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POChannel API closes a channel
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copied!<p>First off, thank you @Moishe for the very useful API. I'm having a little timeout problem, maybe someone knows the answer. Here's how I open the channel:</p> <pre><code>var openChannel = function () { var channel = new goog.appengine.Channel($('#token').val()); var socket = channel.open(); socket.onopen = function () {}; socket.onmessage = function (m) { var message = JSON.parse(m.data); // do stuff }; socket.onerror = function (error) { alert(error); }; socket.onclose = openChannel; }; openChannel(); </code></pre> <p>This works fine, I post my messages and they go to the other clients pretty quickly. But if I stay on the page for roughly 15 minutes, the server loses track of my channel. In dev, it throws an error (which I saw was a known bug: <a href="http://www.mail-archive.com/google-appengine@googlegroups.com/msg44609.html" rel="nofollow">http://www.mail-archive.com/google-appengine@googlegroups.com/msg44609.html</a>). But in prod, it still ignores messages on that channel after about 15 minutes.</p> <p>We fixed it by adding a <code>setInterval(getSomeUrl, everyMinute)</code> to the page, but we'd rather not have to do that. I noticed in Moishe's last commit for the trivia game sample that he took out a keep-alive. I didn't understand how he replaced it, and what he meant by onopen is reliable:</p> <p><a href="http://code.google.com/p/trivia-quiz/source/browse/trunk/src/index.html" rel="nofollow">http://code.google.com/p/trivia-quiz/source/browse/trunk/src/index.html</a></p> <p><em>Update</em>: Server side code is</p> <pre><code>class Home(BaseHandler): def get(self): self.checkUser() if self.user: userId = self.user.user_id() token = channel.create_channel(userId) chatClients[userId] = token self.model['token'] = token players = self.checkChatRoom() self.model['users'] = players self.model['messages'] = map(lambda k:db.get(k), self.chat_room.messages) # TODO: Replace this line and the next with a query self.model['messages'] = sorted(self.model['messages'], key=lambda m: m.timestamp, reverse=True) self.writeTemplate('index.html') </code></pre> <p><code>BaseHandler</code> is just a base class I use for all my GAE handlers, it provides <code>checkUser</code> which redirects if the user isn't logged in, and it provides <code>writeTemplate</code> which takes what's in <code>self.model</code> and writes it in a template. It's just a proof of concept, so no cache or anything else other than what's above.</p>

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