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Introduction to CL Programming

Mike PavlakSolutions Consultant

Zend Technologies, Inc.

Week Five

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Review Week 4

System Functions Retrieve commands Parameter passing

Automating Operations Tasks Display file date validation FTP Job Scheduler

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This week...Tips and tricks...

Self submitting CL programs API magic!

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Self submitting CL program...

Three fundamental components Display File CL program Local Data Area

This program will Receive a Library name from the user Validate the existence of the library Submit itself to batch Reorganize all PF's in the library with deleted

records...

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Data areas...

Spec's at V5R4 Four Data Types Used to store stuff 4 Types of Data areas

*LDA Local Data Area *GDA Group Data Area *PDA Program Init Parm Data Area Named Data Area.

Data Area Specifications

Max Default

*CHAR 2000 32

*DEC 24, 9 15, 5

*LGL 1 1

*DDM N/A N/A

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Local Data Area (*LDA)...

Size is *CHAR and 1024 bytes long Every job on system has one CHGDTAARA command to alter All submitted jobs inherit the *LDA Think of it like a cookie for System i job Be careful, other jobs might need it Only current job can see it

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DSPDTAARA... Display command for the *LDA, like others

Name = *LDA Library is blank Output Format, Character or Hex (like dumps)

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DSPDTAARA

Local data area is often blank Some vendors use it for quick access Let's put something in there

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CHGDTAARA...

Only character data CHGDTAARA *LDA 'LIBRARY1'

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DSPDTAARA

See new value Very fast Exists in memory

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CL Program...

Declarations Work fields Two files

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CL Program...

First, determine environment with RTVJOBA RTVJOBA TYPE(&TYPE) TYPE = '1' is Interactive TYPE = '0' is Batch

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CL Program... If Interactive...

Validate library Get library from user via DSPF Validate & store in *LDA Then submit to batch

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CL Program... Additional screen processing

exit program Default Validate entry

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CL Program...

Validation subroutine... CHKOBJ will examine OS for object Set message if error

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CL Program... When submitted program is in batch...

Retrieve library from *LDA DSPFD to outfile and process where

MLNRTD > 0 & more records Count and accumulate values

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CL Program... When submitted program is in batch...

When EOF is reached, send status message End program

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API Processing...

API = Application Program Interface Just another program Has a specific job to do Some popular API's include

QCMD Command Screen QCMDCHK Validate CL command QCMDEXC Execute CL command QUSCMDLN Command Line window

More info online in System API Programming http://publib.boulder.ibm.com/infocenter/systems/scope/i5os/topic/apiref/api.htm

http://publib.boulder.ibm.com/infocenter/systems/scope/i5os/topic/apiref/api.htmhttp://publib.boulder.ibm.com/infocenter/systems/scope/i5os/topic/apiref/api.htm

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Tweak the previous program...

Enhance the previous program... Add a command line window Tie to function key in main glass Resume processing when complete

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Revise the display file...

Add function key ... Activate indicator Insert text

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Add subroutine to CL...

This will run only from Interactive Call this subroutine from interactive subroutine Return control to main subroutine when complete

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Compile and run...

Press the key to see results...

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Demos as time permits...

Let's have some fun!

WDSC in action!

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Homework...

Write and run some CL programs Assignment on website Will not be collected Can forward copies with question via email

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Q & A

Think of some things you would like us tocover...