New tutorial

Joakim G. <>
Wed Feb 5 15:57:08 CET 2003


Excellent

/Jocke

Joe Armstrong wrote:

>Hello everybody,
>
>  A  while  back Todd  Proebsting  asked me  how  you  build a  simple
>fault-tolerant server.
>
>  After a moment's thought I said "that's easy"
>
>  After two moments thought I said "that's difficult"
>
>  and after three moments thought I said "It's possible".
>
>  To make something fault-tolerant you  need at least two machines and
>you need  to replicate things -  if you think  you can do this  on one
>machine stop reading now and go play with visual basic ...
>
>  I made  myself a  little client-server. The  server is  actually two
>servers and and  data on these two servers  is replicated using shared
>mnesia disk tables.
>
>  The client knows about both servers - if server one is down it tries
>server two and vice versa, this is similar to DNS - the alternative is
>some complicated IP-failover stuff - which is very non-portable.
>
>  Transactions between the client and (virtual) server are idempotent.
>
>  The solution  I came up  with is not  entirely obvious (at  least it
>wasn't to me) but it is (hopefully) simple enough to be grokked if you
>know a small amount of Erlang.
>
>  The solution and all the code are available at:
>
>     http://www.sics.se/~joe/tutorials/robust_server.html
>
>  All comments, corrections and improvements are welcomed.
>
>  /Joe
>
>  
>





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