Efficient Interchange

The EXI standard improves the performance, network efficiency, and power consumption of XML applications across the full range of use cases. Extensive testing shows that EXI performs consistently better than previous XML formats, data compression, and even packed binary data formats. As such, it brings the full range of XML benefits to even the most demanding applications.

What is EXI?

EXI defines a compact encoding of XML documents or other tree-like structures for a wide range of usage scenarios, with a particular attention to keeping the necessary processing under control. You could think of EXI as moving the parsing to the server and simply sending a sequence of parse events over the wire, optionally making use of the grammar from a shared Schema to pre-load the string table at each end and to reduce the information that needs to be sent.

The EXI format uses a hybrid approach drawn from the information and formal language theories, plus practical techniques verified by measurements, for entropy encoding XML information. Using a relatively simple algorithm, which is amenable to fast and compact implementation, and a small set of datatype representations, it reliably produces efficient encodings of XML event streams. The grammar production system and format definition of EXI are specified in the EXI Format 1.0 specification.

In addition to the EXI Format, the EXI Profile for limiting usage of dynamic memory is designed to accomodate very constrained devices (micro-controllers, sensors, etc.). In those environments, dynamic memory allocation is inexistent or very limited, therefore the EXI grammar learning mechanism needs to be controlled.

News and Testimonials

Contact: Carine Bournez <carine@w3.org>