Avoiding update loops in circular flow configurations.

[SvenHoeffler]

If a user has a flow configuration that includes a loop (e.g. A <-> B, or A -> B -> C -> A), there is currently the risk of this leading to endless updates being sent back and forth. For example, in a bidirectional flow configuration A <-> B, the following might happen:

• User updates entry abc in system A
• Connector A propagates that update to connector B
• Connector B updates the entry abc in system B
• In the next flow execution, connector B notices that entry abc has recently been updated, and propagates that update to Connector A
• Connector A updates entry abc in system A.
• In the next flow execution, connector A notices that entry abc has recently been updated...
• repeat forever

They key approach in solving this issue is breaking such a propagation circle in at least one point, preferably several. Some connectors or systems are capable of recognizing that an entry has not actually been modified, and will not propagate it as updated in the next flow executions, breaking the loop at that point.

However, this capability cannot be assumed to be present for most connectors, and as such it would be preferable if an architectural solution as part of the framework could be found.

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To Do

• Discuss and investigate issue of update loops
• Research potential solutions
• Document findings

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