This is the public web page for the Efficient Extensible Interchange (EXI) Working Group of the Efficient XML Interchange (EXI) Format (Second Edition). Feb 11, The Efficient XML Interchange Working Group has published a W3C Recommendation of Efficient XML Interchange (EXI) Format (Second. , Efficient XML Interchange (EXI) Format (Second Edition) Recommendation. , Proposed Edited Recommendation. .

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Evaluate the remainder of the event sequence using RightHandSide. This section describes the process for assigning unique event codes to each production in a normalized EXI grammar. In this case, the unresolved prefix representation is formxt used and can be zero 0 or the compact identifier of any prefix in the associated partition.

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

The algorithms expressed in this section provide a concise and formal description of the EXI grammars for a given set of XML Schema definitions. The second Unsigned Integer represents the fractional portion of the Decimal value with the digits in reverse order to preserve leading zeros. When the grammar currently in effect for the element is either a built-in element grammar see 8. See rule [3] or CS regExp if atom is sub-regexp. The EXI header has the following structure: Six distinct values are needed to identify the first part of these event codes.

Schema-informed grammars accept all XML documents and fragments regardless of whether and how closely they match the schema. An namespace information item maps to a Namespace Declaration NS event with each of its properties subject to further mapping as shown in the following table.

Representing Event Content if any is in effect, otherwise 7. To reduce compression overhead, smaller channels are combined before compressing them, while larger channels are compressed independently.

The syntax and semantics of the NS event are designed to minimize the overhead required for representing namespace prefixes in EXI streams without introducing significant complexity.


Assuming the content model for the element being encoded corresponds to the sequence AT category AT date i. Fidelity options used in this document Fidelity option Value Effect Preserve. The following content items are encoded using a string table: Local-name content items and the local-name portion of qname content items are assigned to partitions based on the namespace URI of the NS event dfficient qname content item of which the local-name is a sxi.

Those grammars were culled upon the completion of grammar normalization because their LeftHandSide are not referenced from RightHandSide of any available productions. Bytes are ordered with the least significant byte first. As is the case with XML, the events occur with nesting pairs of matching start element and end element events where any interchanve does not intersect with another except when it is fully contained in the other.

The set-of-chars for a regex that conforms to the syntax above is the union of the set-of-chars defined for each branch. The number of parts in a given event code is called the event code’s length.

You can get involved by joining the W3C. In the example encodings, whitespaces that are originally present in the example XML effciient are omitted, which is intentional.

Efficient Extensible Interchange Working Group Public Page

Given an EXI stream with its stream cursor positioned just past the first bit of the EXI format version field, the EXI format version number can be computed by going through the forrmat steps with version number initially set to 1.

EXI processors MAY also provide implementation specific means for applications or users to specify itnerchange built-in EXI datatype representations or user-defined datatype representations for representing specific schema datatypes. The value is one of bit-packed intercange, byte-alignment or pre-compressionof which bit-packed is the default value assumed when the “alignment” element is absent in the EXI Options document. EE with an event code of length 1 does not exist in the current element grammar, iinterchange one with event code 0 and increment the first part of the event code of each production in the current grammar with the non-terminal LeftHandSide on the left-hand side.


If the prefix is defined, select the m -th prefix value associated with the URI of the QName as the candidate prefix value. The framework includes support for in-memory and network testing, the latter is particularly useful to measure the performance of a format relative to the available bandwidth. Or server may deny to start the new communication by just sending streamEnd tag with default encoding.

The padding bits field if it is present can contain any values of bits as its contents. This grammar is intentionally simple and succinct, enabling high-performance, low-footprint implementations on a wide range of devices, including those with very limited memory resources. This mailing list is reserved for comments, it is inappropriate to send discussion email to this address.


When a string value is found in the global value partition, the String value may be represented as one 1 encoded as an Unsigned Integer see 7. The EXI stream encoder then represents the stream of events using a set of simple variable length codes called event codes. Similarly, the order of the compressed streams following the second compressed stream in the block is defined by the fprmat in which the first value of the channel inside each compressed stream occurs in the EXI event sequence.

The encoder then represents the stream of events using a set of simple variable length codes called event codes. This is a restricted form of Greibach normal form [Greibach Normal Form].