Mailman 3 June 2005 - Twisted-web

Test
by Philippe Lafoucrière 05 Aug '21

05 Aug '21

Hi all just a test

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XML-RPC and None
by Matt Feifarek 09 Sep '05

09 Sep '05

Hello. We're using twisted.web.xmlrpc to serve an xmlrpclib client, so python-to-python. We'd like to pass None through the rpc connection on occasion. There's a flag in the standard lib to allow this to serialize ( send allow_none=True to the xmlrpclib.Server() ) We're getting this error from the twisted resource when we try to serialize 'None': Fault: <Fault 8002: "can't serialize output"> I know that the twisted resources uses the stock xmlrpclib, but how can we tell it to allow None to serialize the twisted way? Thanks.

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Error: nevow_clientToServerEvent is not defined (Firefox JS Console)
by Michael M 06 Jul '05

06 Jul '05

Firstly, I love nevow, brilliant design, really just plain brilliant. Thanks in advance for any help with this problem. # PROBLEM The livepage/evil example failes with this error in the Firefox JS console # ERROR Error: nevow_clientToServerEvent is not defined # SYSTEM OS: Gentoo Linux Firefox version: 1.0.4 Nevow revision: 1595 # EXAMPLE CODE from nevow import rend, loaders, tags from nevow.liveevil import handler def greeter(client, nodeName): client.alert("Greetings. You clicked the %s node." % nodeName) # Any string arguments after the event handler function will be evaluated # as JavaScript in the context of the web browser and results passed to the # Python event handler handler = handler(greeter, 'node.name') class LivePage(rend.Page): docFactory = loaders.stan( tags.html[ tags.body[ tags.ol[ tags.li(onclick=handler, name="one")["One"], tags.li(onclick=handler, name="two")["Two"], tags.li(onclick=handler, name="three")["Three"] ] ] ]) Thanks

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Formless, custom form layout
by Richard Wall 30 Jun '05

30 Jun '05

I am trying to customise my Formless layout based on examples/customform.py, but I'm not sure how I can group inputs in fieldsets. eg. http://rafb.net/paste/results/dhZOhk37.html That's my ideal layout, can anyone give me hints on howto achieve it? -RichardW.

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How works formless?
by Alberto Trujillo 30 Jun '05

30 Jun '05

Hello: I was trying to follow this example but I'm a bit lost. I can see the form but when I submit the information I receive the next exepction error "global name request is not defined". I don't know why formless has to be autocallable and where I must to defined "request" Could anybody help me? Here are my files. I need to know what I have to do after submit the information. year.tac ---------- from twisted.application import internet, service from nevow import appserver import year application = service.Application("tasks") webserver = internet.TCPServer(8080, appserver.NevowSite(year.Colorful())) webserver.setServiceParent(application) year.py --------- from nevow import rend, loaders import formless class YearChooseable(formless.TypedInterface): def selectYear(self, year=formless.Integer()): pass selectYear = formless.autocallable(selectYear) class Colorful(rend.Page): __implements__ = YearChooseable, rend.Page.__implements__ def selectYear(self, year): self.test = True return rend.Page.locateChild(self, request, childSegments) docFactory = loaders.xmlfile("year.html") year.html ---------- <form action="freeform_post!!selectYear" method="POST"> Type a year: <input type="text" name="year" /> <input type="submit" /> </form>

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Defers, the reactor, and idiomatic/proper usage -- new user needs some advice?
by Richard Meraz 29 Jun '05

29 Jun '05

Hello all, Just getting started with Twisted. Thanks to the community for tremendous work. I diligently went through the entire archives of the mailing list -- reading choice threads -- and I read through all the documentation on the twisted-matrix website. I've never done any event-driven programming, but there was enough on the site for me to start getting a handle on things. Below is a short script that crawls the links from a URI looking for RSS-type feeds. I'm hoping that some of the more experienced developers would be willing to give some advice about whether I'm using twisted.internet.reactor and twisted.web.client.getPage correctly. I've put some comments labeled as #Question where I'm unsure wheter I understand exactly what I'm doing -- Im hoping someone can refute/chastise/critique the understanding that is implied by the code and questions. I have a thick skin so the more talented/vitriolic the response the better. # Find RSS Feeds. # Richard Meraz -- rfmeraz(a)gmail.com. from twisted.internet import reactor from twisted.web.client import getPage import feedlib # Includes modified version of M. Pilgrims feedfinder.py and modified version of # D. Mertz code for url extraction from p. 228 of __TPIP__. MAXTIME = 60 # Kill crawl after this time TIMEOUT = 20 # Kill page retrieval after this time inactive MAXDEPTH = 3 # Recurse this depth when crawling page. # Question: There seem to be many idioms to aggregate information from different defered call-back chains in twisted.. Since everything runs in a single thread I just stuck my stuff in a global class and everybody modifies the vars there as I pass it around to the call-backs that should see it. Seems okay for a small script like this? class StateVars: '''Keep Global state for starting/stopping feedfinding and a record of links we have checked and their status''' connections = 1 links_checked = {} # Structure: {url: (is RSS/ATOM/RDF, page-content)} # Question: start_feed_crawl is where I set up my defers. getPage returns a defer and I attach my call-back process_link. # addCallbacks adds a callback/errback in parallel so only one or the other is called? so I need to add # the final errback to catch errors from callback process_link ? def start_feed_crawl(uri,depth): '''Harvest feeds from a uri''' # Question: how to time-out this deferred chain if getPage is taking too long to finish its work. # what exactly does the argument timeout to getPage do, does it timeout the socket after a no-response # or does it put an upper-bound on how long getPage has to finish its work? getPage(uri, timeout=TIMEOUT).addCallbacks(callback=process_link, callbackArgs=(uri, depth, StateVars), errback = process_error, errbackArgs=(uri,StateVars) ).addErrback(process_error, uri, StateVars) def process_link(data,uri,depth,state): '''Recursive link processing callback. Determines whether a link is a RSS/ATOM/RDF feed. If not then extracts all xml-like links that could point to feeds and starts crawl on those.''' if feedlib.couldBeFeedData(data): #print 'Feed: %s' % uri state.links_checked[uri] = (True,data) else: state.links_checked[uri] = (False,None) if depth <= MAXDEPTH: alinks = feedlib.getALinks(data,uri) links = feedlib.getLinks(data,uri) rawurls = feedlib.extract_urls(data) links_to_check = [feedlib.makeFullURI(u) for u in set(alinks+links+rawurls) if feedlib.isXMLRelatedLink(u)] for l in links_to_check: # Don't need to see it again. if state.links_checked.has_key(l): continue else: state.connections += 1 # Question: since I'm starting up these defers in a callback they are # being created after I've called reactor.run() since we call start_feed_crawl # as we find new links that meet our criteria. Am I doing anything bad here? # All the examples I've seen (eg. p. 548-552 Python Cookbook, great eg by V. Volonghi # and P. Cogolo) have their data up-front and therefore set-up all the defers before calling # reactor.run(). Here I'm discovering my data as I go along and setting up deferrs while # the reactor is spinning. Here is my fundamental lack of understanding. While this script # seems to run okay, is it okay to do this? start_feed_crawl(l,depth+1) state.connections -= 1 # Question: Is this how I kill the reactor -- ie. using some sort of state condition. Is there a better way, # should I try better to understand deferred-list. For example. A top-level deferred-list that contains # other deferred-lists which get created to hold all the defers (created by start_feed_crawl) for the # links on a given page. Could this deferred-list be told to stop the reactor when the other lists have # fired their callback (after the component defers have finished) ? (Sorry for the convoluted question here # I'm new at this) if state.connections <= 0: reactor.stop() return def process_error(error,uri,state): '''Catch errors in link processing''' state.connections -= 1 if state.connections <= 0: reactor.stop() return '' if __name__ == '__main__': import sys if len(sys.argv) < 2: print 'feedfinder_new.py <uri>' sys.exit() uri = feedlib.makeFullURI(sys.argv[1]) start_feed_crawl(uri,1) # Question: I'm killing the process after a pre-determined amount of time. However reactor.stop() seems # to kill network connections. is there a way to stop the reactor but let the connections finish. # Hack to blow out any connections that are hung or uncalled after MAXTIME reactor.callLater(MAXTIME, reactor.stop) reactor.run() for l in StateVars.links_checked: if StateVars.links_checked[l][0]: print l Final question: occasionally I get errors that come from the http.py code in twisted. This get printed to the console, but don't necessarily stop my program. Should my errbacks be catching these? How do I keep errors from getting logged to the console (beside redirecting stderr). I can post an example if necessary of the errors I'm getting. Thanks for your help. Richard F. Meraz -- Never think there is anything impossible for the soul. It is the greatest heresy to think so. If there is sin, this is the only sin – to say that you are weak, or others are weak. Swami Vivekananda

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[PATCH] typo in static.py?
by Wilfredo Sánchez Vega 29 Jun '05

29 Jun '05

I think the patch below fixes a typo in an error case I noticed while reading the code. -wsv Index: twisted/web2/static.py =================================================================== --- twisted/web2/static.py (revision 14048) +++ twisted/web2/static.py (working copy) @@ -215,7 +217,7 @@ self.defaultType) if not self.fp.exists(): - return response.NOT_FOUND + return responsecode.NOT_FOUND if self.fp.isdir(): # If this is a directory, redirect

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child page
by Françoise Maguib 29 Jun '05

29 Jun '05

Hi, I've made a small program. he aim is to access to a Ldap server and to show details of each user. I have a root page, and a child. When I run my program,I'm unable to display items in the root page because on click(in a button on the root page),the program goes immediately in the child page(instead of displaying items in the root page).I can't locate the problem.is someone could help me? ___________________________________________________________________________ Appel audio GRATUIT partout dans le monde avec le nouveau Yahoo! Messenger Téléchargez cette version sur http://fr.messenger.yahoo.com

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Re: [Twisted-web] Livepage, ClientHandle and context [continued]
by Chris Were 28 Jun '05

28 Jun '05

>> I expect this can be rectified in livepage.py (line 728 on my co): >> def locateHandler(self, ctx, path, name): >> ### XXX TODO: Handle path >> return getattr(self, 'handle_%s' % (name, )) > > > The path here is meant to be a string which names a Fragment or other > dispatch path. As you can see, none of this is implemented yet, but > this is my solution to this problem that you and others on this list > have had. Basically the API in javascript would look something like this: > > server.handleWithPath('onclick', 'some/path', 'someArgument') > > locateHandler would change to look more like locateChild, breaking > apart the path into segments and consuming them until it locates the > target. I'm not sure how the default locateHandler implementation will > locate action targets; perhaps with dispatch_* prefixed methods? Here > is a small example: > > class MainPage(Page): > docFactory = loaders.xmlstring("""<html > xmlns:n="http://nevow.com/ns/nevow/0.1"> > <a onclick="server.handleWithPath('onclick', 'someFragment', > 'someArg')"> > Click me > </a> > <span n:render="liveid" /> > <span n:render="liveglue" /> > </html>""") > > def dispatch_someFragment(self, ctx): > return MyFragment() > > > class MyFragment(Fragment): > def handle_onclick(self, ctx, someArg): > assert someArg == 'someArg' > > > Suggestions on different names other than "dispatch_*" are welcome; > the main reason I haven't implemented this functionality yet is > because I can't decide what to call it! :-) I'd say dispatch is fine (and not just because I'd like to see this implemented ;-) Taking from the chatola example: return context.tag(onsubmit=livepage.handler(onSubmit, getValue('inputline'))) What would be good is if something similar could be used with dispatch, perhaps the following (assuming this code is within a fragment): return context.tag(onsubmit=livepage.handler(onSubmit, getValue('inputline',self))) ie: livepage.handler(func,arg,fragment=None) if this mapped the javascript to server.handleWithPath('action','fragment','arg') and also mapped (if not there already) the dispatch_fragment in the MainPage Would something along those lines be feasible? > I suggest using a query parameter rather than an additional URL > segment. xml is a different "view" of the same "object"; in my > opinion, URLs should represent "objects" (Resources) and query > parameters should be used to parameterize how the view renders. One > might also be able to use the "Accept" header that browsers send to > negotiate the rendered content type. But this is just a suggestion. > Whatever works for you is fine with me :-) I tend to agree that xml is a different "view", but I see a benefit in a REST-like approach to have /xml at the end of an existing Resource... perhaps the idea that /xml is an extended view to the existing Resource. Chris.

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Livepage, ClientHandle and context [continued]
by Chris (FeedTagger) 28 Jun '05

28 Jun '05

Sorry, just registered so unable to join existing thread. I'm having similar problems that are outlined here: http://twistedmatrix.com/pipermail/twisted-web/2005-June/001523.html "I also can't see a way to use handler_* methods, because this methods must be inside a rend.Fragment subclass in my case." I expect this can be rectified in livepage.py (line 728 on my co): def locateHandler(self, ctx, path, name): ### XXX TODO: Handle path return getattr(self, 'handle_%s' % (name, )) My implementation is slightly different in that I'm not using rend.Fragment, I have a Page broker that responds to requests and returns a new page that implements from a master page. -------------------------- myserver.py: pageMappings ] { 'search': search.Page 'index': index.Page } class Page(livepage.LivePage): def locateChild(self,ctx,segments): # depending on the value of segments[0] return the correct page # from a predefined map, otherwise 404 page = pageMappings[segments[0]] return page(), segments[1] Then in index.Page.py: class Page(_master.FrontPage): def render_button(self,ctx,data): return ctx.tag(onclick="server.handle('click')") def handle_click(self,ctx,client): client.alert('clicked button') _master.py: class CorePage(livepage.LivePage): # various properties that all generic pages should exhibit class FrontPage(CorePage): # load front page template # provide any default slot fills etc. -------------------- Now the problem as I see it (with primitive livepage knowledge) is that the livepage request that's sent with server.handle('click') is attempting to be mapped to myserver.Page, instead of my intended index.Page class. Is it possible to provide this functionality or should this whole template based approach be re-worked in some other fashion? ... as a side note using a generic dispatcher of pages (myserver.Page) I can do cool things like detect /xml appended to url and instead of loading .xhtml templates, load the appropriate .xml templates. Hence without changing any application code I can generate xml versions of every single webpage across a site. Cheers, Chris

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