Charter of the Efficient XML Interchange Working Group

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.

Table of Contents

  1. Mission
  2. Scope and Goals
  3. Out of scope
  4. Success criteria
  5. Deliverables and duration
  6. Expected milestones
  7. Coordination with Other Groups
  8. Working Group participation
  9. Meetings
  10. Communication
  11. Confidentiality
  12. Patent Policy
  13. About this Charter


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

During this Charter period the working Group will focus on publishing the EXI Recommendation and supporting Notes, and also on gathering requirements for future work. Future work might for example include a new revision of the EXI format to account for XML Schema 1.1 and also the XPath and XQuery Data Model (XDM).

A Profile of EXI 1.0 intended for low-resource or ultra-constrained devices may also be developed. Such devices lack run-time memory allocation capabilities or at best have extremely limited dynamic memory resources.

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 items defined by the XML Information Set and that addresses at least the minimum requirements identified by the XML Binary Characterization Working Group. The Working Group shall also consider properties 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:

  1. Fulfill the design goals of XML with the following exceptions:
    1. The interchange format must be compatible with the XML Information Set instead of being “compatible with SGML” (XML goal 3);
    2. For performance reasons, the format is not required to be “human–legible and reasonably clear” (XML goal 6);
    3. Terseness in efficient interchange is important (XML Goal 10).
  2. Address all requirements and use cases from the XML Binary Characterization Working Group;
  3. Maintaining the existing interoperability between XML applications, as well as XML specifications;
  4. 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;

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:

  1. Introduce a new data model for XML;
  2. Develop an application specific format. Like XML itself, the new format must support a wide variety of applications.

Success criteria

A Recommendation for EXI 1.0 is to be produced.

Deliverables and duration


The Working Group is expected to produce:


The expiration date of this charter is 31 January 2013.

Expected milestones

The following milestones are proposed. As usual, the duration of the review period must be negotiated with other groups. The Working Group is to be chartered for six months beyond the last milestone in order to publish errata, and beyond that for the purpose of liaison with other Working Groups, and for gathering and documenting future requirements. Actual work on a new version of the EXI format would require a new charter.

March 2011
EXI Format Recommendation
May 2011
First Public Working Draft of the EXI Profile for low-resource devices.
August 2011
Final analysis of the performance gains, based on implementation reports.
December 2011
Recommendation, EXI Profile for low-resource devices
June 2012
Close (or renew)

The Working Group is chartered for an additional six months in order to process any errata, and in order to produce requirements and use cases for a future version, should there be a need.

Note: See changes from this initial schedule on the group home page.

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

BiM, ISO/IEC 23001-1:2006
Binary MPEG format for XML or BiM, provides a standardized set of generic technologies for encoding XML documents. It addresses a broad spectrum of applications and requirements by providing generic methods for transmitting and compressing XML documents. Recently two amendments AMD 1:2007 ("Conformance and reference software") and AMD 2:2008 ("Conservation of prefixes and extensions on encoding of wild cards") have been issued.
Fast Infoset (ITU-T Rec. X.891 (2005) | ISO/IEC 24824-1) is in the process of being approved within the ISO.
Open Mobile Alliance (OMA) develops standards for mobile device industry. Specifications such as OMA Device Management use XML and are designed with sensitivity to implementation foot-print and communication bandwidth.
The Web3D Consortium continues to participate in the EXI working group. Web3D intends to upgrade the Extensible 3D (X3D) Graphics Specification Compressed Binary Encoding (CBE) from utilizing Fast Infoset (FI) to EXI, once EXI becomes a W3C Recommendation.

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.


The initial chairs of this Working Group are Michael Cokus (MITRE Corporation), and Takuki Kamiya (Fujitsu).

W3C Team resources

The initial W3C Team contacts are Carine Bournez and Liam Quin. It is expected that this Working Group will consume up to 0.25 FTE, including administrative logistics.


The Working Group will have distributed meetings, one to two hours every week, and face–to–face meetings, every three or four months.


The Working Group will utilize a W3C Member mailing list, member-exi-wg@w3.org.


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.

About this Charter

This charter for the XML Query Working Group has been created according to section 6.2 of the Process Document. In the event of a conflict between the provisions of any charter and the W3C Process, the W3C Process shall take precedence.

This charter was revised in 2011 to add a new deliverable, the profile of EXI format for low-resource devices.

The charter was extended in July 2012 to run until the end of January 2013.

Please also see the previous charter for this group.

Liam Quin, XML Activity Lead and Team Contact

Liam Quin, XML Activity Lead

Last modified $ Date: 2005/09/29 19:06:49 $