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Download: retry-on-return-code.workflow.json

Retry Block

A Retry Block in a JS7 - Retry Instruction includes any number of jobs or instructions. If one of them fails then processing will be repeated from the beginning of the block.

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Explanation:

• This workflow implements
  • an outer Retry Block to repeat execution,
  • an inner Try / Catch Block to handle specific exit codes of the job Job Instruction that fails with varying return codes,
  • an inner If Instruction to decide about the handling of specific return codes.

Try Block

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Job

The job is implemented to complete with varying return codes that are handled like this:

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Explanation:

• Return code 0 signals success and the job will continue after the Retry-End Instruction.
• Return code 1 and 2 similarly are considered successful, however, they are handled by the subsequent If Instruction.

If Instruction

The JS7 - If Instruction applies

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Explanation:

• After a first job job1 the job2 should be restarted for a number of times if it fails with return code 1.
• The JS7 - Retry Instruction manages the retry capability and the intervals.
  • The properties of the Retry Instruction include to specify a common delay for any retries or to use individual delays per retry.
• The JS7 - Try / Catch Instruction 
  • executes any number of instructions and jobs within the Try Block.
    • Should the jobs complete successfully then processing will continue after the Catch Block.
    • Should jobs fail then the instructions and jobs inside the Catch Block will be executed.

Catch Block

The Catch Block is executed in case of failed instructions or jobs in a Try Block.

The solution makes use of an JS7 - If Instruction to apply different types of error handling depending on the return code reported by the failed job.:

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Explanation:

• Within the Catch Retry Block the JS7 - If Instruction is used to check the return code value which gives two options:
  • if the return code value is 1 then the left branch (true) of the If Instruction is used,
  • for any other return code values the right branch (false) is used.
• This is achieved by use of a predicate that checks the built-in $returnCode variable, see JS7 - Expressions for Variables.
• Subsequently we find two occurrences of a JS7 - Fail Instruction.

Left Fail Instruction

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Explanation:

• The left Fail Instruction fails the order with a return code value 1.
• In addition, a message can be added that becomes visible with the JOC Cockpit GUI for the failed order.
• As a consequence the failed order is immediately picked up by the outer Retry Instruction that will repeat execution of job1 having applied the indicated delay.

Right Fail Instruction

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Explanation:

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