Cannot read response from Java socket server using PHP client

Question

I have a server written in Java. Its a simple one that echoes "HELLO" when a client connects and then echoes back any reply the client sends. The code is below:

ServerSocket ss=new ServerSocket(2001);
while(true) {
  Socket s=ss.accept();
  BufferedReader in=new BufferedReader(new InputStreamReader(s.getInputStream()));
  PrintWriter out=new PrintWriter(s.getOutputStream(),true);
  out.println("HELLO");
  String msg=in.readLine();
  out.println(msg);
}

I have a PHP script that connects to the server:

<?php
  $socket=socket_create(AF_INET,SOCK_STREAM,getprotobyname('tcp'));
  socket_connect($socket,'127.0.0.1',2001);
  $msg=socket_read($socket,10);
  echo socket_write($socket,'I am the client.');
  $msg=socket_read($socket,20);
  echo $msg;
?>

I am getting the "HELLO" message from the server, and the server is also getting the "I am the client" message, but the PHP client is not getting the reply back. What am I doing wrong here?

Jon Skeet · Accepted Answer · 2012-05-19 18:39:02Z

4

in.readLine() won't return until it sees a line terminator.

Unless socket_write in PHP implicitly adds a line terminator, you'll need to do so yourself, so that the Java side sees that you've written a complete line of text.

answered May 19, 2012 at 18:39

Jon Skeet

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4 Comments

Sankha Narayan Guria Over a year ago

Ok. So I need to add a newline character after my reply!

goat Over a year ago

Note the op's statement that the server does get the message from php(implying that readline() has returned). Although, I still think you're right.

Jon Skeet Over a year ago

@chris: Ah, I'd missed that. I don't see how the OP would get the message from the client unless socket_write really adds a newline implicitly... or the PHP script has given up and closed the socket.

goat Over a year ago

Agreed. I don't think readline ever really returned because socket_write doesnt add a newline or a null or anything like that.

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