Introduction

Assume the following scenario:

• A number of jobs are executed in sequence.
• If one or more jobs fail with exit code 1 then the jobs should be repeated for a number of times. For any other non-zero exit codes the order should be put to a failed state and should wait for user intervention, for example to resume or to cancel the failed order.

Workflow

The below workflow implements the use case from the following instructions:

• JS7 - Retry Instruction
• JS7 - If Instruction

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.

Explanation:

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

Job

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

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 different types of error handling depending on the return code reported by the failed job:

Explanation:

• Within the Retry Block the JS7 - If Instruction is used to check the return code value, This value is available from the built-in $returnCode variable.
• The first If Instruction excludes by use of the $returnCode != 0 predicate that any successful orders are excluded from the nested If Instruction. For details about predicates, see JS7 - Expressions for Variables.
• The second If Instruction determines the error handling by use of the $returnCode == 1 predicate:
  • 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.
• Subsequently we find two occurrences of a JS7 - Fail Instruction.

Left Fail Instruction

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

Explanation:

• The right Fail Instruction fails the order with a return code value 2.
• In addition, a message can be added that becomes visible with the JOC Cockpit GUI for the failed order.
• The uncatchable checkbox is used to indicate that the failed order cannot be picked by the outer Retry Instruction. Instead, the order will remain with its current position in a failed state and waits for user intervention.