IBM Version 5 manual Web services and DB2 XML Extender, Dadx Group

SOAP 2.2 and that run on J2EE compliant application servers like WebSphere and Tomcat. To create a new Web Service, the developer authors SQL statements in a DADX document and deploys it to the application server. The DADX runtime executes SOAP requests sent to the new service and provides additional support including HTTP GET and POST bindings, test page and WSDL generation, and translation of DTD into XML Schema. This document describes the DADX document format and runtime. In this section, we will generate the DADX from the DAD.

Web services and DB2 XML Extender

The DB2 XML Extender makes it easy to create XML applications using DB2. DB2 XML Extender consists of a set of stored procedures, user defined types (UDT) and user defined functions (UDF) that enable an application programmer to store and retrieve XML data using DB2. DB2 XML Extender allows XML documents to be stored intact, and optionally indexed in side tables, using the XML Column access method, or as a collection of relational tables using the XML Collection access method. DXX uses a DAD to define the mapping between XML and relational data.

Web services are XML based application functions that can be invoked over the Internet. It is, therefore, natural to use DB2 XML Extender to implement Web services. This document specifies a DADX that makes it easy to create Web services using DB2 XML Extender. A DADX document specifies how to create a Web Service using a set of operations that are defined by DAD documents and SQL statements. A Java component, the DxxInvoker, provides the runtime support for invoking DADX documents as Web services in Apache Simple Object Access Protocol (SOAP) 2.2 which is supported by WebSphere Application Server and other J2EE servlet engines.

The DADX Group

The resources for all DADX Web Service groups are stored in the directory WEB-INF/classes/groups where WEB-INF is the directory used by J2EE Web applications to store resources that are not directly available to HTTP requests. This means that users cannot see the contents of your DADX files. DADX files contain the implementation of the Web services, and are therefore, similar to Java classes.

The classes directory is part of the Java class path for the Web application. This means that your DADX files can be loaded by the Java class loader and that your Web application can execute directly from its WAR file if your application server supports that mode of operation.

Within the groups directory each group of DADX Web services is stored in a directory with the same name as its servlet instance. The DxxInvoker servlet

200 The XML Files: Development of XML/XSL Applications Using WebSphere Studio