ITU-T X.891 | ISO/IEC 24824-1 (Fast Infoset) specifies a representation of an instance of the W3C XML Information Set using binary encodings. These binary encodings are specified using the ASN.1 notation and the ASN.1 Encoding Control Notation (
ECN). The Fast Infoset standard can be
downloaded for free from the ITU-T website.
The Fast Infoset technology provides an alternative to W3C XML syntax as a means of representing instances of the W3C XML Information Set. This representation generally provides smaller encoding sizes and faster processing than a W3C XML representation.
Fast Infoset specifies the use of several techniques that minimize the size of the encodings (called fast infoset documents) and that maximize the speed of creating and processing fast infoset documents. These techniques include the use of dynamic tables (for both character strings and qualified names), initial vocabularies, and external vocabularies.
Some compression results are published by the open source Fast Infoset project (parsing performance, size performance). Note that these tests don't use any of the so-called Fast Infoset advanced features which allow for the use of external information (e.g., schema) to employ better representations for "text" nodes (e.g., IEEE float for xsd:float, etc.). Using those features, the performance gains can be significantly better
The ASN.1 Schema for the XML information set provides the capability to encode XML content that is not described by a schema. It defines an alternative to XML 1.0 serialization and, like the ASN.1 Schema for SOAP, ensures the application of a consistent encoding technology.
