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

1. 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.
   C#

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

2. 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
3. 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

1. 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.
2. 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”
3. Add Assign, Assign1 and Invoke Block in “Caller” process:

   

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

   

   Figure 4: "Invoke" Block
5. Initialize “DSLinkRequest” from “Assign” block, choose From->Fixed Value and To->DSLinkRequest>parameters. The fixed value is described as:
   XML

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

   

   Figure 5: Initialize “DSLinkRequest”
6. 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”
7. Initialize “output” from “Assign1” block. Choose From->Fixed Value and To->output>payload. The fixed value is described as:
   XML

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

   

   Figure 7: Initialize “output”
8. 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”
9. 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
10. Create deploy.xml.
    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>

11. 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