JS7 JobScheduler

Space shortcuts

Page tree

Introduction

Consider the following scenario:

  • A number of jobs are executed in sequence.
  • If one or more jobs fail with return code 1 then these jobs should be repeated a number of times. For any other non-zero return codes, the order should be put to a failed state and should wait for user intervention, for example to resume or cancel the failed order.
  • A related scenario is described in the  JS7 - How to retry a job and to catch specific exit codes article.

Solution

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

Download (.json upload): 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 which 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 with the built-in $returnCode variable.
  • The first If Instruction uses the $returnCode != 0 predicate to exclude any successful orders from the nested If Instruction. For details about predicates, see JS7 - Expressions for Variables.
  • The second If Instruction determines the error handling using 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 is 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 is 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 wait for user intervention.

Implications

In this scenario the job is configured to consider return codes 1 and 2 as signaling success. This allows the return code to be checked and appropriate action to be taken by either failing or retrying order execution.

At the same time this implies that the job is not considered to have failed. As a result:

These implications might reflect what some users need. For an alternative solution that fails the offending job and that creates notifications see JS7 - How to retry a job and to catch specific exit codes.