WorkerFactory

A worker factory creates all objects necessary to construct a worker.

Anyone defining a Kobweb worker module is expected to declare exactly ONE implementation of this class.

By implementing this interface, the user will:

• Define a WorkerStrategy, which represents the logic that handles values sent over from the application and performs some (presumably expensive) logic on it.

• Implement serialization / deserialization logic, which is needed to pass messages between the separated application domain and the worker domain.

If you don't care about passing rich objects around and are happy with just using raw strings to communicate, you can implement a WorkerFactory<String, String> and then use the createPassThroughSerializer method when overriding the createIOSerializer method.

If you are using Kotlinx Serialization, consider adding a dependency on the com.varabyte.kobwebx:kobwebx-serialization-kotlinx helper library, which provides a convenience utility method to create a message serializer for you:

// Json.createIOSerializer comes from the kobwebx-serialization-kotlinx library.
// InParams and OutParams must be marked @Serializable or else a runtime error will occur
class ExampleWorkerFactory : WorkerFactory<InParams, OutParams>() {
   override fun createIOSerializer() = Json.createIOSerializer<InParams, OutParams>()
}

Meanwhile, the createStrategy method takes in a postOutput method which can be used to send messages back to the application domain.

The Kobweb Worker Gradle plugin will find this implementation and generate code that wraps it inside a worker class that the application will interact with:

// In the worker module:
class ExampleWorkerFactory : WorkerFactory<InParams, OutParams>() { ... }

// In the application module:
val worker = rememberWorker { ExampleWorker() { outParams -> ... } }

The name of the final class should end with "WorkerFactory" (since a correlated "Worker" class will automatically be generated with its name derived from it, e.g. "ExampleWorkerFactory" to "ExampleWorker". The factory implementation should also be marked internal because there shouldn't be a reason for the application to ever interact with it.