Mailman 3 July 2007 - Twisted-web

Test
by Philippe Lafoucrière Aug. 5, 2021

Aug. 5, 2021

Hi all just a test

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Passing events to (Athena) event handlers.
by kgi Aug. 6, 2007

Aug. 6, 2007

Hi all. In the thread entitled "How to insert an Athena event handler using Stan?" in October and November 2006, Jean-Paul Calderone said: """ The issue with the handler you showed me is most likely that the handler thinks its first argument is an event, but it is actually a node. There is no way to access the event object right now, but I have been considering just passing it as the next argument. """ and: """ [Though] this may shortly change to function doFoo(self, node, event) (which is completely backwards compatible, of course, due to the magic of javascript sucking so much). """ I've just hit this particular issue. Up until now all my events have been heavily node-based (e.g. tabbing out of a field, submitting a form, etc), where you can generally get away with just having access to the node the even happened on. However, not having access to the event itself renders handlers for events like 'onkeyup' almost useless, unless you register them with the top-level document (like the Nevow.Athena._checkEscape() works), and as far as I can tell it makes implementing certain things like drag and drop much more difficult. Is there a branch with experimental support for this? If not, I've been digging around in where I think the relevant code is, namely: Nevow/nevow/athena.py line 1062: _handlerFormat = "return Nevow.Athena.Widget.handleEvent(this, %(event)s, %(handler)s);" and: Nevow/nevow/js/Divmod/Runtime/__init__.js line 963: The Javascript looks like: Nevow.Athena.Widget.handleEvent = function handleEvent(node, eventName, handlerName) { var widget = Nevow.Athena.Widget.get(node); var method = widget[handlerName]; var result = false; if (method === undefined) { Divmod.msg("Undefined event handler: " + handlerName); } else { result = Nevow.Athena.Widget.dispatchEvent( widget, eventName, handlerName, function() { return method.call(widget, node); }); } return result; }; It looks like: 1. Adding an event argument to the handler format in the Python (I don't think that _rewriteEventHandlerToAttribute() needs modification); 2. Adding the corresponding 'event' argument to handleEvent() in the JS; 3. Adding IE hacks (using window.event instead of event, etc) to the start of handleEvent(); 4. Adding the event to the list of arguments of method.call() within the anonymous function passed as the fourth argument to dispatchEvent() would achieve this, and as JP pointed out, this should be backwards compatible, as no extant JS handler functions should be declaring additional arguments. Note that within dispatchEvent() itself the callable is invoked as callable.call(widget), but it looks like the 'widget' argument is ignored entirely by the anonymous function, which contains its own method call with its own "closure-y" arguments. Because of this I reckon dispatchEvent() needs no modification whatsoever. Would a patch posted as a trac ticket be acceptable? I searched trac for 'event' and couldn't find anything resembling this. What would the unit test requirements be for a change like this be? Thanks, Ricky

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Adding Athena JS handlers in render methods?
by kgi Aug. 1, 2007

Aug. 1, 2007

Hi all. I hit something earlier today that has me stumped. It might be a case of programming blindness, but on the other hand I might just be trying to do something that isn't supported. Up until now, I've been adding Athena event handlers directly in the docFactory's stan. However, I needed to add something with an Athena event handler that needs data from an asynchronous external source, so I added data and render methods. These normally Just Work, in the case of "vanilla" XHTML, but the Athena handlers don't seem to be processed by _rewriteEventHandlerToAttribute(). In other words, instead of a proper event handler being inserted into the XHTML, like so: <a href="#" onclick="return Nevow.Athena.Widget.handleEvent(this, "onclick", "onclick");">Click Me 0</a> a tag like this appears: <a href="#"><athena:handler handler="onclick" event="onclick"></athena:handler>Click Me 1</a> Here's some sample code to illustrate this. It's not a complete example in that there's no JS code to be invoked when you click on the first link, but it's runnable enough that you can load the page and view the page source. The first link, "Click Me 0", has correct event handlers inserted. The second and third links ("Click Me 1" and "Click Me 2") both have incorrect event handlers inserted. One of them simply returns a piece of stan, the other also makes a supposedly asynchronous call. Am I trying to do something unsupported, or is this a bug? Thanks, Ricky == from twisted.internet import defer from nevow import athena from nevow import loaders from nevow import flat from nevow import tags as T from nevow.page import renderer _js = athena.handler ( event = 'onclick', handler = 'onclick' ) class MyElement ( athena.LiveElement ): docFactory = loaders.stan ( T.div ( render = T.directive ( 'liveElement' ) ) [ T.a ( href = '#' ) [ _js, "Click Me 0" ], T.br, T.div ( render = T.directive ( 'someStan1' ) ), T.br, T.div ( render = T.directive ( 'someStan2' ) ), ] ) def someStan1 ( self, context, name ): return T.a ( href = '#' ) [ _js, "Click Me 1" ] renderer ( someStan1 ) def someStan2 ( self, context, name ): def _cb ( r ): return T.a ( href = '#' ) [ _js, r ] d = self._getData() d.addCallback ( _cb ) return d renderer ( someStan2 ) def _getData ( self ): return defer.succeed ( "Click Me 2") class MyPage ( athena.LivePage ): docFactory = loaders.stan ( T.html [ T.head ( render = T.directive ( "liveglue" ) ), T.body [ T.div ( render = T.directive ( "myelement" ) ) ], ] ) def render_myelement ( self, request, tag ): e = MyElement() e.setFragmentParent ( self ) return e ###################################################################### from twisted.application import service, internet from nevow import appserver port = 7060 application = service.Application ( "example" ) res = MyPage() site = appserver.NevowSite ( res ) webService = internet.TCPServer ( port, site ) webService.setServiceParent ( application )

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Creating contexts for Unit Tests
by tarjei July 30, 2007

July 30, 2007

Hi, I've run into a problem related to testing my application. I'm trying to create a test for a method that should return a redirect to another page: def return_upload_success(self, ctx): """ File is uploaded, everyone is happy. We show the results :-) """ self.request = inevow.IRequest(ctx) self.request.setComponent(iformless.IRedirectAfterPost, "/view/" + self.file.get_basename() ) return self.request To test this method I write a unittest that tries to create a context object: def test_return_upload_success(self): self.page.context = PageContext(None, remembrances={inevow.ICurrentSegments: ('rrr'), inevow.IRemainingSegments: ()}) ret = self.page.return_upload_success("sqlrsult") The problem is that when I run this I get a typeerror: TypeError: ('Could not adapt', PageContext(tag=None, remembrances={<InterfaceClass nevow.inevow.ICurrentSegments>: 'rrr', <InterfaceClass nevow.inevow.IRemainingSegments>: ()}), <InterfaceClass nevow.inevow.IRequest>) Does anyone have an idea on how I should set up my test? Kind regards, Tarjei

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what happens when browsers close the connection?
by Phil Christensen July 30, 2007

July 30, 2007

Sorry to be so noisy lately, but I've run into another strange problem with web2.wsgi, or more likely, my understanding of it. I'm seeing issues when the browser connection is closed uncleanly, particularly when doing a "fast reload" and clicking the reload before the first request/response has completed. My specific issue is that when this happens, if I'm in the middle of a MySQL query (which in my app, I usually am), subsequent calls to <Cursor>.execute() are failing because the previous resultset was never freed. This is only an issue when using web2 (or my custom twisted.web wsgi layer, which still uses web2's wsgi.WSGIHandler class). Apache/ mod_python seems to allow each request to continue to completion behind the scenes, although it makes up for it by crashing horribly in other ways. What I'd like to know is what exactly happens when a browser closes a connection? Is there any possibility that the lost connection event has some implications further up the call chain? Could any of this somehow stop or kill the thread created in WSGIResource.renderHTTP()? -phil

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wsgi thread synchronization
by Phil Christensen July 27, 2007

July 27, 2007

I'm crossposting because although my use case is in web, this is more of a question about dealing with threads in twisted. I have a decent academic understanding of threads, but I've never really used them in Python or Twisted. I've just moved from a mod_python WSGI container running on prefork apache2 to a container running on twisted.web, and I realized that I now have threading considerations I didn't before. Since my potential synchronization problems are actually quite few, I've been getting by just by using threading.BoundedSemaphore to manage a couple of thread-sensitive areas of the web app. However, I already have a dependency on Twisted core, so it occurs to me that there are probably nicer, twistier ways of doing this. For example, I have a section of code like: host_tree = {} host_tree_lock = threading.BoundedSemaphore def get_application(env): global host_tree, host_tree_lock host = env.get('HTTP_HOST', env['SERVER_NAME']) host_tree_lock.acquire() if not(host in host_tree): _load_plugins(env) host_node = host_tree[host] if not(host_node.has_path(env['REQUEST_URI'])): _load_plugins(env) app = host_node.get_data_at(env['REQUEST_URI']) host_tree_lock.release() return app The only variable shared between threads is the `host_tree` global (the `env` variable is the WSGI environment, which is unique per thread, and the resulting `app` object is immutable). This works for me and is sufficient for my needs, but I'd appreciate a sanity check from anyone with some thread karma to spare. Thanks again, -phil

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twisted.web wsgi support
by Phil Christensen July 26, 2007

July 26, 2007

I had need of WSGI support on twisted.web, so I put together the attached module. I'd like to contribute this back to the project, of course, but I need some guidance on how I should proceed. The attached module is just a proof of concept at this point; I haven't written any unit tests or documentation, but the bigger issue I'd like to discuss is how to remove the dependency on twisted.web2. Since I generally run directly out of SVN HEAD, the web2 dependency isn't a big deal for me. However, removing this dependency would require a great deal of duplication of effort. In the end, the only real changes required were tweaks to twisted.web2.twcgi.createSGIEnvironment() and corresponding changes to twisted.web2.wsgi.WSGIHandler, as well as a twisted.web-compliant WSGIResource implementation. I guess my goal here is to start a dialog about the best way to go forward. I've duplicated this email and attachment in a ticket at: http://twistedmatrix.com/trac/ticket/2753 Your input is appreciated, -phil

1 0

twisted.web.client and HEAD
by Manlio Perillo July 24, 2007

July 24, 2007

Hi all. I'm using Twisted 2.4 on Debian Etch. It seems that twisted.web.client does not handle well HEAD commands. If I do a getPage(url, method='HEAD') I get an exception: twisted.web.client.PartialDownloadError: 200 OK Is this a bug or a feature (since web.client is for page retrivial)? Thanks Manlio Perillo

2 5

twistd and web2 weirdness
by Phil Christensen July 24, 2007

July 24, 2007

I'm totally confounded on this one. For some reason, when using twistd, web2 cannot be found by the interpreter. (I'm running Twisted SVN HEAD on pythonmac's Python 2.4 on Mac OS X.) For example, I've got the following code in a file called twisted.py from twisted.web2 import server, channel, static, wsgi def handler(env, start_response): pass # This part gets run when you run this file via: "twistd -noy modu/web/twisted.py" root = wsgi.WSGIResource(handler) site = server.Site(root) # Start up the server from twisted.application import service, strports application = service.Application("web2") s = strports.service('tcp:8888', channel.HTTPFactory(site)) s.setServiceParent(application) When running it (with twistd -noy twisted.py), I get: Traceback (most recent call last): File "/Library/Frameworks/Python.framework/Versions/Current/ bin/twistd", line 20, in ? from twisted.scripts.twistd import run File "/Users/phil/Desktop/twisted.py", line 1, in ? from twisted.web2 import server, channel, static, wsgi ImportError: No module named web2 This is a standard Twisted installation using `python setup.py install`, and web2 is clearly in my site-packages directory: optimus:~ phil$ ls -la /Library/Frameworks/Python.framework/ Versions/2.4/lib/python2.4/site-packages/twisted/web2 total 1272 drwxr-xr-x 54 root admin 1836 Jul 24 10:54 . drwxr-xr-x 36 root admin 1224 Jul 24 10:54 .. -rw-r--r-- 1 root admin 254 Jun 29 2006 __init__.py -rw-r--r-- 1 root admin 371 Jul 24 10:54 __init__.pyc ... ... Even stranger is that twistd doesn't seem to have any problems finding/loading the web2 plugin optimus:~ phil$ twistd Usage: twistd [options] ... ... ... Commands: web2 An HTTP/1.1 web server that can serve from a filesystem or application resource. ... ... ... And when running the exact interpreter path specified in twistd, there are no problems either: optimus:~ phil$ which twistd /Library/Frameworks/Python.framework/Versions/Current/bin/twistd optimus:~ phil$ head -n 1 /Library/Frameworks/Python.framework/ Versions/Current/bin/twistd #!/Library/Frameworks/Python.framework/Versions/2.4/Resources/ Python.app/Contents/MacOS/Python optimus:~ phil$ /Library/Frameworks/Python.framework/Versions/ 2.4/Resources/Python.app/Contents/MacOS/Python Python 2.4.3 (#1, Apr 7 2006, 10:54:33) [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> from twisted.web2 import server >>> I had this same issue on my other development machine, also a Mac, but I assumed it was some kind of configuration issue with that machine in particular. Has anyone had a similar experience? Any help in this matter would be appreciated. -phil

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how to implement render_POST?
by Søren Bach Christiansen July 23, 2007

July 23, 2007

Dos anyone have and example how to implement the different render function in web. Im trying to implement a REST service and I now have to use the render_POST. My render_POST function looks like this: def render_POST(self,request): print request.received_headers print request.content.readlines() print request return "<html></html>" but the only output i see is: {'content-length': '134', 'content-type': 'application/x-www-form- urlencoded', 'host': 'sbcmac.local:8081', 'user-agent': 'Python- urllib/1.16'} [] <POST /User HTTP/1.0> I wonder why I cant see the data I am posting. Can any of you guys see what im doing wrong??? ps. if anyone have a link to some example code, showing how to implement render_POST, render_PUT and render_DELETE I would be very happy ##### Client POST test code import urllib import sys url = "http://sbcmac.local:8081/User" param={'xml': """<userlist><user ContactName="Soren Bach Christinansen" ID="1" UserName="sbc"/></userlist>"""} if __name__ == '__main__': try: doc=urllib.urlencode(param) remote = urllib.urlopen(url,doc) except: sys.exit() /Søren

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