Sunday, December 14, 2008

EPDL expression for the "on off windows"

Yesterday, I drove my 11 year old (youngest) duaghter, Daphna, with four of her friends (all boys), 65 kilometers to the nearest branch of Max Brenner (see pictures above) a chocolate store which also has a restaurant, most of the menu is the chocolate oriented menu, but for parents there is also some real food. They still did not get to Haifa, but I think that they have brnaches in New York. Anyway, we found the nearest branch and got there...

I have posted an explanation about the approach to the "on off window" that Pedro posted; somebody asked me beyond the explanation -- how this scenario can be expressed in the EPDL meta-language that we are working on. Actually this is a very simple scenario, it is expressed like this:

Let E be the event type; with two attributes param1 and param2 (as given);
we also need to route the event e to the agent a, and the output event to a producer - lets define two output pipes, p1 and p2, both of them carry events of type e.

We define:
  • Context, name = c, type = temporal, initiated-by = event e with param1 = 2, terminated-by = event e with param2 = 0.
  • Agent, name = a, type = filter, within-context = c, filter-condition = all, input = p1, output = p2

Explanation: Context determines which subset of the "event cloud" are applicable, there may be multiple agents within a context, but each agent has a single context. In this case - we can use the simplest type of agent - filter - with a trivial filter-condition - "all". Agent a will not be active before cotnext c will be active. With the event that satisfies the condition, the context is opened, thus agent a receives input, does nothing with it, and post it as output.

This is of course very simple case -- we can also concatenate all selected events to one composite event; we can also use more sophisticated agent e.g. pattern detection.

More educational material about languages -- later.

No comments: