An Example Of BPEL invoking WebService

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Introduction

The example below shows how to invoke an existing/external web service in BPEL. This example uses Eclipse, Eclipse BPLE designer Plug-In and Apache ODE.

Background

Using the Code

There are two parts in this article:

Part A: Prepare a Web Service
Part B: Invoke this web service in BPEL

Part A: Prepare Web Service

Create a web service “DoSomethingWebService”, which has only one class “DoSomething” (under namespace “ws.example”) with only one method “doSomething”. You can use the bottom-up approach to build this web service. Please see this link.

package ws.example;
public class DoSomething {
            public String doSomething(String myinput)
            {
                        System.out.println("doSomething is called");
                        return "doSomething is called ";
            }
}

Check the generated WSDL file, the service name is “DoSomethingService”, Port “DoSomething”, binding address is http://localhost:8080/DoSomethingWebService/services/DoSomething.

Figure 1: "DoSomethingService" Web Service
Export the service to a war file and deploy it under $TomcatHome/webapps. If you like to, export and deploy the test client also, it is good for testing. Please see this link.

Part B: Invoke this Web Service in BPEL

Prepare ODE and BPEL Plug-In and create a BPEL project “InvokeWebServiceProj” and a synchronous BPEL process “Caller” under namespace “http://MyTest.com/Test”. Please see this link.
Import DoSomething.wsdl into the project and create a partner link “DSLink” of type “DSLinkType”, Partner Role of “DSProvider”. Please see this link.

Figure 2: “DSLinkType”
Add Assign, Assign1 and Invoke Block in “Caller” process:

Figure 3: "Caller" BPEL Process
Edit Invoke Block to call “doSomething”.

Figure 4: "Invoke" Block

Initialize “DSLinkRequest” from “Assign” block, choose From->Fixed Value and To->DSLinkRequest>parameters. The fixed value is described as:

<xsd:doSomething xmlns:xsd="http://example.ws">
                            <xsd:myinput/>
                        </xsd:doSomething>

Figure 5: Initialize “DSLinkRequest”

Set the input value for “doSomething” method. Choose From->Variable->input->payload->input and To->Variable->DSLinkRequest->parameters->myinput.

Figure 6: Set “myinput” for “DSLinkRequest”

Initialize “output” from “Assign1” block. Choose From->Fixed Value and To->output>payload. The fixed value is described as:

<tns:CallerResponse xmlns:tns="http://MyTest.com/Test">
                            <tns:result/>
                        </tns:CallerResponse>

Figure 7: Initialize “output”

Set the output value for “Caller” process. Choose From->Variable->DSLinkResponse->parameters->dosomethingReturn and To->Variable->output->payload->result.

Figure 8: Set “result” for “output”
Edit the Caller.wsdl generated, so that a “CallerService” of port “CallerPort” is bound to the “Caller” process with the address “http://localhost:8080/ode/processes/Caller” using SOAP.

Figure 9: "CallerService" Web Service

Create deploy.xml.

<?xml version="1.0" encoding="UTF-8"?>
<deploy xmlns="http://ode.fivesight.com/schemas/2006/06/27/dd"
    xmlns:pns="http://MyTest.com/Test"
    xmlns:wns="http://example.ws">

  <process name="pns:Caller">
    <active>true</active>
    <provide partnerLink="client">
      <service name="pns:CallerService" port="CallerPort"/>
    </provide>
    <!-- If there is a BPEL process which is also deployed under the same project-->
    <!--<provide partnerLink="DSLink">
      <service name="wns:DoSomethingService" port="DoSomething"/>
    </provide>-->
    <!-- DoSomethingService is an existing/external Web Service -->
     <invoke partnerLink="DSLink">
          <service name="wns:DoSomethingService" port="DoSomething"/>
     </invoke>
     <cleanup on="always" />
  </process>
  </deploy>

Test.

Figure 10: Test Result

Here is the complete list of the files of BPEL project (Caller.bpelex, Caller.wsdl and CallerArtifacts.wsdl are generated).

Figure 11: File List

History

27^th February, 2009: Initial post

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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Snail2009

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