Hello Einar, This is a quite long email. What I can tell you, is that querying many command line applications with t.i.utils.getProcessOutput and gathering them in a DeferredList worked for me. Example: the list_cameras in http://svn.sat.qc.ca/trac/miville/browser/trunk/py/scenic/devices/cameras.py
Good luck ! a 2010/2/15 Einar S. Idsø <einar.twis...@norsk-esport.no>: > Hi, > > I am planning to develop an application that will query a number of > services at given intervals, and Twisted seems like a very nice > platform to do so. However, because of little previous experience with > Twisted, especially with building proper applications, using > interfaces and using plugins, I could really need some pointers to get > me started. > > In the following I will try to explain in broad terms what the > application will do, and humbly ask for input on how I may structure > it using factories, protocols etc.: > > 1. A number of more-or-less similar server applications (5-10) have a > number of concurrent instances/servers (1-30) each. > 2. I need to acquire the status of each instance at given intervals. > These will typically range from every 20 seconds to every 3 minutes, > and depend on the which service the instance is based on. > 3. A list of the server instances shall be acquired via an XML-query > every few minutes to pick up on new or removed instances. > 4. An executable already exists which can be used to status-poll > almost all services using different parameters. I will be calling it > from my application to do the polling instead of recreating it in > Python. > 5. I need to be able to create my own polling-protocol for at least > one of the service types which is incompatible with the executable. > 6. Some services can not only be polled at intervals, but additionally > stream information that I am interested in listening to. > 7. At a later point in time, I wish to be able to communicate with > IRC, MSN and other services/protocols using the queried and streamed > data. > > My initial general thought is the following: > 1. Design a class for each server application, where all classes > implement the same interface. The class defines how to deal with > server instances of its corresponding server application type. Classes > are created as Twisted-plugins. > 2. For each new server instance that is discovered, create an object > which contains a timer and polls the server at specific intervals, > writing the result to a globally accessible data structure. > 3. For server instances that stream data continuously in addition to > being polled at regular intervals, create a separate object which > listens to the server. > > I believe I should somehow have a global data structure which contains > references to all the server instance objects, regardless of type, and > allows them to store data. This is sort of like the factory does for > protocols, except in my case I don't think I can use a regular factory > since I need both clients (to poll at intervals) and servers (to > listen to streaming data). I suppose I could use a ClientFactory for > the pollers and a Factory for the stream-listeners, and let them have > a common data-store? But is it possible to use a single ClientFactory > to spawn all poller-objects regardless of server type? Or do I need > one ClientFactory for each server type? Do I perhaps need one > ClientFactory per server instance? Or should I just ignore factories > all together since it is primarily the timer and asyncronicity of > Twisted I need? > > I am quite certain there is a correct twistified way of handling this > sort of problem. I am just not sure what it is, and would sincerely > welcome all feedback on how this should be done. Feel free to point to > examples of applications that are similar to what I sketched above, > and tell me to study the code :) > > Cheers, > Einar > > _______________________________________________ > Twisted-Python mailing list > Twisted-Python@twistedmatrix.com > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python > -- Alexandre Quessy http://alexandre.quessy.net/ _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
