xencura / kagera   0.4.0

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A discrete, colored Petri Net DSL and executor

Kagera: A discrete, colored Petri Net DSL and executor.

Build Status Sonatype Nexus Stable Sonatype Nexus Snapshot

The credits for this library go to @merlijn. I've merely forked the library back in the day when we started Baker together. It now seems that Merlijn removed it from his own GitHub account.

Example of a simple colored Petri net with functions acting on the data in the tokens.

val sum = {

    // places
    val a = Place[Int](id = 1, label = "a")
    val b = Place[Int](id = 2, label = "b")
    val c = Place[Int](id = 3, label = "result")

    // transitions
    val init = Transition(id = 1, label = "init") {
      () => (5, 5)
    }

    val sum = Transition(id = 2, label = "sum") {
      (a: Int, b: Int) => a + b
    }

    // process topology
    process(
      init    ~> %(a, b),
      %(a, b) ~> sum,
      sum     ~> c)
  }

Transition Model

Transition Model

Input:

  • M is the in-adjacent marking of the transition.
  • S is the type of state the transition closes over, Unit indicates no state.
  • I Is the type of input the transition requires (provided from outside the process), Unit indicates case no input is required.

Output:

  • M' is the out-adjacent marking of the transition.
  • E Is the type of event or output the transition emits. Unit indicates no event / output.

The transition's behaviour is defined by 2 functions

  1. (M, I, S) => (M', E) A function producing the out-adjacent marking and event from in-adjancent marking, state and input.
  2. S => E => S An event sourcing function which updates the state using the emitted event / output object.

Roadmap

Short term:

  • HTTP API (using Akka HTTP)
  • Clustering & Sharding
  • Analysis (using Apache Spark or Apache Flink), some examples:
    • Path querying
    • Path prediction
    • Transition timing

Long term:

  • Hierarchical petri nets
  • Timed petri nets
  • Other execution models, such as:
  • Process migration
    • Providing tools to migrate process state when the petri net topology changes.
  • Visual process editor