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Fast Infoset (or FI) is an international standard that specifies a binary encoding format for the XML Information Set (''XML Infoset'') as an alternative to the XML document format. It aims to provide more efficient serialization than the text-based XML format. One can think of FI as a lossless compression, such as ''gzip'', for XML, except that while the original formatting is lost, no information is lost in the conversion from XML to FI and back to XML. While compression is to reduce size, FI aims to optimize both document size and processing performance. The Fast Infoset specification is defined by both the ITU-T and the ISO standards bodies. FI is officially named ''ITU-T Rec. X.891'' and ''ISO/IEC 24824-1 (Fast Infoset),'' respectively. However, it is commonly referred to by the name ''Fast Infoset''. The standard was published by ITU-T on May 14, 2005, and by ISO on May 4, 2007. The Fast Infoset standard can be downloaded from the (ITU website ). There are no intellectual property restrictions on its implementation and use. A common misconception is that FI requires ASN.1 tool support. Although the formal specification uses ASN.1 formalisms, it uses custom encoding rules via Encoding Control Notation (ECN). ASN.1 tools are not required by implementations. An alternative is FleXPath 〔Amer-Yahia, Sihem, Laks VS Lakshmanan, and Shashank Pandit. "FleXPath: flexible structure and full-text querying for XML." Proceedings of the 2004 ACM SIGMOD international conference on Management of data. ACM, 2004.〕 ==Structure== The underlying file format is ASN.1, with tag/length/value blocks. Text values of attributes and elements are therefore stored with length prefixes rather than end delimiters, so there is no need to escape special characters. The equivalent of end tags ("terminators") are only needed at the end of a list of child-elements, and binary data need not be base64 encoded. Fast Infoset is a higher level format built upon ASN.1 formalisms. Element and attribute names are stored within the octet stream, unlike traditional ASN.1. This means that it is possible to recover a conventional XML file from the binary stream without the need to reference any XML Schema. It does not attempt to convert an XML Schema directly into an ASN.1 definition. (ASN.1 "Tags" are just type names, e.g. String, Integer, or complex types.) ASN.1 together with ECN is used to define the file format. An index table is built for most strings, which includes element and attribute names, and their values. This means that the text of repeated tags and values only appears once per document. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Fast Infoset」の詳細全文を読む スポンサード リンク
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