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• The StickySubagent Instruction is the dynamic version of the JS7 - Fork-Join Instruction. Use of the ForkList Instruction with a JS7 - Agent Cluster can be used to execute a number of jobs with the same Subagent of a JS7 - Agent Cluster. Use of Agent Clusters is subject to the terms for clustering with the JS7 - License.
• Technically it implements the Fork/Join operation, however, it allows a number of child orders and branches to be created dynamically in order to execute the same sequence of jobs on a number of Subagents: users can run the same jobs in parallel on a number of servers or containers operating Subagents. Use cases include for example to execute similar backup jobs on a larger number of servers.
  
• The ForkList Instruction expects a Subagent Cluster to be assigned that can include any number of Subagents running on the same or different server nodes that execute the same jobs.
The ForkList Instruction is designed as a single branch when configuring the workflow with the Configuration View of the JOC Cockpit user interface. Depending on the number of Subagents provided with the assigned Subagent Cluster the Controller will dynamically create branches for each Subagent.

• While child orders are running, the parent order waits for its child orders to be completed, i.e. to arrive at the Join Instruction. The parent order therefore is assigned the WAITING state, see JS7 - Order State Transitions.
• the block instruction checks the first available Subagent of a Subagent Cluster. This Subagent will be used for subsequent jobs within the block instruction.
  • The underlying use case is the situation when jobs in a workflow create temporary files that should be picked up by successor jobs. If successor jobs are executed with different Subagents on different servers then they might not find files created by predecessor jobs.
  • If the Subagent used for the first job of the StickySubagent Instruction becomes unavailable for subsequent jobs then the order will be put to the BLOCKED state. Users can decide to cancel the order or to make the Subagent available later on.
  • Jobs within a StickySubagent Instruction block can be assigned the predetermined Subagent or they can be assigned Standalone Agents and Subagent Clusters unrelated to the StickySubagent Instruction
  A variant of this instruction is available with the JS7 - ForkList-Join Instruction for variable sets
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Workflow Instruction:

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StickySubagent

Static Assignment of Subagent Cluster

Download example (upload .json): pdfAgentClusterForkListpdfAgentClusterStickySubagentFork.workflow.json

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Assigning the Subagent Cluster to the

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StickySubagent Instruction

The workflow editor is used to add a ForkList StickySubagent Instruction as shown:

• The ForkList StickySubagent Instruction is assigned a Subagent Cluster.
• The ForkList StickySubagent Instruction includes a number of jobs that should be executed in parallel on all Subagents on the same Subagent of the given Subagent Cluster.
  
  

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Explanation:

• The ForkList StickySubagent Instruction is assigned the Subagent Cluster active-active-all-agents from the AgentCluster001 cluster.
• The jobs inside the ForkList StickySubagent Instruction are executed in parallel on all Subagents included with on the same Subagent that is a member of the active-active-all-agents Subagent Cluster.
  • Users are free to exempt individual jobs from being executed on Subagents of the cluster using the same Subagent and instead to be executed execute the job for example on a Standalone AgentsAgent. 

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Assigning an Agent Cluster

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to a Job Instruction

Individual jobs inside the ForkList StickySubagent Instruction are assigned Subagents like this:

• The Select Agent or Subagent Expression radio  radio button is selected and the same AgentCluster001 cluster as for the ForkList StickySubagent Instruction is selected.
• The Subagent Cluster ID Expression is specified: the $js7ForkListSubagentId variable is automatically available at run-time and holds the identification of the respective Subagent for execution of the job.
  

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Explanation:

• If the Subagent Cluster is modified later on to include fewer or more Subagents then this will be considered without modification of the jobs or workflow.

• active-active-all-agents is selected that corresponds to the Subagent Cluster assigned the StickySubagent Instruction.
  
  

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Dynamic Assignment of Subagent Cluster

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Download example (upload .json): pdfAgentClusterForkListVariablepdfAgentClusterStickySubagentVariable.workflow.json

Using a Workflow Variable to specify the Subagent Cluster

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• The Subagent Cluster indicating the Subagents on which to execute jobs in parallel is dynamically specified from a workflow variable.
• The ForkList StickySubagent Instruction is combined with a JS7 - Fork-Join Instruction that allows parallel execution of jobs with each Subagentwith the same or with other Subagents.
  
  

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Explanation:

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• The subagent_cluster workflow variable is assigned a default value indicating the active-active-all-agents Subagent Cluster.
  • The default value can be overwritten by an order that specifies this variable.

Using a Subagent Expression to assign the Subagent Cluster to the

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StickySubagent Instruction

The workflow editor is used to add a ForkList StickySubagent Instruction as shown:

• The ForkList StickySubagent Instruction is assigned a Subagent Expression.
  • This includes to select an Agent Cluster.
  • This includes to specify an expression, for this example the workflow variable $subagent_cluster, that carries the name of the Subagent Cluster.
• The ForkList StickySubagent Instruction includes a number of jobs that should be executed in parallel on all Subagents on the same Subagent of the given Subagent Cluster.
  
  

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Using a Subagent Expression to assign the Subagent Cluster to the Job Instruction

The workflow editor is used to add a Job Instruction as shown:

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Delimitation

• The StickySubagent Instruction requires a single job or other instruction to be used as the first node in the block instruction.
• The JS7 - Fork-Join Instruction cannot be used as the first node within the StickySubagent Instruction. It can be used with any later node.

Error Handling

The StickySubagent Instruction selects the first available Subagent of the given Subagent Cluster. Subagents not available at the point in time of execution of the instruction are not considered.

• If the Subagent used for the first job of the StickySubagent Instructions becomes unavailable for subsequent jobs then the order will be put to the BLOCKED state.
• Users can decide to cancel the order or to make the Subagent available later on. A BLOCKED order will continue execution when the Subagent becomes available.

Standard error handling applies to jobs within the StickySubagent Instruction.

• This includes use of the JS7 - Retry Instruction and JS7 - Try-Catch Instruction.
• This includes use of the JS7 - Fail Instruction and JS7 - Finish Instruction.

Resources

• JS7 - ForkList-Join Instruction for Agent Clusters

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Explanation:

Error Handling

The same error handling applies as for the JS7 - ForkList-Join Instruction.

Resources

• JS7 - Fork-Join Instruction
• JS7 - ForkList-Join Instruction
• JS7 - Order State Transitions
• JS7 - How To - Error Handling

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