Process Pilot

Process Pilot is a workflow gem for Rails applications based on the bpmn standard. It executes business processes and rules defined in a modeler.

Process Pilot executes business processes like this one.

To start the process, initialize Process Pilot with the BPMN source, then call start.

process = ProcessPilot.new(File.read("hello_world.bpmn")).start

The 'HelloWorld' process begins at the 'Start' event and waits when it reaches the 'SayHello' service task. It's often useful to print the process state to the console.

process.print

HelloWorld started * Flow_0zlro9p

0 StartEvent Start: completed * out: Flow_0zlro9p
1 ServiceTask SayHello: waiting * in: Flow_0zlro9p

It's common to save the state the process until a task is complete. For example, a user task might be waiting for a person to complete a form, or a service task might run in a background job. Calling serialize on a process will return the execution state so it can be continued later.

# Returns a hash of the process state for saving in a database.
execution_state = process.serialize

# Restores the process from the execution state.
process = ProcessPilot.new(File.read("hello_world.bpmn")).restore(execution_state)

After the task is completed, the waiting step is sent a signal with result.

step = process.step_by_element_id("SayHello")
step.signal(message: "Hello World!")

Now the 'SayHello' task is completed, it's result is merged into the process variables, and the process continues to the 'End' event.

HelloWorld completed *

{
  "message": "Hello World!"
}

0 StartEvent Start: completed * out: Flow_0zlro9p
1 ServiceTask SayHello: completed { "message": "Hello World!" } * in: Flow_0zlro9p * out: Flow_1doumjv
2 EndEvent End: completed * in: Flow_1doumjv

The previous example is a simple process with a single task, but BPMN can express more complex workflows.

TODO: Add a kitchen sink example.

• Processes
• Tasks
• Events
• Event Definitions
• Gateways
• Expressions
• Data Flow
• Execution

Execute:

$ bundle add "process_pilot"

Or install it directly:

$ gem install process_pilot

$ git clone ...
$ bin/setup
$ bin/rake
$ bin/guard

The gem is available as open source under the terms of the MIT License.

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