Ruote in 20 Minutes

A quick introduction to the Ruote workflow and BPM engine by John Mettraux, presented by myself at the third monthly Ruby on Beer meetup.

Transcript

1. ruote - open source ruby workflow and bpm engine Developed by John Mettraux jmettraux.wordpress.com Presented by Kenneth Kalmer in 20 minutes opensourcery.co.za
2. Workflows? BPM? • “Improved state machine” • Long running processes, long-lived process interpreter • Diverse participants • Complex rules & decisions • Implement clearly defined business processes
3. Joe's Mortgages • Applies on your behalf at seven different institutions • Selects the best deal for you • Handles application for you • You sign • You buy • You pay
4. State Machine • :requested • :evaluation • :acquired • :accepted • :applied • :approved • Where? • When? • Rate? • Comparison? • Who?
5. Rule: Notify Client when 4 quotes are received aasm_state :pending_four_left aasm_state :pending_three_left aasm_state :pending_two_left aasm_state :pending_one_left aasm_state :pending_but_notified_client ... aasm_state :is_this_ridiculous_or_what?
6. Rule: Wait up to 7 days for quotes aasm_state :pending_four_remaining_timeout aasm_state :pending_three_remaining_timout aasm_state :pending_two_remaining_timout aasm_state :pending_one_remaining_timout … aasm_state :call_recruiter_for_new_dev!
7. Recap • State machines are only valuable when they have a few, well defined states • Tempted to setup hundreds of states, with complex transitions • State machines help manage the results of real life processes, not the processes
8. Modified State Machine class Mortgage aasm_initial_state :pending aasm_state :pending aasm_state :quoted aasm_state :applied aasm_state :approved aasm_state :rejected end
9. Enter ruote • Clearly defined DSL for workflow • Clearly defined processes – Expressions – Participants • Concurrent tasks • Timeouts • Easy decision making
10. Expressions • Utility statements that give structure to your processes • Conditional statements that facilitate branching and merging patterns
11. Participants • A point in the process where work gets done • Can be automated code • Can be human interaction • Ruote provides plenty of participants out the box • Breeze to write new ones
12. First round: Participants class MortgageApplication < OpenWFE::ProcessDefinition sequence do institution_1 :activity => 'Mortgage Quote' institution_2 :activity => 'Mortgage Quote' institution_3 :activity => 'Mortgage Quote' institution_4 :activity => 'Mortgage Quote' institution_5 :activity => 'Mortgage Quote' institution_6 :activity => 'Mortgage Quote' institution_7 :activity => 'Mortgage Quote' end end
13. Problems so far • Will request quotations in serial • 14 days to complete if each institution takes 2 days on average
14. Concurrency! • Not the Erlang kind, the business kind • Send all requests in one go, and continue the process once we've received at least 4 quotes • Also, quote process may not take longer than 7 days to complete
15. Second round: Concurrency and Timeout class MortgageApplication < OpenWFE::ProcessDefinition sequence do timeout :after => '7d' do concurrence :count => 4 do institution_1 :activity => 'Mortgage Quote' institution_2 :activity => 'Mortgage Quote' institution_3 :activity => 'Mortgage Quote' institution_4 :activity => 'Mortgage Quote' institution_5 :activity => 'Mortgage Quote' institution_6 :activity => 'Mortgage Quote' institution_7 :activity => 'Mortgage Quote' end end end end
16. Achievements so far • Quotations requested simultaneously • Process will take 7 days at most to complete • First 4 institutions stand the chance of earning new business • Mortgage is still “pending”
17. Rule: Joe can re-request quotes • Joe drives a hard bargain • Can request quotes any number of times • But, wants to let the client know he's doing his best!
18. Third round: Bargain hard class MortgageApplication < OpenWFE::ProcessDefinition sequence do loop do concurrence :timeout => '7d', :count => 4 do institution_1 :activity => 'Mortgage Quote' # ... end joe :activity => 'Review quotes' _break :if => “${f:joe_happy}” email :activity => “Getting new quotes”, :to => “${f:client.email}” end end end
19. Achievements so far • Loop used to keep the quote request process running until Joe is happy, or cancels the process • Client notified everytime the quote request process starts all over again • First glimpse of workitems • Mortgage is still “pending”
20. Workitems? • The internal “message” passed from participant to participant • They're JSON friendly Ruby hashes • Participants can modify workitems • Processes can be launched with an initial payload, client details in this case, which is accessed through the workitems • Workitem attributes accessed in process definitions through the “dollar notation”
21. Quote found, action the client class MortgageApplication < OpenWFE::ProcessDefinition sequence do loop do # ... end secretary :activity => “Send client application forms” end end
22. Application received, apply at institution class MortgageApplication < OpenWFE::ProcessDefinition sequence do # ... secretary :activity => “Send client application forms” participant :ref => “${f:selected_institution}”, :activity => “Apply for mortgage” end end
23. Achievements so far • Dynamic participant specification from workitem attributes • Another human participant • Mortgage now in “applied” state
24. Let Joe Know • Joe reviews the results of the application, and notifies the client • Might attempt to restart the entire process
25. Joe has last say class MortgageApplication < OpenWFE::ProcessDefinition sequence do # ... participant :ref => “${f:selected_institution}”, :activity => “Apply for mortgage” joe :activity => “Review application results” end end
26. What happens here? • Joe will inform the client of the institutions response • Mortgage will stay in “applied” state, or move to “approved”/”rejected” states • Process ends
27. Possibilities from here • Automated decision making – Decision tables – Better conditional tests • Automated response processing, streamlines the feedback loop and decision making • Harass institutions that don't respond within 2 days of process timeout • Joe improves his handicap
28. Ruote & AASM • Great combination • Ruote handles business logic, AASM the state • AASM becomes skinny, ruote stays declarative
29. More ruote: Listeners • Start process, or wait for – Messages from SQS – Jabber messages – Atom feed entries
30. More ruote: Cancel, cursors, replay & redo • When processes are cancelled, run sub- processes for “cleanup” tasks • Replay failed steps • Redo steps based on conditions • Jump to any point in the workflow using cursors
31. More ruote: ruote-fluo • Graphical representation of process definitions • Edit process definitions on the fly
32. More ruote: Active*Participants • ActiveRecordParticipant – Save workitem information in database • ActiveResourceParticipant – Interact with any Rails resource as DHH intended you to do
33. Shameless Self Promotion • Developed the JabberParticipant and JabberListener now bundled with ruote • Added support for daemonizing ruote-rest • In talks on refactoring ruote-rest to become preferred “Rails-friendly” implementation of ruote
34. Summary • Process definitions built up from expressions • Expressions are “steps in the workflow” • Participants perform explicit function during workflow • Workitems used as “internal messaging” mechanism between expressions/participants • The best complement to any state machine implementation • Simplifies complex business process implementations • You have full control over the entire process
35. Thank You opensourcery.co.za @kennethkalmer openwferu.rubyforge.org #ruote on Freenode groups.google.com/group/openwferu-users @jmettraux