The application/smil and application/smil+xml Media Types
draft-hoschka-smil-media-type-13
The information below is for an old version of the document that is already published as an RFC.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 4536.
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Author | Philipp Hoschka | ||
Last updated | 2015-10-14 (Latest revision 2006-02-27) | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Intended RFC status | Informational | ||
Formats | |||
Stream | WG state | (None) | |
Document shepherd | (None) | ||
IESG | IESG state | Became RFC 4536 (Informational) | |
Action Holders |
(None)
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Consensus boilerplate | Unknown | ||
Telechat date | (None) | ||
Responsible AD | Ted Hardie | ||
Send notices to | (None) |
draft-hoschka-smil-media-type-13
Network Working Group P. Hoschka INTERNET DRAFT W3C draft-hoschka-smil-media-type-13.txt February 2006 The application/smil and application/smil+xml Media Types 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. Abstract This document specifies the Media Type for versions 1.0, 2.0 and 2.1 of the Synchronized Multimedia Integration Language (SMIL 1.0, SMIL 2.0, SMIL 2.1). SMIL allows integration of a set of independent multimedia objects into a synchronized multimedia presentation. 1. Introduction The World Wide Web Consortium has issued specifications which define versions 1 [1], 2 [2] and 2.1 [3] of the Synchronized Multimedia Integration Language (SMIL). This memo provides information about the application/smil and application/smil+xml Media Types. The definition is based on RFC3023 defining the use of the "application/xml" media type [4]. Before using the "application/smil" or "application/smil+xml" media type, implementors must thus be familiar with [4]. 2. Synchronized Multimedia Integration Language SMIL allows integrating a set of independent multimedia objects into a synchronized multimedia presentation. Using SMIL, an author can 1.describe the temporal behavior of the presentation 2.describe the layout of the presentation on a screen 3.associate hyperlinks with media objects 4.define conditional content inclusion/exclusion based on system/network properties 3. Registration Information To: ietf-types@iana.org Subject: Registration of MIME media type application/smil Expiration Date: August 2006 [Page 1] INTERNET DRAFT February 2006 MIME media type name: application MIME subtype name: smil Required parameters: none Optional parameters: charset Same as charset parameter considerations of application/xml in RFC 3023 profile See Section 5 of this document. Encoding considerations: Same as encoding considerations of application/xml in RFC 3023 Security considerations: see Section "6. Security Considerations" below Interoperability considerations: SMIL documents contain links to other media objects. The SMIL player must be able to decode the media types of these media in order to display the whole document. To increase interoperability, SMIL has provisions for including alternate versions of a media object in a document. Published specification: see [1], [2] and [3] Applications which use this media type: SMIL players and editors Additional information: Semantics of fragment identifiers in URIs: The SMIL media type allows a fragment identifier to be appended to a URI pointing to a SMIL resource (e.g. http://www.example.com/test.smil#foo). The semantics of fragment identifiers for SMIL resources are defined in the SMIL specification. Magic number(s): There is no single initial byte sequence that is always present for Expiration Date: August 2006 [Page 2] INTERNET DRAFT February 2006 SMIL files. However, Section 4 below gives some guidelines for recognizing SMIL files. File extension(s): .smil, .smi, .sml NOTE: On the Windows operating system and the Macintosh platform, the ".smi" extension is used by other formats. To avoid conflicts, it is thus recommended to use the extension ".smil" for storing SMIL files on these platforms. Macintosh File Type Code(s): "TEXT", ".SMI", "SMIL" Object Identifier(s) or OID(s): none Person & email address to contact for further information: The author of this memo. Intended usage: OBSOLETE Author/Change controller: The SMIL specification is a work product of the World Wide Web Consortium's SYMM Working Group. The W3C has change control over the specification. To: ietf-types@iana.org Subject: Registration of MIME media type application/smil+xml MIME media type name: application MIME subtype name: smil+xml Required parameters: see registration of application/smil Optional parameters: see registration of application/smil Encoding considerations: see registration of application/smil Security considerations: see Section "6. Security Considerations" below Interoperability considerations: see registration of application/smil Published specification: see registration of application/smil Applications which use this media type: see registration of application/smil Expiration Date: August 2006 [Page 3] INTERNET DRAFT February 2006 Additional information: see registration of application/smil Magic number(s): see registration of application/smil File extension(s): see registration of application/smil Macintosh File Type Code(s): see registration of application/smil Object Identifier(s) or OID(s): see registration of application/smil Person & email address to contact for further information: see registration of application/smil Intended usage: COMMON Author/Change controller: see registration of application/smil 4. Recognizing SMIL files All SMIL files will have the string "<smil" near the beginning of the file. Some will also begin with an XML declaration which begins with "<?xml", though that alone does not indicate a SMIL document. All SMIL 2.0 files must include a declaration of the SMIL 2.0 namespace. This should appear shortly after the string "<smil", and should read 'xmlns="http://www.w3.org/2001/SMIL20/Language"'. All SMIL 2.1 files must include a declaration of a SMIL 2.1 namespace, appearing shortly after the string "<smil". The namespace string depends on the language profile. Please refer to the SMIL 2.1 specification for the definition of therelevant namespace names. 5. The "profile" optional parameter This parameter is meant to be used in MIME media type based content negotiation (such as that done with the HTTP "Accept" header) to negotiate for a variety of SMIL based languages. It is modelled after the "profile" parameter in the application/xhtml+xml MIME type registration [5], and is motivated by very similar considerations. The parameter is intended to be used only during content negotiation. It is not expected that it be used to deliver content, or that origin web servers have any knowledge of it (though they are welcome to). It is primarily targetted for use on the network by proxies in the HTTP chain that manipulate data formats (such as transcoders). The value of the profile attribute is a URI that can be used as a name to identify a language. Though the URI need not be resolved in Expiration Date: August 2006 [Page 4] INTERNET DRAFT February 2006 order to be useful as a name, it could be a namespace, schema, or a language specification. As an example, user agents supporting only SMIL Basic (see http://www.w3.org/TR/smil20/smil-basic.html) currently have no standard means to convey their inability to fully support SMIL 2.0. While SMIL 2.0 Basic user agents are required to parse the full SMIL 2.0 language, there is potentially a substantial burden in receiving and parsing document content that will not be presented to the user, since its functionality is not included in SMIL Basic. In future, the functionality afforded by this parameter will also be achievable by the emerging work on a protocol to transfer CC/PP descriptions [6]. It is suggested that the "profile" parameter be used until the CC/PP protocol work has been finalized. An example use of this parameter as part of a HTTP GET transaction would be: Accept: application/smil+xml; profile="http://www.w3.org/2001/SMIL20/HostLanguage" 6. Security Considerations SMIL documents contain a construct that allows "infinite loops". This is indispensable for a multimedia format. However, SMIL clients should foresee provisions such as a "stop" button that lets users interrupt such an "infinite loop". As with HTML, SMIL documents contain links to other media (images,sounds, videos, text, ...) and those links are typically followed automatically by software, resulting in the transfer of files without the explicit request of the user for each one. The security considerations of each linked file are those of the individual registered types. The SMIL language contains "switch" elements. SMIL provides no mechanism that assures the media objects contained in a "switch" element provide equivalent information. An author knowing that one SMIL player will display one alternative of a "switch" and another will display a different part, can put different information in the two parts. While there are legitimate use cases for this, this also gives rise to a security consideration: The author can fool viewers into thinking that the same information was displayed when in fact it was not. In addition, all of the security considerations of RFC3023 also apply to SMIL. Expiration Date: August 2006 [Page 5] INTERNET DRAFT February 2006 7. Normative References [1] "Synchronized Multimedia Integration Language (SMIL) 1.0 Specification", W3C Recommendation REC-smil-19980615, http://www.w3.org/TR/1998/REC-smil/, July 1998. [2] "Synchronized Multimedia Integration Language (SMIL 2.0) - [Second Edition]", W3C Recommendation, http://www.w3.org/TR/2005/REC-SMIL2-20050107/, January 2005. [3] "Synchronized Multimedia Integration Language (SMIL 2.1)", W3C Recommendation, http://www.w3.org/TR/2005/REC-SMIL2-20051213/, December 2005. [4] M. Murata, S. St.Laurent, D. Kohn E. "XML Media Types", RFC 3023, January 2001. 8. Non-normative References [5] M. Baker, P. Stark. "The 'application/xhtml+xml' Media Type", RFC 3236, January 2002. [6] H. Ohto, J. Hjelm, G. Klyne, M. Butler, L. Tran, F. Reynolds, C. Woodrow "Composite Capability/Preferences Profiles (CC/PP): Structure and Vocabularies 1.0", W3C Recommendation http://www.w3.org/TR/CCPP-struct-vocab/, January 2004. 8. Author's Address Philipp Hoschka W3C/ERCIM 2004, route des Lucioles - B.P. 93 06902 Sophia Antipolis Cedex FRANCE EMail: ph@w3.org Copyright (C) The Internet Society (2006) 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 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. Internet-Drafts are working documents of the Internet Engineering Expiration Date: August 2006 [Page 6] INTERNET DRAFT February 2006 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. Expiration Date: August 2006