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Can any file be a GSAM file?

 
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mf_user
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PostPosted: Mon Nov 26, 2007 6:27 pm    Post subject: Can any file be a GSAM file?
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Hi,

An EASYTRIEVE program is reading 10 files and creating a PS file an output file. This file is should be read by an IMS/DB program for further processing.

Can we consider the PS file as GSAM and read it in IMS/DB fashion (like use GN etc)?

What is the problem in reading a PS file as GSAM file using IMS/DB?

Please explain.

TIA.
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Bitneuker

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PostPosted: Mon Nov 26, 2007 7:09 pm    Post subject:
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What type is the IMS program?
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Sandy Zimmer

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PostPosted: Mon Nov 26, 2007 7:45 pm    Post subject:
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Why do want to create a GSAM file? The only type of IMS program that cannot read a sequential file is an online program. Why consider the additional overhead of a GSAM file if there is no need?
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Bitneuker

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PostPosted: Mon Nov 26, 2007 8:08 pm    Post subject:
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About your original question; not any file can be a GSAM file. Follow the first link in this sticky, search for GSAM, explore and learn icon_idea.gif
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dr_te_z

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PostPosted: Tue Nov 27, 2007 6:23 pm    Post subject:
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Sandy Zimmer wrote:
Why consider the additional overhead of a GSAM file
What overhead? Why not code ALL file I/O as GSAM.
A BMP with GSAM file I/O can be a restartable step in your job, does not have to be.
A BMP with COBOL file I/O can never be a restartable step in you job, and it is al hell of a job to make it one (both program and JCL changes).
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Sandy Zimmer

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PostPosted: Tue Nov 27, 2007 6:30 pm    Post subject:
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dr_te_z

Why not wait and see what the requirements are? We do not know how long the job runs - if run time is short - if run time is extensive. We just do not know.
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dr_te_z

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PostPosted: Tue Nov 27, 2007 6:46 pm    Post subject:
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Sandy Zimmer wrote:
if run time is short
Do you imply that GSAM I/O is slower than "normal" I/O? Been measuring? Care to share the results?
As far as I know there is 1 disadvantage using GSAM: you must pre-allocate your dataset in the JCL, so you cannot benefit from the RLSE possibility in the SPACE parameter of your DD card.
If you mean development efford... only the 1st takes extra time. Once you get the hang of it ... copy/paste is your friend.
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Sandy Zimmer

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PostPosted: Tue Nov 27, 2007 6:58 pm    Post subject:
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I have been doing IMS for over 30 years - done lots of database and systems design. Like I said, let's just wait for the requirements.
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Bitneuker

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PostPosted: Tue Nov 27, 2007 10:17 pm    Post subject:
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Let's return to the original question;

Quote:
Can we consider the PS file as GSAM and read it in IMS/DB fashion (like use GN etc)?

What is the problem in reading a PS file as GSAM file using IMS/DB?


Like I said before a PS file cannot just be used as GSAM. Also the DBD is involved. We don't know what type of program TS uses. And what's most important; we don't know his business case.

Let's wait for an answer from TS. If our Dutch collegue still feels he likes to promote the use of GSAM he is free and wellcome to write a story about these benefits in the Diamond Corner icon_wink.gif
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Sandy Zimmer

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PostPosted: Tue Nov 27, 2007 11:47 pm    Post subject:
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Hey George! I have an idea......well, actually, lots of ideas. This deals with IMS file access and database access. For instance, we all know that if most of a system is online, then HDAM is the most efficient database - when you extract from it, you would then need to sort the extract since it will not be in key sequence. HIDAM is better for reporting purposes since it is alwyas in "extract" sequence.
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Bitneuker

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PostPosted: Wed Nov 28, 2007 12:02 am    Post subject:
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Sandy: what is the relationship between your last post and the question of TS icon_rolleyes.gif I might miss something but, if there is a relationship, please explain a bit in detail.
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Sandy Zimmer

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PostPosted: Wed Nov 28, 2007 1:05 am    Post subject:
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OK - George! Many of us of lots and lots of experience. We come here to HELP - we do not get paid - we do not gain much of anything except to try to help people just learning or stuck in a problem that perhaps we have faced in our previous experiences. References and book learning are great if you have basic concepts and know what you are looking for. A very basic understanding of IMS helps immensely. I have seen very few posters that have a "mentor" - or, even the basics of IMS. Most of IMS, you cannot learn in a book - you need to learn by doing and having someone to guide you along the way.

Years and years ago, people just learning wanted to "impress" - we called them "closet programmers". They shut themselves away with no basic concept of problem solving. They thought that they would impress everyone by making their system as complex and un-maintainable as possible. Hopefully, most of these people got out of the business. The secret to a successful system is to make it as easily maintainable and easy to understand as possible.

Why have a system with lots of overhead if you do not need to do it that way? KISS - keep it simple stupid!
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Bitneuker

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PostPosted: Wed Nov 28, 2007 1:38 am    Post subject:
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Compressing your post I read:

Why would TS want to use a GSAM file, including DBD-stuff, instead of simply reading the OS-file as a PS one.

Is it a business requirement or did he discover some new toy and likes to explore it. May be TS knows nothing about GSAM and the program type where it's used for and is just........whatever icon_wink.gif
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Bitneuker

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PostPosted: Wed Nov 28, 2007 5:10 am    Post subject:
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dr_te_z wrote:
Sandy Zimmer wrote:
if run time is short
Do you imply that GSAM I/O is slower than "normal" I/O? Been measuring? Care to share the results?
As far as I know there is 1 disadvantage using GSAM: you must pre-allocate your dataset in the JCL, so you cannot benefit from the RLSE possibility in the SPACE parameter of your DD card.
If you mean development efford... only the 1st takes extra time. Once you get the hang of it ... copy/paste is your friend.


Hello fellow countryman......... I invite you to go to the Diamont corner and explain there all about the wonderfull GSAM. It might contribute to this site and inspire. I myself used it from early 1980 but one has to know when and how to use it. Be my guest and write an artical in the corner; it's meant for that.
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dr_te_z

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PostPosted: Wed Nov 28, 2007 12:38 pm    Post subject:
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Mogge George

No, I am not a GSAM fanboy. But when you observe a site
- where all batches are run as BMP
- where there are many ways of doing sequetial file I/O (cobol, assembler routines, GSAM, you name it)
- where they have big problems about programs being "setup" one way and later on restartablity requirements came up. So files are subdiveded in "critical" and "not critical" and only the criticals are changed to GSAM... In the middle of the night you are called to solve abends... perhaps in the next step... something with double records, or, missing records.

Then you think to yourself: "I wish they'd started a more uniform way so it would not be such a mess now". I know it is more work and people find it difficult. But when you've coded your first 3, the 4th is relatively easy.

Years later, on a forum like this, you can share that thought. That's all.
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Bitneuker

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PostPosted: Wed Nov 28, 2007 3:19 pm    Post subject:
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You're right about sites that demand all IMD/DB batches to run as BMP. Worked at a similar site (NMB later ING). And it helps indeed when you have to troubleshoot at night.

In this case however we don't know the requirements of TS. If it's just a simple batch then why even think about GSAM. But still no reply from this guy.
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dr_te_z

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PostPosted: Wed Nov 28, 2007 4:25 pm    Post subject:
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Yeah. I was refering to that other bank. The one that is now seizing to exist because it will be assimilated by some belgian bank.
but that's okay. feyenoord overtaking ajax, thats good icon_smile.gif
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Bitneuker

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PostPosted: Wed Nov 28, 2007 4:41 pm    Post subject:
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dr_te_z wrote:
Yeah. I was refering to that other bank. The one that is now seizing to exist because it will be assimilated by some belgian bank.
but that's okay. feyenoord overtaking ajax, thats good icon_smile.gif


Would be great; my wife is a FEY supporter and I left AJA aside once they called themselves 'sons of God' icon_evil.gif

Any consequences for you because of this take-over?
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dr_te_z

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PostPosted: Wed Nov 28, 2007 5:21 pm    Post subject:
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No. I was a "huurling" then. Left more than 2 years ago now.
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