Custom State Machine Behavior

[johnnychoque]

Hi all,

As part of the integration process of the EDC connector with another system, we need to modify the standard behavior of the Provider's state machine during the transfer process, as shown in the following figure.

After the Provider receives the Transfer Request Message, it is necessary to execute a specific task of the system to be integrated with the connector. Once this task is completed, the Transfer Start Message will be executed and the standard state machine flow will continue.

Is it possible to interrupt and modify the standard state machine behavior? If so, could you give me some ideas on how to implement it?

Regards,

Johnny

[paullatzelsperger]

Hi @johnnychoque I think you could investigate the following two (actually just the first) ways:

1. Use PendingGuards: these give you a way to exclude a certain TransferProcess from the StateMachine: the TP would be in "pending" state, and the state machine doesn't pick it up until the "pending" state is reset. This could come in handy for example when some manual human interaction is necessary.
   Technically, you'd have to create an extension that injects an implementation of the TransferProcessPendingGuard into the context, so that the state machine picks it up. In that implementation you can implement whatever logic you require.

2. Implement your own TransferProcessManager. I only mention this for the sake of completeness. In reality I would not recommend doing that, because it would mean replacing the entire control-plane-transfer module. Drilling a hole through your knee sounds more fun. We have never tested this, nor would we support it.

[ndr-brt]

for sake of completion, you could also register a sync EventSubscriber on the EventRouter, there, you can write specific logic that will executed when the transfer transitions into REQUESTED (catching the TransferProcessRequested event).
By the "sync" attribute, the code will be executed in the same thread/transaction context.