[Pipet Devel] UI\DL support BL\PL requests?

jarl van katwijk jarl at casema.net
Fri Apr 7 18:02:38 EDT 2000

> >
> > In GMS I've not only the engine serving request out of the GUI,
> > but also the other way around. Like when the processing part
> > detects a data flow which is a deadend, it will trigger an event
> > in the GUI. I can imaging various other random events inside the
> > VSH PL and BL that need to be passed to the DL and UI.
> > I'm wondering if Loci allowes such abilities? Or should I put all
> > the logic for handling the error\notify events inside the BL? It
> > seems a good thing, and I'm willing to implement it, but I needs
> > some feedback first ofcourse :)
> You're aware that Loci's front 'listens' to a stream of XML commands from the
> middle.  All communication, including that of unexpected error messages,
> travels through that stream.

No, I didn't knew that.. so there's no problem. Good. I leave gms\BL the way it
now, you do so 2 and we only need to define the communication some day.
Not now please :-)
I'm just orientating if we still have mayor design differences.

> But, right now the mechanism is not threaded.  So, the middle literally cannot
> do anything until the front issues a command, and visa versa.  And I believe
> the front doesn't listen for unexpected messages (is that right, Brad?).  IOW,
> the middle cannot YET trigger an event in the front.  It was planned, though.

That is enough for now :)

> I don't know if the logic for this belongs in the DL or BL.  But, of course,
> the communication should pass through the DL before going to the front.

I think events once they are triggered in a layer, it will 'travel upwards' to
the UI. But it might be handled by a layer before it reaches the UI.


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