Newbie question regarding circuits.web.clien

[Andreas Zielke]

Hi all,

i want to use circuits to implement a client which passes messages via TCP to a server and reacts to incoming messages.

The client has to fetch an authentication token from a (different) HTTP server.

I'm using python 3.3 and circuits 3.0.0.dev

After reading the tutorial and experimenting a little with the examples, I'm currently stuck with the following code:

import logging

from circuits import Debugger

from circuits.web.client import Client, request

logging.basicConfig(level='DEBUG')

logger = logging.getLogger(__name__)

class DemoHttpClient(Client):

    def __init__(self):

        super(DemoHttpClient, self).__init__()

        

    def started(self, *args):

        logger.debug('Started!')

        self.fire(request('GET', 'http://www.google.com'))

        logger.debug(self.response())

        

        

if __name__ == '__main__':

    logger.debug('GO!')

    (DemoHttpClient() + Debugger()).run()

I'm trying to fire a request event and receive the response event.

There are several questions - (I'm absolutely new to event driven programming, so please bear with me):

1. The started handler is never called and I don't understand why. Could some kind soul point out my error for me?
2. What is the intended way to react to the response - instinctively I'd say override the handler in the base class and call the super implementation first, but the Client class has a "private" handler for the response - so I suppose that would be the wrong approach    @handler("response")    def _on_response(self, response): ...
   
   

Thanks in advance for your help and kind regards

Andreas

[James Mills]

On Wed, Apr 30, 2014 at 10:29 PM, Andreas Zielke <andreas...@gmail.com> wrote:

i want to use circuits to implement a client which passes messages via TCP to a server and reacts to incoming messages.

The client has to fetch an authentication token from a (different) HTTP server.

I'm using python 3.3 and circuits 3.0.0.dev

After reading the tutorial and experimenting a little with the examples, I'm currently stuck with the following code:

import logging

from circuits import Debugger

from circuits.web.client import Client, request

logging.basicConfig(level='DEBUG')

logger = logging.getLogger(__name__)

class DemoHttpClient(Client):

    def __init__(self):

        super(DemoHttpClient, self).__init__()

        

    def started(self, *args):

        logger.debug('Started!')

        self.fire(request('GET', 'http://www.google.com'))

        logger.debug(self.response())

        

        

if __name__ == '__main__':

    logger.debug('GO!')

    (DemoHttpClient() + Debugger()).run()

I'm trying to fire a request event and receive the response event.

Hi!

Weocme to circuits!

Your only minor problem was: http://linkode.org/wgnJdZEntM6KtbnJ9qGSw5

``circuits.web.client`` inherits from ``circuits.core.components.BaseComponent``

which __does not__ automagically decorate methods as **Event Handlers*.

Plsee see this part of the documentation:

http://circuits.readthedocs.org/en/latest/man/handlers.html

Other than that you're on the right track with your code there

just the missing @handler("started")

cheers

James

James Mills / prologic

E: prol...@shortcircuit.net.au

W: prologic.shortcircuit.net.au

[James Mills]

On Wed, Apr 30, 2014 at 10:29 PM, Andreas Zielke <andreas...@gmail.com> wrote:

There are several questions - (I'm absolutely new to event driven programming, so please bear with me):

1. The started handler is never called and I don't understand why. Could some kind soul point out my error for me?

See my previous response.

Missing @handler("started')

circuits.web.Client inherits from BaseComponent

and does not decorate methods as event handlers.

Component OTOH does.

 

1. What is the intended way to react to the response - instinctively I'd say override the handler in the base class and call the super implementation first, but the Client class has a "private" handler for the response - so I suppose that would be the wrong approach    @handler("response")    def _on_response(self, response): ...
   
   

Normally you would create an event handler.

For example (based on your example):

http://linkode.org/BK3XaJ8s0xN7B9dG20XwA5

Which when run gives:

http://linkode.org/UZGUxkN228cdGJCrRV1Fl6

[Andreas Zielke]

Cheers, James for the kind and quick response :-)

[James Mills]

No problems at all! Any time!

Please when you're using circuits.web.Client

if you can identify any ways in which it can

be improved let us know! It's quite new to the

circuits component library (the Web Client)

cheers

James

James Mills / prologic

E: prol...@shortcircuit.net.au

W: prologic.shortcircuit.net.au

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[Andreas Zielke]

Hi James,

you asked for feedback, so I'll post my observations in this thread.

Using the following code I found that if I try to send HTTPs GETs (or POSTs, for that matter) to secured sites, the response handler does not fire.

import logging

from circuits import Debugger

from circuits.web.client import Client, request, handler

logging.basicConfig(level='DEBUG')

class DemoHttpClient(Client):

    def __init__(self):

        super(DemoHttpClient, self).__init__()

        self.logger = logging.getLogger(self.__class__.__name__)

        

    @handler('started')

    def started(self, *args):

        self.logger.debug('Started!')

        self.fire(request('GET', 'https://www.google.com'))

        

    @handler('response')

    def response_received(self, response):

        self.logger.debug('Own response handler %r', response.read())

        

if __name__ == '__main__':

    (DemoHttpClient() + Debugger()).run()

I can see from the output that the connect seems to work alright (number of port is ok, etc.). The debugger reports:

<connected[client] ('www.google.com', 443 )>

<connected_done[client] (None )>

Changing the URL from https to http will let the result handler fire.

Kind regards

Andreas

[James Mills]

I think I know why... I'll try to respond in more detail as soon as I can! (My Desktop SSD died recently so I'm a little useless right now!)

[James Mills]

Actually looking through the ``circuits.web.client`` code:

https://bitbucket.org/circuits/circuits/src/tip/circuits/web/client.py

I cannot at first identify why HTTPS is not working...

Do you notice that wehn we parse the URL we keep a bit of

state called ``secure``? This in turns gets passed along with

the ``connect()`` event and so should initiate a secure (i.e: SSL)

TCP connection to the host.

Are you getting errors via the Debugger at all?

cheers

James

James Mills / prologic

E: prol...@shortcircuit.net.au

W: prologic.shortcircuit.net.au

[Andreas Zielke]

Hi James,

sorry for not responding - I've been quite busy with other things.

When I run my example with https://www.google.com, I get the following Debugger output:

Using circuits-dev serial

<registered[client] (<TCPClient/client 2596:MainThread (queued=0) [S]>, <DemoHttpClient/client 2596:MainThread (queued=4) [R]> )>

<registered[client] (<HTTP/client 2596:MainThread (queued=0) [S]>, <TCPClient/client 2596:MainThread (queued=0) [S]> )>

<registered[*] (<Debugger/* 2596:MainThread (queued=0) [S]>, <DemoHttpClient/client 2596:MainThread (queued=4) [R]> )>

<started[client] (<DemoHttpClient/client 2596:MainThread (queued=3) [R]> )>

DEBUG:DemoHttpClient:Started!

<registered[select] (<Select/select 2596:MainThread (queued=0) [S]>, <TCPClient/client 2596:MainThread (queued=0) [S]> )>

<ready[client] (<TCPClient/client 2596:MainThread (queued=0) [S]> )>

<request[client] ('GET', 'https://www.google.com', None, {} )>

<connect[client] ('www.google.com', 443, True )>

<connect[<TCPClient/client 2596:MainThread (queued=0) [S]>] ('www.google.com', 443, True )>

<connected[client] ('www.google.com', 443 )>

<connected_done[client] (None )>

<write[<TCPClient/client 2596:MainThread (queued=0) [S]>] (b'GET / HTTP/1.1\r\nHost: www.google.com\r\n\r\n' )>

So afaik the client connects on the secure HTTP port and sends a correct get request - only there's no response...

Kind regards

Andreas

[James Mills]

Hi Andreas,

Sorry for the late reply.

What version of circuits are you using btw?

There seems to be something odd about SSL

(at least for client connectivity) in circuits. With 3.0.0.dev I get

this error:

$ ./examples/wget.py https://www.google.com.au/

ERROR <handler[*.connect] (TCPClient.connect)> (<connect[<TCPClient/client 93141:MainThread (queued=0) [S]>] ('www.google.com.au', 443, True )>) {<type 'exceptions.AttributeError'>}: 'NoneType' object has no attribute 'do_handshake'

  File "/Users/s2092651/work/circuits/circuits/core/manager.py", line 603, in _dispatcher

    value = handler(*eargs, **ekwargs)

  File "/Users/s2092651/work/circuits/circuits/net/sockets.py", line 270, in connect

    _do_handshake_for_non_blocking(self._ssock)

  File "/Users/s2092651/work/circuits/circuits/net/sockets.py", line 210, in _do_handshake_for_non_blocking

    ssock.do_handshake()

  File "/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ssl.py", line 305, in do_handshake

    self._sslobj.do_handshake()

I'm not sure why this fails yet... Still looking into it...

Some help would be appreciated :)

cheers

James

James Mills / prologic

E: prol...@shortcircuit.net.au

W: prologic.shortcircuit.net.au

[James Mills]

I think this might be relevant: http://bugs.python.org/issue11326

Perhaps we need to rework ``circuitsnet.sockets.TCPClient``'s connect handler a bit?

cheers

James

James Mills / prologic

E: prol...@shortcircuit.net.au

W: prologic.shortcircuit.net.au

[James Mills]

I've created an issue to track this: https://bitbucket.org/circuits/circuits/issue/101/improve-circuitsnetsockets-client

I'm hoping that improving the ``circuits.net.sockets.TCPClient`` connect handling

will fix this ssl problem and improve the overall usability of TCPClient(s).

One thing we've had missing the whole time (*borrowed indirectly from Twisted who have not solved this either*)

is not knowing whether our async socket has actually connected or not.

(We and Twisted assumed it is connected.)

cheers

James

James Mills / prologic

E: prol...@shortcircuit.net.au

W: prologic.shortcircuit.net.au

[Andreas Zielke]

Hi James,

thank you very much for your feedback.

I'm using 3.0.0-dev on Python 3.3.

The http client is only needed once to get an auth token. Afterwards I'm dealing with TcpClients, which work beautifully. :-)

I've switched to the requests lib temporarily  to implement getting the token.

All the best

Andreas

[James Mills]

Sure no worries. That's a good workaround :)

We'll try to get this fixed in circuits though

so you can swap out ``requests.get()`` for

an async call :)

cheers

James

James Mills / prologic

E: prol...@shortcircuit.net.au

W: prologic.shortcircuit.net.au