Re: Question about accessing internal object *PTCSPC programmatically from my job

On 11/05/2010, at 8:06 AM, Dave Fiorillo wrote:

> I have been "challenged" to find a way to determine from a program  
> that
> gets called to be able to figure out what the last function key was  
> that
> was pressed.  I cant use the INFDS directly, because I am running in a
> different program than the program where the DSPF is defined (DDS),  
> and
> the handling of the function key being pressed.
>
> For example, Program A has the logic that when F9 is pressed - then  
> call
> program B - and I am program B.   So, in Program B I want to be able  
> to
> retrieve from memory what was the last function key pressed in Program
> A.

Umm ... if you're PGMB and PGMB is called when F9 is pressed then  
surely you can infer that F9 was pressed in the caller but really why  
do you care? PGMB has been invoked so it should do whatever it is that  
it does. Why does it matter which F-key was used to invoke it?

That's a serious question because if we know WHY you're trying to do  
something we may be able offer a different (better) solution.

> Its ok if I have to tell Program B the name of the display file for
> now, but phase 2 might be nice to be able to figure out the last  
> display
> file used.

Information about the last display file is easy. See the QWSRTVOI  
(Retrieve Output Operation) API.

The Work Control Block (or PCO Associated Space) of the job has some  
of this information at position x'451' but the API is the approved  
mechanism.

>
> What I have been able to figure out so far, by using DMPJOB, is that
> when I search on the DSPF name in the dump, I can consistently see a
> space defined with the identifier of "19 FC" for the display file used
> in program A, and at offset x'7D3' from this particular section is the
> AID byte of the function key.  I am assuming that this is the place in
> memory of the job that stores the INFDS for program A.   I tried this
> with 5 different function keys and got consistent results with the AID
> byte so I am very hopeful that this is the sweet spot in memory (at
> least for V5R4).

I think you're finding the pointer to the ODP of the display file in  
the Data Management Communications Queue.

Leif's MI Book has some information on the DMCQ including how to walk  
the ODP chain. See:
	http://www.leif.org/as400/

You can compare the layout of the data you've found with the Feedback  
structures described in the (I keep thinking Appendix A. of the Data  
Management Guide because that's where it used to be) buried in the  
Reference Chapter of the Database File Management manual.

> My question:  is there an easy way to access this information using  
> MI?
>> From my research so far, I have learned that a "19 FC" is a *PTCSPC
> internal object to the job, and I keep scouring the dump to try and
> glean more information.

Easy is such a relative term. As far as I know there is no MI  
instruction to materialise the information you want, nor is there an  
API, so you'll have to follow the chain of WCB->DMCQ->ODP->I/O  
Feedback and you'll need system-state to access these objects so if  
you're after a commercial solution then I suspect you'll need to find  
another way.


Regards,
Simon Coulter.
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