7.15.3 Messages

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The interface of a Logiweb machine performs an input-eval-output-loop in which it converts input to a list of input messages and applies the handler to that input list. The return value is supposed to be a list of output messages which the interface executes.

Execution of one output message results in one input message which is passed to the handler in the next loop. Apart from an initial 'boot' input message, all input messages are replies to output messages. We shall refer to output and input messages as requests and replies, respectively.

As an exception we refer to the boot input message as an 'event' because it is not a reply to a request. The boot event is the only input message which is not a reply.

The interface has the ability to load code dynamically into the running machine. Such code can improve the efficiency of the engine and can add new abilities to the interface. A Logiweb machine is virgin from it starts and until first time it loads code. The virgin Logiweb machine has very few abilities.

The virgin machine knows the following messages:

   boot event ( a , e , c , s )
   quit request ( x )
   write request ( s )
   read request
   read reply ( c )
   extend request ( r , s )
   extend reply ( x )
   exec request ( p , h )
   exec reply ( i , p )

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Copyright © 2010 Klaus Grue, GRD-2010-01-05