Can I intercept VSAM commands in z/OS?



Help for IBM's record-oriented filesystem VSAM, ESDS, KSDS, RRDS, LDS and Storage management Subsystems

Can I intercept VSAM commands in z/OS?

Postby Balr14 » Thu Oct 07, 2010 7:23 pm

I would like to intercept VSAM reads that occur in batch COBOL programs and direct them to an alternate data access method. So far, I'm not having any success. VSAM exits are driven after data is accessed, as far as I can tell. I need to get the commands BEFORE they are executed. Any ideas?
Balr14
 
Posts: 38
Joined: Fri Oct 01, 2010 9:43 pm
Has thanked: 0 time
Been thanked: 0 time

Re: Can I intercept VSAM commands in z/OS?

 

Re: Can I intercept VSAM commands in z/OS?

Postby NicC » Thu Oct 07, 2010 9:06 pm

The question is: Why would you want to do that??
The problem I have is that people can explain things quickly but I can only comprehend slowly.
Regards
Nic
NicC
Global moderator
 
Posts: 2690
Joined: Sun Jul 04, 2010 12:13 am
Location: Pushing up the daisys (almost)
Has thanked: 4 times
Been thanked: 105 times

Re: Can I intercept VSAM commands in z/OS?

Postby Balr14 » Thu Oct 07, 2010 10:54 pm

It's part of proof of concept for a performance enhancement product.
Balr14
 
Posts: 38
Joined: Fri Oct 01, 2010 9:43 pm
Has thanked: 0 time
Been thanked: 0 time

Re: Can I intercept VSAM commands in z/OS?

Postby steve-myers » Fri Oct 08, 2010 12:44 am

It most certainly is possible. The IAM product does it every day.

Even if I knew how they do it, I certainly would not disclose it here!
steve-myers
Global moderator
 
Posts: 1885
Joined: Thu Jun 03, 2010 6:21 pm
Has thanked: 4 times
Been thanked: 197 times

Re: Can I intercept VSAM commands in z/OS?

Postby dick scherrer » Fri Oct 08, 2010 1:40 am

Hello,

Quite a few products do this.

VSAM commands are intercepted before vsam data is addressed. The intercept looks at some control table (in some load module or stored data) and determines whether to re-route the vsam command elsewhere or continue to the normal vsam processing.

Some of the products that do this call it "VSAM Transparency". For example, cobol code that "works with vsam" will run unchanged against a database if that database supports vsam transparency.
Hope this helps,
d.sch.
User avatar
dick scherrer
Global moderator
 
Posts: 6304
Joined: Sat Jun 09, 2007 8:58 am
Has thanked: 3 times
Been thanked: 91 times

Re: Can I intercept VSAM commands in z/OS?

Postby Balr14 » Fri Oct 08, 2010 2:10 am

IAM and other VSAM transparency products simply front-end the VSAM executable. I'd like to be able to do that, but that's not what this proof of concept is attempting to prove.
Balr14
 
Posts: 38
Joined: Fri Oct 01, 2010 9:43 pm
Has thanked: 0 time
Been thanked: 0 time

Re: Can I intercept VSAM commands in z/OS?

Postby littlechicken » Thu Oct 28, 2010 11:01 am

how can you do/code performance enhancement if you do not have the knowledge to even front end VSAM?
littlechicken
 
Posts: 25
Joined: Thu Oct 28, 2010 10:15 am
Has thanked: 0 time
Been thanked: 0 time

Re: Can I intercept VSAM commands in z/OS?

Postby expat » Thu Oct 28, 2010 11:41 am

Surely you need to implement the product and test it agaianst the current methodology in place and compare the results.
expat
 
Posts: 382
Joined: Sat Jun 09, 2007 3:21 pm
Has thanked: 0 time
Been thanked: 1 time

Re: Can I intercept VSAM commands in z/OS?

Postby Balr14 » Fri Oct 29, 2010 10:32 pm

littlechicken wrote:how can you do/code performance enhancement if you do not have the knowledge to even front end VSAM?


Front-ending VSAM is easy; just module substitution of the main VSAM executables. Doing it without swapping modules is a lot more involved.
Balr14
 
Posts: 38
Joined: Fri Oct 01, 2010 9:43 pm
Has thanked: 0 time
Been thanked: 0 time

Re: Can I intercept VSAM commands in z/OS?

Postby Balr14 » Fri Oct 29, 2010 10:37 pm

expat wrote:Surely you need to implement the product and test it agaianst the current methodology in place and compare the results.


Huh??? There is no current methodology for intercepting VSAM without module substitution and if I could implement this product I wouldn't be here asking.
Balr14
 
Posts: 38
Joined: Fri Oct 01, 2010 9:43 pm
Has thanked: 0 time
Been thanked: 0 time

Next

Return to VSAM/SMS

 


  • Related topics
    Replies
    Views
    Last post