<?php

/**

* $Id: session.php,v 1.1 2012/11/15 13:26:41 gaudenz Exp $

* Copyright (c) 2006, Gaudenz Alder

*/

include_once("../src/mxServer.php");

// enables logging to a file

mxLog::addLogfile("session.log");

session_start();

mxLog::enter("main (session ".session_id().")");

if (!is_dir("test"))

{

mkdir("test");

chmod("test", 0777);

}

$document = $_SESSION['document'];

$sid = session_id();

$filename = $document."/".$sid;

$delta = $document."/delta.xml";

if (!isset($document) || isset($_GET["init"]))

{

$document = "test";

$filename = $document."/".session_id();

$delta = $document."/delta.xml";

$_SESSION["document"] = $document;

session_commit();

header("Pragma: public");

header("Expires: 0");

header("Cache-Control: must-revalidate, post-check=0, pre-check=0");

header("Content-Type: application/xhtml+xml");

// Gives the client a unique namespace that

// is used as a prefix for new cell ids.

$ns = md5(uniqid(rand(), true));

mxLog::debug("session $sid initialized: ns=$ns");

echo "<message namespace=\"$ns\">";

echo "<state>";

$fp = fopen("diagrams/graphmodel.xml", "r");

fpassthru($fp);

fclose($fp);

echo "</state>";

echo "<delta>";

if (is_file($delta))

{

$fp = fopen($delta, "r+");

fpassthru($fp);

fclose($fp);

}

echo "</delta>";

echo "</message>";

// Deletes existing buffer

if (is_file($filename))

{

unlink($filename);

}

touch($filename);

chmod($filename, 0777);

}

else

{

// Gets the XML parameter from the POST request and converts all linefeeds

// into a HTML entity. This is required for correct handling of the XML on

// the client side.

if (isset($_POST["xml"]))

{

$xml = str_replace("\n", "&#xa;", stripslashes($_POST["xml"]));

// TODO: Take only the edits from the XML

$edits = "";

$doc = mxUtils::parseXml($xml);

$child = $doc->documentElement;

if ($child->nodeName == "message")

{

$child = $child->firstChild;

while ($child != null)

{

if ($child->nodeName == "delta")

{

$edit = $child->firstChild;

while ($edit != null)

{

if ($edit->nodeName == "edit")

{

$edits .= $doc->saveXML($edit);

}

$edit = $edit->nextSibling;

}

}

$child = $child->nextSibling;

}

}

// Appends the change to all connected sessions except the incoming

// session and the global delta file

if (strlen($edits) > 0)

{

mxLog::debug("received changes from ".session_id().

": ".strlen($edits)." bytes");

// Makes sure the global delta file exists so that the change is

// appended below

if (!is_file($delta))

{

touch($delta);

chmod($delta, 0777);

}

// Clears out the delta file if this change contains a mxRootChange

// in which case the previous changes will no longer be visible and

// just waste bandwidth.

if (strpos($edits, "mxRootChange") > 0)

{

$fp = fopen($delta, "r+");

fpassthru($fp);

ftruncate($fp, 0);

fflush($fp);

fclose($fp);

}

// Dispatches the XML to all sessions except the incoming session

// TODO: Remove dead sessions

$fp = opendir($document);

while($filename = readdir($fp))

{

if ($filename!= "." &&

$filename != ".." &&

!is_dir("$document/$filename") &&

$filename != session_id())

{

mxLog::debug("dispatch changes to $filename");

$tmp = fopen("$document/$filename", "a");

fwrite($tmp, $edits);

fflush($tmp);

fclose($tmp);

}

}

flush();

}

}

else

{

// Makes sure to cancel existing pending requests before they consume the

// change data after a refresh, where the request must be served instead.

$requestid = md5(uniqid(rand(), true));

$_SESSION['requestid'] = $requestid;

session_commit();

mxLog::debug("request $requestid enters");

if (!is_file($filename))

{

touch($filename);

chmod($filename, 0777);

}

else

{

// Keeps the request for 10 secs and asks for changes each second

$timeout = 10;

$count = 0;

while (is_file($filename) &&

filesize($filename) == 0 &&

$count < $timeout &&

$_SESSION['requestid'] == $requestid)

{

sleep(1);

clearstatcache();

$count++;

// Sync the session state

session_start();

session_commit();

}

// Sync the session state

session_start();

session_commit();

if ($_SESSION['requestid'] != $requestid)

{

mxLog::debug("request $requestid has died");

}

else if (filesize($filename) > 0)

{

mxLog::debug("request $requestid leaves: ".filesize($filename)." bytes");

header("Pragma: public");

header("Expires: 0");

header("Cache-Control: must-revalidate, post-check=0, pre-check=0");

header("Content-Type: application/xhtml+xml");

// Sends the changes to the client

echo "<message>";

echo "<delta>";

$fp = fopen($filename, "r+");

fpassthru($fp);

ftruncate($fp, 0);

fflush($fp);

fclose($fp);

echo "</delta>";

echo "</message>";

}

else

{

touch($filename);

}

}

}

}

mxLog::leave();

mxLog::close();

?>