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Pekko Runtime

PekkoRuntime leverages Pekko Persistence and Cluster Sharding to provide a distributed runtime for workflows.

"org.business4s" %% "workflows4s-pekko" % "undefined"

Example​

Here is an example of using PekkoRuntime in a workflow:

import MyWorkflowCtx.*
given IORuntime                                               = ???
given ActorSystem[?]                                          = ???
val knockerUpper: KnockerUpper.Agent[PekkoRuntime.WorkflowId] = ???
val workflow: WIO.Initial                                     = ???

val runtime: PekkoRuntime[Ctx] = PekkoRuntime.create("my-workflow", workflow, InitialState(), knockerUpper)

runtime.initializeShard()

val instance: WorkflowInstance[Future, State] = runtime.createInstance_("my-workflow-id")

Caveats​

While PekkoRuntime offers robust distributed capabilities, it comes with some caveats:

  1. Configuration Complexity:
    • A significant amount of complexity is encapsulated within Pekko.
    • Proper configuration is essential to ensure smooth operation.
  2. Initial State Limitation:
    • Unlike other runtimes, PekkoRuntime does not support arbitrary initial states during workflow instance creation. Initial state has to be build uniformly across all instances based on EntityContext.
  3. Shard Initialization:
    • The initializeShard method must be invoked before creating workflow instances to ensure proper setup.