add webchat: Tornado's long polling chat demo adapted to run on django and gevent.wsgi2

examples/webchat/README

+An example of AJAX chat taken from Tornado demos and converted to use django and gevent.
+
+To start the server, run
+$ python run.py

examples/webchat/chat/views.py

+import uuid
+import simplejson
+from django.shortcuts import render_to_response
+from django.template.loader import render_to_string
+from django.http import HttpResponse
+from gevent.event import Event
+from webchat import settings
+
+messages = []
+MESSAGES_SIZE = 200
+new_message_event = Event()
+
+
+def new_message(from_, body):
+    data = {'id': str(uuid.uuid4()), 'from': from_, 'body': body}
+    data['html'] = render_to_string('message.html', dictionary={'message': data})
+    return data
+
+def last_message_id():
+    if messages:
+        return messages[-1]['id']
+
+def main(request):
+    if messages:
+        request.session['cursor'] = messages[-1]['id']
+    return render_to_response('index.html', {'MEDIA_URL': settings.MEDIA_URL, 'messages': messages})
+
+def message_new(request):
+    name = request.META.get('REMOTE_ADDR') or 'Anonymous'
+    msg = new_message(name, request.POST['body'])
+    messages.append(msg)
+    if len(messages)>MESSAGES_SIZE:
+        del messages[0]
+    new_message_event.set()
+    new_message_event.clear()
+    return json_response(msg)
+
+def message_updates(request):
+    cursor = request.session.get('cursor')
+    if cursor==last_message_id():
+        new_message_event.wait()
+    assert cursor!=last_message_id(), cursor
+    try:
+        for index, m in enumerate(messages):
+            if m['id'] == cursor:
+                return json_response({'messages': messages[index+1:]})
+        return json_response({'messages': messages})
+    finally:
+        if messages:
+            request.session['cursor'] = messages[-1]['id']
+        else:
+            request.session.pop('cursor', None)
+
+def json_response(value, **kwargs):
+    kwargs.setdefault('content_type', 'text/javascript; charset=UTF-8')
+    return HttpResponse(simplejson.dumps(value), **kwargs)
+

examples/webchat/manage.py

+#!/usr/bin/python
+from django.core.management import execute_manager
+try:
+    import settings # Assumed to be in the same directory.
+except ImportError:
+    import sys
+    sys.stderr.write("Error: Can't find the file 'settings.py' in the directory containing %r. It appears you've customized things.\nYou'll have to run django-admin.py, passing it your settings module.\n(If the file settings.py does indeed exist, it's causing an ImportError somehow.)\n" % __file__)
+    sys.exit(1)
+
+if __name__ == "__main__":
+    execute_manager(settings)

examples/webchat/run.py

+#!/usr/bin/python
+from gevent import monkey; monkey.patch_all()
+from gevent import wsgi2
+import os
+import traceback
+from django.core.handlers.wsgi import WSGIHandler
+from django.core.management import call_command
+from django.core.signals import got_request_exception
+
+os.environ['DJANGO_SETTINGS_MODULE'] = 'webchat.settings'
+
+def exception_printer(sender, **kwargs):
+    traceback.print_exc()
+
+got_request_exception.connect(exception_printer)
+
+call_command('syncdb')
+print 'Serving on 8088...'
+wsgi2.WSGIServer(('', 8088), WSGIHandler()).serve_forever()
+

examples/webchat/settings.py

+from os.path import dirname, join, abspath
+__dir__ = dirname(abspath(__file__))
+
+DEBUG = True
+TEMPLATE_DEBUG = DEBUG
+ADMINS = ()
+MANAGERS = ADMINS
+DATABASE_ENGINE = 'sqlite3'
+DATABASE_NAME = ':memory:'
+DATABASE_USER = ''
+DATABASE_PASSWORD = ''
+DATABASE_HOST = ''
+DATABASE_PORT = ''
+TIME_ZONE = 'America/Chicago'
+LANGUAGE_CODE = 'en-us'
+SITE_ID = 1
+USE_I18N = True
+MEDIA_ROOT = join(__dir__, 'static')
+MEDIA_URL = '/media/'
+SECRET_KEY = 'nv8(yg*&1-lon-8i-3jcs0y!01+rem*54051^5xt#^tzujdj!c'
+TEMPLATE_LOADERS = (
+    'django.template.loaders.filesystem.load_template_source',
+    'django.template.loaders.app_directories.load_template_source',
+)
+MIDDLEWARE_CLASSES = (
+    'django.middleware.common.CommonMiddleware',
+    'django.contrib.sessions.middleware.SessionMiddleware',
+)
+ROOT_URLCONF = 'webchat.urls'
+TEMPLATE_DIRS = (
+    join(__dir__, 'templates')
+)
+INSTALLED_APPS = (
+    'django.contrib.contenttypes',
+    'django.contrib.sessions',
+    'django.contrib.sites',
+    'webchat.chat',
+)

examples/webchat/static/chat.css

+/*
+ * Copyright 2009 FriendFeed
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License. You may obtain
+ * a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+body {
+  background: white;
+  margin: 10px;
+}
+
+body,
+input {
+  font-family: sans-serif;
+  font-size: 10pt;
+  color: black;
+}
+
+table {
+  border-collapse: collapse;
+  border: 0;
+}
+
+td {
+  border: 0;
+  padding: 0;
+}
+
+#body {
+  position: absolute;
+  bottom: 10px;
+  left: 10px;
+}
+
+#input {
+  margin-top: 0.5em;
+}
+
+#inbox .message {
+  padding-top: 0.25em;
+}
+
+#nav {
+  float: right;
+  z-index: 99;
+}

examples/webchat/static/chat.js

+// Copyright 2009 FriendFeed
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations
+// under the License.
+
+$(document).ready(function() {
+    if (!window.console) window.console = {};
+    if (!window.console.log) window.console.log = function() {};
+
+    $("#messageform").live("submit", function() {
+	newMessage($(this));
+	return false;
+    });
+    $("#messageform").live("keypress", function(e) {
+	if (e.keyCode == 13) {
+	    newMessage($(this));
+	    return false;
+	}
+    });
+    $("#message").select();
+    updater.poll();
+});
+
+function newMessage(form) {
+    var message = form.formToDict();
+    var disabled = form.find("input[type=submit]");
+    disabled.disable();
+    $.postJSON("/a/message/new", message, function(response) {
+	updater.showMessage(response);
+	if (message.id) {
+	    form.parent().remove();
+	} else {
+	    form.find("input[type=text]").val("").select();
+	    disabled.enable();
+	}
+    });
+}
+
+function getCookie(name) {
+    var r = document.cookie.match("\\b" + name + "=([^;]*)\\b");
+    return r ? r[1] : undefined;
+}
+
+jQuery.postJSON = function(url, args, callback) {
+    args._xsrf = getCookie("_xsrf");
+    $.ajax({url: url, data: $.param(args), dataType: "text", type: "POST",
+	    success: function(response) {
+	if (callback) callback(eval("(" + response + ")"));
+    }, error: function(response) {
+	console.log("ERROR:", response)
+    }});
+};
+
+jQuery.fn.formToDict = function() {
+    var fields = this.serializeArray();
+    var json = {}
+    for (var i = 0; i < fields.length; i++) {
+	json[fields[i].name] = fields[i].value;
+    }
+    if (json.next) delete json.next;
+    return json;
+};
+
+jQuery.fn.disable = function() {
+    this.enable(false);
+    return this;
+};
+
+jQuery.fn.enable = function(opt_enable) {
+    if (arguments.length && !opt_enable) {
+        this.attr("disabled", "disabled");
+    } else {
+        this.removeAttr("disabled");
+    }
+    return this;
+};
+
+var updater = {
+    errorSleepTime: 500,
+    cursor: null,
+
+    poll: function() {
+	var args = {"_xsrf": getCookie("_xsrf")};
+	if (updater.cursor) args.cursor = updater.cursor;
+	$.ajax({url: "/a/message/updates", type: "POST", dataType: "text",
+		data: $.param(args), success: updater.onSuccess,
+		error: updater.onError});
+    },
+
+    onSuccess: function(response) {
+	try {
+	    updater.newMessages(eval("(" + response + ")"));
+	} catch (e) {
+	    updater.onError();
+	    return;
+	}
+	updater.errorSleepTime = 500;
+	window.setTimeout(updater.poll, 0);
+    },
+
+    onError: function(response) {
+	updater.errorSleepTime *= 2;
+	console.log("Poll error; sleeping for", updater.errorSleepTime, "ms");
+	window.setTimeout(updater.poll, updater.errorSleepTime);
+    },
+
+    newMessages: function(response) {
+	if (!response.messages) return;
+	updater.cursor = response.cursor;
+	var messages = response.messages;
+	updater.cursor = messages[messages.length - 1].id;
+	console.log(messages.length, "new messages, cursor:", updater.cursor);
+	for (var i = 0; i < messages.length; i++) {
+	    updater.showMessage(messages[i]);
+	}
+    },
+
+    showMessage: function(message) {
+	var existing = $("#m" + message.id);
+	if (existing.length > 0) return;
+	var node = $(message.html);
+	node.hide();
+	$("#inbox").append(node);
+	node.slideDown();
+    }
+};

examples/webchat/templates/index.html

+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/> 
+    <title>Chat Demo</title>
+    <link rel="stylesheet" href="{{ MEDIA_URL }}chat.css" type="text/css"/>
+  </head>
+  <body>
+    <div id="body">
+      <div id="inbox">
+	{% for message in messages %}
+          {% include "message.html" %}
+	{% endfor %}
+      </div>
+      <div id="input">
+	<form action="/a/message/new" method="post" id="messageform">
+	  <table>
+	    <tr>
+          <td><input name="body" id="message" style="width:500px"/></td>
+	      <td style="padding-left:5px">
+		<input type="submit" value="{{ _("Post") }}"/>
+		<input type="hidden" name="next" value="{{ request.path }}"/>
+	      </td>
+	    </tr>
+	  </table>
+	</form>
+      </div>
+    </div>
+    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js" type="text/javascript"></script>
+    <script src="{{MEDIA_URL}}chat.js" type="text/javascript"></script>
+  </body>
+</html>

examples/webchat/templates/message.html

+<div class="message" id="m{{ message.id }}"><b>{{ message.from }}: </b>{{ message.body }}</div>

examples/webchat/urls.py

+from django.conf.urls.defaults import patterns
+from webchat import settings
+
+urlpatterns = patterns('webchat.chat.views',
+                       ('^$', 'main'),
+                       ('^a/message/new$', 'message_new'),
+                       ('^a/message/updates$', 'message_updates'))
+
+urlpatterns += patterns('django.views.static',
+    (r'^%s(?P<path>.*)$' % settings.MEDIA_URL.lstrip('/'), 
+      'serve', {
+      'document_root': settings.MEDIA_ROOT,
+      'show_indexes': True }))
+