ScalaFlow

An attempt to write a workflow engine that supports a natural language for workflow definition.

Components

1. scalaflow-core
2. scalaflow-grapher
3. scalaflow-atompub

Scalaflow-core

The core components for defining a ScalaFlow. Also includes the WorkflowInstance classes for using a ScalaFlow as seen below.

Here's an example definition of a ScalaFlow

object CustomerCoffeeWorkflow extends ScalaFlow("Customer Coffee") {
  state('start) {
    event('Place_Order) -> 'Order_Placed
  }
  state('Order_Placed) {
    event('Pay) -> 'Paid
    event('Update_Order) -> 'Order_Updated
  }
  state('Order_Updated) {
    event('Update_Accepted) -> 'Order_Placed
    event('Update_Rejected) -> 'Order_Placed
  }
  state('Paid) {
    event('Pickup) -> 'Drink_Received
  }
  state('Drink_Received) {
    event('leave) -> 'Drink
  }
  endstate('Drink)
}

Example usage from scala console:

scala> val wi = WorkflowInstance definedAs CustomerCoffeeWorkflow
wi: org.doxla.scalaflow.engine.WorkflowInstance = WorkflowInstance currently in start

scala> wi !?
res11: List[Symbol] = List('Place_Order)

scala> wi ! 'Place_Order
res12: Boolean = true

scala> wi
res13: org.doxla.scalaflow.engine.WorkflowInstance = WorkflowInstance currently in Order_Placed

scala> wi !?
res14: List[Symbol] = List('Pay, 'Update_Order)

scala> wi ! 'Pay
res15: Boolean = true

scala> wi !?
res16: List[Symbol] = List('Pickup)

scala> wi
res17: org.doxla.scalaflow.engine.WorkflowInstance = WorkflowInstance currently in Paid

Scalaflow-grapher

A very basic extension of Google's guice-grapher module. To generate for cool visual representations of ScalaFlows. Use Graphviz viewer to view the generated files.

CustomerCoffeeWorkflow generated image

Example code from here

val renderer = new ScalaFlowGraphvizRenderer()
val printWriter = new PrintWriter(new File("testoutput.dot"), "UTF-8")
renderer.setOut(printWriter)
renderer.setRankdir("TB")

new ScalaFlowGrapher(renderer).of(CustomerCoffeeWorkflow).graph

Scalaflow-atompub

I started playing with some ideas for generating atompub XML documents. Still very much work in progress.