: Testing for Equality  . . . . . . . . . . . . . .  25
   5.5.6  Example: Relative Comparisons  . . . . . . . . . . . . . .  25



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   5.6    DAV:orderby  . . . . . . . . . . . . . . . . . . . . . . .  26
   5.6.1  Comparing Natural Language Strings . . . . . . . . . . . .  26
   5.6.2  Example of Sorting . . . . . . . . . . . . . . . . . . . .  26
   5.7    Boolean Operators: DAV:and, DAV:or, and DAV:not  . . . . .  27
   5.8    DAV:eq . . . . . . . . . . . . . . . . . . . . . . . . . .  27
   5.9    DAV:lt, DAV:lte, DAV:gt, DAV:gte . . . . . . . . . . . . .  27
   5.10   DAV:literal  . . . . . . . . . . . . . . . . . . . . . . .  27
   5.11   DAV:typed-literal (optional) . . . . . . . . . . . . . . .  28
   5.11.1 Example for typed numerical comparison . . . . . . . . . .  28
   5.12   Support for matching xml:lang attributes on properties . .  29
   5.12.1 DAV:language-defined (optional)  . . . . . . . . . . . . .  29
   5.12.2 DAV:language-matches (optional)  . . . . . . . . . . . . .  29
   5.12.3 Example of language-aware matching . . . . . . . . . . . .  29
   5.13   DAV:is-collection  . . . . . . . . . . . . . . . . . . . .  30
   5.13.1 Example of DAV:is-collection . . . . . . . . . . . . . . .  30
   5.14   DAV:is-defined . . . . . . . . . . . . . . . . . . . . . .  30
   5.15   DAV:like . . . . . . . . . . . . . . . . . . . . . . . . .  30
   5.15.1 Syntax for the Literal Pattern . . . . . . . . . . . . . .  31
   5.15.2 Example of DAV:like  . . . . . . . . . . . . . . . . . . .  31
   5.16   DAV:contains . . . . . . . . . . . . . . . . . . . . . . .  31
   5.16.1 Result scoring (DAV:score element) . . . . . . . . . . . .  32
   5.16.2 Ordering by score  . . . . . . . . . . . . . . . . . . . .  32
   5.16.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . .  32
   5.17   Limiting the result set  . . . . . . . . . . . . . . . . .  33
   5.17.1 Relationship to result ordering  . . . . . . . . . . . . .  33
   5.18   The 'caseless' XML attribute . . . . . . . . . . . . . . .  33
   5.19   Query schema for DAV:basicsearch . . . . . . . . . . . . .  34
   5.19.1 DTD for DAV:basicsearch QSD  . . . . . . . . . . . . . . .  34
   5.19.2 DAV:propdesc Element . . . . . . . . . . . . . . . . . . .  34
   5.19.3 The DAV:datatype Property Description  . . . . . . . . . .  35
   5.19.4 The DAV:searchable Property Description  . . . . . . . . .  35
   5.19.5 The DAV:selectable Property Description  . . . . . . . . .  36
   5.19.6 The DAV:sortable Property Description  . . . . . . . . . .  36
   5.19.7 The DAV:caseless Property Description  . . . . . . . . . .  36
   5.19.8 The DAV:operators XML Element  . . . . . . . . . . . . . .  36
   5.19.9 Example of Query Schema for DAV:basicsearch  . . . . . . .  37
   6.     Internationalization Considerations  . . . . . . . . . . .  38
   7.     Security Considerations  . . . . . . . . . . . . . . . . .  39
   7.1    Implications of XML External Entities  . . . . . . . . . .  39
   8.     Scalability  . . . . . . . . . . . . . . . . . . . . . . .  40
   9.     Authentication . . . . . . . . . . . . . . . . . . . . . .  41
   10.    IANA Considerations  . . . . . . . . . . . . . . . . . . .  42
   11.    Contributors . . . . . . . . . . . . . . . . . . . . . . .  43
   12.    Acknowledgements . . . . . . . . . . . . . . . . . . . . .  44
          Normative References . . . . . . . . . . . . . . . . . . .  45
          Informative References . . . . . . . . . . . . . . . . . .  46
          Authors' Addresses . . . . . . . . . . . . . . . . . . . .  47
   A.     Three-Valued Logic in DAV:basicsearch  . . . . . . . . . .  48



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   B.     Change Log (to be removed by RFC Editor before
          publication) . . . . . . . . . . . . . . . . . . . . . . .  50
   B.1    From draft-davis-dasl-protocol-xxx . . . . . . . . . . . .  50
   B.2    since start of draft-reschke-webdav-search . . . . . . . .  51
   B.3    since draft-reschke-webdav-search-00 . . . . . . . . . . .  53
   B.4    since draft-reschke-webdav-search-01 . . . . . . . . . . .  53
   B.5    since draft-reschke-webdav-search-02 . . . . . . . . . . .  54
   B.6    since draft-reschke-webdav-search-03 . . . . . . . . . . .  54
   B.7    since draft-reschke-webdav-search-04 . . . . . . . . . . .  55
   C.     Resolved issues (to be removed by RFC Editor before
          publication) . . . . . . . . . . . . . . . . . . . . . . .  56
   C.1    1.3-import-condition-code-terminology  . . . . . . . . . .  56
   C.2    1.3-import-requirements-terminology  . . . . . . . . . . .  56
   C.3    1.3-import-DTD-terminology . . . . . . . . . . . . . . . .  56
   C.4    invalid-scope  . . . . . . . . . . . . . . . . . . . . . .  56
   C.5    JW24d  . . . . . . . . . . . . . . . . . . . . . . . . . .  57
   C.6    scope-vs-versions  . . . . . . . . . . . . . . . . . . . .  58
   C.7    DB2/DB7  . . . . . . . . . . . . . . . . . . . . . . . . .  58
   D.     Open issues (to be removed by RFC Editor before
          publication) . . . . . . . . . . . . . . . . . . . . . . .  61
   D.1    1.3-apply-condition-code-terminology . . . . . . . . . . .  61
   D.2    2.4-multiple-uris  . . . . . . . . . . . . . . . . . . . .  61
   D.3    result-truncation  . . . . . . . . . . . . . . . . . . . .  61
   D.4    qsd-optional . . . . . . . . . . . . . . . . . . . . . . .  62
   D.5    5.1-name-filtering . . . . . . . . . . . . . . . . . . . .  62
   D.6    5.4.2-multiple-scope . . . . . . . . . . . . . . . . . . .  63
   D.7    5.4.2-scope-vs-redirects . . . . . . . . . . . . . . . . .  63
   D.8    language-comparison  . . . . . . . . . . . . . . . . . . .  63
   D.9    JW16b/JW24a  . . . . . . . . . . . . . . . . . . . . . . .  63
   D.10   typed-literal  . . . . . . . . . . . . . . . . . . . . . .  64
          Index  . . . . . . . . . . . . . . . . . . . . . . . . . .  65
          Intellectual Property and Copyright Statements . . . . . .  67



















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1. Introduction

1.1 DASL

   This document defines WebDAV SEARCH, an application of HTTP/1.1
   forming a lightweight search protocol to transport queries and result
   sets and allows clients to make use of server-side search facilities.
   It is based on the expired draft for WebDAV DASL [DASL]. [DASLREQ]
   describes the motivation for DASL.

   DASL will minimize the complexity of clients so as to facilitate
   widespread deployment of applications capable of utilizing the DASL
   search mechanisms.

   DASL consists of:

   o  the SEARCH method,

   o  the DASL response header,

   o  the DAV:searchrequest XML element,

   o  the DAV:query-schema-discovery XML element,

   o  the DAV:basicsearch XML element and query grammar, and

   o  the DAV:basicsearchschema XML element.

   For WebDAV-compliant servers, it also defines a new live property
   DAV:supported-query-grammar-set.

1.2 Relationship to DAV

   DASL relies on the resource and property model defined by [RFC2518].
   DASL does not alter this model. Instead, DASL allows clients to
   access DAV-modeled resources through server-side search.

1.3 Terms

   This document uses the terms defined in [RFC2616], in [RFC2518], in
   [RFC3253] and in this section.

   Criteria

      An expression against which each resource in the search scope is
      evaluated.

   Query



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      A query is a combination of a search scope, search criteria,
      result record definition, sort specification, and a search
      modifier.

   Query Grammar

      A set of definitions of XML elements, attributes, and constraints
      on their relations and values that defines a set of queries and
      the intended semantics.

   Query Schema

      A listing, for any given grammar and scope, of the properties and
      operators that may be used in a query with that grammar and scope.

   Result

      A result is a result set, optionally augmented with other
      information describing the search as a whole.

   Result Record

      A description of a resource. A result record is a set of
      properties, and possibly other descriptive information.

   Result Record Definition

      A specification of the set of properties to be returned in the
      result record.

   Result Set

      A set of records, one for each resource for which the search
      criteria evaluated to True.

   Scope

      A set of resources to be searched.

   Search Modifier

      An instruction that governs the execution of the query but is not
      part of the search scope, result record definition, the search
      criteria, or the sort specification. An example of a search
      modifier is one that controls how much time the server can spend
      on the query before giving a response.

   Sort Specification



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      A specification of an ordering on the result records in the result
      set.


1.4 Notational Conventions

   The augmented BNF used by this document to describe protocol elements
   is exactly the same as the one described in Section 2.1 of [RFC2616].
   Because this augmented BNF uses the basic production rules provided
   in Section 2.2 of [RFC2616], those rules apply to this document as
   well.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT"
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   This document uses XML DTD fragments as a purely notational
   convention. WebDAV request and response bodies can not be validated
   due to the specific extensibility rules defined in section 23 of
   [RFC2518] and due to the fact that all XML elements defined by this
   specification use the XML namespace name "DAV:". In particular:

   1.  element names use the "DAV:" namespace,

   2.  element ordering is irrelevant unless explicitly stated,

   3.  extension elements (elements not already defined as valid child
       elements) may be added anywhere, except when explicitly stated
       otherwise,

   4.  extension attributes (attributes not already defined as valid for
       this element) may be added anywhere, except when explicitly
       stated otherwise.

   When an XML element type in the "DAV:" namespace is referenced in
   this document outside of the context of an XML fragment, the string
   "DAV:" will be prefixed to the element type.

   Similarily, when an XML element type in the namespace "http://
   www.w3.org/2001/XMLSchema" is referenced in this document outside of
   the context of an XML fragment, the string "xs:" will be prefixed to
   the element type.

1.5 Editorial note on usage of 'DAV:' namespace

   *Note that this draft currently defines elements and properties in
   the WebDAV namespace "DAV:" which it shouldn't do as it isn't a work
   item of the WebDAV working group. The reason for this is the desire



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   for some kind of backward compatibility to the expired DASL drafts
   and the assumption that the draft may become an official RFC
   submission of the WebDAV working group at a later point of time.*

1.6 An Overview of DASL at Work

   One can express the basic usage of DASL in the following steps:

   o  The client constructs a query using the DAV:basicsearch grammar.

   o  The client invokes the SEARCH method on a resource that will
      perform the search (the search arbiter) and includes a text/xml or
      application/xml request entity that contains the query.

   o  The search arbiter performs the query.

   o  The search arbiter sends the results of the query back to the
      client in the response. The server MUST send an entity that
      matches the [RFC2518] PROPFIND response.
































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2. The SEARCH Method

2.1 Overview

   The client invokes the SEARCH method to initiate a server-side
   search. The body of the request defines the query. The server MUST
   emit an entity matching the [RFC2518] PROPFIND response.

   The SEARCH method plays the role of transport mechanism for the query
   and the result set. It does not define the semantics of the query.
   The type of the query defines the semantics.

2.2 The Request

   The client invokes the SEARCH method on the resource named by the
   Request-URI.

2.2.1 The Request-URI

   The Request-URI identifies the search arbiter. Any HTTP resource may
   function as search arbiter. It is not a new type of resource (in the
   sense of DAV:resourcetype as defined in [RFC2518]), nor does it have
   to be a WebDAV-compliant resource.

   The SEARCH method defines no relationship between the arbiter and the
   scope of the search, rather the particular query grammar used in the
   query defines the relationship. For example, a query grammar may
   force the request-URI to correspond exactly to the search scope.

2.2.2 The Request Body

   The server MUST process a text/xml or application/xml request body,
   and MAY process request bodies in other formats. See [RFC3023] for
   guidance on packaging XML in requests.

   Marshalling:

      If a request body with content type text/xml or application/xml is
      included, it MUST be either a DAV:searchrequest or a
      DAV:query-schema-discovery XML element. It's single child element
      identifies the query grammar.

      For DAV:searchrequest, the definition of search criteria, the
      result record, and any other details needed to perform the search
      depend on the individual search grammar.

      For DAV:query-schema-discovery, the semantics is defined in
      Section 4.



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   Preconditions:

      (DAV:search-grammar-discovery-supported): when an XML request body
      is present and has a DAV:query-schema-discovery document element,
      the server MUST support the query schema discovery mechanism
      described in Section 4.

      (DAV:search-grammar-supported): when an XML request body is
      present, the search grammar identified by the document element's
      child element must be a supported search grammar.

      (DAV:search-scope-valid): the supplied search scope must be valid.
      There can be various reasons for a search scope to be invalid,
      including unsupported URI schemes and communication problems.
      Servers MAY add [RFC2518] compliant DAV:response elements as
      content to the condition element indicating the precise reason for
      the failure.


2.3 The Successful 207 (Multistatus) Response

   If the server returns 207 (Multistatus), then the search proceeded
   successfully and the response MUST match that of a PROPFIND. The
   results of this method SHOULD NOT be cached.

   There MUST be one DAV:response for each resource that matched the
   search criteria. For each such response, the DAV:href element
   contains the URI of the resource, and the response MUST include a
   DAV:propstat element.

   Note that for each matching resource found there may be multiple URIs
   within the search scope mapped to it. In this case, a server SHOULD
   report all of these URIs. Clients can use the live property
   DAV:resource-id defined in [BIND] to identify possible duplicates.

2.3.1 Extending the PROPFIND Response

   A response MAY include more information than PROPFIND defines so long
   as the extra information does not invalidate the PROPFIND response.
   Query grammars SHOULD define how the response matches the PROPFIND
   response.

2.3.2 Example: A Simple Request and Response

   This example demonstrates the request and response framework. The
   following XML document shows a simple (hypothetical) natural language
   query. The name of the query element is natural-language-query in the
   XML namespace "http://example.com/foo". The actual query is "Find the



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   locations of good Thai restaurants in Los Angeles". For this
   hypothetical query, the arbiter returns two properties for each
   selected resource.

    >> Request:

   SEARCH / HTTP/1.1
   Host: example.org
   Content-Type: application/xml
   Content-Length: xxx

   <?xml version="1.0" encoding="UTF-8"?>
   <D:searchrequest xmlns:D="DAV:" xmlns:F="http://example.com/foo">
     <F:natural-language-query>
       Find the locations of good Thai restaurants in Los Angeles
     </F:natural-language-query>
   </D:searchrequest>

    >> Response:

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="UTF-8"?>
   <D:multistatus xmlns:D="DAV:"
      xmlns:R="http://example.org/propschema">
     <D:response>
       <D:href>http://siamiam.test/</D:href>
       <D:propstat>
         <D:prop>
           <R:location>259 W. Hollywood</R:location>
           <R:rating><R:stars>4</R:stars></R:rating>
         </D:prop>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
   </D:multistatus>


2.3.3 Example: Result Set Truncation

   A server MAY limit the number of resources in a reply, for example to
   limit the amount of resources expended in processing a query. If it
   does so, the reply MUST use status code 207, return a DAV:multistatus
   response body and indicate a status of 507 (Insufficient Storage) for
   the search arbiter URI. It SHOULD include the partial results.




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   When a result set is truncated, there may be many more resources that
   satisfy the search criteria but that were not examined.

   If partial results are included and the client requested an ordered
   result set in the original request, then any partial results that are
   returned MUST be ordered as the client directed.

   Note that the partial results returned MAY be any subset of the
   result set that would have satisfied the original query.

    >> Request:

   SEARCH / HTTP/1.1
   Host: example.net
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

    ... the query goes here ...

    >> Response:

   HTTP/1.1 207 Multistatus
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8"?>
   <D:multistatus xmlns:D="DAV:">
     <D:response>
       <D:href>http://www.example.net/sounds/unbrokenchain.au</D:href>
       <D:propstat>
         <D:prop/>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
     <D:response>
       <D:href>http://tech.mit.test/archive96/photos/Lesh1.jpg</D:href>
       <D:propstat>
         <D:prop/>
         <D:status>HTTP/1.1 200 OK</D:status>
       </D:propstat>
     </D:response>
     <D:response>
       <D:href>http://example.net</D:href>
       <D:status>HTTP/1.1 507 Insufficient Storage</D:status>
       <D:responsedescription xml:lang="en">
          Only first two matching records were returned
       </D:responsedescription>
     </D:response>



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   </D:multistatus>


2.4 Unsuccessful Responses

   If a SEARCH request could not be executed or the attempt to execute
   it resulted in an error, the server MUST indicate the failure with an
   appropriate status code and SHOULD add a response body as defined in
   [RFC3253], section 1.6. Unless otherwise stated, condition elements
   are empty, however specific conditions element MAY include additional
   child elements that describe the error condition in more detail.

2.4.1 Example of an Invalid Scope

   In the example below, a request failed because the scope identifies a
   HTTP resource that was not found.

    >> Response:

   HTTP/1.1 409 Conflict
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="UTF-8"?>
   <d:error xmlns:d="DAV:">
     <d:search-scope-valid>
       <d:response>
         <d:href>http://www.example.com/X</d:href>
         <d:status>HTTP/1.1 404 Object Not Found</d:status>
       </d:response>
     </d:search-scope-valid>
   </d:error>



















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3. Discovery of Supported Query Grammars

   Servers MUST support discovery of the query grammars supported by a
   search arbiter resource.

   Clients can determine which query grammars are supported by an
   arbiter by invoking OPTIONS on the search arbiter. If the resource
   supports SEARCH, then the DASL response header will appear in the
   response. The DASL response header lists the supported grammars.

   Servers supporting the WebDAV extensions [RFC3253] and/or [ACL] MUST
   also

   o  report SEARCH in the live property DAV:supported-method-set for
      all search arbiter resources and

   o  support the live property DAV:supported-query-grammar-set as
      defined in Section 3.3.


3.1 The OPTIONS Method

   The OPTIONS method allows the client to discover if a resource
   supports the SEARCH method and to determine the list of search
   grammars supported for that resource.

   The client issues the OPTIONS method against a resource named by the
   Request-URI. This is a normal invocation of OPTIONS defined in
   [RFC2616].

   If a resource supports the SEARCH method, then the server MUST list
   SEARCH in the OPTIONS response as defined by [RFC2616].

   DASL servers MUST include the DASL header in the OPTIONS response.
   This header identifies the search grammars supported by that
   resource.

3.2 The DASL Response Header

   DASLHeader = "DASL" ":" Coded-URL-List
   Coded-URL-List : Coded-URL [ "," Coded-URL-List ]
   Coded-URL ; defined in section 9.4 of [RFC2518]

   The DASL response header indicates server support for a query grammar
   in the OPTIONS method. The value is a URI that indicates the type of
   grammar. Note that although the URI can be used to identify each
   supported search grammar, there is not necessarily a direct
   relationship between the URI and the XML element name that can be



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   used in XML based SEARCH requests (the element name itself is
   identified by it's namespace name (a URI reference) and the element's
   local name).

   This header MAY be repeated.

    For example:

   DASL: <http://foobar.test/syntax1>
   DASL: <http://akuma.test/syntax2>
   DASL: <DAV:basicsearch>
   DASL: <http://example.com/foo/natural-language-query>


3.3 DAV:supported-query-grammar-set (protected)

   This WebDAV property is required for any server supporting either
   [RFC3253] and/or [ACL] and identifies the XML based query grammars
   that are supported by the search arbiter resource.

   <!ELEMENT supported-query-grammar-set (supported-query-grammar*)>
   <!ELEMENT supported-query-grammar grammar>
   <!ELEMENT grammar ANY>

   ANY value: a query grammar element type

3.4 Example: Grammar Discovery

   This example shows that the server supports search on the /somefolder
   resource with the query grammars: DAV:basicsearch, http://
   foobar.test/syntax1 and http://akuma.test/syntax2. Note that every
   server MUST support DAV:basicsearch.

    >> Request:

   OPTIONS /somefolder HTTP/1.1
   Host: example.org

    >> Response:

   HTTP/1.1 200 OK
   Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
   Allow: MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, SEARCH
   DASL: <DAV:basicsearch>
   DASL: <http://foobar.test/syntax1>
   DASL: <http://akuma.test/syntax2>

   This example shows the equivalent taking advantage of a server's



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   support for DAV:supported-method-set and
   DAV:supported-query-grammar-set.

    >> Request:

   PROPFIND /somefolder HTTP/1.1
   Host: example.org
   Depth: 0
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="UTF-8" ?>
   <propfind xmlns="DAV:">
     <prop>
       <supported-query-grammar-set/>
       <supported-method-set/>
     </prop>
   </propfind>

    >> Response:

   HTTP/1.1 207 Multi-Status
   Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx

   <?xml version="1.0" encoding="utf-8" ?>
   <multistatus xmlns="DAV:">
    <response>
     <href>http://example.org/somefolder</href>
     <propstat>
      <prop>
       <supported-query-grammar-set>
        <supported-query-grammar>
         <grammar><basicsearch/></grammar>
        </supported-query-grammar>
        <supported-query-grammar>
         <grammar><syntax1 xmlns="http://foobar.test" /></grammar>
        </supported-query-grammar>
        <supported-query-grammar>
         <grammar><syntax2 xmlns="http://akuma.test/"/></grammar>
        </supported-query-grammar>
       </supported-query-grammar-set>
       <supported-method-set>
        <supported-method name="COPY" />
        <supported-method name="DELETE" />
        <supported-method name="GET" />
        <supported-method name="HEAD" />
        <supported-method name="LOCK" />



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        <supported-method name="MKCOL" />
        <supported-method name="MOVE" />
        <supported-method name="OPTIONS" />
        <supported-method name="POST" />
        <supported-method name="PROPFIND" />
        <supported-method name="PROPPATCH" />
        <supported-method name="PUT" />
        <supported-method name="SEARCH" />
        <supported-method name="TRACE" />
        <supported-method name="UNLOCK" />
       </supported-method-set>
      </prop>
      <status>HTTP/1.1 200 OK</status>
     </propstat>
    </response>
   </multistatus>

   Note that the query grammar element names marshalled as part of the
   DAV:supported-query-grammar-set can be directly used as element names
   in an XML based query.































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4. Query Schema Discovery: QSD

   Servers MAY support the discovery of the schema for a query grammar.

   The DASL response header and the DAV:supported-query-grammar-set
   property provide means for clients to discover the set of query
   grammars supported by a resource. This alone is not sufficient
   information for a client to generate a query. For example, the
   DAV:basicsearch grammar defines a set of queries consisting of a set
   of operators applied to a set of properties and values, but the
   grammar itself does not specify which properties may be used in the
   query. QSD for the DAV:basicsearch grammar allows a client to
   discover the set of properties that are searchable, selectable, and
   sortable. Moreover, although the DAV:basicsearch grammar defines a
   minimal set of operators, it is possible that a resource might
   support additional operators in a query. For example, a resource
   might support a optional operator that can be used to express
   content-based queries in a proprietary syntax. QSD allows a client to
   discover these operators and their syntax. The set of discoverable
   quantities will differ from grammar to grammar, but each grammar can
   define a means for a client to discover what can be discovered.

   In general, the schema for a given query grammar depends on both the
   resource (the arbiter) and the scope. A given resource might have
   access to one set of properties for one potential scope, and another
   set for a different scope. For example, consider a server able to
   search two distinct collections, one holding cooking recipes, the
   other design documents for nuclear weapons. While both collections
   might support properties such as author, title, and date, the first
   might also define properties such as calories and preparation time,
   while the second defined properties such as yield and applicable
   patents. Two distinct arbiters indexing the same collection might
   also have access to different properties. For example, the recipe
   collection mentioned above might also indexed by a value-added server
   that also stored the names of chefs who had tested the recipe. Note
   also that the available query schema might also depend on other
   factors, such as the identity of the principal conducting the search,
   but these factors are not exposed in this protocol.

4.1 Additional SEARCH semantics

   Each query grammar supported by DASL defines its own syntax for
   expressing the possible query schema. A client retrieves the schema
   for a given query grammar on an arbiter resource with a given scope
   by invoking the SEARCH method on that arbiter with that grammar and
   scope and with a root element of DAV:query-schema-discovery rather
   than DAV:searchrequest.




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   Marshalling:

      The request body MUST be DAV:query-schema-discovery element.

   <!ELEMENT query-schema-discovery ANY>
   ANY value: XML element defining a valid query

      The response body takes the form of a RFC2518 DAV:multistatus
      element, where DAV:response is extended to hold the returned query
      grammar inside a DAV:query-schema container element.

   <!ELEMENT response (href, ((href*, status)|(propstat+)),
     query-schema?, responsedescription?) >
   <!ELEMENT query-schema ANY>

   The content of this container is an XML element whose name and syntax
   depend upon the grammar, and whose value may (and likely will) vary
   depending upon the grammar, arbiter, and scope.

4.1.1 Example of query schema discovery

   In this example, the arbiter is recipes.test, the grammar is
   DAV:basicsearch, the scope is also recipes.test.

    >> Request:

   SEARCH / HTTP/1.1
   Host: recipes.test
   Content-Type: application/xml
   Content-Length: xxx

   <?xml version="1.0"?>
   <query-schema-discovery xmlns="DAV:">
     <basicsearch>
       <from>
         <scope>
           <href>http://recipes.test</href>
           <depth>infinity</depth>
         </scope>
       </from>
     </basicsearch>
   </query-schema-discovery>

    >> Response:

   HTTP/1.1 207 Multistatus
   Content-Type: application/xml
   Content-Length: xxx



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   <?xml version="1.0"?>
   <multistatus xmlns="DAV:">
     <response>
       <href>http://recipes.test</href>
       <status>HTTP/1.1 200 OK</status>
       <query-schema>
         <basicsearchschema>
           <!-- (See section "Query schema for DAV:basicsearch" for
           the actual contents) -->
         </basicsearchschema>
       </query-schema>
     </response>
   </multistatus>

   The query schema for DAV:basicsearch is defined in Section 5.19.




































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5. The DAV:basicsearch Grammar

5.1 Introduction

   DAV:basicsearch uses an extensible XML syntax that allows clients to
   express search requests that are generally useful for WebDAV
   scenarios. DASL-extended servers MUST accept this grammar, and MAY
   accept other grammars.

   DAV:basicsearch has several components:

   o  DAV:select provides the result record definition.

   o  DAV:from defines the scope.

   o  DAV:where defines the criteria.

   o  DAV:orderby defines the sort order of the result set.

   o  DAV:limit provides constraints on the query as a whole.


5.2 The DAV:basicsearch DTD

   <!ELEMENT basicsearch   (select, from, where?, orderby?, limit?) >

   <!ELEMENT select        (allprop | prop) >

   <!ELEMENT from          (scope) >
   <!ELEMENT scope         (href, depth) >

   <!ENTITY %comp_ops      "eq | lt | gt| lte | gte">
   <!ENTITY %log_ops       "and | or | not">
   <!ENTITY %special_ops   "is-collection | is-defined">
   <!ENTITY %string_ops    "like">
   <!ENTITY %content_ops   "contains">

   <!ENTITY %all_ops       "%comp_ops; | %log_ops; | %special_ops; |
                            %string_ops; | %content_ops;">

   <!ELEMENT where         ( %all_ops; ) >

   <!ELEMENT and           ( ( %all_ops; ) +) >

   <!ELEMENT or            ( ( %all_ops; ) +) >

   <!ELEMENT not           ( %all_ops; ) >




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   <!ELEMENT lt            (prop, literal) >
   <!ATTLIST lt            caseless   (yes|no) >

   <!ELEMENT lte           (prop, literal) >
   <!ATTLIST lte           caseless   (yes|no) >

   <!ELEMENT gt            (prop, literal) >
   <!ATTLIST gt            caseless   (yes|no) >

   <!ELEMENT gte           (prop, literal) >
   <!ATTLIST gte           caseless   (yes|no) >

   <!ELEMENT eq            (prop, literal) >
   <!ATTLIST eq            caseless   (yes|no) >

   <!ELEMENT literal       (#PCDATA)>

   <!ELEMENT is-defined    (prop) >

   <!ELEMENT like          (prop, literal) >
   <!ATTLIST like          caseless   (yes|no) >

   <!ELEMENT contains      (#PCDATA)>

   <!ELEMENT orderby       (order+) >
   <!ELEMENT order         ((prop | score), (ascending | descending)?)
   <!ATTLIST order         caseless   (yes|no) >
   <!ELEMENT ascending     EMPTY>
   <!ELEMENT descending    EMPTY>

   <!ELEMENT limit         (nresults) >
   <!ELEMENT nresults      (#PCDATA) >


5.2.1 Example Query

   This query retrieves the content length values for all resources
   located under the server's "/container1/" URI namespace whose length
   exceeds 10000.

   <d:searchrequest xmlns:d="DAV:">
     <d:basicsearch>
       <d:select>
         <d:prop><d:getcontentlength/></d:prop>
       </d:select>
       <d:from>
         <d:scope>
           <d:href>/container1/</d:href>



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           <d:depth>infinity</d:depth>
         </d:scope>
       </d:from>
       <d:where>
         <d:gt>
           <d:prop><d:getcontentlength/></d:prop>
           <d:literal>10000</d:literal>
         </d:gt>
       </d:where>
         <d:orderby>
           <d:order>
           <d:prop><d:getcontentlength/></d:prop>
           <d:ascending/>
         </d:order>
       </d:orderby>
     </d:basicsearch>
   </d:searchrequest>


5.3 DAV:select

   DAV:select defines the result record, which is a set of properties
   and values. This document defines two possible values: DAV:allprop
   and DAV:prop, both defined in [RFC2518] and revised in [RFC3253].

5.4 DAV:from

   <!ELEMENT scope            (href, depth, include-versions?) >
   <!ELEMENT include-versions EMPTY >

   DAV:from defines the query scope. This contains exactly one DAV:scope
   element. The scope element contains mandatory DAV:href and DAV:depth
   elements.

   DAV:href indicates the URI to use as a scope.

   When the scope is a collection, if DAV:depth is "0", the search
   includes only the collection. When it is "1", the search includes the
   (toplevel) members of the collection. When it is "infinity", the
   search includes all recursive members of the collection. When the
   scope is not a collection, the depth is ignored and the search
   applies just to the resource itself.

   When the child element DAV:include-versions is present, the search
   scope will include all versions (see [RFC3253], section 2.2.1) of all
   version-controlled resources in scope. Servers that do support
   versioning but do not support the DAV:include-versions feature MUST
   signal an error if it is used in a query.



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5.4.1 Relationship to the Request-URI

   If the DAV:scope element is an absolute URI, the scope is exactly
   that URI.

   If the DAV:scope element is  is an absolute URI reference, the scope
   is taken to be relative to the request-URI.

5.4.2 Scope

   A Scope can be an arbitrary URI.

   Servers, of course, may support only particular scopes. This may
   include limitations for particular schemes such as "http:" or "ftp:"
   or certain URI namespaces.

5.5 DAV:where

   The DAV:where element defines the search condition for inclusion of
   resources in the result set. The value of this element is an XML
   element that defines a search operator that evaluates to one of the
   Boolean truth values TRUE, FALSE, or UNKNOWN. The search operator
   contained by DAV:where may itself contain and evaluate additional
   search operators as operands, which in turn may contain and evaluate
   additional search operators as operands, etc. recursively.

5.5.1 Use of Three-Valued Logic in Queries

   Each operator defined for use in the where clause that returns a
   Boolean value MUST evaluate to TRUE, FALSE, or UNKNOWN. The resource
   under scan is included as a member of the result set if and only if
   the search condition evaluates to TRUE.

   Consult Appendix A for details on the application of three-valued
   logic in query expressions.

5.5.2 Handling Optional operators

   If a query contains an operator that is not supported by the server,
   then the server MUST respond with a 422 (Unprocessable Entity) status
   code.

5.5.3 Treatment of NULL Values

   If a PROPFIND for a property value would yield a non-2xx (see
   [RFC2616], section 10.2) response for that property, then that
   property is considered NULL.




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   NULL values are "less than" all other values in comparisons.

   Empty strings (zero length strings) are not NULL values. An empty
   string is "less than" a string with length greater than zero.

   The DAV:is-defined operator is defined to test if the value of a
   property is NULL.

5.5.4 Treatment of properties with mixed/element content

   Comparisons of properties that do not have simple types (text-only
   content) is out-of-scope for the standard operators defined for
   DAV:basicsearch and therefore is defined to be UNKNOWN (as per
   Appendix A). For querying the DAV:resourcetype property, see Section
   5.13.

5.5.5 Example: Testing for Equality

   The example shows a single operator (DAV:eq) applied in the criteria.

   <d:where>
     <d:eq>
       <d:prop>
         <d:getcontentlength/>
       </d:prop>
       <d:literal>100</d:literal>
     </d:eq>
   </d:where>

5.5.6 Example: Relative Comparisons

   The example shows a more complex operation involving several
   operators (DAV:and, DAV:eq, DAV:gt) applied in the criteria. This
   DAV:where expression matches those resources that are "image/gifs"
   over 4K in size.

   <D:where>
     <D:and>
       <D:eq>
         <D:prop>
           <D:getcontenttype/>
         </D:prop>
         <D:literal>image/gif</D:literal>
       </D:eq>
       <D:gt>
         <D:prop>
           <D:getcontentlength/>
         </D:prop>



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         <D:literal>4096</D:literal>
       </D:gt>
     </D:and>
   </D:where>

5.6 DAV:orderby

   The DAV:orderby element specifies the ordering of the result set. It
   contains one or more DAV:order elements, each of which specifies a
   comparison between two items in the result set. Informally, a
   comparison specifies a test that determines whether one resource
   appears before another in the result set. Comparisons are applied in
   the order they occur in the DAV:orderby element, earlier comparisons
   being more significant.

   The comparisons defined here use only a single property from each
   resource, compared using the same ordering as the DAV:lt operator
   (ascending) or DAV:gt operator (descending). If neither direction is
   specified, the default is DAV:ascending.

   In the context of the DAV:orderby element, null values are considered
   to collate before any actual (i.e., non null) value, including
   strings of zero length (this is compatible with [SQL99]).

5.6.1 Comparing Natural Language Strings

   Comparisons on strings take into account the language defined for
   that property. Clients MAY specify the language using the xml:lang
   attribute. If no language is specified either by the client or
   defined for that property by the server or if a comparison is
   performed on strings of two different languages, the results are
   undefined.

   The "caseless" attribute may be used to indicate case-sensitivity for
   comparisons.

5.6.2 Example of Sorting

   This sort orders first by last name of the author, and then by size,
   in descending order, so that for each author, the largest works
   appear first.

   <d:orderby>
     <d:order>
       <d:prop><r:lastname/></d:prop>
       <d:ascending/>
     </d:order>
     <d:order>



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       <d:prop><d:getcontentlength/></d:prop>
       <d:descending/>
     </d:order>
   </d:orderby>

5.7 Boolean Operators: DAV:and, DAV:or, and DAV:not

   The DAV:and operator performs a logical AND operation on the
   expressions it contains.

   The DAV:or operator performs a logical OR operation on the values it
   contains.

   The DAV:not operator performs a logical NOT operation on the values
   it contains.

5.8 DAV:eq

   The DAV:eq operator provides simple equality matching on property
   values.

   The "caseless" attribute may be used with this element.

5.9 DAV:lt, DAV:lte, DAV:gt, DAV:gte

   The DAV:lt, DAV:lte, DAV:gt, and DAV:gte operators provide
   comparisons on property values, using less-than, less-than or equal,
   greater-than, and greater-than or equal respectively. The "caseless"
   attribute may be used with these elements.

5.10 DAV:literal

   DAV:literal allows literal values to be placed in an expression.

   White space in literal values is significant in comparisons. For
   consistency with [RFC2518], clients SHOULD NOT specify the attribute
   "xml:space" (section 2.10 of [XML]) to override this behaviour.

   In comparisons, the contents of DAV:literal SHOULD be treated as
   string, with the following exceptions:

   o  when operand for a comparison with a DAV:getcontentlength
      property, it SHOULD be treated as an integer value (the behaviour
      for non-integer values is undefined),

   o  when operand for a comparison with a DAV:creationdate or
      DAV:getlastmodified property, it SHOULD be treated as a date value
      in the ISO-8601 subset defined for the DAV:creationdate property



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      ([RFC2518], section 13.1).

   o  when operand for a comparison with a property for which the type
      is known, it MAY be treated according to this type.


5.11 DAV:typed-literal (optional)

   There are situations in which a client may want to force a comparison
   not to be string-based (as defined for DAV:literal). In these cases,
   a typed comparison can be enforced by using DAV:typed-literal
   instead.

   <!ELEMENT typed-literal (#PCDATA)>

   The data type is specified using the xsi:type attribute defined in
   [XS1], section 2.6.1. If the type is not specified, it defaults to
   "xs:string".

   A server MUST reject a request with an unknown type.

5.11.1 Example for typed numerical comparison

   Consider a set of resources with the dead property "edits" in the
   namespace "http://ns.example.org":

                        +-----+----------------+
                        | URI | property value |
                        +-----+----------------+
                        | /a  | "-1"           |
                        |     |                |
                        | /b  | "01"           |
                        |     |                |
                        | /c  | "3"            |
                        |     |                |
                        | /d  | "test"         |
                        |     |                |
                        | /e  | (undefined)    |
                        +-----+----------------+

   The expression

   <lt xmlns="DAV:"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:xs="http://www.w3.org/2001/XMLSchema">
     <prop><edits xmlns="http://ns.example.org"/></prop>
     <typed-literal xsi:type="xs:integer">3</typed-literal>
   </lt>



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   will evaluate to TRUE for the resources "/a" and "/b" (their property
   values can be parsed as type xs:number, and the numerical comparison
   evaluates to true), to FALSE for "/c" (property value is compatible,
   but numerical comparison evaluates to false) and UNKNOWN for "/d" and
   "/e" (the property either is undefined, or its value can not be
   parsed as xs:number).

5.12 Support for matching xml:lang attributes on properties

   The following two optional operators can be used to express
   conditions on the language of a property value (as expressed using
   the xml:lang attribute).

5.12.1 DAV:language-defined (optional)

   <!ELEMENT language-defined (prop)>

   This operator evaluates to TRUE if the language for the value of the
   given property is known, FALSE if it isn't and UNKNOWN if the
   property itself is not defined.

5.12.2 DAV:language-matches (optional)

   <!ELEMENT language-matches (prop, literal)>

   This operator evaluates to TRUE if the language for the value of the
   given property is known and matches the language name given in the
   <literal> element, FALSE if it doesn't match and UNKNOWN if the
   property itself is not defined.

   Languages are considered to match if they are the same, or if the
   language of the property value is a sublanguage of the language
   specified in the <literal> element (see [XPATH], section 4.3, "lang
   function").

5.12.3 Example of language-aware matching

   The expression below will evaluate to TRUE if the property "foobar"
   exists and it's language is either unknown, English or a sublanguage
   of English.

   <or xmlns="DAV:">
     <not>
       <language-defined>
         <prop><foobar/></prop>
       </language-defined>
     </not>
     <language-matches>



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       <prop><foobar/></prop>
       <literal>en</literal>
     </language-matches>
   </or>


5.13 DAV:is-collection

   The DAV:is-collection operator allows clients to determine whether a
   resource is a collection (that is, whether it's DAV:resourcetype
   element contains the element DAV:collection).

   Rationale: This operator is provided in lieu of defining generic
   structure queries, which would suffice for this and for many more
   powerful queries, but seems inappropriate to standardize at this
   time.

5.13.1 Example of DAV:is-collection

   This example shows a search criterion that picks out all and only the
   resources in the scope that are collections.

   <where xmlns="DAV:">
     <is-collection/>
   </where>

5.14 DAV:is-defined

   The DAV:is-defined operator allows clients to determine whether a
   property is defined on a resource. The meaning of "defined on a
   resource" is found in Section 5.5.3.

   Example:

   <d:is-defined>
     <d:prop><x:someprop/></d:prop>
   </d:is-defined>

5.15 DAV:like

   The DAV:like is an optional operator intended to give simple
   wildcard-based pattern matching ability to clients.

   The operator takes two arguments.

   The first argument is a DAV:prop element identifying a single
   property to evaluate.




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   The second argument is a DAV:literal element that gives the pattern
   matching string.

5.15.1 Syntax for the Literal Pattern

   Pattern := [wildcard] 0*( text [wildcard] )
   wildcard := exactlyone | zeroormore
   text := 1*( <character> | escapesequence )
   exactlyone : = "_"
   zeroormore := "%"
   escapechar := "\"
   escapesequence := "\" ( exactlyone | zeroormore | escapechar )
   character: valid XML characters (see section 2.2 of [XML]),
              minus ( exactlyone | zeroormore | escapechar )

   The value for the literal is composed of wildcards separated by
   segments of text. Wildcards may begin or end the literal.

   The "_" wildcard matches exactly one character.

   The "%" wildcard matches zero or more characters

   The "\" character is an escape sequence so that the literal can
   include >"_" and "%". To include the "\" character in the pattern,
   the escape sequence "\\" is used.

5.15.2 Example of DAV:like

   This example shows how a client might use DAV:like to identify those
   resources whose content type was a subtype of image.

   <D:where>
     <D:like caseless="yes">
       <D:prop><D:getcontenttype/></D:prop>
       <D:literal>image/%</D:literal>
     </D:like>
   </D:where>

5.16 DAV:contains

   The DAV:contains operator is an optional operator that provides
   content-based search capability. This operator implicitly searches
   against the text content of a resource, not against content of
   properties. The DAV:contains operator is intentionally not overly
   constrained, in order to allow the server to do the best job it can
   in performing the search.

   The DAV:contains operator evaluates to a Boolean value. It evaluates



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   to TRUE if the content of the resource satisfies the search.
   Otherwise, It evaluates to FALSE.

   Within the DAV:contains XML element, the client provides a phrase: a
   single word or whitespace delimited sequence of words. Servers MAY
   ignore punctuation in a phrase. Case-sensitivity is left to the
   server.

   The following things may or may not be done as part of the search:
   Phonetic methods such as "soundex" may or may not be used. Word
   stemming may or may not be performed. Thesaurus expansion of words
   may or may not be done. Right or left truncation may or may not be
   performed. The search may be case insensitive or case sensitive. The
   word or words may or may not be interpreted as names. Multiple words
   may or may not be required to be adjacent or "near" each other.
   Multiple words may or may not be required to occur in the same order.
   Multiple words may or may not be treated as a phrase. The search may
   or may not be interpreted as a request to find documents "similar" to
   the string operand.

5.16.1 Result scoring (DAV:score element)

   Servers SHOULD indicate scores for the DAV:contains condition by
   adding a DAV:score XML element to the DAV:response element. It's
   value is defined only in the context of a particular query result.
   The value is a string representing the score, an integer from zero to
   10000 inclusive, where a higher value indicates a higher score (e.g.
   more relevant).

   Modified DTD fragment for DAV:propstat:

   <!ELEMENT response (href, ((href*, status)|(propstat+)),
                       responsedescription?, score?) >
   <!ELEMENT score    (#PCDATA) >

   Clients should note that, in general, it is not meaningful to compare
   the numeric values of scores from two different query results unless
   both were executed by the same underlying search system on the same
   collection of resources.

5.16.2 Ordering by score

   To order search results by their score, the DAV:score element may be
   added as child to the DAV:orderby element (in place of a DAV:prop
   element).

5.16.3 Examples




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   The example below shows a search for the phrase "Peter Forsberg".

   Depending on its support for content-based searching, a server MAY
   treat this as a search for documents that contain the words "Peter"
   and "Forsberg".

   <D:where>
     <D:contains>Peter Forsberg</D:contains>
   </D:where>

   The example below shows a search for resources that contain "Peter"
   and "Forsberg".

   <D:where>
     <D:and>
       <D:contains>Peter</D:contains>
       <D:contains>Forsberg</D:contains>
     </D:and>
   </D:where>

5.17 Limiting the result set

   <!ELEMENT limit (nresults) >
   <!ELEMENT nresults (#PCDATA)> ;only digits

   The DAV:limit XML element contains requested limits from the client
   to limit the size of the reply or amount of effort expended by the
   server. The DAV:nresults XML element contains a requested maximum
   number of DAV:response elements to be returned in the response body.
   The server MAY disregard this limit. The value of this element is an
   integer.

5.17.1 Relationship to result ordering

   If the result set is both limited by DAV:limit and ordered according
   to DAV:orderby, the results that are included in the response
   document must be those that order highest.

5.18 The 'caseless' XML attribute

   The "caseless" attribute allows clients to specify caseless matching
   behaviour instead of character-by-character matching for
   DAV:basicsearch operators.

   The possible values for "caseless" are "yes" or "no". The default
   value is server-specified. Caseless matching SHOULD be implemented as
   defined in [CaseMap].




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   Support for the "caseless" attribute is optional. A server should
   respond with a status of 422 if it is used but cannot be supported.

5.19 Query schema for DAV:basicsearch

   The DAV:basicsearch grammar defines a search criteria that is a
   Boolean-valued expression, and allows for an arbitrary set of
   properties to be included in the result record. The result set may be
   sorted on a set of property values. Accordingly the DTD for schema
   discovery for this grammar allows the server to express:

   1.  the set of properties that may be either searched, returned, or
       used to sort, and a hint about the data type of such properties

   2.  the set of optional operators defined by the resource.


5.19.1 DTD for DAV:basicsearch QSD

   <!ELEMENT basicsearchschema  (properties, operators)>
   <!ELEMENT any-other-property EMPTY>
   <!ELEMENT properties         (propdesc*)>
   <!ELEMENT propdesc           (prop|any-other-property), datatype?,
                                 searchable?, selectable?, sortable?,
                                 caseless?)>
   <!ELEMENT operators          (opdesc*)>
   <!ELEMENT opdesc             ANY>
   <!ELEMENT operand-literal    EMPTY>
   <!ELEMENT operand-property   EMPTY>

   The DAV:properties element holds a list of descriptions of
   properties.

   The DAV:operators element describes the optional operators that may
   be used in a DAV:where element.

5.19.2 DAV:propdesc Element

   Each instance of a DAV:propdesc element describes the property or
   properties in the DAV:prop element it contains. All subsequent
   elements are descriptions that apply to those properties. All
   descriptions are optional and may appear in any order. Servers SHOULD
   support all the descriptions defined here, and MAY define others.

   DASL defines five descriptions. The first, DAV:datatype, provides a
   hint about the type of the property value, and may be useful to a
   user interface prompting for a value. The remaining four
   (DAV:searchable, DAV:selectable, DAV:sortable, and DAV:caseless)



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   identify portions of the query (DAV:where, DAV:select, and
   DAV:orderby, respectively). If a property has a description for a
   section, then the server MUST allow the property to be used in that
   section. These descriptions are optional. If a property does not have
   such a description, or is not described at all, then the server MAY
   still allow the property to be used in the corresponding section.

5.19.2.1 DAV:any-other-property

   This element can be used in place of DAV:prop to describe properties
   of WebDAV properties not mentioned in any other DAV:prop element. For
   instance, this can be used to indicate that all other properties are
   searchable and selectable without giving details about their types (a
   typical scenario for dead properties).

5.19.3 The DAV:datatype Property Description

   The DAV:datatype element contains a single XML element that provides
   a hint about the domain of the property, which may be useful to a
   user interface prompting for a value to be used in a query. Datatypes
   are identified by an element name. Where appropriate, a server SHOULD
   use the simple datatypes defined in [XS2].

   <!ELEMENT datatype ANY >

   Examples from [XS2], section 3:

                +----------------+---------------------+
                | Qualified name | Example             |
                +----------------+---------------------+
                | xs:boolean     | true, false, 1, 0   |
                |                |                     |
                | xs:string      | Foobar              |
                |                |                     |
                | xs:dateTime    | 1994-11-05T08:15:5Z |
                |                |                     |
                | xs:float       | .314159265358979E+1 |
                |                |                     |
                | xs:integer     | -259, 23            |
                +----------------+---------------------+

   If the data type of a property is not given, then the data type
   defaults to xs:string.

5.19.4 The DAV:searchable Property Description

   <!ELEMENT searchable EMPTY>




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   If this element is present, then the server MUST allow this property
   to appear within a DAV:where element where an operator allows a
   property. Allowing a search does not mean that the property is
   guaranteed to be defined on every resource in the scope, it only
   indicates the server's willingness to check.

5.19.5 The DAV:selectable Property Description

   <!ELEMENT selectable EMPTY>

   This element indicates that the property may appear in the DAV:select
   element.

5.19.6 The DAV:sortable Property Description

   This element indicates that the property may appear in the
   DAV:orderby element.

   <!ELEMENT sortable EMPTY>

5.19.7 The DAV:caseless Property Description

   This element only applies to properties whose data type is
   "xs:string" and derived data types as per the DAV:datatype property
   description. Its presence indicates that compares performed for
   searches, and the comparisons for ordering results on the string
   property will be caseless (the default is character-by-character).

   <!ELEMENT caseless EMPTY>

5.19.8 The DAV:operators XML Element

   The DAV:operators element describes every optional operator supported
   in a query. (Mandatory operators are not listed since they are
   mandatory and permit no variation in syntax.). All optional operators
   that are supported MUST be listed in the DAV:operators element. The
   listing for an operator consists of the operator (as an empty
   element), followed by one element for each operand. The operand MUST
   be either DAV:operand-property or DAV:operand-literal, which indicate
   that the operand in the corresponding position is a property or a
   literal value, respectively. If an operator is polymorphic (allows
   more than one operand syntax) then each permitted syntax MUST be
   listed separately.

   <operators xmlns='DAV:'>
     <opdesc>
       <like/><operand-property/><operand-literal/>
     </opdesc>



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   </operators>


5.19.9 Example of Query Schema for DAV:basicsearch

   <D:basicsearchschema xmlns:D="DAV:"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"">
     <D:properties>
       <D:propdesc>
         <D:prop><D:getcontentlength/></D:prop>
         <D:datatype><xs:nonNegativeInteger/></D:datatype>
         <D:searchable/><D:selectable/><D:sortable/>
       </D:propdesc>
       <D:propdesc>
         <D:prop><D:getcontenttype/><D:displayname/></D:prop>
         <D:searchable/><D:selectable/><D:sortable/>
       </D:propdesc>
       <D:propdesc>
         <D:prop><fstop xmlns="http://jennicam.org"/></D:prop>
         <D:selectable/>
       </D:propdesc>
       <D:propdesc>
         <D:any-other-property/>
         <D:searchable/><D:selectable/>
       </D:propdesc>
     </D:properties>
     <D:operators>
       <D:opdesc>
         <D:like/><D:operand-property/><D:operand-literal/>
       </D:opdesc>
     </D:operators>
   </D:basicsearchschema>

   This response lists four properties. The datatype of the last three
   properties is not given, so it defaults to xs:string. All are
   selectable, and the first three may be searched. All but the last may
   be used in a sort. Of the optional DAV operators, DAV:is-defined and
   DAV:like are supported.

   Note: The schema discovery defined here does not provide for
   discovery of supported values of the "caseless" attribute. This may
   require that the reply also list the mandatory operators.









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6. Internationalization Considerations

   Properties may be language-tagged using the xml:lang attribute (see
   [RFC2518], section 4.4). The optional operators DAV:language-defined
   (Section 5.12.1) and DAV:language-matches (Section 5.12.2) allow to
   express conditions on the language tagging information.













































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7. Security Considerations

   This section is provided to detail issues concerning security
   implications of which DASL applications need to be aware. All of the
   security considerations of HTTP/1.1 also apply to DASL. In addition,
   this section will include security risks inherent in searching and
   retrieval of resource properties and content.

   A query must not allow one to retrieve information about values or
   existence of properties that one could not obtain via PROPFIND. (e.g.
   by use in DAV:orderby, or in expressions on properties.)

   A server should prepare for denial of service attacks. For example a
   client may issue a query for which the result set is expensive to
   calculate or transmit because many resources match or must be
   evaluated.

7.1 Implications of XML External Entities

   XML supports a facility known as "external entities", defined in
   section 4.2.2 of [XML], which instruct an XML processor to retrieve
   and perform an inline include of XML located at a particular URI. An
   external XML entity can be used to append or modify the document type
   declaration (DTD) associated with an XML document. An external XML
   entity can also be used to include XML within the content of an XML
   document. For non-validating XML, such as the XML used in this
   specification, including an external XML entity is not required by
   [XML]. However, [XML] does state that an XML processor may, at its
   discretion, include the external XML entity.

   External XML entities have no inherent trustworthiness and are
   subject to all the attacks that are endemic to any HTTP GET request.
   Furthermore, it is possible for an external XML entity to modify the
   DTD, and hence affect the final form of an XML document, in the worst
   case significantly modifying its semantics, or exposing the XML
   processor to the security risks discussed in [RFC3023]. Therefore,
   implementers must be aware that external XML entities should be
   treated as untrustworthy.

   There is also the scalability risk that would accompany a widely
   deployed application which made use of external XML entities. In this
   situation, it is possible that there would be significant numbers of
   requests for one external XML entity, potentially overloading any
   server which fields requests for the resource containing the external
   XML entity.






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8. Scalability

   Query grammars are identified by URIs. Applications SHOULD not
   attempt to retrieve these URIs even if they appear to be retrievable
   (for example, those that begin with "http://")














































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9. Authentication

   Authentication mechanisms defined in WebDAV will also apply to DASL.
















































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10. IANA Considerations

   This document uses the namespace defined by [RFC2518] for XML
   elements. All other IANA considerations mentioned in [RFC2518] are
   also applicable to DASL.














































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11. Contributors

   This document is based on prior work on the DASL protocol done by the
   WebDAV DASL working group until the year 2000 -- namely by Alan
   Babich, Jim Davis, Rick Henderson, Dale Lowry, Saveen Reddy and
   Surendra Reddy.













































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12. Acknowledgements

   This document has benefited from thoughtful discussion by Lisa
   Dusseault, Sung Kim, Elias Sinderson, Martin Wallmer, Jim Whitehead
   and Kevin Wiggen.














































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Normative References

   [ACL]      Clemm, G., Hopkins, A., Sedlar, E. and J. Whitehead,
              "WebDAV Access Control Protocol", ID
              draft-ietf-webdav-acl-12, October 2003, <http://
              www.webdav.org/acl/protocol/draft-ietf-webdav-acl-12.htm>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2518]  Goland, Y., Whitehead, E., Faizi, A., Carter, S. and D.
              Jensen, "HTTP Extensions for Distributed Authoring --
              WEBDAV", RFC 2518, February 1999.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Nielsen, H.,
              Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC3023]  Makoto, M., St.Laurent, S. and D. Kohn, "XML Media Types",
              RFC 3023, January 2001.

   [RFC3253]  Clemm, G., Amsden, J., Ellison, T., Kaler, C. and J.
              Whitehead, "Versioning Extensions to WebDAV", RFC 3253,
              March 2002.

   [XML]      Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
              "Extensible Markup Language (XML) 1.0 (2nd ed)", W3C
              REC-xml, October 2000, <http://www.w3.org/TR/2000/
              REC-xml-20001006>.

   [XMLNS]    Bray, T., Hollander, D. and A. Layman, "Namespaces in
              XML", W3C REC-xml-names, January 1999, <http://www.w3.org/
              TR/REC-xml-names>.

   [XPATH]    Clark, J. and S. DeRose, "XML Path Language (XPath)
              Version 1.0", W3C REC REC-xpath, November 1999, <http://
              www.w3.org/TR/xpath>.

   [XS1]      Thompson, H., Beech, D., Maloney, M., Mendelsohn, N. and
              World Wide Web Consortium, "XML Schema Part 1:
              Structures", W3C XS1, May 2001, <http://www.w3.org/TR/
              xmlschema-1/>.

   [XS2]      Biron, P., Malhotra, A. and World Wide Web Consortium,
              "XML Schema Part 2: Datatypes", W3C XS2, May 2001, <http:/
              /www.w3.org/TR/xmlschema-2/>.





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Informative References

   [BIND]     Clemm, G., Crawford, J., Reschke, J., Slein, J. and J.
              Whitehead, "Binding Extensions to WebDAV", ID
              draft-ietf-webdav-bind-02, June 2003, <http://
              www.webdav.org/bind/draft-ietf-webdav-bind-02.htm>.

   [CaseMap]  Davis, M., "Case Mappings", Unicode Techical Reports 21,
              February 2001, <http://www.unicode.org/unicode/reports/
              tr21>.

   [DASL]     Reddy, S., Lowry, D., Reddy, S., Henderson, R., Davis, J.
              and A. Babich, "DAV Searching & Locating", ID
              draft-dasl-protocol-00, July 1999, <http://www.webdav.org/
              dasl/protocol/draft-dasl-protocol-00.html>.

   [DASLREQ]  Davis, J., Reddy, S. and J. Slein, "Requirements for DAV
              Searching and Locating", ID draft-dasl-requirements-01,
              February 1999, <http://www.webdav.org/dasl/requirements/
              draft-dasl-requirements-01.html>.

   [SQL99]    Milton, J., "Database Language SQL Part 2: Foundation
              (SQL/Foundation)", ISO ISO/IEC 9075-2:1999 (E), July 1999.




























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URIs

   [1]   <mailto:www-webdav-dasl@w3.org>

   [2]   <mailto:www-webdav-dasl-request@w3.org?subject=subscribe>

   [3]   <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         2003JanMar/0042.html>

   [4]   <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         2003JulSep/0012.html>

   [5]   <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         1999AprJun/0002.html>

   [6]   <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         2002AprJun/0047.html>

   [7]   <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         1999OctDec/0023.html>

   [8]   <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         2002JanMar/0163.html>

   [9]   <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         2003JulSep/0002.html>

   [10]  <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         2003JulSep/0012.html>

   [11]  <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         2003OctDec/0010.html>

   [12]  <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         2002JanMar/0122.html>

   [13]  <http://lists.w3.org/Archives/Public/www-webdav-dasl/
         1999AprJun/0002.html>













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Authors' Addresses

   Julian F. Reschke (editor)
   greenbytes GmbH
   Salzmannstrasse 152
   Muenster, NW  48159
   Germany

   Phone: +49 251 2807760
   Fax:   +49 251 2807761
   EMail: julian.reschke@greenbytes.de
   URI:   http://greenbytes.de/tech/webdav/


   Surendra Reddy
   Oracle Corporation
   600 Oracle Parkway, M/S 6op3
   Redwoodshores, CA  94065

   Phone: +1 650 506 5441
   EMail: Surendra.Reddy@oracle.com


   Jim Davis
   Intelligent Markets
   410 Jessie Street 6th floor
   San Francisco, CA  94103

   EMail: jrd3@alum.mit.edu


   Alan Babich
   FileNET Corp.
   3565 Harbor Blvd.
   Costa Mesa, CA  92626

   Phone: +1 714 327 3403
   EMail: ababich@filenet.com













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Appendix A. Three-Valued Logic in DAV:basicsearch

   ANSI standard three valued logic is used when evaluating the search
   condition (as defined in the ANSI standard SQL specifications, for
   example in ANSI X3.135-1992, section 8.12, pp. 188-189, section 8.2,
   p. 169, General Rule 1)a), etc.).

   ANSI standard three valued logic is undoubtedly the most widely
   practiced method of dealing with the issues of properties in the
   search condition not having a value (e.g., being null or not defined)
   for the resource under scan, and with undefined expressions in the
   search condition (e.g., division by zero, etc.). Three valued logic
   works as follows.

   Undefined expressions are expressions for which the value of the
   expression is not defined. Undefined expressions are a completely
   separate concept from the truth value UNKNOWN, which is, in fact,
   well defined. Property names and literal constants are considered
   expressions for purposes of this section. If a property in the
   current resource under scan has not been set to a value, then the
   value of that property is undefined for the resource under scan. DASL
   1.0 has no arithmetic division operator, but if it did, division by
   zero would be an undefined arithmetic expression.

   If any subpart of an arithmetic, string, or datetime subexpression is
   undefined, the whole arithmetic, string, or datetime subexpression is
   undefined.

   There are no manifest constants to explicitly represent undefined
   number, string, or datetime values.

   Since a Boolean value is ultimately returned by the search condition,
   arithmetic, string, and datetime expressions are always arguments to
   other operators. Examples of operators that convert arithmetic,
   string, and datetime expressions to Boolean values are the six
   relational operators ("greater than", "less than", "equals", etc.).
   If either or both operands of a relational operator have undefined
   values, then the relational operator evaluates to UNKNOWN. Otherwise,
   the relational operator evaluates to TRUE or FALSE, depending upon
   the outcome of the comparison.

   The Boolean operators DAV:and, DAV:or and DAV:not are evaluated
   according to the following rules:

   UNKNOWN and UNKNOWN = UNKNOWN

   UNKNOWN or UNKNOWN = UNKNOWN




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   not UNKNOWN = UNKNOWN

   UNKNOWN and TRUE = UNKNOWN

   UNKNOWN and FALSE = FALSE

   UNKNOWN and UNKNOWN = UNKNOWN

   UNKNOWN or TRUE = TRUE

   UNKNOWN or FALSE = UNKNOWN

   UNKNOWN or UNKNOWN = UNKNOWN






































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Appendix B. Change Log (to be removed by RFC Editor before publication)

B.1 From draft-davis-dasl-protocol-xxx

   Feb 14, 1998 Initial Draft

   Feb 28, 1998 Referring to DASL as an extension to HTTP/1.1 rather
      than DAV.
      Added new sections "Notational Conventions", "Protocol Model",
      "Security Considerations".
      Changed section 3 to "Elements of Protocol".
      Added some stuff to introduction.
      Added "result set" terminology.
      Added "IANA Considerations".

   Mar 9, 1998 Moved sub-headings of "Elements of Protocol" to first
      level and removed "Elements of Protocol" Heading.
      Added an sentence in introduction explaining that this is a
      "sketch" of a protocol.

   Mar 11, 1998 Added orderby, data typing, three valued logic, query
      schema property, and element definitions for schema for
      basicsearch.

   April 8, 1998 - made changes based on last week's DASL BOF.

   May 8, 1998 Removed most of DAV:searcherror; converted to
      DAV:searchredirect
      Altered DAV:basicsearch grammar to use avoid use of ANY in DTD

   June 17, 1998 -Added details on Query Schema Discovery
      -Shortened list of data types

   June 23, 1998 moved data types before change history
      rewrote the data types section
      removed the casesensitive element and replace with the
      casesensitive attribute
      added the casesensitive attribute to the DTD for all operations
      that might work on a string

   Jul 20, 1998 A series of changes. See Author's meeting minutes for
      details.

   July 28, 1998 Changes as per author's meeting. QSD uses SEARCH, not
      PROPFIND.
      Moved text around to keep concepts nearby.
      Boolean literals are 1 and 0, not T and F.
      contains changed to contentspassthrough.



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      Renamed rank to score.

   July 28, 1998 Added Dale Lowry as Author

   September 4, 1998 Added 422 as response when query lists
      unimplemented operators.
      DAV:literal declares a default value for xml:space, 'preserve'
      (see XML spec, section 2.10)
      moved to new XML namespace syntax

   September 22, 1998 Changed "simplesearch" to "basicsearch"
      Changed isnull to isdefined
      Defined NULLness as having a 404 or 403 response
      used ENTITY syntax in DTD
      Added redirect

   October 9, 1998 Fixed a series of typographical and formatting
      errors.
      Modified the section of three-valued logic to use a table rather
      than a text description of the role of UNKNOWN in expressions.

   November 2, 1998 Added the DAV:contains operator.
      Removed the DAV:contentpassthrough operator.

   November 18, 1998 Various author comments for submission

   June 3, 1999 Cosmetic and minor editorial changes only. Fix nits
      reported by Jim Whitehead in email of April 26, 1999. Converted to
      HTML from Word 97, manually.

   April 20, 2000 Removed redirection feature, since 301/302 suffices.
      Removed Query Schema Discovery (former chapter 4). Everyone agrees
      this is a useful feature, but it is apparently too difficult to
      define at this time, and it is not essential for DASL.


B.2 since start of draft-reschke-webdav-search

   October 09, 2001 Added Julian Reschke as author.
      Chapter about QSD re-added.
      Formatted into RFC2629-compliant XML document.
      Added first comments.
      ID version number kicked up to draft-dasl-protocol-03.

   October 17, 2001 Updated address information for Jim Davis.
      Added issue of datatype vocabularies.
      Updated issue descriptions for grammar discovery, added issues on
      query schema DTD.



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      Fixed typos in XML examples.

   December 17, 2001 Re-introduced split between normative and
      non-normative references.

   January 05, 2002 Version bumbed up to 04. Started work on resolving
      the issues identified in the previous version.

   January 14, 2002 Fixed some XML typos.

   January 22, 2002 Closed issues naming-of-elements. Fixed query search
      DTD and added option to discover properties of "other"
      (non-listed) properties.

   January 25, 2002 Changed into private submission and added reference
      to historic DASL draft. Marked reference to DASL requirements
      non-normative.
      Updated reference to latest deltav spec.

   January 29, 2002 Added feedback from and updated contact info for
      Alan Babich.
      Included open issues collected in http://www.webdav.org/dasl/
      protocol/issues.html.

   February 8, 2002 Made sure that all artwork fits into 72 characters
      wide text.

   February 18, 2002 Changed Insufficient storage handling
      (multistatus). Moved is-collection to operators and added to DTD.
      Made scope/depth mandatory.

   February 20, 2002 Updated reference to SQL99.

   February 28, 2002 "Non-normative References" -> "Informative
      References". Abstract updated. Consistently specify a charset when
      using text/xml (no change bars). Do not attempt to define
      PROPFIND's entity encoding (take out specific references to text/
      xml). Remove irrelevant headers (Connection:) from examples (no
      change bars). Added issue on querying based on DAV:href. Updated
      introduction to indicate relationship to DASL draft. Updated HTTP
      reference from RFC2068 to RFC2616. Updated XML reference to XML
      1.0 2nd edition.

   March 1, 2002 Removed superfluous namespace decl in 2.4.2. Reopened
      JW14 and suggest to drop xml:space support.






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   March 3, 2002 Removed "xml:space" feature on DAV:literal. Added issue
      about string comparison vs. collations vs. xml:lang. Updated some
      of the open issues with details from JimW's original mail in April
      1999. Resolved scope vs relative URI references. Resolved issues
      about DAV:ascending (added to index) and the BNF for DAV:like
      (changed "octets" to "characters").

   March 8, 2002 Updated reference to DeltaV (now RFC3253). Added Martin
      Wallmer's comments, moved JW5 into DAV:basicsearch section.

   March 11, 2002 Closed open issues regaring the type of search
      arbiters (JW3) and their discovery (JW9). Rephrased requirements
      on multistatus response bodies (propstat only if properties were
      selected, removed requirement for responsedescription).

   March 23, 2002 RFC2376 -> RFC3023. Added missing first names of
      authors. OPTIONS added to example for DAV:supported-method-set.


B.3 since draft-reschke-webdav-search-00

   March 29, 2002 Abstract doesn't refer to DASL WG anymore.

   April 7, 2002 Fixed section title (wrong property name
      supported-search-grammar-set. Changed DAV:casesensitve to
      "casesensitive" (it wasn't in the DAV: namespace after all).

   May 28, 2002 Updated some issues with Jim Davis's comments.

   June 10, 2002 Added proposal for different method for query schema
      discovery, not using pseudo-properties.

   June 25, 2002 QSD marshalling rewritten. Added issue
      "isdefined-optional".


B.4 since draft-reschke-webdav-search-01

   July 04, 2002 Added issue "scope-collection".

   July 08, 2002 Closed issue "scope-collection".

   August 12, 2002 Added issues "results-vs-binds" and "select-allprop".

   October 22, 2002 Added issue "undefined-expressions".






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   November 18, 2002 Changed example host names (no change tracking).

   November 25, 2002 Updated issue "DB2/DB7". Closed issues "undefined
      expressions", "isdefined-optional" and "select-allprop".


B.5 since draft-reschke-webdav-search-02

   November 27, 2002 Added issues "undefined-properties",
      "like-exactlyone" and "like-wildcard-adjacent". Closed issue
      "query-on-href". Added acknowledgments section.

   November 28, 2002 Closed issue "like-exactlyone". Added issue
      "mixed-content-properties".

   December 14, 2002 Closed issues "undefined-properties",
      "results-vs-binds", "mixed-content-properties". Updated issue
      "like-wildcard-adjacent". Added informative reference to BIND
      draft. Updated reference to ACL draft.

   January 9, 2003 Removed duplicate section on invalid scopes. Added
      comments to some open issues. Closed issues JW25/26,
      score-pseudo-property and null-ordering.

   January 10, 2003 Issue limit-vs-ordering plus resolution. Closed
      issue JW17/JW24b.

   January 14, 2003 New issue order-precedence. Started resolution of
      DB2/DB7.

   January 15, 2003 Started spec of DAV:typed-literal.

   January 17, 2003 Fix one DAV:like/DAV:getcontenttype example (add /
      to like expression, make case-insensitive).

   January 28, 2003 Update issue(s) result-truncation, JW24d. Fixed
      response headers in OPTIONS example. Added issue qsd-optional.
      Closed issue(s) order-precedence, case-insensitivity-name.

   February 07, 2003 Added issue scope-vs-versions.
      score-pseudo-property: allow DAV:orderby to explicitly specify
      DAV:score.


B.6 since draft-reschke-webdav-search-03






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   April 24, 2003 Fixed two "?" vs "_" issues (not updated in last
      draft).

   June 13, 2003 Improve index.


B.7 since draft-reschke-webdav-search-04

   July 7, 2003 Typo fixed (propstat without status element).

   August 11, 2003 Remove superfluous IP and copyright sections.

   September 09, 2003 Added issues "2.4-multiple-uris" and
      "5.1-name-filtering".

   October 06, 2003 Fix misplaced section end in 5.11, add table
      formatting. Enhance table formatting in 5.18.3. Updated ACL and
      BIND references. Added XPATH reference. Closed issue JW24d by
      adding new optional operators. Updated more open issues, added
      issues from January meeting. Add K. Wiggen to Acknowledgements.
      Add Contributors section for the authors of the original draft.
      Close issue "scope-vs-versions" (optional feature added). Close
      (new) issue "1.3-import-DTD-terminology". Add issue
      "1.3-import-requirements-terminology".

   October 07, 2003 Typos fixed. Moved statement about DAV: namespace
      usage into separate (sub-)section. Closed
      "1.3-import-requirements-terminology". Update I18N Considerations
      with new xml:lang support info (see issue JW24d). Close issue
      "DB2/DB7" (remaining typing issues are now summarized in issue
      "typed-literal"). Fix misplaced section end in section 7. Started
      change to use RFC3253-style method definitions and error
      marshalling.

   October 08, 2003 Remove obsolete language that allowed reporting
      invalid scopes and such inside multistatus. Add new issue
      "5.4.2-scope-vs-redirects".














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Appendix C. Resolved issues (to be removed by RFC Editor before
            publication)

   Issues that were either rejected or resolved in this version of this
   document.

C.1 1.3-import-condition-code-terminology

   Type: change

   [3]

   julian.reschke@greenbytes.de (2003-10-05): Import RFC3253 pre/
   postcondition code terminology and use it throughout the document to
   identify conditions.

   Resolution: Section 2.5 rewritten.

C.2 1.3-import-requirements-terminology

   Type: change

   julian.reschke@greenbytes.de (2003-10-06): Import terminology from
   DASLREQ.

   Resolution: Done.

C.3 1.3-import-DTD-terminology

   Type: change

   [4]

   julian.reschke@greenbytes.de (2003-09-27): Import DTD usage notes
   from ordering spec.

C.4 invalid-scope

   Type: change

   julian.reschke@greenbytes.de (2003-01-09): Marshalling a BAD REQUEST
   with an (extended) multistatus body seems to be a weird approach.
   Should be resolved by finally adopting the RFC3253 error marshalling.

   julian.reschke@greenbytes.de (2003-01-28): Funny enough, Roy
   Fielding's feedback on a related issue indicates that this may be the
   absolutely right thing to do. Needs coordination with RFC2518bis
   activity.



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   Resolution: Document style change to use RFC3253 preconditions.

C.5 JW24d

   Type: edit

   [5]

   ejw@ics.uci.edu (2000-04-20): Where does xml:lang go in a query?

   julian.reschke@greenbytes.de (2002-02-28): What would be the
   *purpose* of putting xml:lang into a query?

   jrd3@alum.mit.edu (2002-05-28): The purpose is to allow one to
   express queries more precisely, e.g. to distinguish between the
   English word "hoop" (a circular object) and Dutch "hoop" (hope).
   Imagine a property that holds keywords for a resource.   See 4.4 in
   http://www.ietf.org/rfc/rfc2518.txt, and 2.12 in http://www.w3.org/
   TR/REC-xml

   julian.reschke@greenbytes.de (2002-05-28): I think this would be an
   interesting feature, but it seems to be extremely hard to implement.
   So assuming a query that - the query specifies a language and - be
   the text content of the property matches The result will be: 1) true
   (match), if the property was stored with a matching xml:lang property
   (where the language tag matching rules would have to apply) 2)
   undefined if the property was stored without xml:lang 3) false
   otherwise On the other hand if - the query doesn't specify a language
   the result will be: 4) undefined (at least according to the current
   wording). So, 1) requires that the query engine actually knows how to
   match language tags -- I'm not sure that everybody is willing to
   implement that. 2) is this desirable? 3) ok. 4) that seems to be
   wrong. If the query doesn't care, it should match, right? Other
   problems: - what is the language of a date-typed property? - (sic!)
   where should xml:lang go into the query? There's no XML feature to
   undefine an xml:lang which is in scope, but there may be cases where
   this is needed. On the other hand, if we drop this requirement, a
   client can still do a query and then process the result set -- the
   property elements in the response body will be reported with xml:lang
   (when persisted with language) anyway. So I'd recommend to drop the
   feature. Defining string comparisons vs. collation sequences is hard
   enough.

   julian.reschke@greenbytes.de (2003-01-09): (Proposal to reject)

   julian.reschke@greenbytes.de (2003-01-28): WG meeting feedback:
   should be moved into explicit operators (see proposal on mailing
   list). Open: is this optional or required?



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   Resolution: Add new optional operators.

C.6 scope-vs-versions

   Type: change

   [6]

   julian.reschke@greenbytes.de (2003-02-05): A relatively frequent use
   case for servers that both support versioning and DASL seems to have
   searches that include all versions of the resources in scope. In
   general, the version URIs may not be in the scope of the query.
   Therefore, I'd like to extend the DAV:scope to specify inclusion of
   versions. This would be an optional extension -- however, a server
   that does not support his feature should reject the request (so that
   the client would know that the request could not be satisfied).
   Example: <d:from xmlns:d="DAV:"> <d:scope> <d:href>/container1/</
   d:href> <d:depth>infinity</d:depth> <d:include-versions /> </d:scope>
   </d:from>

   Martin.Wallmer@softwareag.com (2003-02-06): just to clarify: 1. If a
   resource in scope has versions, the server SHOULD take care of
   versions as well. 2. If the client specifies <d:include-versions />,
   the server MUST take care of versions or MUST reject the request. 3.
   If the user does not want to get versions, he must specify <not
   xmlns="DAV:"><is-defined><version-name /></is-defined></not> ... Is
   my understanding correct? However, a defined "switch" (include -
   exclude) could be a good hint for the server in terms of performance,
   so I'd prefer a <d:exclude-versions/> as well. Alternatively the
   server should only include the versions, if <d:include-versions /> is
   specified. Does this make sense?

   julian.reschke@greenbytes.de (2003-02-06): I don't like that, because
   I'd prefer to keep the definition of "scope" intact. If versions
   happen to be in the namespace scope, they should be in scope of the
   search as well. Thus the proposal to add a specific element that
   *extends* the scope of the query.

C.7 DB2/DB7

   Type: change

   [7]

   ejw@ics.uci.edu (2000-04-20): Dates (HTTPDate in getlastmodified).

   ejw@ics.uci.edu (2000-04-20): Agreement that it is OK to submit
   isodate to search HTTPDate (i.e., it's a marshalling issue only).



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   ejw@ics.uci.edu (2000-04-20): Booleans appear to be underspecified in
   the specification. How is a boolean tested, and what are the behavior
   of operators like less than, greater than, etc.

   julian.reschke@greenbytes.de (2002-01-28): I think similar questions
   apply to booleans. Proposal: allow specification of the literal's
   type using XML Schema simple types, and declare that "both" WebDAV
   date types are compatible.

   ABabich@filenet.com (2002-01-29): The current DASL draft doesn't
   really have Booleans or any other data type. It's trying to skate on
   data types. Booleans could be tested using the "eq" and the
   combination "not eq", if you had well defined literals for TRUE and
   FALSE. With the current syntax, that is the way you would have to
   test a Boolean. Generally, Boolean values are not considered to be
   ordered, so "gt" etc. wouldn't apply. However, if the literal values
   of a Boolean were 1 and 0 for TRUE and FALSE (using the most commonly
   used convention of positive logic), then you would have an obvious
   ordering. 1 and 0 have the advantage of being language independent.
   You now see a lot of electronic and electro-mechanical devices (air
   conditioners, computers, etc.) with a "1/0" label on the power
   switch, "1" meaning "on", and "0" meaning "off". SQL databases don't
   have Booleans. SQL doesn't control DASL, of course, but SQL databases
   are so widely used that they are important. The closest thing in SQL
   is a bit field. Each bit in a bit field is zero or 1. So, why not
   close the issue by saying: DASL doesn't have data types. You can
   simulate Booleans by an integer data type, using 1 for "TRUE" and 0
   for "FALSE".

   julian.reschke@greenbytes.de (2002-10-22): let's consider a dead
   property "foo", and some resources a, b and c on which this dead
   property is defined and has the values "1", "3" and "10". Consider a
   DAV:basicsearch with the where clause: <gte xmlns="DAV:"> <prop><foo
   xmlns=""/></prop> <literal>3</literal> </gte> Which resource will
   match? As DAV:basicsearch currently isn't type-aware, the server will
   have to do a string comparison, and only the b (with value "3") will
   match. Is this really sufficient? It basically means that dead
   property comparisons are restricted to strings. Proposals: a) If the
   server happens to have type information for a dead property, it
   should try to do a comparison according to the known property type,
   if the literal can be parsed into this type. This basically
   replicates the behaviour that a client would expect when querying on
   live properties such as DAV:getcontentlength, so it could be taken as
   a simple clarification. Extended proposal: b) A client can enforce
   comparison using a specific data type by specifying the type in the
   query, for instance using: <gte xmlns="DAV:"> <prop><foo xmlns=""/></
   prop> <literal xsi:type="xs:long">3</literal> </gte>




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   Martin.Wallmer@softwareag.com (2002-11-25): What about existing
   implementations? Currently a server might react with "xsi:type
   unknown entity" or just ignore it (which would mean: String
   comparison)

   julian.reschke@greenbytes.de (2002-11-25): OK, how about *adding* an
   alternative to DAV:literal? Therefore: DAV:literal: untyped, server
   can compare according to it's internal knowledge of types (with the
   clarification above) DAV:typed-literal: typed according to the
   xsi:type attribute -- "new" servers can implement this without
   affecting any existing code. We'll need to think about discovery of
   this feature, though. It might be possible to do this with QSD (in
   the meantime, are there any QSD implementations except ours?)

   Resolution: WG meeting feedback: define DAV:typed-literal. Also allow
   DAV:literal to be evaluated by the server according "internal" type
   knowledge. Require timestamps to be ISO, even for
   DAV:getlastmodified.

































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Appendix D. Open issues (to be removed by RFC Editor before publication)

D.1 1.3-apply-condition-code-terminology

   Type: change

   julian.reschke@greenbytes.de (2003-10-07): (Umbrella issue that will
   be left open until RFC3253 condition terminlogy is used throughout
   the document)

D.2 2.4-multiple-uris

   Type: change

   julian.reschke@greenbytes.de (2003-09-09): However, the set of URIs
   for a given resource may be unlimited due to possible bind loops.
   Therefore consider to report just one URI per resource.

D.3 result-truncation

   Type: change

   [8]

   ldusseault@xythos.com (2002-03-29): I believe the same response body
   that contains the first N <DAV:response> elements should also contain
   a *different* element stating that the results were incomplete and
   the result set was truncated by the server. There may also be a need
   to report that the results were incomplete and the result set was
   truncated at the choice of the client (isn't there a limit set in the
   client request?)  That's important so the client knows the difference
   between receiving 10 results because there were >10 but only 10 were
   asked for, and receiving 10 results because there were only exactly
   10 results and it just happens that 10 were asked for.

   jrd3@alum.mit.edu (2002-05-28): I agree that this could be useful,
   but I think this issue should be consolidated with issue JW5 (see
   below), which proposes that DASL basicsearch ought to have a way for
   client to request additional result sets.  It should be moved because
   there is little or no value in allowing a client to distinguish
   between the case where "N results were requested, and there are
   exactly N available" and "N results were requested, and there are
   more than N available" if there is no way for client to get the next
   batch of results.

   julian.reschke@greenbytes.de (2003-01-28): Feedback from interim WG
   meeting: agreement that marshalling should be rewritten and backwards
   compatibility is not important. Proposal: extend DAV:multistatus by a



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   new child element that indicates (1) the range that was returned, (2)
   the total number of results and (3) a URI identifying the result (for
   resubmission when getting the "next" results). Such as <multistatus
   xmlns='DAV:'> <search-result> <href>...identifier for result set...</
   href> <total><-- number of results --></total> <start><-- 1-based
   index of 1st result --></start> <length><-- size of result set
   returned --></length> <partial-result/><-- indicates that this is a
   partial result --> </search-result> ...response elements for search
   results... </multistatus> The example below would then translate to:
   HTTP/1.1 207 Multistatus Content-Type: text/xml; charset="utf-8"
   Content-Length: xxx <?xml version="1.0" encoding="utf-8"?>
   <D:multistatus xmlns:D="DAV:"> <D:search-result> <D:partial-result/>
   </D:search-result> <D:response> <D:href>http://www.example.net/
   sounds/unbrokenchain.au</D:href> <D:propstat> <D:prop/>
   <D:status>HTTP/1.1 200 OK</D:status> </D:propstat> </D:response>
   <D:response> <D:href>http://tech.mit.test/archive96/photos/
   Lesh1.jpg</D:href> <D:propstat> <D:prop/> <D:status>HTTP/1.1 200 OK</
   D:status> </D:propstat> </D:response> </D:multistatus> Q: do we need
   all elements, in particular start and length?

   julian.reschke@greenbytes.de (2003-10-07): Related: if this is
   supposed to be normative to DAV:basicsearch, it can't stay in an
   "example" sub-section.

D.4 qsd-optional

   Type: change

   julian.reschke@greenbytes.de (2003-01-28): WG January meeting
   feedback: QSD should be made required.

   kwiggen@xythos.com (2003-10-03): (significant pushback, see mailing
   list thread at http://lists.w3.org/Archives/Public/www-webdav-dasl/
   2003OctDec/0003.html).

D.5 5.1-name-filtering

   Type: change

   [9]

   julian.reschke@greenbytes.de (2003-09-08): This query grammar
   supports properties and content, but not conditions on URL elements
   (such as the last segment that many WebDAV implementations treat as
   "file name"). Discuss possible extension such as adding name filters
   to the scope, or adding a specific operator.





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D.6 5.4.2-multiple-scope

   Type: change

   [10]

   prakash.yamuna@covigna.com (2003-09-27): (asks for the ability to
   specify multiple scopes in a single query)

   julian.reschke@greenbytes.de (2003-10-03): Consider making this an
   optional extension iff we can come up with a simple enough definition
   of it's impact on sorting/ranking and so on. Otherwise propose to
   reject.

D.7 5.4.2-scope-vs-redirects

   Type: change

   [11]

   julian.reschke@greenbytes.de (2003-10-08): Clarify the relation of
   scope and redirect (3xx) resources.

D.8 language-comparison

   Type: change

   [12]

   julian.reschke@greenbytes.de (2002-03-03): XPath/XQuery (see draft,
   and open issue) specify string comparisons based on collations, not
   languages. I think we should adopt this. This would mean that
   "xml:lang" would be removed, and an optional attribute specifying the
   name of the collation is added.

   julian.reschke@greenbytes.de (2003-01-09): Proposal: adopt "lang" and
   "collation" attribute from XSLT 2.0's xsl:sort.

D.9 JW16b/JW24a

   Type: change

   [13]

   ejw@ics.uci.edu (2000-04-20): Define how comparisons on strings work,
   esp for i18n. Need policy statement about sort order in various
   national languages. (JW said "non-Latin" but it's an issue even in
   languages that use the latin char set.)



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   julian.reschke@greenbytes.de (2003-01-28): This issue not only
   applies to the comparison operators, but also to ordering!

D.10 typed-literal

   Type: change

   julian.reschke@greenbytes.de (2003-01-15): 1. (insert language
   defining the comparison following the rules defined in http://
   www.w3.org/TR/xpath20/#id-comparisons). 2. Extend Basicsearch QSD
   grammar to support discovery of typed-literal 3. Update DTD. 4.
   Discuss behaviour of DAV:literal when the property's type is known
   for the complete search scope (is the server allowed to be "smart"?)






































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Index

C
   caseless attribute  27, 33
   Criteria  5

D
   DAV:and  27
   DAV:ascending  26
   DAV:contains  31
   DAV:depth  23
   DAV:descending  26
   DAV:eq  27
      caseless attribute  27
   DAV:from  23
   DAV:gt  27
   DAV:gte  27
   DAV:include-versions  23
   DAV:is-collection  30
   DAV:is-defined  30
   DAV:language-defined  29
   DAV:language-matches  29
   DAV:like  30
   DAV:limit  33
   DAV:literal  27
   DAV:lt  27
   DAV:lte  27
   DAV:not  27
   DAV:nresults  33
   DAV:or  27
   DAV:orderby  26
   DAV:scope  23
   DAV:score  32
      relationship to DAV:orderby  33
   DAV:search-grammar-discovery-supported precondition  10
   DAV:search-grammar-supported precondition  10
   DAV:search-scope-valid precondition  10
   DAV:select  23
   DAV:supported-query-grammar-set
      property  15
   DAV:typed-literal  28
   DAV:where  24

O
   OPTIONS method  14
      DASL response header  14

P



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   Preconditions
      DAV:search-grammar-discovery-supported  10
      DAV:search-grammar-supported  10
      DAV:search-scope-valid  10

Q
   Query Grammar Discovery  14
      using live property  15
      using OPTIONS  14
   Query Grammar  6
   Query Schema  6
   Query  5

R
   Result Record Definition  6
   Result Record  6
   Result Set Truncation
      Example  11
   Result Set  6
   Result  6

S
   Scope  6
   SEARCH method  9
   Search Modifier  6
   Sort Specification  6

























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