W3C

Efficient representation for Web formats

EXI is a format that sends an efficient data stream of parse events that can have noticeable, measurable savings in CPU, memory and bandwidth. Test results have consistently shown EXI advantages for XML, HTML, and now CSS/JavaScript minify, over gzip and zip formats. You may want to look at EXI overview presentation for CSS.

Since the start of the EXI Working Group, the focus of group members has been to make XML interchange more efficient. Participants plan to further continue this effort by making improvements to what has been achieved by EXI and its related specifications. We are now exploring how to consistently apply EXI approaches to other Web formats besides XML.

  • JavaScript Object Notation (JSON) exchange can be more efficient by applying EXI for JSON.
  • Cascading Style Sheets (CSS) performance using EXI for CSS.
  • JavaScript parse-tree equivalence using EXI for JavaScript.

The acronym “EXI” now stands for “Efficient Extensible Interchange” instead of “Efficient XML Interchange.” This adjustment indicates that EXI is not only useful for XML documents, but improves compactness and performance across many Web technologies.

We encourage everyone to take a look at how EXI for JSONEXI for CSS, and EXI for JavaScript work.  All comments are of interest.  We are looking to

  • See if multiple capabilities emerging from the EXI work are likely to interest Web application developers, Web authors and browser developers.
  • Get technical review on the way JSON/CSS/JavaScript are being encoded, emphasizing round-trip functional correctness.
  • Examine the feasibility of “one” common efficient exchange (regarding compact size and processing speed) across all Web formats, together in concert.
  • Power-sensitive EXI efficiencies also appear to be widely useful for the Web of Things (WoT).

Multiple EXI implementations are available.  Public participation and feedback are welcome!  Send a comment to EXI participants through the public-exi@w3.org mailing list or leave a comment here in the blog. Thanks for considering these possibilities for the Web.

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