Port of VB Point of Sale to Distributed ErLang

Joe Armstrong (AL/EAB) joe.armstrong@REDACTED
Mon May 9 08:46:10 CEST 2005

> Hello ALL,
> What I want to do is Port a server application to Erlang, while still 
> keeping my Internet/Network Clients on their current VB Apps. 
> I have a Point 
> of sale that I would like to expand to take advantage of 
> Erlangs distributed 
> and fault tolerant features......I also have a game server 
> that Erlang would 
> work well with too.
> Is it possible to keep some of the POS Server application in 
> VB and enhance 
> it with Erlang process to do some of the back end processes.
> Any way for this to work to increase the thru put and 
> increase max # of 
> client connections?

Well yes - I guess it would be possible, but it might not be a good idea.
Whether this is a good ideas depends upon the granularity of the tasks that you
wish to perform. Splitting an application into different servers in different languages
involves a severe penalty every time you cross the language boundary - it's far better
to stay in one server and do a large amount of computation, then go to the other server
and do a large chunk of computation than to flip backwards and forwards between the
different servers.

I would try to stick to server in Erlang client in VB - use the languages for what they are good at.
Erlang is good at concurrency - it will happily handle thousands of simultaneous sessions, and the
sessions will be protected from each other (ie a software error in one will not crash the others)
VB is good for making GUIs and doing user interactions.

Keep the components well isolated by sockets and use a well defined protocol between the components
(the very act of isolating the components and writing down the protocols between the components 
should clarify the design :-)  
Then program the different components in the best language for the job.


> Any pointers would be appreciated.
> Thanks Jim

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