# Fountainedge

**NOTICE: VERSION 0.1 to VERSION 1.0 UPGRADE HAS BREAKING API CHANGES**

----

**Fountainedge** is a simple workflow engine written in [Elixir](https://elixir-lang.org/) that roughly models forks and joins as described in the paper, *[Process Modeling Notations and
Workflow Patterns](https://github.com/emden-norfolk/fountainedge/raw/master/BPMN_wfh.pdf) by Stephen A. White, IBM Corporation*. 
Uses [Graphviz](https://graphviz.org/) for graphical representations as [UML](https://www.omg.org/spec/UML/) Activity Diagrams.

 * [Hex Package](https://hex.pm/packages/fountainedge)
 * [Documentation](https://hexdocs.pm/fountainedge)

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

## Example

![test6](images/test6.svg)

Define a schema:

```elixir
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:

```elixir
workflow = Workflow.initialize(schema)
```

Get a list of valid out edges:

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

Transition along an out edge:

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

Graphing:

```elixir
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`:

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

## Author

2019 (c) Damien Bezborodov