alan5281 / cometd Goto Github PK

If you run any of the demos and hack the twisted-cometd-client.py client,
it will work (receive messages from the browser via server), but after 3
messages, will stop receiving anything.

The problem can be traced to a producer queue in the twisted code being
filled and never emptied.  For example, adding the following lines to the
beginning of the twisted-cometd-client.py code can "delay" the problem:

  import twisted.web2.stream
  twisted.web2.stream.ProducerStream.bufferSize = 5000

I haven't quite figured out what's going on _really_ yet.

We need to be able to answer the question "how do I really scale a comet
setup?"

From conversations on IRC in the #twisted channel, the word on the street
is that using ClientCreator is a weakness of the current code, as it makes
it hard to use e.g. TrafficLogging.  

I don't understand enough of the various abstractions in twisted to figure
out what the right refactoring it yet.

Auth fields to be removed from the spec as they are not defined.
any cometd specific auth can be done in ext fields or with cookies
and thus does not need partially defined auth fields.

I found and fixed two small bugs. The first, the JSONP callback is set to
jsonpcallback, but jQuery send jsonp(epoch). The seconds is if you have ext
set, but do not have json-comment-filtered set, an exception will be thrown
on the null ext.

That would make it be importable, which would be a Good Thing.

Also, the fact that it's twisted-based doesn't matter _that much_ to the user.

What steps will reproduce the problem?
1. url for python path module is no longer valid in setup dependencies

What version of the product are you using? On what operating system?

trunk

Please provide any additional information below.

Here's the patch necessary:

Index: setup_dependencies.sh
===================================================================
--- setup_dependencies.sh       (revision 410)
+++ setup_dependencies.sh       (working copy)
@@ -20,9 +20,9 @@
 cd ..

 echo "installing path"
-wget http://www.jorendorff.com/articles/python/path/path-2.1.zip
-unzip path-2.1.zip
-cd path-2.1
+wget http://cheeseshop.python.org/packages/source/p/path.py/path-2.2.zip
+unzip path-2.2.zip
+cd path-2.2
 sudo python setup.py install
 cd ..

Who do I ask?

jorendorff.com, the host for python path (a requisit to cometd-twistd) has 
been offline.  i have attempted to contact the author about his website 
being down but have recieved no reply.

i realize this is somewhat not a cometd issue (ok, not at all) but relying 
on an ill-ly hosted module has been causing me significant angst and i 
thought i'd mention and see if perhaps someone would be kind enough to 
paste their own copy while jorendorff.com is awol.

thanks
rektide

Comet needs a load balancer that can handle lots of zombie requests.
Things like apache+mod_proxy just don't cut it.

So a paper discussing the options and architecture is required

What steps will reproduce the problem?
1. Checkout http://svn.cometd.com/trunk/
2. Run twistd -noy cometd.tac in cometd-twisted/

Everything breaks in cometd-twisted/bayeux.py, line 94 with
JSON decoding errors.

Indeed, after checking bayeux/bayeux.json and bayeux/bayeux_error_codes.json, I 
can confirm that 
they do not follow JSON syntax. There are a lot of missing commas.

One other issue is that simplejson (Python library used to decode JSON) somewhy 
doesn't recognize 
000 as a number, so I also had to convert those to plain 0. This can't 
generally hurt, except for 
readability.

The patch against r480 is attached.

nested defs are exceedingly slow in Python, because the nested function
gets parsed and built on every function call.  Take all of them out.

What steps will reproduce the problem?
1. Follow the instructions in the Installation section of the README.
2. Attempt to start twisted-cometd using the installed files.

What is the expected output? What do you see instead?

The server should start.  Instead the server halts immediately with module
import errors for the bayeux-*.py modules.

What version of the product are you using? On what operating system?

Latest SVN (around May 4th 2008)

Please provide any additional information below.

What steps will reproduce the problem?
1. Start the default/example cometd.py server
2. Start the twisted-cometd-client.py
3. Watch it throw a KeyError-Exception

Expected output: Connecting to the server, subscribing to topics.

Observed output: KeyError being raised
  File ".../python2.5/site-packages/cometd.py", line 491, in initHandshake
   if message["id"] is not None:
  exceptions.KeyError: 'id'


With: cometd-twisted SVN Rev. 462, Python2.5, Ubuntu Linux Gutsy.

Could be fixed with checking message.has_key("id") before trying to access it.
Or the twisted-cometd-client.py is the culprit with not sending a "id" field.

Both should be fixed ;)

JavaScript is misspelled as Javacript on the web site.

The description of Cometd as having a single event server seems to be
outdated as it doesn't reflect that there are multiple implementations.

Given the involvement of Jetty/Webtide and BEA, perhaps the top right
description of who produces Cometd should be updated?