COP 4020 Lecture -*- Outline -*-

* distributed programming in Erlang

** definition and applications
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    WHAT IS DISTRIBUTED PROGRAMMING?

A program is distributed when it executes
on 



Advantages:

 - true concurrency
 - scalability (speed, data size)
 - extensibility
 - availability
 - fault tolerance
 - access to large set of resources
 
Disadvantages:

 - true concurrency (synchroniztion hard)
 - time lags
 - no global state

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     ...more than one physically distinct 
        computers, with no shared memory.

     The advantages are technological
     The disadvantages are in terms of programming, 
        but we can overcome them

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  ERLANG CONCEPTS FOR DISTRIBUTED SYSTEMS

Node = a computer running Erlang
   an alive node has a name (unique atom)

def: when a node N is *monitored* by 
a node L, then if N is not responding
then a {nodedown, N} message is sent to L.

def: when a node N is *linked* to node L,
then when either exits, the other does also.

Message passing semantics:
 - messages are delivered in the order sent
 - messages are never corrupted or lost
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** fault tolerance and atomicity

*** databases
*** atomic transactions

** reconfiguration