TCP Transport

The TCP transport allows you to send and receive SOAP messages over the Transmission Control Protocol (TCP) to the TCP Proxy through the same TCP connection.

The TCP transport is included with the WSO2 Enterprise Service Bus (WSO2 ESB) distribution, but must be enabled before use. To enable the TCP transport, open the <ESB_HOME>/repository/conf/axis2/axis2.xml file in a text editor and add the following transport receiver configuration and sender configuration:

<!-- Enable TCP message -->  
<transportReceiver name="tcp" class="org.apache.axis2.transport.tcp.TCPTransportListener">
    <parameter name="transport.tcp.port">6060</parameter>
</transportReceiver>

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

If you want to use the sample Axis2 client to send TCP messages, uncomment the TCP transport sender configuration in the following file:

<ESB_HOME>/samples/axis2Client/client_repo/conf/axis2.xml

Transport receiver parameters

Parameter Name	Description	Required	Possible Values	Default Value
`port`	The port on which the TCP server should listen for incoming messages.	No	A positive integer less than 65535	8000
`hostname`	The host name of the server to be displayed in WSDLs, etc.	No	A valid host name or an IP address	N/A
`contentType`	The content type of the input message	No	A valid content type (e.g., `application/xml`, `application/json`, `text/html` etc.)	N/A
`responseClient`	Whether the client needs to get the response or not	No	True or false	true

For more information, see Working with Transports .

Sending multiple messages via the same TCP channel

Generally, you can send only one message via one generic TCP channel as described above. Nevertheless, WSO2 ESB also supports sending multiple messages via the same TCP channel by splitting them in different ways.

Hence, the TCP transport needs to determine the end of the message that is mediated through the ESB to split it by a character, a sequence of characters, message length and special characters in hex form. Client can select which input type to use to send the request to the TCP proxy out of the available options (i.e., binary and String). Splitting the message by a single character is the most efficient method.

Following are the properties that are specific to sending multiple messages via the same TCP channel.

Property	Description	Required	Possible Values	Default Value
recordDelimiterType	Type of the record delimiter you use to split the message	No	Character, byte or String	String
`recordDelimiter`	The delimiter of the record you use to split the message	No	A valid vale that matches the specified delimiter type	N/A
`recordLength`	Length of the message to be split. If you set this, then the delimiter properties are omitted.	No	A valid integer value. This will be identified in bytes.	N/A
`inputType`	Input type of the message	No	String or binary	String

You can split the following sample request input message in different ways as explained below.

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">""<soapenv:Header/><soapenv:Body/></soapenv:Envelope>"

Splitting by a character

The sample proxy below splits the message by a character. It receives a message with an empty body, which it will forward to the HTTP endpoint after enriching the body with the symbolic value "IBM".

 <proxy name="TCPProxy" 
          transports="tcp" 
          startOnLoad="true" 
          trace="disable"> 
      <description/> 
      <target> 
         <inSequence> 
            <property name="symbol" value="IBM" scope="default" type="STRING"/> 
            <enrich> 
               <source type="inline" clone="true"> 
                  <m:getQuote xmlns:m="http://services.samples"> 
                     <m:request> 
                        <m:symbol>?</m:symbol> 
                     </m:request> 
                  </m:getQuote> 
               </source> 
               <target type="body"/> 
            </enrich> 
            <enrich> 
               <source type="property" clone="true" property="symbol"/> 
               <target xmlns:m="http://services.samples" xpath="//m:getQuote/m:request/m:symbol"/> 
            </enrich> 
            <log level="full" separator=","/> 
            <send> 
               <endpoint> 
                  <address uri="http://localhost:9000/services/SimpleStockQuoteService" format="soap11"/> 
               </endpoint> 
            </send> 
         </inSequence> 
         <outSequence> 
            <log level="full"/> 
            <send/> 
         </outSequence> 
      </target> 
      <parameter name="transport.tcp.responseClient">true</parameter> 
      <parameter name="transport.tcp.recordDelimiter">|</parameter> 
      <parameter name="transport.tcp.inputType">string</parameter> 
      <parameter name="transport.tcp.port">6789</parameter> 
      <parameter name="transport.tcp.recordDelimiterType">character</parameter> 
      <parameter name="transport.tcp.contentType">text/xml</parameter> 
   </proxy>

Splitting by a special character

The sample proxy below splits the input message by appending a special character to the end of the message.

<proxy name="TCPProxy" 
          transports="tcp" 
          startOnLoad="true" 
          trace="disable"> 
      <description/> 
      <target> 
         <inSequence> 
            <property name="symbol" value="IBM" scope="default" type="STRING"/> 
            <enrich> 
               <source type="inline" clone="true"> 
                  <m:getQuote xmlns:m="http://services.samples"> 
                     <m:request> 
                        <m:symbol>?</m:symbol> 
                     </m:request> 
                  </m:getQuote> 
               </source> 
               <target type="body"/> 
            </enrich> 
            <enrich> 
               <source type="property" clone="true" property="symbol"/> 
               <target xmlns:m="http://services.samples" xpath="//m:getQuote/m:request/m:symbol"/> 
            </enrich> 
            <log level="full" separator=","/> 
            <send> 
               <endpoint> 
                  <address uri="http://localhost:9000/services/SimpleStockQuoteService" format="soap11"/> 
               </endpoint> 
            </send> 
         </inSequence> 
         <outSequence> 
            <log level="full"/> 
            <send/> 
         </outSequence> 
      </target> 
      <parameter name="transport.tcp.recordDelimiter">0x03</parameter> 
      <parameter name="transport.tcp.responseClient">true</parameter> 
      <parameter name="transport.tcp.inputType">binary</parameter> 
      <parameter name="transport.tcp.port">6789</parameter> 
      <parameter name="transport.tcp.recordDelimiterType">byte</parameter> 
      <parameter name="transport.tcp.contentType">text/xml</parameter> 
   </proxy>

Splitting by a character sequence

The sample proxy below splits the input message by a sequence of characters.

<proxy name="TCPProxy" 
          transports="tcp" 
          startOnLoad="true" 
          trace="disable"> 
      <description/>
<target> 

        <inSequence> 
            <property name="symbol" value="IBM" scope="default" type="STRING"/> 
            <enrich> 
               <source type="inline" clone="true"> 
                  <m:getQuote xmlns:m="http://services.samples"> 
                     <m:request> 
                        <m:symbol>?</m:symbol> 
                     </m:request> 
                  </m:getQuote> 
               </source> 
               <target type="body"/> 
            </enrich> 
            <enrich> 
               <source type="property" clone="true" property="symbol"/> 
               <target xmlns:m="http://services.samples" xpath="//m:getQuote/m:request/m:symbol"/> 
            </enrich> 
            <log level="full" separator=","/> 
            <send> 
               <endpoint> 
                  <address uri="http://localhost:9000/services/SimpleStockQuoteService" format="soap11"/> 
               </endpoint> 
            </send> 
         </inSequence> 
         <outSequence> 
            <log level="full"/> 
            <send/> 
         </outSequence> 
      </target>
<parameter name="transport.tcp.responseClient">true</parameter> 
      <parameter name="transport.tcp.recordDelimiter">split</parameter>
      <parameter name="transport.tcp.inputType">string</parameter> 
      <parameter name="transport.tcp.port">6789</parameter> 
      <parameter name="transport.tcp.recordDelimiterType">string</parameter> 
      <parameter name="transport.tcp.contentType">text/xml</parameter> 
 </proxy>

Developing the Java Client for the Transport

The sample Java Client below splits the input message by a special character. (Also, you can develop a character delimiter client by changing the below client accordingly.)

import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.net.Socket;
 
 public class TCPClient {
 
 String host = "localhost";
 int port = 6789;
 Socket socket = null;
 int count = 0;
 
 public static void main(String args[]) throws Exception {
 Character aByte = 0x10;
 TCPClient client = new TCPClient();
 String message = "<soapenv:Envelope xmlns:soapenv=\"http://schemas.xmlsoap.org/soap/envelope/\">"
                 + "<soapenv:Header/><soapenv:Body/></soapenv:Envelope>" + aByte;
 client.sendToServer(message);
 client.recieveFromServer();
 client.sendToServer(message);
 client.recieveFromServer();
 client.close();
 }
 
 TCPClient() throws Exception {
 socket = new Socket(host, port);
 }
 
 void sendToServer(String msg) throws Exception {
 //create output stream attached to socket
 PrintWriter outToServer = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
 //send msg to server
 outToServer.print(msg);
 outToServer.flush();
 }
 
 void recieveFromServer() throws Exception {
 char delimiter = 0x10;
 InputStream inFromServer = socket.getInputStream();
 //read from server
 int next = inFromServer.read();
 ByteArrayOutputStream bos = new ByteArrayOutputStream();
 while (next > -1) {
 if (delimiter != next) {
 bos.write(next);
 }
 next = inFromServer.read();
 if (delimiter == next) {
 System.out.println(new String(bos.toByteArray()));
 count++;
 if (count == 1 || count == 2) {
 break;
 }
 bos = new ByteArrayOutputStream();
 }
 }
 
 if (count == 2) {
 close();
 }
 }
 
 void close() throws IOException {
 socket.close();
 }
 }