Reading Time: 2 minutes

Right now TCP inbound endpoints are implemented as TCP servers that listen for data coming from different clients. In Mule ESB 2.2.6 we are adding a new feature to inverse the control: TCP inbounds can now poll data from remote servers.

It is really easy to switch to this strategy. Let’s take a look of how a mule configuration looks like:

?View Code XML
<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns="http://www.mulesource.org/schema/mule/core/2.2"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:tcp="http://www.mulesource.org/schema/mule/tcp/2.2"
    xmlns:vm="http://www.mulesource.org/schema/mule/vm/2.2"
    xsi:schemaLocation="
           http://www.mulesource.org/schema/mule/core/2.2
           http://www.mulesource.org/schema/mule/core/2.2/mule.xsd
           http://www.mulesource.org/schema/mule/vm/2.2 
           http://www.mulesource.org/schema/mule/vm/2.2/mule-vm.xsd
           http://www.mulesource.org/schema/mule/tcp/2.2 
           http://www.mulesource.org/schema/mule/tcp/2.2/mule-tcp.xsd">
 
    <vm:connector name="queue" queueEvents="true" />
 
    <tcp:polling-connector name="pollingConnector"
        clientSoTimeout="3000" pollingFrequency="1000">
        <tcp:direct-protocol payloadOnly="true" />
    </tcp:polling-connector>
 
    <model name="echoModel">
        <service name="echo">
            <inbound>
                <tcp:inbound-endpoint host="localhost"
                    port="4444" />
            </inbound>
            <outbound>
                <pass-through-router>
                    <vm:outbound-endpoint path="out"
                        connector-ref="queue" />
                </pass-through-router>
            </outbound>
        </service>
    </model>
</mule>

Notice the new tcp:polling-connector element in the mule configuration file. This element tells mule to poll data with a frequency of 1000ms and a timeout of 3000ms.
Using the above configuration we can create a TCP server that writes messages like this:

?View Code JAVA
String stringMessage = "the message";
ServerSocket serverSocket = new ServerSocket(4444);
Socket clientSocket = serverSocket.accept();
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
out.print(stringMessage);
out.close();
clientSocket.close();

You can check the value received in the out outbound using the MuleClient like this:

latest report
Learn why we are the Leaders in API management and iPaaS
Read reports
?View Code JAVA
MuleClient client = new MuleClient();
MuleMessage message = client.request("vm://out?connector=queue", 10000);
String receivedMessage = message.getPayloadAsString();

The receivedMessage variable will hold the received value from the TCP Server.

If you want to try it, please download Mule ESB 2.2.6 or the latest 3.0 milestone