Fountainedge

Fountainedge is a simple workflow engine written in Elixir that roughly models forks and joins as described in the paper, Process Modeling Notations and Workflow Patterns by Stephen A. White, IBM Corporation. Uses Graphviz for graphical representations as UML Activity Diagrams.

Execution of tasks is not supported; however, such functionality could be built on top.

• Hex Package
• Documentation

The workflow is modelled as graphs consisting of nodes and edges. Parallel forks and joins are tracked using tokens.

Example

Define a schema:

alias Fountainedge.{Workflow, Schema, Node, Edge}
schema = %Schema{
  nodes: [
    %Node{id: 100, type: :initial},
    %Node{id: 1, label: "Decision"},
    %Node{id: 2, label: "Choice 1"},
    %Node{id: 3, label: "Choice 2"},
    %Node{id: 4, label: "Before Forking"},
    %Node{id: 5, type: :fork, join: 9},
    %Node{id: 6, label: "Parallel 1.1"},
    %Node{id: 7, label: "Parallel 1.2"},
    %Node{id: 8, label: "Parallel 2"},
    %Node{id: 9, type: :join},
    %Node{id: 10, label: "After Joining"},
    %Node{id: 11, type: :final},
  ],
  edges: [
    %Edge{id: 100, next: 1},
    %Edge{id: 1, next: 2, attributes: [label: "Y"]},
    %Edge{id: 1, next: 3, attributes: [label: "N"]},
    %Edge{id: 2, next: 4},
    %Edge{id: 3, next: 4},
    %Edge{id: 4, next: 5},
    %Edge{id: 5, next: 6},
    %Edge{id: 5, next: 8},
    %Edge{id: 6, next: 7},
    %Edge{id: 7, next: 6},
    %Edge{id: 7, next: 9},
    %Edge{id: 8, next: 9},
    %Edge{id: 9, next: 10},
    %Edge{id: 10, next: 11},
  ],
}   

Initialise the workflow:

workflow = Workflow.initialize(schema)

Get a list of valid out edges:

Fountainedge.out_edges(workflow)
# [%Edge{id: 1, next: 2}]

Transition along an out edge:

workflow = Fountainedge.transition(workflow, %Edge{id: 1, next: 2})

Graphing:

Fountainedge.Graph.graph(workflow)
|> Graphvix.Graph.compile(filename, :svg)

Installation

This package can be installed by adding fountainedge to your list of dependencies in mix.exs:

def deps do
  [
    {:fountainedge, "~> 1.0.0"}
  ]
end

Author

2019 (c) Damien Bezborodov