WSO2 ESB exposing Web Service Proxy to a TCP client. ( A.K.A TCP proxy)

In this article I am going to explain how to create a proxy to a back end web service which accept TCP messages.

In our case our TCP client was sending a delimited string to the ESB and we need ESB to convert the delimited string into a SOAP/XML file and call the web service.

In our case we does not intend to send the response immediately back to the client rather than sending response as batches of several requests. Since I will explain how the batch response in another article.

To accept the TCP requests you need to change your axis2.xml file inside <ESB_LOCATION>/repository/conf/axis2.xml file and add below two transport handler.

1. Configure TCPTransportListener to listen to in coming TCP requests.

<transportReceiver name=”tcp” class=”org.apache.axis2.transport.tcp.TCPTransportListener”>
      <parameter name=”transport.tcp.port”>6060</parameter>
    </transportReceiver>

2. Configure TCPTransportSender to send responses over TCP (this handler will not want for this article but this will be used in next article for batch response sending )

<transportSender name=”tcp” class=”org.apache.axis2.transport.tcp.TCPTransportSender”/>

Then we use inbuilt smooks handler to transform the delimited values into a XML entries.

To do this we first need to add smooks configuration which act as a template to smooks handler. We need to add the smooks configuration as a local XML entry to ESB. To do this go to Main - > Service Bus -> Local Entries. And add a in-lined XML entry.

(This is an example of smooks configuration which use to trans form delimited text to XML)

<smooks-resource-list xmlns=”http://www.milyn.org/xsd/smooks-1.1.xsd” xmlns:csv=”http://www.milyn.org/xsd/smooks/csv-1.2.xsd”>
      <resource-config selector=”org.xml.sax.driver”>
         <resource>org.milyn.csv.CSVReader</resource>
         <param name=”fields”>id,password,userName</param>
         <param name=”rootElementName”>addLogin</param>
         <param name=”recordElementName”>login</param>
      </resource-config>
   </smooks-resource-list>
                                   

Then add a new proxy which use the smooks mediator in “Advance -> smooks”, with TCP transport type allowed, and finally with port and content type properties as below.

Below is a sample

<?xml version=”1.0” encoding=”UTF-8”?>
<proxy xmlns=”http://ws.apache.org/ns/synapse”
       name=”LoginProxy”
       transports=”tcp”
       statistics=”disable”
       trace=”disable”
       startOnLoad=”true”>
   <target>
      <inSequence>
         <smooks config-key=”LoginDetails”>
            <input type=”text”/>
            <output type=”xml”/>
         </smooks>
         <send>
            <endpoint>
               <wsdl service=”HelloServiceImplService”
                     port=”HelloServiceImpl”
                     uri=”http://localhost:8080//HelloWebService/services/HelloServiceImpl?wsdl”/>
            </endpoint>
         </send>
         <log level=”full”/>
      </inSequence>
      <outSequence>
         <log/>
      </outSequence>
   </target>
   <parameter name=”transport.tcp.port”>9446</parameter>
   <parameter name=”transport.tcp.contentType”>text/plain</parameter>
   <description/>
</proxy>