PHP Socket Java message exchange

Question

I'm trying to make a communication between a PHP page and running Java server. Just a simple string exchange through sockets.

This is my Java Code for thread that handles the connection:

            InputStream in = clientSocket.getInputStream();
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            BufferedWriter out = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));

                String request;

                if((request=br.readLine())!=null){
                System.out.println("got the following request: " + request);
                out.write(request +"\n");
                out.flush();

                out.close();
                in.close();
                }

I tested it with simple Java client that sends the string then receives the result and prints it back and it worked. Both client and the server had the same output.

This is my PHP code:

$fp = @fsockopen ($host, $port, $errno, $errstr);

if($fp){
    fputs($fp, $str);
    //echo fgets($fp);
}

close($fp);

Which sends the string to the Server, and the Server receives it. But once I uncomment the line with fgets($fp) I am blocked until some sort of timeout happens after 1-2 minutes. During that Block my server is not receiving anything. After timeout my server prints, that it has received the line, and probably sends the response back, however, the PHP code doesn't print anything.

What could be the problem?

Thank you in advance.

P.S. It is probably worth saying that I am accessing this web page through AJAX, so it "echoes" the result back to the other page.

mway · Accepted Answer · 2010-11-12 23:45:10Z

1

I prefer the socket_* functions, personally. But either way, you're likely missing checking for a terminating character:

$sock = socket_create(AF_INET, SOCK_STREAM, 0);
socket_connect($sock, $host, $port);

socket_write($sock, $str);

$response = '';
while($resp = socket_read($sock, 1024)) {
    if(!$resp)
        break;
    $response .= $resp;
    if(strpos($resp, "\n") !== false)
        break;
}

echo "Server said: {$response}";

answered Nov 12, 2010 at 23:45

mway

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Comments

bcosca · Accepted Answer · 2010-11-12 16:49:33Z

1

Try adding after fsockopen():

stream_set_blocking($fp,0);
$info=stream_get_meta_data($fp);
if ($fp) {
    fputs($fp,$str);
    $reply=''.
    while (!feof($fp) && !$info['timed_out']) {
        $reply.=fgets($fp);
    echo $reply;
}
close($fp);

edited Nov 12, 2010 at 16:49

answered Nov 12, 2010 at 15:36

bcosca

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6 Comments

Dmitry Over a year ago

now the blocking disappeared, but i still don't get anything with fgets().

bcosca Over a year ago

Seems like the server is expecting a newline-terminated string. Have you tried fputs($fp,$str."\n"); ?

Dmitry Over a year ago

The Java Server gets the $str as I have it now, without "\n"

Dmitry Over a year ago

It is the PHP Server that doesn't get the string back, although in Java while sending a put a "\n" in the end.

bcosca Over a year ago

See my reply for a more comprehensive solution

|

Dmitry · Accepted Answer · 2010-11-12 23:06:19Z

0

My friend sent me this link http://abejali.com/?p=56 with a very nice code that does the trick. There is a trick inside that solves the problem

The following code works. The trick was to add chr(13) . chr(10) to the end of the string.

$str.= chr(13) . chr(10);
stream_set_blocking($fp,0);
$info=stream_get_meta_data($fp);
if ($fp) {
    fputs($fp,$str);
    $reply='';
    while (!feof($fp) && !$info['timed_out']) {
        $reply.= fread($fp, 1);
    }
    echo $reply;
}

answered Nov 12, 2010 at 23:06

Dmitry

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1 Comment

SimonJ Over a year ago

It's not a "trick". BufferedReader.readLine() reads until it sees a carriage return or linefeed character, which is what chr(13) and chr(10) are respectively. See: download.oracle.com/javase/6/docs/api/java/io/…

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