Network Working Group J. Gregorio, Ed. Internet-Draft Intended status: Standards Track M. Hadley, Ed. Expires: January 10, 2008 Sun Microsystems M. Nottingham, Ed. D. Orchard BEA Systems, Inc. July 9, 2007 URI Template draft-gregorio-uritemplate-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. 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 January 10, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract URI Templates are strings that can be transformed into URIs after embedded variables are substituted. This document defines the syntax and processing of URI Templates. Gregorio, et al. Expires January 10, 2008 [Page 1] Internet-Draft URI Template July 2007 Editorial Note To provide feedback on this Internet-Draft, join the W3C URI mailing list (http://lists.w3.org/Archives/Public/uri/) [1]. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 3. URI Template . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Template Variables . . . . . . . . . . . . . . . . . . . . 4 3.2. URI Template Substitution . . . . . . . . . . . . . . . . . 4 3.3. Using URI Templates . . . . . . . . . . . . . . . . . . . . 5 3.3.1. Examples . . . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 6. Normative References . . . . . . . . . . . . . . . . . . . . . 7 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . . 7 Appendix B. Revision History . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . . . 9 Gregorio, et al. Expires January 10, 2008 [Page 2] Internet-Draft URI Template July 2007 1. Introduction URI Templates are strings that contain embedded variables that are transformed into URIs after embedded variables are substituted. This is useful when it's necessary to convey the structure of a URI in a well-defined way. For example, documentation of an interface exposed by a Web site might use a template to show people how to find information about a user; http://www.example.com/users/{userid} URI Templates can also be thought of as the basis of a machine- readable forms language; by allowing clients to form their own identifiers based on templates given to them by the URI's authority, it's possible to construct dynamic systems that use more of the URI than traditional HTML forms are able to. For example, http://www.example.org/products/{upc}/buyers?page={page_num} Finally, URI Templates can be used to compose URI-centric protocols without impinging on authorities' control of their URIs. For example, there are many emerging conventions for passing around login information between sites using URIs. Forcing people to use a well- known query parameter isn't good practice, but using a URI parameter allows different sites to specify local ways of conveying the same information; http://login.example.org/login?back={return-uri} http://auth.example.com/userauth;{return-uri} This specification defines the basic syntax and processing of URI Templates. Each application of URI Templates will need to define its own profile of this specification that indicates what template variables are available, how to convey them to clients, and what their appropriate use is in that context. 2. Notational Conventions 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 specification uses the Augmented Backus-Naur Form (ABNF) notation of [RFC4234]. See [RFC3986] for the definitions of the URI- reference, reserved, and unreserved rules. Gregorio, et al. Expires January 10, 2008 [Page 3] Internet-Draft URI Template July 2007 3. URI Template A URI Template is a sequence of characters that contains one or more embedded template variables, see Section 3.1. A URI Template becomes a URI when the template variables are substituted with their values (see Section 3.2). For example: http://example.com/widgets/{widget_id} If the value of the widget_id variable is "xyzzy", the resulting URI after substitution is: http://example.com/widgets/xyzzy 3.1. Template Variables Template variables are the parameterized components of a URI Template. A template variable MUST match the template-var rule. template-char = unreserved template-name = 1*template-char template-var = "{" template-name "}" 3.2. URI Template Substitution Evaluating a URI Template ("substitution") consists of replacing all template variables with their respective string values. During substitution, the string value of a template variable MUST have any characters that do not match the reserved or unreserved rules (i.e., those characters not legal in URIs without percent encoding) percent-encoded, as per [RFC3986], section 2.1. Specific applications of URI Templates MAY specify additional constraints and encoding rules in addition to this. Any number of template variables MAY appear in a URI Template; a single template-name MAY appear multiple times. The result of substitution MUST match the URI-reference rule and SHOULD also match any known rules for the scheme of the resulting URI. Typically, this is ensured by the definitions of the template variables used. For example, they may specify that a variable's value is not to contain certain characters, or that some characters should be percent-encoded before substitution. Gregorio, et al. Expires January 10, 2008 [Page 4] Internet-Draft URI Template July 2007 3.3. Using URI Templates Applications using URI Templates will typically need to specify a number of things, including; o The template to use. o What template variables are available. o For each of the variables; * What characters are allowed in the template's value. * What encodings should be applied to the value before substitutions. * How to handle errors such as the output of substitution being an invalid URI. URI Template processors SHOULD allow applications to indicate that; o A variable's value is required to contain at least one character o A variable's value is required to match one of a set of supplied options o A variable's value is to have all reserved characters, as per RFC3986, percent-escaped before substitution Processors MAY make additional options available. 3.3.1. Examples Given the following template names and values: +--------+--------------------------+ | Name | Value | +--------+--------------------------+ | a | fred | | b | barney | | c | cheeseburger | | d | one two three | | e | 20% tricky | | f | | | 20 | this-is-spinal-tap | | scheme | https | | p | quote=to+be+or+not+to+be | | q | hullo#world | +--------+--------------------------+ Table 1 (Note that the name 'wilma' has not been defined, and the value of 'f' is the empty string.) Gregorio, et al. Expires January 10, 2008 [Page 5] Internet-Draft URI Template July 2007 The following URI Templates will be expanded as shown: http://example.org/page1#{a} http://example.org/page1#fred http://example.org/{a}/{b}/ http://example.org/fred/barney/ http://example.org/{a}{b}/ http://example.org/fredbarney/ http://example.com/order/{c}/{c}/{c}/ http://example.com/order/cheeseburger/cheeseburger/cheeseburger/ http://example.org/{d} http://example.org/one%20two%20three http://example.org/{e} http://example.org/20%25%20tricky http://example.com/{f}/ http://example.com// {scheme}://{20}.example.org?date={wilma}&option={a} https://this-is-spinal-tap.example.org?date=&option=fred http://example.org?{p} http://example.org?quote=to+be+or+not+to+be http://example.com/{q} http://example.com/hullo#world 4. Security Considerations A URI Template does not contain active or executable content. Other security considerations are the same as those for URIs, see section 7 of RFC3986. 5. IANA Considerations In common with RFC3986, URI scheme names form a registered namespace that is managed by IANA according to the procedures defined in [RFC4395]. No IANA actions are required by this document. Gregorio, et al. Expires January 10, 2008 [Page 6] Internet-Draft URI Template July 2007 6. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005. [RFC4395] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and Registration Procedures for New URI Schemes", BCP 115, RFC 4395, February 2006. [1] Appendix A. Contributors The following people made significant contributions to this specification: DeWitt Clinton and James Snell. Appendix B. Revision History 01 00 - Initial Revision. Authors' Addresses Joe Gregorio (editor) Email: joe@bitworking.org URI: http://bitworking.org/ Marc Hadley (editor) Sun Microsystems Email: Marc.Hadley@sun.com URI: http://sun.com/ Gregorio, et al. Expires January 10, 2008 [Page 7] Internet-Draft URI Template July 2007 Mark Nottingham (editor) Email: mnot@pobox.com URI: http://mnot.net/ David Orchard BEA Systems, Inc. Email: dorchard@bea.com URI: http://bea.com/ Gregorio, et al. Expires January 10, 2008 [Page 8] Internet-Draft URI Template July 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat 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 implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Gregorio, et al. Expires January 10, 2008 [Page 9]