Web services technology enables application-to-application interaction over the Web – regardless of platform, language, or data formats. The key ingredients, including XML, SOAP, WSDL, and UDDI, have been adopted across the entire software industry. Web services technology usually refers to services implemented and deployed in middle-tier application servers. However, in heterogeneous and disconnected environments, there is an increasing need to access stored procedures as well as data and metadata, through Web services interfaces. Database Web services technology is a database approach to Web services.
It works in two directions:
accessing database resources as a Web service
consuming external Web services from the database itself
Turning the Oracle database into a Web service provider leverages investment in Java stored procedures, PL/SQL packages, pre-defined SQL queries and DML. Conversely, consuming external Web services from the database itself, together with integration with the SQL engine, enables Enterprise Information Integration.
This chapter focuses on the advantages of opening up the Oracle Database, through PL/SQL packages and Java classes deployed within the database, to the world of Web services, using the Oracle Application Server and the Oracle database.
Refer to the Oracle9iAS Web Services Developer’s Guide for information on:
Testing and securing Web services.
Using PL/SQL-specific legacy types and REF CURSORS.
Writing static or dynamic Java clients to call Web Services.
This chapter also provides a general road map for database Web services, mapping out Web services support for additional database capabilities, such as SQL queries, DML statements, and Java Stored Procedures–through synchronous invocation.
See the Oracle9iAS Web Services Developer’s Guide on how to create Web services and invoke them from clients. This chapter covers how to call out to Web services from within the database and how a Web service can call in to the database.