Next Generation Z39.50 A Web Services Approach for Search and Retrieve 6 th Annual State GILS Conference, March 31 – April 3, 2004, Raleigh, NC William E. Moen School of Library and Information Sciences Texas Center for Digital Knowledge University of North Texas Denton, TX 72603

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 2 Overview Quick description of SRW Brief background – historical, political, conceptual Non-technical (almost) introduction to SRW Common Query Language (CQL) briefly Concluding thoughts

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 3 What is SRW? Search and Retrieve Web Service (SRW) An XML-based protocol for searching, retrieving, and other information retrieval transactions Cast in the standards/technologies for web services XML SOAP HTTP Brings the concepts and experience of Z39.50 into the web environment using web technologies

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 4 Why SRW? Genesis: several years of soul searching by Z39.50 developers and implementors The “web” had become the common implementation environment Z39.50 was not perceived as web friendly Pivotal moments: December 2000 ZIG meeting July 2001 meeting

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 5 Turning point: December 2000 “Z39.50 Future” discussion Perceptions of Z39.50  broken  heavy-weight  difficult and complex  old technology  not web friendly Several options presented Rewrite the protocol from the ground up Rewrite as an XML protocol Separate the Z39.50 protocol from its use of BER as a wire protocol Simplify the protocol specifications to focus on core features Recognition of the intellectual contribution of Z39.50

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 6 Taking action: June 2001 Invitational meeting to discuss moving Z39.50 to an XML- based protocol Goal Lower the barriers to implementation while preserving the existing intellectual contributions of Z39.50, discarding those aspects no longer useful or meaningful. Objective Define specifications for a new web service definition based on Z39.50 together with web technologies Separate the Z39.50 abstract and associated semantic model from its specific encoding and wire protocol (i.e., ASN.1/BER and TCP/IP) Initially called Z39.50 Next Generation (ZNG) Intended as proof-of-concept Defining only those protocol specifications that would actually be implemented by participants

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 7 ZING – Z39.50 International Next Generation Make intellectual/semantic content of Z39.50 more broadly available Make Z39.50 more attractive by lowering barriers to implementation Use of XML – to represent and encode data Use of HTTP – for transport Use of SOAP – for interaction between client and server based on Remote Procedural Call (RPC) Several ZING initiatives: ZOOM, ez39.50, ZeeRex, SRW/U FOR MORE INFORMATION, VISIT THE ZING WEBSITE…

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 8 SRW/U, SRW, SRU SRW/U: Search and Retrieve for the Web General designation for this initiative SRW: Search and Retrieve Web Service HTTP Post Simple Object Access Protocol (SOAP) XML messages SRU: Search and Retrieve URL Service HTPP Get Request parameters included in URL syntax Development Version 1.0 November 2001 Version 1.1 February 2002 FOR MORE INFORMATION, VISIT THE SRW WEBSITE…

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 9 Networked information retrieval What’s needed: Identifying a target to search A vocabulary for expressing search requests, search criteria, retrieval requests, etc. Methods to encode the requests and responses from the target Methods to transport the requests and responses across a network In other words, a protocol and supporting specifications

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 10 Abstract Model of IR

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 11 Abstract model of Z39.50

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 12 Z39.50 classic & SRW

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 13 SRW Overview Builds on Z39.50 concepts and web technologies Web technologies: XML, SOAP, HTTP Uses new, human-readable query language Combines several Z39.50 features into several “operation types” searchRetrieve operation scan operation explain operation

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 14 searchRetrieve operation The core of the protocol Expresses the search and additional criteria Records are returned in XML Request parameters version query Optional parameters sortkeys recordPacking recordSchema recordXPath stylesheet Response parameters version numberOfRecords Optional parameters resultSetID resultSetIdleTime records diagnostics

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 15 SRW & XML XML as foundation for protocol Provides syntax for intelligent markup Defines or references XML schemas Example XML schema for SRW specifications searchRetrieveRequest searchRetrieveResponse

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 16 searchRetrieveRequest example Sent as a HTTP Post XML document is sent to the server Using SOAP to wrap the request 1.1 dc.title all "Squirrel Hungry" 1 dc

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 17 searchRetrieveResponse example info:srw/schema/1/dc- v1.1 Squirrel is Hungry

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 18 searchRetrieve response Records returned in response All records in XML syntax According to one or more XML schemas (semantics) Dublin Core Onix MODS MarcXml

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 19 searchRetrieve example Retrieval results XML view Screen shot 1.1 dc.title computer 1 10 xml dc>

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 20 SRW results

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 21 SRU briefly Protocol requests can be carried via HTTP Get searchRetrieveRequest parameters expressed in standard URL syntax baseURL and search part separated by question mark “?” Response is XML document containing records The searchRetrieveRequest in SRU: rchRetrieve&version=1.1&query=dc.title=%22compute r%22&recordSchema=DC&startRecord=1&maximumR ecords=10&recordPacking=xml

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 22 search/Retrieve query SRW query consists of one or more query statements linked by Boolean operators Five categories of query statements: 1.single search clause 2.two or more search clauses linked by Boolean 3.search clauses and result sets linked by Boolean 4.two or more result sets linked by Boolean 5.single result set Expressed in the Common Query Language (CQL)

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 23 Common Query Language (CQL) A formal language for representing queries to information retrieval systems Human-readable Search clause Always includes a term simple terms consist of one or more words May include index name To limit search to a particular field/element Index name includes base name and may include prefix title, subject dc.title, dc.subject Several index sets have been defined (called Context Sets in SRW) dc bath srw Context set defines the available indexes for a particular application

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 24 Other components of CQL Relation, =, =, <> exact used for string matching all when term is list of words to indicate all words must be found any when term is list of words to indicate any words must be found Boolean operators: and, or, not Proximity (prox operator) relation (, =, =, <>) distance (integer) unit (word, sentence, paragraph, element) ordering (ordered or unordered) Masking rules and special characters single asterisk (*) to mask zero or more characters single question mark (?) to mask a single character carat/hat (^) to indicate anchoring, left or right

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 25 CQL examples Simple queries: dinosaur "the complete dinosaur" Boolean dinosaur and bird or dinobird "feathered dinosaur" and (yixian or jehol) Proximity foo prox bar foo prox/>/4/word/ordered bar Indexes title = dinosaur bath.title="the complete dinosaur" srw.serverChoice=dinosaur Relations year > 1998 title all "complete dinosaur" title any "dinosaur bird reptile" title exact "the complete dinosaur"

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 26 SRW & classic Z39.50 SRW No explicit concept of connection, session, or state Results sets named by server Single record syntax (XML), multiple schemas String (i.e., human- readable) queries CQL Named indexes Classic Z39.50 Stateful Results sets named by client Multiple record syntaxes No human-readable query language Type 1 query using attribute sets Use attribute to identify access point Z39.50 Concepts Retained Result sets Abstract access points Abstract record schemas Explain Diagnostics

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 27 What problems does SRW solve Addresses need for standards-based searching in the networked environment Shows the vitality of the Z39.50 concepts and implements those in a web services & URL access context Offers database providers with a web-friendly method for offering standards-based searching of resources Provides low barrier to entry solution using commonly available technologies XML format of records provide for more reuse, and more interesting use of resources

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 28 Possible implementation venues Gateways to existing Z39.50 servers Lightweight SRW/U servers to specialized databases Cost-effective search access to commercial databases (e.g., citation, full- text) Metasearching Beyond libraries to many other information communities

Moen 6th Annual State GILS Conference -- March 31 – April 3, Raleigh, NC 29 References Z39.50 International Next Generation – ZING  Search and Retrieve for the Web – SRW/U  A Gentle Introduction to SRW  A Gentle Introduction to CQL  Search and Retrieval in The European Library: A New Approach by van Veen and Oldroyd in D-Lib (Feb04) 