Oracle SOA BPEL Process Manager 11gR1 - A Hands-on Tutorial: Your step-by-step, hands-on guide to Oracle SOA BPEL PM 11gR1

BPEL is an XML-based language for creating end-to-end process flow. BPEL is based on the WS-BPEL 2.0 specification and built on the Web Services Description Language (WSDL) 1.1 specifications.

A BPEL process always starts with a process element. A process element must have at least one activity. Activities are the core of the BPEL language framework. Usually a process element also has several attributes. The basic structure of the BPEL code is as follows:

<process name="ncname">
  
<!-- Activities  -->
</process>

Every BPEL has activities such as <receive>, <reply>, and <invoke>. Activities describe different action steps in a BPEL process that enable the interaction with external and internal services. Note, that Oracle BPEL also allows interaction with JCA adapters and EDN.

The most important concepts of BPEL are activities, partner links, variables, correlation, and handlers. The BPEL processes expose WSDL interface...

BPEL processes have a series of steps and each step is an activity. BPEL process logic is performed by the activities. For clients, BPEL processes looks like any other web service. In other words, a BPEL process is a web service that coordinates, integrates, and orchestrates the basic web services to serve a business function. OASIS WS-BPEL specifications classify activities in the following categories:

Synchronous processes have a default timeout of 60 seconds. If the synchronous flow takes more than 60 seconds, we must increase the timeout by configuring the Timeout property for the Receive activity.

As shown in the following screenshot, edit the Receive activity and add a Timeout value. Chapter 3, Invoking a BPEL Process, covers more details of Timeout:

The timeout property can be added in the Partner Link as well. The following screenshot shows how to add a timeout value for synchronous processes in JDeveloper. Right-click and edit the process that requires the timeout value.

Click on the Property tab on the Edit Partner Link window. As shown in the following screenshot, click on the green + sign to add the timeout property. Please note that the timeout value set here is a client timeout:

Correlation is a process that matches incoming messages to a particular BPEL process instance. Synchronous BPEL does not require correlation. Correlation is only required for asynchronous BPEL processes.

Oracle BPEL Process Manager automatically establishes correlation using WS-Addressing. However, manual content-based correlation is required if the asynchronous service doesn't support WS-Addressing or the BPEL message is coming from an external system.

Oracle BPEL Processor Manager has the following two methods for correlating asynchronous callback messages to the calling instance.

One needs to write a manual correlation for the following scenarios:

Property alias is for telling the BPEL process how to extract the value of the property from the specified message. The property aliases assist us in mapping a property to a field in a specific message part and that can be used in XPath expressions. Multiple property aliases may be required for correlation, such as the one for instantiation and another one for validation.

To create a property alias in JDeveloper, double-click on the Property Aliases icon, as shown in the following screenshot. Select the correlation set to associate with a property alias. If the message part is an element or a complex type, you can define an XPath query to identify the location of the property within the element or type. In the Query field, add appropriate XPath expressions. An XPath expression is for navigating within an XML document and helps to directly define a part of the XML document.

As a final verification, you may review the WSDL file content to ensure that the properties...

Adapters facilitate a configurable integration among disparate business systems without worrying about underlying frameworks, tools, and technologies used in implementation of an individual business system. Use of adapters enable reusability of existing applications and systems, therefore, it increases ROI and provides agility for any organization.

The Oracle SOA Suite's adapters are designed and developed using the J2EE Connector Architecture (JCA). Oracle provides adapters to integrate various packaged applications, legacy applications, databases, middleware messaging systems, and web services.

BPEL processes may require working with multiple external resources. The following are some of the common use cases for BPEL processes to connect to as part of your application(s):

In this chapter, we learned the details of Business Process Execution Language (BPEL) structure, language framework, adapters, and how to create a BPEL process using Oracle JDeveloper IDE. We also learned the use cases and implementation steps for synchronous BPEL processes, asynchronous BPEL processes, manual correlations, and human tasks. In the next chapter, you will learn how to invoke BPEL processes from Java and vice versa. You will also learn about BPEL processes transaction timeout.