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POJava and TCP messages - messages sending on different ports each time
 

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    <p>I've very new to networking and using networks to send messages through programming. Anyways, I have a client and server java command line application (server is running in a VM on the same machine with a bridged network adapter, and host to guest pinging works and vice versa), and it would appear on the server side that each message it receives is coming from a different port. Is this normal behavior? What happens when the machine runs out of ports to use? Does Java's libraries intelligently close the ports after it's done with them? </p> <p>So basically, is this even a problem? If it is, how do I go about fixing it? <strong>Output from the server</strong> and then <strong>code for the client</strong> listed below. </p> <p>SERVER OUTPUT AFTER SENDING SOME MESSAGES:</p> <pre><code>Received (/192.168.1.122:59628): shsfh Received (/192.168.1.122:59629): dfsh Received (/192.168.1.122:59631): dfh Received (/192.168.1.122:59632): fdshdf Received (/192.168.1.122:59633): shf Received (/192.168.1.122:59637): fgfggsdfhsfdh Received (/192.168.1.122:59638): fdshf Received (/192.168.1.122:59639): hs Received (/192.168.1.122:59640): hfh </code></pre> <p>CODE FOR THE CLIENT THAT SENT THOSE MESSAGES:</p> <pre><code>import java.io.*; import java.util.*; import java.net.*; class TCPClient { public static void main(String argv[]) throws Exception { Scanner scan = new Scanner(System.in); while (true) { String msgcont = scan.nextLine(); System.out.println(tcpSend("192.168.1.153", 6789, 5000, msgcont)); } } public static String tcpSend(String ip, int port, int timeout, String content) { String ipaddress = ip; int portnumber = port; String sentence; String modifiedSentence; Socket clientSocket; try { clientSocket = new Socket(ipaddress, portnumber); DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream()); BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); outToServer.writeBytes(content + '\n'); clientSocket.setSoTimeout(timeout); modifiedSentence = inFromServer.readLine(); clientSocket.close(); outToServer.close(); inFromServer.close(); } catch (Exception exc) { modifiedSentence = ""; } return modifiedSentence; } } </code></pre>
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    1. COYou are creating a new connection for each comment sent so it's going to be on a different port. If you use the same connection each time it will be 100x more efficient and use the same port each time.
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      1. USPeter Lawrey
    2. COThanks Peter and neeagl for the quick and useful responses. They were both helpful.
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      1. USSop Wyin
 

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