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sachin.mandaliya
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Joined: 17 Jan 2007
Posts: 24
Location: India
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| If there is a program A, which triggers program B with a transaction, but there is no data or commarea being passed to B. How can program B access the storage address/data present in commarea of A? |
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dick scherrer
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Joined: 23 Nov 2006
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Location: Inside the Matrix
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Hello,
Why should an independent program have any access to some other program?
If program B needs access to something from program A, they both need to follow some convention. . . |
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rajesh_mbt
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If there is no data or commarea passed to B program, then it can't access the commarea storage of A program. As Dick advised what is the neccessary of calling B program when an independent program have any access to some other program.
Please correct me if am wrong |
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Robert Sample
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Location: Dubuque, Iowa, USA
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| There's a term in CICS for the case of program B attempting to access program A's COMMAREA or other data, and that term is STORAGE VIOLATION. CICS specifically protects against this type of access. |
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CICS Guy
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Joined: 18 Jul 2007
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| sachin.mandaliya wrote: |
| If there is a program A, which triggers program B with a transaction, but there is no data or commarea being passed to B. How can program B access the storage address/data present in commarea of A? |
As Robert said, that could end up being a storage violation.
But, if protected or in some way made available, the address could be saved by A in a TS/TD queue that B could retrieve. |
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Earl Haigh
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Joined: 25 Jul 2006
Posts: 475
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if you do get addressability to Program A's working storage from a
different transaction.
move some data to it from Program B. Let us know what happens !!
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Garry Carroll
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Joined: 08 May 2006
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Location: Dublin, Ireland
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| Quote: |
| But, if protected or in some way made available, the address could be saved by A in a TS/TD queue that B could retrieve |
But what could protect it? This is a storage area of a task that may well have ended, freeing up all its storage. The passed pointer could be pointing at anything! If Task A continues for long enough, in parallel to Task B, what's to prevent either from modifying storage that the other's using?
If storage could be protected past task-end, how could clean-up be achieved? There may be potential for a memory-leak here....
Garry. |
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CICS Guy
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Joined: 18 Jul 2007
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| Garry Carroll wrote: |
| But what could protect it? This is a storage area of a task that may well have ended, freeing up all its storage. The passed pointer could be pointing at anything! If Task A continues for long enough, in parallel to Task B, what's to prevent either from modifying storage that the other's using? |
Minor design problem, but it is solvable. For instance, task A starts non-terminal B and then waits on an ECB for B to finish....
| Quote: |
| If storage could be protected past task-end, how could clean-up be achieved? There may be potential for a memory-leak here.... |
Proper design would prevent attempted access to freed storage. |
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Garry Carroll
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Joined: 08 May 2006
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Location: Dublin, Ireland
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| Quote: |
| For instance, task A starts non-terminal B and then waits on an ECB for B to finish.... |
Yes, but isn't this kinda like going back to conversational technique? All that program and task storage tied-up while waiting for Task B to POST the ECB ! A bit like hogging storage while waiting for the terminal user to return from coffee/lunch...
I guess we're only discussing theoretical ways of doing something that can be better achieved by proper design in the first instance.
Garry. |
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CICS Guy
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| Quote: |
| Yes, but isn't this kinda like going back to conversational technique? |
In an application I worked on, the CICS transaction was entirely pseudo-conversational but had to wait for either the other task to succeed or timeout. The other task did an external request to another site that sometimes failed to complete in a timely manner. |
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sachin.mandaliya
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Joined: 17 Jan 2007
Posts: 24
Location: India
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Thanks guys for your answers....
Actually I have been asked this question in some interview and I had some doubts about it. Now they are cleared. |
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Earl Haigh
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Joined: 25 Jul 2006
Posts: 475
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Sachin,
out of courtesy, please identify with original posting for questions that come from an interview process.
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