Middle men wanted

Hakan Mattsson <>
Wed May 5 15:48:33 CEST 2004


On Wed, 5 May 2004, Ulf Wiger (AL/EAB) wrote:

Uffe> Perhaps you could add some thinking about how to handle issues
Uffe> like fault tolerance, in-service upgrade, etc... you know, that
Uffe> OTP framework that you and some others invented a few years ago. ;)
Uffe> 
Uffe> There's not necessarily much discrepancy there, but I believe it
Uffe> would be helpful to reveal how you've thought about it. 
Uffe> Proposing a uniform way of reporting unexpected things would 
Uffe> also be good; in one part of your examples, you use io:format/2,
Uffe> while in another, you use something called ed_log:error/1.

This middle man plugin architecture is quite interesting, but why not
take it a step further and make it independent of the actual transport
(in this case TCP/IP)?

In the Megaco application there are three types of plugins:

 - transport (TCP, UDP, SCTP, ...)
 - encoding (text pretty/compact, ASN.1 BER/PER, erlang binaries, ...)
 - user logic (gateway, controller, proxy,  ...)

The architecture is explained here:

 http://www.erlang.org/project/megaco/download/LATEST_MEGACO_DOC/html/megaco_architecture.html#2.2
 http://www.erlang.org/project/megaco/download/LATEST_MEGACO_DOC/index.html

Even if this application (of course) is biased towards the
Megaco/H.248 protocol, its architecture is rather generic.
It was not designed to be a generic man in the middle framework,
but it almost is.

/Håkan




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