|Intended status: Standards Track||March 29, 2012|
|Expires: September 28, 2012|
The +exi Media Type Suffix
Efficient XML Interchange (EXI) is an XML representation technique specified by the W3C to provie a binary alternative to the standard text XML representation. This document defines a new Structure Syntax Suffix "+exi" for use in a specific class of protocols, where "exi" content-type encoding or the generic "application/exi" Media Type are not applicable.
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Efficient XML Interchange (EXI) [W3C.REC-exi-20110310] is an XML representation technique specified by the W3C to provie a binary alternative to the standard text XML representation. EXI is not a generic compression technique like gzip or deflate, but an encoding technique specifically for XML that uses either learnt or pre-informed schema information.
This document defines a new Structure Syntax Suffix "+exi" for use in a specific class of protocols, where the "exi" content-type encoding or generic "application/exi" Media Type defined in [W3C.REC-exi-20110310] are not applicable.
The EXI standard already defines both an "exi" content-type encoding and an "application/exi" Media Type. This sections discusses when it is appropriate to use the new "+exi" Structured Syntax Suffix when registring a Media Type.
Appendix F.1 of [W3C.REC-exi-20110310] clearly describes when the exi content-type encoding should be used: "Protocols that can identify and negotiate the content coding of XML information independent of its media type, SHOULD use the content coding "exi" (case-insensitive) to convey the acceptance or actual use of EXI encoding for XML information."
Thus when a protocol depends on the media type to identify that the payload is EXI, it can make use of the "application/exi" Media Type defined in Appendix F.2 of [W3C.REC-exi-20110310]. This works particularly well for applications using EXI in a generic way, and in particular in non Schema-informed mode, where protocol specific information is not needed to process the payload, in particular the XML schema used. In these cases it is recommended to use the "application/exi" Media Type or "exi" content-type encoding.
The "+exi" Structure Syntax Suffix defined in this document is appropriate for use with a special class of protocols that:
Security considerations are discussed in Section 4.
This document requests registration of the Structured Syntax Suffix "+exi" as follows, following the registration template from Section 6.2 of [I-D.ietf-appsawg-media-type-regs].
This draft is the result of discussions on the Apps Area Working Group mailing list. Thanks to Carine Bournez and Guido Moritz for their helpful comments.
|[W3C.REC-exi-20110310]||Kamiya, T. and J. Schneider, "Efficient XML Interchange (EXI) Format 1.0", World Wide Web Consortium Recommendation REC-exi-20110310, March 2011.|
|[I-D.ietf-appsawg-media-type-regs]||Klensin, J, Hansen, T and N Freed, "Media Type Specifications and Registration Procedures", Internet-Draft draft-ietf-appsawg-media-type-regs-01, February 2012.|
|[RFC3023]||Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC 3023, January 2001.|