A Rails engine which providing essential infrastructure of workflow.
It's based on [Workflow Net](http://mlwiki.org/index.php/Workflow_Nets) technique.
WorkflowCore is originally designed for Business Process Management (BPM), in this scenario:
The gem provides:
- Workflows are usually defined by users in runtime
- Task may tight with application features
- Models to describe workflow nets
- Models to describe workflow instances
- Interfaces to define transitions
WorkflowCore is based on [Workflow Net](http://mlwiki.org/index.php/Workflow_Nets) technique, and only providing essential features for a workflow engine.
## Features
### Models to describe workflow net
Workflow Net is a special case of [Petri net](http://mlwiki.org/index.php/Petri_Nets)
There are 2 kinds of nodes
- Place (circles): represent the states of a system
- Transition (squares): represent state changes
WorkflowCore provides Place & Transition models that can represent a workflow net, and a Workflow model as root.
### Models to describe workflow instances
Workflow net use Token (dots in places) to tracking states of a process, every place can contain one or more tokens.
WorkflowCore provides WorkflowInstance model represent processes, and it has many tokens.
### Interfaces to define how to transit
Transition has a transactional `fire` method which accept a token that would consume it and generate new token(s), developer could create many kinds of transitions and overrides `on_fire` to define how to transit
In addition, `on_error` is used for error handling.
## Why “core”
...
...
@@ -27,10 +53,7 @@ BTW, the dummy app is a full-featured app with production level codebase that yo
## Todo
- Make sure transit must be an atomic operation, and help developers to avoiding Rails' nested transaction pitfalls.
- Find a good way to validate all nodes of the net, when? where? how?
- Consider consequences of changing the net, well handle it changes. e.g: what about running instances?
- Consider side-effect if interactive non-workflow resources.
- Consider native workflows (those which defined in code and tight with the app) support
- Stabilizing interfaces.
- Evaluate that can supporting async, scheduled and event-based transition properly.
...
...
@@ -89,42 +112,6 @@ The dummy app integrates with [Form Core](https://github.com/rails-engine/form_c
### Features
#### Importing workflow definitions from a BPMN2 xml,
Because there isn't have a easy-to-use web-based flowchart designer, I implement a stupid BPMN2 importer, it have many restrictions:
- Only supports `Sequence`, `Start event`, `End event`, `Parallel gateway` and `Exclusive gateway`
- Using gateway to fork flows must have corresponding join (or merge) gateway
- Only read `name` property, other such as `condition expression` must configure on the dummy app
You can check `_samples` folder, I've already provided some samples, or you can try a BPMN2 designer (e.g [Camunda modeler](https://github.com/camunda/camunda-modeler)).
#### Defining form
You can defining a dynamic form for a workflow.
In transition's options, you can configure field's accessibility
Exclusive choice is a special transition that needs to configure conditions that determine how to transit to a branch.
The condition is a Ruby expression, and running in a mRuby sandbox (powered by ScriptCore but it's also undone yet), and you can access form data through `@input[:payload]`, for example, there is a field named `approved`, we can check the field checked by `@input[:payload]["approved"]`
#### Run a workflow
See `Instance` tab, that should make sense.
### Usage
**You need install Graphviz first**
Clone the repository.
...
...
@@ -159,6 +146,40 @@ $ bin/rails s
Open your browser, and visit `http://localhost:3000`
### Features
#### Importing workflow definitions from a BPMN2 xml,
Because there isn't have a easy-to-use web-based flowchart designer, I implement a stupid BPMN2 importer, it have many restrictions:
- Only supports `Sequence`, `Start event`, `End event`, `Parallel gateway` and `Exclusive gateway`
- Using gateway to fork flows must have corresponding join (or merge) gateway
- Only read `name` property, other such as `condition expression` must configure on the dummy app
You can check `_samples` folder, I've already provided some samples, or you can try a BPMN2 designer (e.g [Camunda modeler](https://github.com/camunda/camunda-modeler)).
#### Defining form
You can defining a dynamic form for a workflow.
In transition's options, you can configure field's accessibility
Exclusive choice is a special transition that needs to configure conditions that determine how to transit to a branch.
The condition is a Ruby expression, and running in a mRuby sandbox (powered by ScriptCore but it's also undone yet), and you can access form data through `@input[:payload]`, for example, there is a field named `approved`, we can check the field checked by `@input[:payload]["approved"]`
