How BPEL and SOA Are Changing Web Services Development

E very organization faces the challenge of integrating diverse IT systems. Developers must first solve communication-level integration issues, ensuring that systems using different transport protocols and data formats can exchange information. Once these issues are resolved, organizations must decide how their various IT systems can interact to support business processes. Business process modeling (BPM) environments seek to solve these issues. Historically , however, these systems have been proprietary , locking an organization — and sometimes its business partners — into a single product. BPMs also have had limited interoperability with various IT systems, creating further integration problems. Increasingly, developers are using the Business Process Execution Language (ftp://www6.soft ware.ibm.com/software/developer/library/ws-bpel. pdf) for modeling business processes within the Web services architecture. 1 BPEL is an XML-based standard for defining business process flows. In addition to facilitating the orchestration of synchronous (client-server) and asynchronous (peer-to-peer) Web services, BPEL provides specific support for long-running and stateful processes. BPEL is an open standard, making it interoperable and portable across many environments. BPEL is ideally suited to the service-oriented architecture, a set of guidelines for integrating disparate systems by presenting each system as a service that implements a specific business function. BPEL provides an ideal way to orchestrate services within SOA into complete business processes. Here, I describe how BPEL fits into the Web services stack, some of BPEL's key benefits, and how targeting Web services for use with BPEL makes the creation of an SOA easier than ever. To illustrate some of the SOA principles and how BPEL affects Web service design, I'll use a sample integration project in which a phone company wants to automate its sign-up process for new customers. This process involves four separate systems based on different technologies: • Payment gateway: a third-party system that handles credit-card transactions and is already exposed as a Web service. • Billing system: hosted on a mainframe, this system uses a Java Message Service (JMS) queuing system for communication. • Customer-relationship management (CRM) system: a packaged off-the-shelf application. • Network administration system: a packaged off-the-shelf application implemented in Corba. As the use of Web services grows, organizations are increasingly choosing the Business Process Execution Language for modeling business processes within the Web services architecture. In addition to orchestrating organizations' Web services, BPEL's strengths include asynchronous message handling, reliability, and recovery. By developing Web services with BPEL in mind, organizations can implement aspects of the service-oriented architecture …