--- 1/draft-ietf-webdav-quota-01.txt 2006-02-05 02:11:23.000000000 +0100 +++ 2/draft-ietf-webdav-quota-02.txt 2006-02-05 02:11:23.000000000 +0100 @@ -1,18 +1,18 @@ B. Korver Xythos L. Dusseault Xythos Internet Draft C. Warner - Document: draft-ietf-webdav-quota-01.txt Netezza - Expires: September 2003 March 2003 + Document: draft-ietf-webdav-quota-02.txt Netezza + Expires: January 2004 July 2003 Quota and Size Properties for DAV Collections 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 @@ -33,35 +33,35 @@ Abstract WebDAV servers are frequently deployed with quota (size) limitations. This Internet-Draft discusses the properties and minor behaviors needed for clients to interoperate with quota implementations on WebDAV repositories. Table of Contents Introduction.......................................................2 - DAV:quota-limit-bytes..............................................3 - DAV:quota-used-bytes...............................................3 + DAV:quota-available-bytes..........................................3 + DAV:quota-used-bytes...............................................4 DAV:quota-assigned-bytes...........................................4 Example PROPFIND request and response..............................5 Error reporting....................................................6 Notes..............................................................6 Security Considerations............................................7 Internationalization Considerations................................7 IANA Considerations................................................7 - Dusseault Expires March 2003 1 + Dusseault Expires July 2003 1 - DAV Collection Size and Quota January 2003 + DAV Collection Size and Quota July 2003 - Intellectual Property..............................................7 + Intellectual Property..............................................8 Acknowledgements...................................................8 References.........................................................9 Author's Addresses.................................................9 Introduction Notational Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this @@ -85,266 +85,279 @@ - Sometimes the storage service is provided free, but the storage service provider has limited storage space (e.g. www.sharemation.com and university-provided student accounts) - Even in cases where the storage can be upgraded, the storage managers may choose to limit quota in order to encourage users to limit the files they store on the system and to clean up obsolete files. (e.g. IT departments within corporations). In order to work best with repositories that support quotas, client - software should be able to determine and display the quota-limit on - collections. Further, client software should have some way of + software should be able to determine and display the quota-available + on collections. Further, client software should have some way of fairly reliably determining how much storage space is already counted towards that quota. - In addition to displaying the quota-limit and quota-used on + In addition to displaying the quota-available and quota-used on collections, this specification does not forbid these properties on any resource. Solution Overview The approach to meeting the requirements and scenarios outlined above is to define three live properties. This specification can be - Korver Expires Jul 2003 2 + Korver Expires January 2004 2 - DAV Collection Size and Quota January 2003 + DAV Collection Size and Quota July 2003 - met on a server by implementing both quota-limit and quota-used on - collections only. Implementing both quota-limit and quota-used on - all resources is recommended. + met on a server by implementing both quota-available and quota-used + on collections only. Implementing both quota-available and quota- + used on all resources is RECOMMENDED. None of these properties need be returned in a request though the server may include them. However, these property names MUST be returned in a request for a resource that supports the properties, except in the case of infinite limits which are explained below. - The definitions below for quota-limit and quota-used borrow heavily - from the definition of quota in the NFS [RFC3010] specification. + The quota-available and quota-used definitions below borrow heavily + from the quota definitions in the NFS [RFC3010] specification. -DAV:quota-limit-bytes +DAV:quota-available-bytes - Name: quota-limit-bytes + Name: quota-available-bytes Namespace: DAV: - Purpose: Indicates the total amount of storage potentially - allocated. - DTD: + Purpose: Indicates the maximum amount of additional storage + available to be allocated to a resource. + DTD: - The DAV:quota-limit-bytes property value is the total amount of - storage space potentially allocated to this file or directory, - measured in octets. + The DAV:quota-available-bytes property value is the value in octets + representing the amount of additional disk space beyond the current + allocation that can be allocated to this file or directory before + further allocations will be refused. It is understood that this + space may be consumed by allocations to other files or directories. Support for this property is REQUIRED on collections, and OPTIONAL on other resources. A server SHOULD implement this property for each resource that has the DAV:quota-used-bytes property. - A value of 0 indicates that storage is limited to 0. Users will + Clients SHOULD expect that as the quota-available on a file or + directory approaches 0, further allocations to that file or + directory may be refused. A value of 0 indicates that users will probably not be able to perform operations that write additional information (e.g. a PUT inside a collection), but may be able to replace through overwrite an existing resource of equal size. - If a resource has no quota enforced or unlimited storage, the server - MAY choose not to return this property (404 Not Found response in - Multi-Status), although this specification RECOMMENDS that servers - return some appropriate value (e.g. the amount of free disc space). - A client cannot entirely assume that there is no quota enforced on a - resource that does not have this property, but might as well act as - if there is no quota. + Note that there may be a number of distinct but overlapping limits, + which may even include physical media limits. When reporting quota- + available, the server is at liberty to choose any of those limits + but SHOULD do so in a repeatable way. The rule may be configured + per repository, or may be Œchoose the smallest numberŽ. + + If a resource has no quota enforced or unlimited storage (Œinfinite + limitsŽ), the server MAY choose not to return this property (404 Not + Found response in Multi-Status), although this specification + RECOMMENDS that servers return some appropriate value (e.g. the + amount of free disc space). A client cannot entirely assume that + there is no quota enforced on a resource that does not have this + property, but might as well act as if there is no quota. + + Korver Expires January 2004 3 + + DAV Collection Size and Quota July 2003 The value of this property is protected. A 403 Forbidden response is RECOMMENDED for attempts to write a protected property. DAV:quota-used-bytes Name: quota-used-bytes Namespace: DAV: - Purpose: Contains the amount of storage counted against the quota- - limit of a resource. + Purpose: Contains the amount of storage counted against the quota on + a resource. DTD: - Korver Expires Jul 2003 3 - - DAV Collection Size and Quota January 2003 - The DAV:quota-used-bytes value is the value in octets representing the amount of space used by this file or directory and possibly a number of other similar files or directories, where the set of - ôsimilarö meets at least the criterion that allocating space to any - file or directory in the set will count against the quota-limit. It - MUST include the total count including usage derived from sub- + ŒsimilarŽ meets at least the criterion that allocating space to any + file or directory in the set will count against the quota-available. + It MUST include the total count including usage derived from sub- resources if appropriate. It SHOULD include metadata storage size - if metadata storage is counted against the quota-limit. - - Clients SHOULD expect that once the quota-used on a file or - directory meets or exceeds the quota-limit, further allocations to - that file or directory will be refused. A resource may show more - quota-used than its quota-limit or quota-assigned appears to allow. + if metadata storage is counted against the quota-available. Note that there may be a number of distinct but overlapping sets of - files or directories for which a quota-used is maintained (e.g. ôall - files with a given ownerö, ôall files with a given group ownerö, + files or directories for which a quota-used is maintained (e.g. Œall + files with a given ownerŽ, Œall files with a given group ownerŽ, etc.). The server is at liberty to choose any of those sets but SHOULD do so in a repeatable way. The rule may be configured per - repository, or may be ôchoose the set with the smallest quotaö. + repository. Support for this property is REQUIRED on collections, and OPTIONAL on other resources. A server SHOULD implement this property for - each resource that has the DAV:quota-limit-bytes property. + each resource that has the DAV:quota-available-bytes property. Support for this property enhances the client experience, because - together with DAV:quota-limit-bytes, the client has a chance of + together with DAV:quota-available-bytes, the client has a chance of managing its files to avoid running out of allocated storage space. Clients may not be able to calculate the value as accurately on their own, depending on how total space used is calculated by the server. DAV:quota-assigned-bytes Name: quota-assigned-bytes Namespace: DAV: Purpose: Indicates the amount of storage assigned. DTD: The DAV:quota-assigned-bytes property value is the amount of storage space potentially either assigned to or requested for this file or - directory, measured in octets. + directory, measured in octets. DAV:quota-assigned-bytes is primarily + intended to support implementations that allow quota to be + PROPPATCHed or configured by some other means. The value of this property will usually be protected, although a user with sufficient privileges may be permitted to change the + + Korver Expires January 2004 4 + + DAV Collection Size and Quota July 2003 + value. The property is useful even if it is protected. A 403 Forbidden response is RECOMMENDED for attempts to write a protected - property. + property. This property will usually be read-only for instance + because a users quota should generally not configurable by other + users. Support for this property is OPTIONAL. Note that a resource may show more quota-used than its quota- - assigned appears to allow, and that quota-assigned MUST NOT be less - - Korver Expires Jul 2003 4 + assigned appears to allow, and that quota-available MUST never be + greater than the value of quota-assigned. - DAV Collection Size and Quota January 2003 + As an example of quota-assigned, imagine a quota system where each + collection may have a quota assigned and where a resource contained + in a collection is subject to the quota constraints of all parent + collections. Assume the administrator creates a collection A and + gives it a quota-assigned of 500KB and then creates a sub- + collections B which is given quota-assigned of 1000KB. In this + case, the initial quota-available for B is 500KB, not 1000KB, since + the constraint on A applies to B as well. - than the quota-limit. Servers which receive a request to change - quota-assigned to a value less than quota-limit MUST reduce quota- - limit to this value at the same time. + DAV:quota-assigned-bytes DAV:quota-available-bytes + /A 500KB 500KB + /A/B 1000KB 500KB - For many quota systems, quota-assigned is synonymous with quota- - limit. However, in any system, quota-limit is a hard limit. For - example, imagine a quota system where each collection may have a - quota assigned and where a resource contained in a collection is - subject to the quota constraints of all parent collections. Assume - the administrator creates a collection A and gives it a quota- - assigned of 1,000,000 bytes and then creates a sub-collections B - which is given quota-assigned of 10,000,000 bytes. In this case, - the quota-limit for B is 1,000,000 bytes. + Note that this is only one example quota system, and that other + quota systems are possible. Example PROPFIND request and response Request: PROPFIND /~milele/public/ HTTP/1.1 Depth: 0 Host: www.sharemation.com Content-Type: text/xml Content-Length: xxx - + Response: HTTP/1.1 207 Multi-Status Date: Tue, 16 Oct 2001 22:13:39 GMT Content-Length: xxx Content-Type: text/xml; charset=UTF-8 + + Korver Expires January 2004 5 + + DAV Collection Size and Quota July 2003 + http://www.sharemation.com/~milele/public/ - 1000000 + 596650 403350 HTTP/1.1 200 OK - Korver Expires Jul 2003 5 - - DAV Collection Size and Quota January 2003 - Error reporting WebDAV (RFC2518) defines the status code 507 (Insufficient Storage). This status code SHOULD be used when a client request (e.g. a PUT, PROPFIND, MKCOL, MOVE or COPY) is forbidden because it would exceed their allotted quota. In order to differentiate the response from other storage problems, the server SHOULD include an XML error body as defined by DeltaV [RFC3253] with the precondition tag. Example error response: HTTP/1.1 507 Insufficient Storage Content-Length: 100 Content-Type: text/xml - - + + Notes Server implementations store and account for their data in many different ways. Some of the challenges: - Some server implementations find it prohibitive to count storage used for metadata, others may choose to do so for better accounting. - Older versions of resources may be stored as well. - Variants of one resource may exist with different content lengths - Content may be dynamically generated. - Resource bodies can be compressed - - Some resources may be stored for ôfreeö, not counting against + - Some resources may be stored for ŒfreeŽ, not counting against quota. Since server storage accounting can vary so much, clients should expect the following: - - The size of a file on the clientÆs file system, or in a PUT + Korver Expires January 2004 6 + + DAV Collection Size and Quota July 2003 + + - The size of a file on the clients file system, or in a PUT message, may not correspond to the amount of storage required by the server to store the resource. Thus, the client cannot predict with 100% accuracy whether a given file will be allowed given the storage quota. - Deleting or overwriting a resource may not free up the same amount of storage as indicated by the DAV:getcontentlength property defined in [RFC2518] for the resource. If deleting a resource does - not free up any space, the file may have been moved to a ôtrashö - - Korver Expires Jul 2003 6 - - DAV Collection Size and Quota January 2003 - - folder or ôrecycle binö, or retained as in versioning systems + not free up any space, the file may have been moved to a ŒtrashŽ + folder or Œrecycle binŽ, or retained as in versioning systems [RFC3253]. - The total size of a collection, DAV:quota-used-bytes, is not necessarily a sum of the DAV:getcontentlength properties for resources stored in the collection. - On some systems where quota is counted by collection and not by user, a quota on a sub-collection may be larger than the quota on its parent collection that contains it. For example, the quota on /~milele/ may be 100 MB, but the quota on /~milele/public/ may be @@ -372,84 +385,86 @@ Internationalization Considerations Quota is counted in Arabic numerals expressed in strings. There are no internationalization considerations. IANA Considerations There are no IANA considerations. + Korver Expires January 2004 7 + + DAV Collection Size and Quota July 2003 + Intellectual Property The following notice is copied from [RFC2026], and describes the position of the IETF concerning intellectual property claims made against this document. The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it - - Korver Expires Jul 2003 7 - - DAV Collection Size and Quota January 2003 - has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards-related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Acknowledgements - Jim Whitehead and Jim Luther provided valuable comments on this - document. + Stefan Eissing, Jim Luther, Julian Reschke, and Jim Whitehead and + provided valuable comments on this document. - Korver Expires Jul 2003 8 + Korver Expires January 2004 8 - DAV Collection Size and Quota January 2003 + DAV Collection Size and Quota July 2003 References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. - [RFC2026] Bradner, S., ôThe Internet Standards Process û Revision - 3ö, BCP 9, RFC2026, October 1996. + [RFC2026] Bradner, S., ŒThe Internet Standards Process ± Revision + 3Ž, BCP 9, RFC2026, October 1996. [RFC2518] Goland, Y., Whitehead, E., Faizi, A., Carter, S., and Jensen, D., "HTTP Extensions for Distributed Authoring -- WebDAV", RFC2518, February 1999. [RFC3010] Shepler S., B. Callaghan, D. Robinson, R. Thurlow, C. - Beame, M. Eisler, D. Noveck, ôNFS version 4 Protocolö, RFC3010, + Beame, M. Eisler, D. Noveck, ŒNFS version 4 ProtocolŽ, RFC3010, December 2000. Author's Addresses Brian Korver Xythos Software, Inc. - 77 Maiden Lane, Suite 200 Phone: 1-415-248-9033 + 25 Maiden Lane, Suite 200 Phone: 1-415-248-9033 San Francisco, CA, USA Email: briank@xythos.com Lisa Dusseault Xythos Software, Inc. - 77 Maiden Lane, Suite 200 Phone: 1-415-248-9004 + 25 Maiden Lane, Suite 200 Phone: 1-415-248-9004 San Francisco, CA, USA Email: lisa@xythos.com Clark Warner Netezza Corporation 200 Crossing Blvd. Phone: 1-508-665-6800 x889 Framingham, MA 01702 Email: webdav@thewarners.com - Korver Expires Jul 2003 9 + Korver Expires January 2004 9 + +-brian +briank@xythos.com