Signal Resume
Remotely signal another Process to resume from dehydration.
If you want to separate polling or triggering logic from your Long Running Process in order to keep it visually simple, a Signal Resume shape can be used in another Process to remotely and automatically resume a paused Long Running Process when the conditions match.
What is Signal Resume?
Signal Resume shape allows resuming another Process by sending a signal with the matching Correlation ID field.
For example, it would be possible to have a Long Running Process to handle a complete business process in tandem with external systems, and another Process that receives status updates from the external systems and can resume the Long Running Process whenever an update comes in.
This allows for a separate, centralized polling or webhook Process while keeping the Long Running Process easier to understand by business personnel.
Usage
Signal Resume shape can be used in any Process that should resume another Process Instance. As such, the shape's effect does not participate in the current Process Instance it is executed on, but in some another Process Instance that has a Checkpoint shape and it is paused.
Signal Resume shape can be placed anywhere within a Process between a Trigger and a Return or Throw shape, much like the other Activity or Scope shapes.
Once added to Process, you need to define which Checkpoint will resume by providing the Correlation ID set for that Checkpoint.
As there is no direct method of providing or knowing the IDs for currently paused Checkpoint shapes or the used Correlation IDs in general, a scheme relying on Stored State Tasks or external systems is required to be able to know which Correlation ID to use.
For example, an external system may provide a Customer ID or a Correlation ID of its own for each case being handled in Frends, and those could be used as the Correlation ID in Long Running Processes and with Processes containing Signal Resume shape to connect them together and resuming the correct Process Instances.
In case a matching Correlation ID is not found when executing a Signal Resume shape, the shape throws an exception that needs to be caught, or the Process will end in failure.
Architecture
When Signal Resume shape is used with a Correlation ID, the Agent database storing the paused Process states is queried for the Correlation ID to find if there is a matching paused Process. If a match is found, the matching Process is resumed from the Checkpoint.
If there's a database reset or other issues with the Agent store that has altered or removed the paused Process data, it might not be possible to correctly resume a Process using a Signal Resume.
Any paused Processes are resumed on the same Agent as where the execution started in. In case a High Availability configuration is in use, it is not possible to switch the executing Agent while resuming a Process.
Configuration
To set up a Signal Resume shape, add the shape to Process canvas and connect it as part of your Process. After that, you can configure the parameters for the shape.
The following configuration parameters are available for Signal Resume.
Display name
Shapes can be given a display name in Frends Processes to distinquish them from each other. Shape's display name has no technical purpose and is only for documentational and visual purposes only. For shapes returning a #result reference value, the display name can be used to specify which result is meant.
Display name is given to the shape by double-clicking it on the canvas or through its configuration parameters.
Correlation ID
String value to reference a Checkpoint shape in another Process that is paused during the execution of this shape.
Reference Values
Signal Resume shape does not provide any reference values.
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