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Fast Web Services

​Fast Web Services is the term applied to the use of ASN.1 to provide message exchanges based on a SOAP envelope and WSDL specification of services that can have a higher transaction-processing rate and less bandwidth requirements than use of a character-based XML representation.

ITU-T X.694 | ISO/IEC 8825-5 "Mapping W3C XML Schema definitions into ASN.1" is an important building block for Fast Web Services because XSD is used in WSDL to define the structure of messages. Consequently, the XML schema referenced in a WSDL document can be considered an abstract schema, with an equivalent ASN.1 description, whose instances can be encoded using XML or an ASN.1 encoding. In the latter case it is possible to use an efficient binary encoding such as Packed Encoding Rules (PER).

ITU-T X.892 | ISO/IEC 24824-2 "Fast Web Services" consists of an ASN.1 Schema for SOAP as well as annotations for WSDL, but does not define any new specific binary encoding of XSD. There is no need to invent a new technology. Instead, the existing ASN.1 standards can be applied and if necessary evolved to meet future requirements. The standard can be downloaded for free from the ITU-T website.

Fast Web Services annotations for WSDL allow services to explicitly state that a binding can support the ITU-T X.892 | ISO/IEC 24824-2encoding (in addition to XML).

The ASN.1 schema for SOAP is based on the W3C SOAP 1.2 specification and ensures that the SOAP semantics and processing model are preserved. This enables WSDL-defined content to be efficiently encapsulated in a SOAP-based envelope using the same encoding technology. No changes to the SOAP binding syntax are required.

Use cases

​In general Fast Web Services are used for the cases where the self-description (structured) property of XML is not important, or is not as important as a boost to serialization/parsing and compact messages. This can be considered for more tight-coupled inter-operation.Here are some explicit use cases as documented by the W3C XML Binary Characterization (XBC) working group:

Fast Web Services Security

​The ASN.1 Group has begun to work on a new ITU-T Recommendation | International Standard, entitled "Information Technology - Generic Applications of ASN.1 - Fast Infoset and Fast Web Services Security, that will specify the application of standard security methods to the Fast Web Services specification.

In order for applications to apply standard security methods to the Fast Infoset specification, it is necessary to specify transformations to be applied to fast infoset documents (or parts of them) to support the application of those security methods.

The scope of the work includes the following:
  • specification of a canonical form for fast infoset documents;
  • specification of an encryptable form for fast infoset documents;
  • use of a fast infoset document canonical form to support XML Signature Syntax and Processing for the signing of fast infoset documents or parts of them;
  • use of a fast infoset encryptable form to support XML Encryption Syntax and Processing for the encryption of fast infoset documents or parts of them.
The above specification will enable standard security solutions as specified in "OASIS Web Services Security: SOAP Message Security" to be applied to Fast Web Services.

ITU-T Rec. X.893 | ISO/IEC 24824-3 was approved on May 2007.