Visiflow

Let's start with what Workflows are not. They are not state machines. A state machine allows your class to take certain actions based on it's internal state. But those changes are driven by external factors. Any sequence of 'transitions' is incidental, and driven by whatever is controlling your class with the state machine.

A workflow is very different. It's just a sequence of steps that can branch. Intuitively, if you've ever creating a flowchart, you've created a workflow. In fact, Visiflow will generate one based on your code automatically using GraphViz

So while you may have found this in ruby-toolbox under state machines, it isn't one. Choose what most closely mirrors your needs

Features

• Direct 1:1 mapping to simple workflows
• Generate workflow images using graphviz with rake
• Orthogonal extension points for logging, benchmarking, tracing, exception handling etc.
• Includes a facility to do portions of work on a background thread. It does not care what system you use, so long as you implement perform_async(*args) (Which sidekiq and resque do automatically)

To Note Before You Start

This gem manages the sequence of steps in a workflow, but it does not concern itself with what those steps are, or what kind of object you bind it to. You can use it with Sidekiq, Resque, or DelayedJob. We use Virtus for managing the context of data stored in the system, because most background job processors serialize to JSON, which means most typing info is lost. Virtus provides a simple mechanism by which that typing can be preserved.

Design Decisions

Visiflow expects each step to take in what it needs to perform it's job, and outputs whatever should be contributed back for the next steps. Those parameters are matched for you automatically by name. For complicated workflows with large contexts, this makes it easier to declare what each step depends upon and outputs.

Installation

Add this line to your application's Gemfile:

gem 'visiflow'

And then execute:

$ bundle

Or install it yourself as:

$ gem install visiflow

Usage

1. include Visiflow::Workflow into whatever class you want to turn into a workflow
2. define a class method called steps using the hash-based dsl (more on that later)
3. Create a 'context' class with all of the properties you will want your workflow to process. It should be a separate class, because of the way Visiflow automatically sources each step's input parameters, and automatically updates them after each step.
4. Understand that your workflow class instance will be the 'context' that shares data between the steps of your flow. So define attr_accessors appropriately

Optional

If you wish, for whatever reason, for your workflow to stop running for a certain period of time (waiting for an external event to come in, a 3rd party service is temporarily down, etc) implement persist_step, TODO: and whatever else might be necessary... Perhaps a delay_until for delayed_job, resque, and sidekiq would be nice.

Create Diagrams

rake workflow:diagram will generate workflow diagrams for every class that includes the Driver

Contributing

1. Fork it ( http://github.com//visiflow/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request