.. include:: <s5defs.txt>

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py.execnet - simple ad-hoc networking
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:Authors: Holger Krekel, merlinux GmbH
:Date: 13th March 2006 

remote method invocation is cumbersome
========================================

- CORBA/RMI/SOAP model is cumbersome 
- "infection" with object references throughout your program
- need to define interfaces, generate stubs/skeletons
- need to start server processes ahead of time 
- complicates programming 

what you want of ad-hoc networks 
====================================

- ad hoc **local protocols**
- avoid defining and maintaining global interfaces 
- deploy protocols purely from the client side 
- zero installation required on server side 

py.execnet model of ad-hoc networks
====================================

- *Gateways* can be setup via e.g. SSH logins or via Popen
- *Gateway.remote_exec* allows execution of arbitrary code 
- means of communication between the two sides: *Channels* 
  (with send & receive methods) 
- example requirements: ssh login + python installed

py.execnet.SshGateway example 
====================================

interactive::

    gw = py.execnet.SshGateway('codespeak.net')

    channel = gw.remote_exec("""
        for filename in channel: 
            try:
                content = open(filename).read()
            except (OSError, IOError):
                content = None
            channel.send(content)
    """)
            
next steps / references 
====================================

- ad-hoc p2p networks 
- chaining channels / passing channels around 
- ensure it also works nicely on win32 
- btw, py.execnet is part of the py lib 

     http://codespeak.net/py/ 
        
.. |bullet| unicode:: U+02022
.. footer:: Holger Krekel (merlinux) |bullet| 13th March 2006