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JCL to get submitted once dataset has data - DEV region

 
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vinu78

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PostPosted: Thu Feb 16, 2017 7:32 am    Post subject: JCL to get submitted once dataset has data - DEV region
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Hi All,

My requirement is as follows.
I will manually submit JOB1, that automatically submits JOB2 (FTP step) in DEV region. Then we need to wait for approximately 10 min to get a flat dataset populated with data. Once the dataset has some data, we need to have JOB3 run automatically.

I have used SUBMIT job concept at the end of JOB1 that automatically submits JOB2. However I am not sure, how to make JCL wait or check for the dataset populated with data again and then automatically submit JOB3.
We can check empty dataset using IDCAMS, but please help me to understand, how to queue JCL to look for existence of data in dataset in DEV region.

Thanks
Vinu
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Robert Sample

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PostPosted: Thu Feb 16, 2017 9:03 am    Post subject:
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Unless you have a scheduler available in your DEV region, what you want to do cannot be done -- period. Batch jobs waiting are a VERY BAD IDEA, and there is no (easy) way to determine when a data set has data placed in it.
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steve-myers

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PostPosted: Thu Feb 16, 2017 9:57 am    Post subject:
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Robert Sample wrote:
Unless you have a scheduler available in your DEV region, what you want to do cannot be done -- period. Batch jobs waiting are a VERY BAD IDEA, and there is no (easy) way to determine when a data set has data placed in it.
  • Batch jobs waiting are a VERY BAD IDEA.
    Agreed.
  • there is no (easy) way to determine when a data set has data placed in it.
    Yes and no, though some agent has to be waiting and periodically checking
    • Check DS1LSTAR in the format 1 DSCB.
    • Check DS1REFD in the format 1 DSCB
    • Intercept SMF writes. Assume the data set has been modified when a type 15 record appears for the data set.
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PeterHolland

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PostPosted: Thu Feb 16, 2017 1:35 pm    Post subject:
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Quote:

there is no (easy) way to determine when a data set has data placed in it.
Yes and no, though some agent has to be waiting and periodically checking

Check DS1LSTAR in the format 1 DSCB.
Check DS1REFD in the format 1 DSCB
Intercept SMF writes. Assume the data set has been modified when a type 15 record appears for the data set.


And that is (using SMF/JES2) what a scheduler is doing.
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Arun Raj

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PostPosted: Thu Feb 16, 2017 7:30 pm    Post subject:
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vinu78 wrote:
Then we need to wait for approximately 10 min to get a flat dataset populated with data
Just curious what is going on in this 10 mins, and how you arrived at this number. icon_rolleyes.gif
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vinu78

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PostPosted: Thu Feb 16, 2017 8:53 pm    Post subject:
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Thanks all for the information.
The dataset normally gets populated with data approximately within 5-6 min after JOB2 has run. So another idea (will check for DS1LSTAR and DS1REFD option) that came to my mind is, whether we can start JOB3 exactly 10 min after running JOB2.

Please let me know whether is it possible to delay running JOB3 for 10 min, even if JOB2 automatically triggers JOB2.

Thanks
Vinu
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Nic Clouston

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PostPosted: Thu Feb 16, 2017 8:55 pm    Post subject:
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How is the data sert being populated?
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vinu78

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PostPosted: Thu Feb 16, 2017 9:13 pm    Post subject:
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Dataset gets populated from some 3rd party system.
Our intention is, once the dataset gets data (within 5-6 min), we should run JOB3 whose source is this dataset.

In short, I will submit JOB1 only. Then it automatically submits JOB2 and then JOB2 submits JOB3. However JOB3 will run exactly 10 min after it gets submitted.
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UmeySan

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PostPosted: Thu Feb 16, 2017 9:19 pm    Post subject:
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Perhaps read about "event-triggered tracking" called ETT.

Regards, UmeySan
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Arun Raj

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PostPosted: Thu Feb 16, 2017 9:26 pm    Post subject:
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Since manual submission is required anyways, so why don't we just submit JOB1 (and possibly make it submit the other 2 jobs) after you know you have the '3rd party data set'. (assuming you don't have a scheduler available in DEV)
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daveporcelan

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PostPosted: Thu Feb 16, 2017 9:27 pm    Post subject:
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I agree with everyone above, having a batch Job wait is a bad idea.

However it would be pretty easy to do this with a Rexx exec.

Assuming the dataset in question has been created empty.
This exec would work.
It should be an added step in your JCL.
Use the return code to determine if you should run the Submit step for Job3.
You may want to put the check dataset as DD CHKFILE in your JCL then the ALLOC and FREE can be removed.

Code:

/* REXX EXEC TO CHECK FOR DATA EXISTENCE            */
/* MAXRC = 0 - DATA FOUND                           */
/* MAXRC = 4 - DATA NOT FOUND MAX-SECS REACHED      */
/*   THIS IS TO PREVENT AN INFINITE LOOP            */

INREC. = ''

TOTAL_SECS = 0
SLEEP_SECS = 3
MAX_SECS   = 20
MAXRC = 0

CHECK_FILE = 'CHECK.DATASET'
"ALLOC DD(CHECKFIL) DA('"CHECK_FILE"') SHR REUSE"
"EXECIO 1 DISKR CHECKFIL(STEM INREC. OPEN FINIS)"
"FREE DD(CHECKFIL)"
SAY 'CHECKING' CHECK_FILE 'AFTER' TOTAL_SECS 'SECONDS'

IF INREC.1 = '' THEN DO FOREVER

  SLEEP SLEEP_SECS
  TOTAL_SECS = TOTAL_SECS + SLEEP_SECS
  SAY 'CHECKING' CHECK_FILE 'AFTER' TOTAL_SECS 'SECONDS'

  "ALLOC DD(CHECKFIL) DA('"CHECK_FILE"') SHR REUSE"
  "EXECIO 1 DISKR CHECKFIL(STEM INREC. OPEN FINIS)"
  "FREE DD(CHECKFIL)"

  IF INREC.1 /= '' THEN DO
    MAXRC = 0
    LEAVE
  END
  ELSE IF TOTAL_SECS > MAX_SECS THEN DO
    MAXRC = 4
    LEAVE
  END

SAY 'CHKDATA COMPLETED MAXRC =' MAXRC
ZISPFRC = MAXRC
"ISPEXEC VPUT (ZISPFRC) SHARED"

EXIT (ZISPFRC)
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vinu78

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PostPosted: Thu Feb 16, 2017 9:52 pm    Post subject:
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Not sure whether I have explained it correctly.
JOB2 will FTP some data to 3rd party system and then only 3rd party system populates data in the dataset. After which we need to run JOB3.
So at the time of submission of JOB2, we can't check for the data in dataset. It will be empty only. Only after submitting JOB2, the dataset will get data (after 5-6- min).

Dave - Thanks for the Rexx code. Whether we need to have the abvoe mentioned REXX code at the end of JOB2.
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daveporcelan

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PostPosted: Thu Feb 16, 2017 11:12 pm    Post subject:
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I got it.

After the FTP step, add a step to execute this Rexx step.

Set your Sleep seconds to 300 (5 minutes) and Max seconds to 1200 so that after twenty minutes you stop checking.

You should be able to take it from here (or not).
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Terry Heinze

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PostPosted: Fri Feb 17, 2017 12:24 am    Post subject:
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Won't the REXX step in Job2 tie up the initiator until data arrives from the 3rd party?
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daveporcelan

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PostPosted: Fri Feb 17, 2017 12:29 am    Post subject:
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Yep, it sure will. Not saying it is a good idea. It is not.

Just showing it is not very difficult to do.

What should be done, is to use your scheduler to recognize the arrival of the file from an external site.
Then have Job3 submitted by the scheduler.
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Robert Sample

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PostPosted: Fri Feb 17, 2017 5:35 am    Post subject:
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Another option would be to have the process putting the data into the file use FTP after the data is transferred to submit JOB3 into JES (which can be done depending upon the site options); no waits are required with this approach.
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vinu78

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PostPosted: Fri Feb 17, 2017 6:45 am    Post subject:
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Thanks Dave for the clarification and everybody for pouring in ideas.
I will try the REXX code. Also I find some code like below

Code:
//STEP010  EXEC PGM=AOPBATCH,PARM='/sh/bin/sleep 600'
//STDOUT   DD   SYSOUT=*                         
//STDERR   DD   SYSOUT=*                         
//STDIN    DD   DUMMY


Whether this works. If yes, whether having this code at the end of JOB2 will hold the resources for that specified time of 10 min?
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daveporcelan

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PostPosted: Fri Feb 17, 2017 5:46 pm    Post subject:
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Robert, That is an excellent approach. We use that for internal transfers from in house servers.

Our shop would not allow that with transfers from an external site.

Vinu78, AOPBATCH is allowing you to run a 'program' called sleep found in a unix directory. Pretty much the same thing as what I wrote without the checking for data. Just sleep for 10 minutes, and hope the file has been populated.

It will not use much resources, but it will tie up the initiator, not allowing anything else run there.
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