Charter of the Efficient XML Interchange Working Group
[This charter has been extended until 31 December
2008]
The Efficient XML Interchange Working Group is part of the W3C XML Activity and follows the Working
Group process described in section 6.2
Working Groups and Interest Groups of the W3C Process Document. Except
as specified in this charter, the Working Group follows the Common Procedures
for XML Working Groups.
Table of Contents
- Mission
- Scope and Goals
- Out of scope
- Success criteria
- Deliverables and duration
- Expected milestones
- Coordination with Other Groups
- Working Group participation
- Meetings
- Communication
- Confidentiality
- Patent Policy
Mission
The main objective of the Efficient XML Interchange (EXI) Working Group is to develop a
format that allows efficient interchange of the XML Information Set, based on
the conclusions
of the XML Binary Characterization Working Group.
Scope and Goals
XML has been enormously successful as a markup language for documents and
data, but is not an optimal format for all purposes. The XML Binary
Characterization Working Group established a set of use cases for which XML
employment may be problematic. The Efficient XML Interchange Working Group is
chartered to define an alternative encoding of the XML Information
Set that addresses at least the minimum
requirements identified by the XML Binary Characterization Working
Group. The Working Group shall also consider properties that
shouldn't be prevented, as listed in the second list of the decision tree.
Such support will be considered as extensions to the XML Information
Set or extensions introduced in the XML Schema 1.0
Post–Schema–Validation Infoset and in the XQuery 1.0
and XPath 2.0 data model.
The goals of this Working Group are:
- Fulfill the design
goals of XML with the following exceptions:
- The interchange format must be compatible with the XML Information
Set instead of being “compatible with SGML” (XML goal 3);
- For performance reasons, the format is not required to be
“human–legible and reasonably clear” (XML goal 6);
- Terseness in efficient interchange is important (XML Goal 10).
- Address all requirements
and use cases from the
XML Binary Characterization Working Group;
- Maintaining the existing interoperability between XML applications, as
well as XML specifications;
- Establish sufficient confidence in the proposed format, in particular
establishing confidence that the performance gains are significant, and
the potential for disruption to existing processors is small;
There are several approaches to achieve the integration with XML. The
Working Group will provide at least one way for the new format to be both
recognized as XML by existing parsers and also rejected in a meaningful way,
such as by defining a new value for the pseudo–attribute
encoding.
The Working Group will start by considering existing solutions and will
evaluate each in terms of implementability and performance against the
requirements and use cases documents produced by the XML Binary
Characterization Working Group.
Out of scope
This Working Group is not chartered to:
- Introduce a new data model for XML;
- Develop an application specific format. Like XML itself, the new format
must support a wide variety of applications.
Success criteria
Two of the entrance criteria used for the Last Call phase will be:
- the Working Group Note on the impact of the new format on existing XML
technologies;
- the Working Group Note analyzing the performance gains of the new
format, based on the criteria included in the measurement
methodologies document. For example, in the case of compactness,
the information compression is expected to be at most 20% larger than its
equivalent ASN.1 PER, when a schema optimization is in use. Some of the
analysis require to have an implementation and will be done during the
Candidate Recommendation phase, such as processing
efficiency.
Careful review will be given to the feedback from other Groups, within and
outside the XML Activity. Findings that suggest that the proposed format has
a significant impact and disruption of existing XML technologies and
processors might dissuade W3C from advancing the format to W3C Candidate
Recommendation, or might persuade W3C to do so but without referring to the
format as a flavor of XML.
Two of the entrance criteria used for the Proposed Recommendation phase
will be:
- demonstrate the performance gains of the new format, based on the prior
analysis done as an entrance criteria of the Last Call phase. In
addition, an analysis regarding the properties that need an
implementation to be evaluated, such as processing efficiency,
will be conducted.
- demonstrate at least two interoperable implementations supporting all
the features provided in the specification. One of the implementations
must be available for public use.
The Working Group may at any stage recommend the use of an already
published format, provided that it satisfies the above criteria, instead of
providing a W3C Recommendation.
Deliverables and duration
Deliverables
The Working Group is expected to produce:
- A W3C Working Group Note, providing an analysis of the
performance measurements using the measurement
methodologies document, and performance gains. The analysis
should use a wide range of sizes and complexity in XML input documents,
representing at least each of the use cases. Favorable
performance results will help build community support by illustrating the
advantages that some applications may gain with this format over ordinary
XML text streams.
- A Test Suite and corpus of measurable documents which can demonstrate
the results described in the performance measurements Note.
- A W3C Working Group Note, providing an analysis of the new
format’s impact on existing XML technologies — in
particular XML Canonicalization, XML Signature, and XML Encryption
— and processors.
- A W3C Recommendation for efficient XML
interchange.
Duration
The expiration date of this charter is 31 December 2007.
Expected milestones
The following milestones are proposed. As usual, the duration of the
review period must be negotiated with other groups, in particular the XML
Coordination Group for the Last Call phase duration.
- December 2005
- Working Group created
- February 2006
- First face–to–face meeting.
- May 2006
- First draft of the Working Group Note providing the analysis of the
performance measurements and of the Test Suite
- September 2006
- First Public Working Draft of the efficient XML interchange
format.
- January 2007
- Last Call Working Draft, along with the analysis of its impact on
existing XML applications and specifications, and the analysis of the
performance gains.
- June 2007
- Candidate Recommendation.
- October 2007
- Proposed Recommendation, along with the final analysis of the
performance gains, based on implementation reports.
Coordination with Other Groups
W3C Groups
The Working Group should coordinate its efforts with W3C Working Groups,
in particular in the XML Activity as well as the Technical Architecture
Group.
External Groups
- ISO/MPEG-7
- MPEG-7 has an ISO standard binary infoset serialization, BiM, and is
currently working on a second version.
- ISO/MPEG-4
- MPEG-4 is currently re–evaluating its BIFS encoding, and may be
interested in providing input notably regarding efficient decoding on
small devices.
- ISO/IEC/ITU-T
- Fast Infoset (ITU-T Rec. X.891 (2005) | ISO/IEC 24824-1) is in the
process of being approved within the ISO.
- Web3D
- Web3D has explicitly asked the W3C about binary formats, and has
researched them itself.
Working Group participation
Effective participation is expected to consume one workday per week for
each Working Group participant; two days per week for editors. The Chair
shall ensure that the criteria for Good
Standing are understood and followed.
To be successful, we expect the Working Group to have 10 or more active
participants for its duration.
Chair
The initial chairs of this Working Group are Oliver Goldman, Adobe
Systems, and Robin Berjon, Expway.
W3C Team resources
The initial W3C Team
contact is Carine Bournez. It is expected that this Working Group will
consume about 0.5 FTE,
including administrative logistics.
Meetings
The Working Group will have distributed meetings, one to two hours every
week, and face–to–face meetings, every two to three months.
Communication
The Working Group will utilize a W3C Member mailing list, member-exi-wg@w3.org.
Confidentiality
The proceedings of this Working Group are “Member-only”,
subject to exceptions made by the Chair, after consultation with the Working
Group.
Patent Policy
This Working Group operates under the W3C Patent
Policy (5 February 2004 Version). To promote the widest adoption of Web
standards, W3C seeks to issue Recommendations that can be implemented,
according to this policy, on a Royalty–Free basis.
Philippe Le Hégaret, Architecture Domain
Leader, following comments from many individuals
Last modified $ Date: 2005/09/29 19:06:49 $