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Service Activator

This page explains how you can implement a sample scenario of Service Activator EIP using WSO2 Micro Integrator.

Introduction to Service Activator

The Service Activator EIP allows an application to design a service to be invoked both via various messaging technologies and non-messaging techniques. Service Activator interfaces methods and services in the back-end service layer so that the back-end services can be filtered and displayed to the client.

Info

For more information, see the Service Activator documentation.

Messaging adapter solution

Sample scenario

This sample scenario demonstrates how WSO2 MI can be used to activate only a specific number of services on a back-end Axis2 server. Using the publishWSDL property, the service WSDL file is modified to filter out only a specific number of services. The ability of the WSO2 MI to create proxy services allows the client to invoke the proxy instead of invoking the service directly on the Axis2 server.

The diagram below depicts how to simulate the sample scenario using WSO2 MI.

Service activator

Before digging into implementation details, let's take a look at the relationship between the sample scenario and the Service Activator EIP by comparing their core components.

Service Activator EIP Service Activator Sample Scenario
Requestor Simple Stock Quote Client
Service Activator Proxy Service
Replier Simple Stock Quote Service

Synapse configuration of the artifacts

<?xml version="1.0" encoding="UTF-8"?>
<proxy name="ServiceActivatorProxy" startOnLoad="true" transports="http https" xmlns="http://ws.apache.org/ns/synapse">
   <target>
      <inSequence>
            <call>
               <endpoint key="StockQuoteServiceEP"/>
            </call>
            <respond/>
      </inSequence>
      <faultSequence>
            <log level="full">
               <property name="MESSAGE" value="Executing default &#34;fault&#34; sequence"/>
               <property name="ERROR_CODE" expression="get-property('ERROR_CODE')"/>
               <property name="ERROR_MESSAGE" expression="get-property('ERROR_MESSAGE')"/>
            </log>
            <drop/>
      </faultSequence>
   </target>
   <publishWSDL uri="project_path/src/main/wso2mi/resources/sample_proxy_1.wsdl" preservePolicy="true"/>
</proxy>

<?xml version="1.0" encoding="UTF-8"?>
<endpoint name="StockQuoteServiceEP" xmlns="http://ws.apache.org/ns/synapse">
   <address uri="http://localhost:9000/services/SimpleStockQuoteService">
   </address>
</endpoint>

Note

Replace project_path with the extracted path of your project folder. This way, the publishWSDL URI will be the absolute path to the sample_proxy_1.wsdl file.

How the implementation works

Let's break down the key components of the configuration:

  • Proxy - The proxy service creates a virtual service between the real back-end service and a requestor.
  • publishWSDL - By default, a proxy service defines a one-to-one mapping of the back-end service interface in the form of a WSDL file that requestors can use to connect to the proxy service. By using the publishWSDL mediator, the proxy service can publish a custom interface. In this example, the publishWSDL mediator is used to provide access only to a subset of all the service methods available to the back-end service.

Set up the sample scenario

Follow the below instructions to simulate this sample scenario.

  1. Install WSO2 Micro Integrator.

    Info

    Follow the Install the Micro Integrator Runtime documentation for more information.

  2. Launch Visual Studio Code with the Micro Integrator for VS Code extension (MI for VS Code) installed.

    Info

    Follow the Install Micro Integrator for VS Code documentation for a complete installation guide.

  3. Download the backend service.

  4. Extract the downloaded zip file.

  5. Open a terminal, and navigate to the axis2Server/bin/ directory inside the extracted folder.

  6. Execute the following command to start the axis2server with the SimpleStockQuote backend service:

    sh axis2server.sh

    axis2server.bat

  7. Download the artifacts of the sample.

    Download ZIP

  8. Import the artifacts to WSO2 MI.

    Click File -> Open Folder -> Select the extracted ZIP file to import the downloaded ZIP file.

  9. Start the project in the WSO2 MI server.

    For instructions, go to Build and Run Documentation.

  10. Start SoapUI.

    For instructions on downloading and starting, go to SoapUI Getting Started Documentation.

Execute the sample

Send the following requests to the service using SoapUI (or any other SOAP client):

   POST http://localhost:8290/services/ServiceActivatorProxy

   Accept-Encoding: gzip,deflate
   Content-Type: text/xml;charset=UTF-8
   SOAPAction: "urn:getQuote"
   Connection: Keep-Alive

   <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ser="http://services.samples" xmlns:xsd="http://services.samples/xsd">
      <soapenv:Header/>
      <soapenv:Body>
         <ser:getQuote>
            <ser:request>
               <ser:symbol></ser:symbol>
            </ser:request>
         </ser:getQuote>
      </soapenv:Body>
   </soapenv:Envelope>

Analyze the output

Browse http://localhost:9000/services/SimpleStockQuoteService?wsdl. The back-end service StockQuoteService offers the following services:

  • getFullQuote
  • getMarketActivity
  • getQuote
  • getSimpleQuote
  • placeOrder

Only some of the back-end features will be published through the Service Activator Proxy. Browse http://localhost:8290/services/ServiceActivatorProxy?wsdl to view the services offered through the ServiceActivatorProxy, and note that services getMarketActivity and getSimpleQuote are not available. Others are available and active.