Efficient XML Interchange Current Status

This page summarizes the relationships among specifications, whether they are finished standards or drafts. Below, each title links to the most recent version of a document.

Completed Work

W3C Recommendations have been reviewed by W3C Members, by software developers, and by other W3C groups and interested parties, and are endorsed by the Director as Web Standards. Learn more about the W3C Recommendation Track.

Group Notes are not standards and do not have the same level of W3C endorsement.



Canonical EXI

The specification of the canonical form of EXI 1.0, for use in applications that need document signature without the burden of going through plain-text XML (e.g. in constrained environments)


Efficient XML Interchange (EXI) Profile for limiting usage of dynamic memory

This profile of the EXI 1.0 specification allows restrictions on the memory consumption of EXI internal structures. It is intended for application areas and devices that are not capable or allowed to require arbitrary memory growth at runtime. Certain evaluations of EXI in the context of such areas exposed some challenges to the attempt to restrict memory usage predictably within their limited respective threshold.


Efficient XML Interchange (EXI) Format 1.0 (Second Edition)

Efficient XML Interchange (EXI) is a compact XML-specific format that does not require an XML parser on the receiving end; it is stream-based and supports both compression and Schema-aware coding to save even more bandwidth. The second edition clarifies a number of issues raised by implementers.

Group Notes



The Efficient XML Interchange (EXI) format is a compact representation that simultaneously optimizes performance and the utilization of computational resources. The EXI format was designed to support XML representation. With a relatively small set of transformations it may also be used for JSON, a popular format for exchange of structured data on the Web.


XML Binary Characterization Properties

This document is the result of a study to identify desirable properties in an XML format. An XML format is a format that is capable of representing the information in an XML document. The properties have been derived from requirements induced by use cases collected in the [XBC Use Cases] document. Properties are divided into two categories: algorithmic and format. Besides these two categories, Section 6 Additional Considerations lists additional considerations which, because of the difficulty to establish an accurate measurement, have not been listed as properties but are nonetheless relevant for an accurate comparison between different proposals.


XML Binary Characterization Use Cases

This document describes use cases for evaluating the potential benefits of an efficient serialization format for XML. The use cases are documented here to understand the constraints involved in environments for which XML employment may be problematic because of one or more characteristics of XML. Desirable properties of XML and alternative formats to address the use cases are derived and discussed in a separate publication of the XML Binary Characterization Working Group (XBC WG) [XBC Properties].


XML Binary Characterization

This document describes the processes and results of the XML Binary Characterization Working Group in evaluating the need and feasibility of a "binary XML" recommendation. It includes an analysis of which properties such a format must possess. It recommends that the W3C produce a "binary XML" recommendation and enumerates the minimum requirements which this "binary XML" recommendation must meet.


XML Binary Characterization Measurement Methodologies

This document describes measurement aspects, methods, caveats, test data, and test scenarios for evaluating the potential benefits of a candidate binary XML format.


Below are draft documents: other Working Drafts . Some of these may become Web Standards through the W3C Recommendation Track process. Others may be published as Group Notes or become obsolete specifications.

Other Working Drafts


Efficient XML Interchange (EXI) Primer

This is a non-normative document intended to provide an easily readable technical background on the Efficient XML Interchange (EXI) format. It is oriented towards quickly understanding how the EXI format can be used in practice and how options can be set to achieve specific needs. Section 2. Concepts describes the structure of an EXI document and introduces the notions of EXI header, EXI body and EXI grammar which are fundamental to the understanding of the EXI format. Additional details about data type representation, compression, and their interaction with other format features are presented. Finally, Section 3. Efficient XML Interchange by Example provides a detailed, bit-level description of a schema-less example.


Efficient XML Interchange Evaluation

This Working Draft is an evaluation of the Efficient XML Interchange (EXI) Format 1.0 with reference to the Properties identified by the XML Binary Characterization (XBC) Working Group, relative to XML, gzipped XML and ASN.1 PER. It is conducted using the XBC Measurement methodology. For the "compactness" and "processing efficiency" Properties, the performance is measured with EXI Measurement framework, over the test data collected for the EXI measurements, representing XBC Use Cases.


Efficient XML Interchange (EXI) Impacts

The Efficient XML Interchange (EXI) format defines a new representation for the Extensible Markup Language (XML) Information Set. The introduction of such a format may cause disruption in systems that have so far been able to assume XML as the only representation of XML Information Set data. This document reviews areas where the introduction of EXI may disrupt or otherwise have an impact on existing XML technologies, XML processors, and applications. It also describes EXI design features and steps that may be taken by implementors to reduce or eliminate disruption and impacts.


Efficient XML Interchange (EXI) Best Practices

The purpose of this document is to provide guidelines for the interoperable deployment of the Efficient XML Interchange (EXI) format. It provides explanations of format features and techniques to support interoperable information exchanges using EXI. While intended primarily as a practical guide for systems architects and programmers, it also presents information suitable for the general reader interested in EXI's intended role in the expanding Web.


Efficient XML Interchange Measurements Note

This Working Group Note presents measurement results of various high-performance XML interchange encoding formats and their associated processors, made by the Efficient XML Interchange (EXI) Working Group. The measurements have been conducted following the recommendations of the XML Binary Characterization (XBC) Working Group. In particular, this draft covers measurements of the properties of "compactness", "processing efficiency" and "roundtrip support", as defined by the XBC WG. We start by describing the context in which this analysis is being made, and the position of an efficient format in the landscape of high performance XML strategies. Then we describe the measured quantities in detail and the test framework in which they were made, and give a short description of each format. Finally, a summary of the results and the conclusions of the group are included. The full measurements and analysis are included in an appendix and supporting documents.

As a result of the measurements described here, the working group selected Efficient XML ([EffXML]) to be the basis for the proposed encoding specification to be prepared as a candidate W3C Recommendation. Follow up work has centered around integrating some features from the other measured format technologies, particularly variations for both more efficient structural and value encodings.