Establishing a p2p connection in python

[Jeremy Jones]

gs wrote:

>Hi!
>
>This is my first time posting to a newsgroup so please be gentle to me
>:)
>
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>
Welcome.  You have little to fear from this crowd.

>Introduction to my problem:
>
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<snip>
I think that your problem can be solved with Twisted.  That is _a_ 
solution.  Not the only, maybe not the best for everything you're 
wanting to do (which it seems that learning a lot is important to you), 
but _a_ solution.  It's got a bit of a learning curve to wrap your head 
around how everything fits together, but it's a powerful framework.  
I've used it less than I plan to, but I've got some interest in how it 
works.

>Problems:
>1) I've written a threaded server that stores information about
>connected servers in a "container class". This class holds information
>about username, a unique ID, the connecting adress and the actual
>socket. I have not been able to find any information online on how i
>could go about to connect two sockets. It would seem like the socket
>is already "occupied" since it is connected to the server. Could one
>duplicate, or otherwise get a dedicated socket for sending binary
>data, to one connected socket from another? A few pointers and/or tips
>would be greatly appreciated!
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Are you talking about your server binding two different ports?  If you 
are using the Python standard SocketServer, you should be able to just 
spin off a thread for each server you start and tell it to 
serve_forever() (or what have you).  If you're using Twisted, I think 
all you would need to do is factory.listenTCP(<port number>, <factory>), 
then reactor.run().  I'll leave getting data between the different ports 
you've bound as an exercise for the reader.

>2) I've also failed to find python specific information on how abouts
>one would do file resuming. I would think that you, somehow, use
>md5-checksums to check file status and somehow skip the first part of
>the datastream. Also, pointers and maybe an explanation in (short)
>pseudo-code would be much appreciated.
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Can't help you here, sorry.

>3) Is this too big of a project for a novice programmer such as
>myself? I do want to go through with this since it's a genuine
>problem, but i do not know if i'm ready. I'm not a "quitter" per say,
>but i'm afraid doing something TOO advanced in the beginning might be
>overwhelming :)
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I don't think this is too big at all.  But I do think you'll want to 
break it down a little bit and set smaller goals for yourself.  Try to 
first get the smallest fairly usable thing working.  Then you can start 
adding functionality from there.

>Thanks for reading,
>gs
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>
HTH,


Jeremy Jones