W3C Ubiquitous Web Domain | XML

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


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:

  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

Two of the entrance criteria used for the Last Call phase were:

  1. the Working Group Note on the impact of the new format on existing XML technologies;
  2. 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.

Two of the entrance criteria used for the Proposed Recommendation phase will be:

  1. 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.
  2. 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


The Working Group is expected to produce:


The expiration date of this charter is 31 January 2010.

Charter update history:

* On 16 February 2010 this charter was extended until 30 September 2010.

Expected milestones

The following milestones are proposed. As usual, the duration of the review period must be negotiated with other groups.

January 2009
Candidate Recommendation.
June 2009
Proposed Recommendation, along with the final analysis of the performance gains, based on implementation reports.
September 2009

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 contact is Carine Bournez, with Liam Quin as a backup. It is expected that this Working Group will consume up to 0.35 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.

Liam Quin, XML Activity Lead
Carine Bournez, Team contact
Last modified $ Date: 2005/09/29 19:06:49 $