Update 2004-03-04: "US LOC SRW Maintenance Agency Releases Search/Retrieve Web Service Version 1.1."

A posting distributed on behalf of the Z39.50 Maintenance Agency announces the release of SRW and CQL Version 1.0 specifications. SRW (Search/Retrieve Web Service) protocol "aims to integrate access to various networked resources, and to promote interoperability between distributed databases, by providing a common utilization framework. SRW features both SOAP and URL-based access mechanisms to provide for a wide variety of possible clients ranging from Microsoft's .Net initiative to simple Javascript and XSLT transformations. It leverages the CQL query language which provides a powerful yet intuitive means to formulate searches. XCQL is the CQL query language expressed in an XML form, designed to be part of a SOAP structure; it encodes the structure of the CQL within 'searchClause' and 'triple' elements. The SRW protocol mandates the use of open and industry-supported standards XML and XML Schema, and where appropriate, XPath and SOAP. SRW has been developed by an international team, minimizing cross-language pitfalls and other potential internationalization problems. SRW defines a web service combining several Z39.50 features, most notably, the Search, Present, and Sort Services. Additional features/services may be added later or defined later as new web services. The SRW and CQL version 1.0 specifications will remain stable for a six- to nine-month implementation-experience period."

From the announcement:

The SRW Initiative recognizes the importance of Z39.50 (as currently defined and deployed) for business communication, and focuses on getting information to the user. SRW provides semantics for searching databases containing metadata and objects, both text and non-text. Building on Z39.50 semantics enables the creation of gateways to existing Z39.50 systems while reducing the barriers to new information providers, allowing them to make their resources available via a standard search and retrieve service.

The SRW and CQL version 1.0 specifications will remain stable for a six- to nine-month implementation-experience period. During this period developers are encouraged to implement the specification (see the implementors page), join the list of implementors, participate in interoperability testing, and help develop the next version, 1.1. Please direct questions, comments, and suggestions to z3950@loc.gov.

From the SRW description: "The SRW Initiative, building on Z39.50 along with web technologies, recognizes the importance of Z39.50 (as currently defined and deployed) for business communication, and focuses on getting information to the user. SRW provides semantics for searching databases containing metadata and objects, both text and non-text. Building on Z39.50 semantics enables the creation of gateways to existing Z39.50 systems while reducing the barriers to new information providers, to make their resources available via a standard search and retrieve service."

About XCQL. "XCQL is the Common Query Language (CQL) expressed in an XML form, designed to be part of a SOAP structure. This is used in the xQuery parameter of the searchRetrieveRequest message in SRW, but is not tied to this and may be used in other environments. An XML schema is available which defines the elements used in XCQL. As this structure is designed to be used within a SOAP request, it does not use any attributes and is has been kept as simple as possible. This has meant that when otherwise attributes would have been used, they are represented as separate elements. XCQL encodes the structure of the CQL within 'searchClause' and 'triple' elements. Thus the parentheses which record this information in CQL are not used, nor is there a need for a left to right precedence rule as this is explicit in the XML. The 'triple' element contains three elements. The first is the boolean for the triple and the second and third positions are the left and right operands of the boolean. 'searchClause' may contain 'index', 'relation' and 'term' elements..."

About Z39.50. "'Z39.50' refers to the International Standard, ISO 23950: Information Retrieval (Z39.50): Application Service Definition and Protocol Specification, and to ANSI/NISO Z39.50. The Library of Congress is the Maintenance Agency and Registration Authority for both standards, which are technically identical..."