Scope and methodology issues

Web services

Web services (or, less confusingly, application services) have been succinctly defined as “self-contained, self-describing modular applications that can be published, located and invoked across the Web”. Web services “perform functions, which can be anything from simple requests to complicated business processes”. In other words, they are “interoperable building blocks for constructing applications” (Gardner 2001). Web services allow an application to invoke a remote process or application as if it were part of the invoking application (Jacobson 2002). The infrastructure required to support Web services may be described in terms of three roles: service provider, service requestor and service registry, and three interactions: publish, find, bind. It may be seen that Web services have the potential to provide robust interoperability between different systems (compare the discussion of library system components above, p. .). Major commercial software providers heavily support them: the two competing environments for the development of Web services are Enterprise Java Beans (Sun Microsystems) and Microsoft’s .NET.

1. 
   The Web Services Description Language (WSDL) which describe a service as a set of “ports” which group related interactions that are possible between the application (service requestor) and the Web service (service provider);
   
2. 
   The Simple Object Access Protocol (SOAP), a standard for XML-based information exchange between distributed applications. It is typically transmitted over HTTP. It has the advantage of working across firewalls;
   
3. 
   Universal Discovery, Description and Integration (UDDI), which is a specification for distributed registries and services.
   

Other than library portal solutions (see above, p.....) I have not been able to identify any commercially-available library systems incorporating Web services. However, there are a number of local implementations and experimental projects within the library community which are highly significant:

1. 
   The work of ZiNG on Web services implementations of Z39.50 has already been discussed (above p. )
   
2. 
   The Portuguese National Library is using Web services architecture to support the Portuguese National Catalogue. The system allows record retrieval and the searching, insertion, validation and updating of records (Tennant 2002).
   
3. 
   The ALADIN digital library system of the Washington Research Library Consortium (WRLC) uses Web services to provide a network-based interface to its services, permitting more effective integration with the systems of the individual member libraries. ¹⁹
   
4. 
   Most significant, perhaps, is the PYTHEAS experimental multi-tier open source library system or library application framework (see above….) developed by Rhyno and his team at the University of Windsor, Ontario (Rhyno 2002c). PYTHEAS uses RDF and MARC as its major metadata formats. The server is based on XML, Web services, and Enterprise Java Beans, with Exolab’s Castor XML mapping tool as middleware.
   

Web services are currently receiving a great deal of attention within the information technology industry as a whole. It remains to be seen whether the early expectations will be borne out.

3. 
   Java
   

Java is an important enabling technology for library systems, allowing the rapid development of new functions. It relates closely to XML in that many XML tools and applications are coded in Java. It shares with it the characteristic of platform-independence. . Using XML and Java together, developers can build sophisticated, interoperable Web applications more quickly and at a lower cost.

Sun Microsystems made a deliberate pitch for the library systems market at an early stage (Chu 1996, Pasquinelli 1997); it was perceived that its platform independence could effectively extend the life of legacy library computer systems. However, it has made a presence in library automation only slowly (Breeding 1997). While the trend towards its use is not overwhelming, there are now a number of major products using Java in one or more of their components. TLC has a cataloguing system, CATNOW!, and a Java-based circulation systems and OPAC, Library*Solution. Innovative’s Millenium system incorporates several Java modules, while CyberTools, BiblioMondo, and epixtech have Java OPACs. The new Java 2 Enterprise Edition (J2EE) is claimed to have transformed a streamlined, thin programming language into a complete computing platform, of which the language is just one component. It has recently started to be implemented within integrated library systems, for instance Talis’ new library portal, TalisPrism.