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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:

<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns=""
    <vm:connector name="queue" queueEvents="true" />
    <tcp:polling-connector name="pollingConnector"
        clientSoTimeout="3000" pollingFrequency="1000">
        <tcp:direct-protocol payloadOnly="true" />
    <model name="echoModel">
        <service name="echo">
                <tcp:inbound-endpoint host="localhost"
                    port="4444" />
                    <vm:outbound-endpoint path="out"
                        connector-ref="queue" />

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:

String stringMessage = "the message";
ServerSocket serverSocket = new ServerSocket(4444);
Socket clientSocket = serverSocket.accept();
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

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

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