Askemos/BALL

The basic objects (termed places) of the Askemos DVM execute a process step when they receive a message. A reply function

reply = function(place, message)

is computed in each step, where

• reply an aggregate denoting the answer the process step yields to the incoming message.

  A programmer who is used to traditional operating system terms might think of the reply element content as a list all those system calls which the function needs to complete and which might modify values.

• function Step response, a two-ari function defined by the ActionDocument.

• message A read only accessor to the aggregate denoting the current input.

• place A r/o (read type request) or r/w (write type request) accessor to the aggregate denoting "this" place. Often called "me".

The input area (message and place) and the output area (reply) each are described as an xml document, and the function is defined as an XSLT transformation.

These process step are executed by several physical machines in parallel and a byzantine agreement over the value of the reply is required for the step to be actually performed.