Patterns: Implementing Self-Service in an SOA Environment

132 Patterns: Implementing Self-Service in an SOA Environment

The value of WSDL is that it enables development tooling and middleware for

any platform and language to understand service operations and invocation

mechanisms. For example, given the WSDL interface to a service that is

implemented in Java, running in a WebSphere environment, and offering

invocation through HTTP, a developer working in the Microsoft .Net platform can

import the WSDL and easily generate application code to invoke the service.

As with SOAP, the WSDL specification is extensible and provides for additional

aspects of service interactions to be specified, such as security and

transactionality.

Universal Description, Discovery, Integration

Universal Description, Disccover, Integration (UDDI) servers act as a directory of

available services and service providers. SOAP can be used to query UDDI to

find the locations of WSDL definitions of services, or the search can be

performed through a user interface at design or development time. The original

UDDI classification was based on a U.S. government taxonomy of businesses,

and recent versions of the UDDI specification have added support for custom

taxonomies.

A public UDDI directory is provided by IBM, Microsoft, and SAP, each of whom

runs a mirror of the same directory of public services. However, there are many

patterns of use that involve private registries. For more information, see the

following articles:

򐂰 The role of private UDDI nodes in Web services, Part 1: Six species of UDDI

http://www.ibm.com/developerworks/webservices/library/ws-rpu1.html

򐂰 The role of private UDDI nodes, Part 2: Private nodes and operator nodes

http://www.ibm.com/developerworks/webservices/library/ws-rpu2.html

6.4.2 J2EE Connector Architecture

The J2EE Connector Architecture is aimed at providing a standard way to access

enterprise applications from a J2EE-based Java application. It defines a set of

Java interfaces through which application developers can access Enterprise

Information Systems (EIS), for example, CICS, and Enterprise Resource

Planning (ERP) applications.

J2EE Connector Architecture V1.5 support is a requirement of the J2EE V1.4

specification. Resource adapters allow J2EE applications to connect to a

particular EIS. The J2EE Connector Architecture specification defines two

different types of resource adapters: