15 - Database as web services provider service

Abstract

This chapter describes exposing database functionality as Web services. As database developers, DBAs, and data architects know, the Oracle database furnishes a rich set of functionality and APIs for building data-centric applications. This chapter first discusses the implementation of Web services with RDBMSs in general, and then looks more specifically at the Oracle's implementation of database as Web service provider. The database functionality to be exposed as Web services (i.e., PL/SQL packages, Java classes in the database, queries, DML, and streams AQ queues) usually already exist in databases. Creating a database Web service from an existing resource is called a bottom-up approach as opposed to a top-down approach consisting of creating/generating the service implementation from the WSDL. The Oracle AS Web Services framework allows us to turn database Web services into first-class citizens of the service-oriented architecture, since they inherit all the quality of services (e.g., Web services security, Web services reliability, Web services logging, Web services auditing). Web services consist of a service client and service provider exchanging SOAP messages. The Web service provider is composed of a Web service layer and the service implementation.