This document discusses ruote, a pure Ruby workflow engine. It provides an operating system for business processes that uses a process definition language to define workflows. Processes can be linear, parallel, or nested. Process instances run in isolation and workitems are passed between participants, which can be human or autonomous. Ruote allows for complex workflows with conditional logic and callbacks. It sees use in a variety of domains including internet exchanges and scientific organizations.

1. ruote
the awesomeness that is a pure Ruby workflow
engine from japan

2. Kenneth Kalmer
CTO - Internet Exchange
opensourcery.co.za
@kennethkalmer
github.com/kennethkalmer

3. ruote
Developed by John Mettraux
ruote.rubyforge.org
github.com/jmettraux/ruote
@jmettraux

4. ruote != state_machine

5. operating system for
business processes

6. Players
Engine
Workers
Human participants
Autonomous participants
All work to towards achieving a goal, defined in a process
definition (aka participating in a workflow)

7. Process DSL
Ruote.process_definition :name => 'fuza' do
sequence do
participant :alpha
participant :bravo
end
end

8. Process definitions
Expressions are used to build a workflow
Workflows can be:
Linear
Parallel
Nested
and more...

9. Process instances
Processes run in isolation
The AST is stored in the engine
Original code used to launch the process can be altered
without affecting running processes
Processes can be versioned

10. Workitems
Set the initial “payload” when launching a process
Workitems are passed between participants
Participants can update workitems, or just read
Process flow can be altered by workitem values

11. Workitems and flows
Ruote.process_definition :name => 'loan_approval' do
cursor do
participant 'planning team'
concurrence do
participant 'ceo' :if => '${f:total} > 100000' do
participant 'cfo'
end
rewind :unless => '${f:approved}'
participant 'execution team'
end
end

12. Human participants
Persist the workitem
Load it from another application to present to a “human”,
which should take action
ruote-couch
ruote-dm
ruote-redis
and more...

13. Autonomous participants
Local participants
Instantiated classes that respond to #consume()
Remote participants
ruote-amqp & daemon-kit
Scatter your participants over different systems

14. Notes on participants
They are abstractions
They are stateless
Once the engine hands over a workitem to a participant,
it will wait indefinitely for a response (unless a timeout is
specified)
They rely on the workitem to know what is expected of
them

15. Process administration
Often overlooked!
Canceling processes, or just part of a process
(expression)
Re-applying segments of processes
Graceful error handling
“Callbacks” for process lifecycle

16. ruote-kit
RESTful wrapper around ruote
Rich environment for exploring, perfectly capable of
production use
Can be used as rack middleware (preferably not)
github.com/tosch/ruote-kit

17. In the wild
Internet Exchange / ISP in a Box
Huge number of processes running daily
Mostly autonomous, humans handle exceptions
Provisions dozens of services
Some processes involve a dozen participants, running all
over the globe and complete within 5 seconds :)

18. In the wild
Meego BOSS
Used to orchestrate the CI ecosystem for the OS
http://wiki.meego.com/BOSS

19. In the wild
Fermilab
Rackspace
Universidad Politécnica de Madrid
Geographic Institute of the University of Zuerich
and plenty more

20. ruote.rubyforge.org/quickstart.html

21. Thanks
John Mettraux
Torsten Schönebaum
Plenty of other contributors
Internet Exchange / ISP in a Box

22. Thanks!