In some views SOA is represented as a series of 4 layers: Presentation Layer (SOA 1), Business Process Layer (SOA 2), Business Service Layer (SOA 3) and Technical Layer (SOA 4). Typically each layer higher up in the hierarchy consumes services exposed by the layer under it. So the Presentation Layer would consume services provided by the Business Process or Business Service Layers. Service interfaces are described using Web Services Description Language (WSDL), sheltering service consumers from details of service implementation. Web Services are seen as the technical means to implement the decoupled functional layers in a SOA development. Decoupling allows implementations of business functionality at different layers to be swapped in and out without disturbing other layers in the stack.
In this document I will walk through the process of developing a SOA Composite Application, exposed as a Web Service, which will make available simple business functionality using a multi-operation service. We will use the GalssFish ESB v2.1 infrastructure. The service will use the SOAP/HTTP Binding Component, the Database Binding Component and the BPEL 2.0 Service Engine. This simple service will introduce the components and discuss how a multi-operation web service can be constructed using the GalssFish ESB.
The business idea is that patients are looked after in various healthcare facilities. Frequently applications need to allow selection of a facility and to access facility details for display to human operators. A relational database is used to hold the details of facilities which are a part of the healthcare enterprise. To shelter application developers from the details of the data store facility list and details will be made available as a multi-operation web service. This web service will be used elsewhere to construct a portlet that can be used in an enterprise portal.
The document is available as 01_FacilityService_GFESBv21.pdf
Late breaking news: The MySQL JDBC Driver, which I used in the example, mysql-connector-java-5.1.7-bin.jar, and which is distributed with the GlassFish ESB v2.1, causes connection pool exhaustion and other issues with the example. If you experience these issues pleases download the latest MySQL JDBC Driver, mysql-connector-java-5.1.11-bin.jar as at now, from http://dev.mysql.com/downloads/connector/j/5.1.html and replace the original in domains/domain1/lib/ext.