This document discusses ruote, an open source Ruby workflow engine project. It provides an overview of ruote and its subprojects, which include ruote-fluo for process definitions, and ruote-web and ruote-rest for integrating ruote with web applications. The document also covers using Ruby for workflow applications, the concept of a workflow language and expressions, and making workflow resources and processes accessible via web standards like HTTP and REST.

1. Stockholm University - 2008/10/08

2. ruote

3. ruote
• open source project
• “ruote” is a nickname
• formal name is “openwferu”
http://openwferu.rubyforge.org

4. ja to ru
• OpenWFE project started in late 2001
• became OpenWFEru late 2006
• java to python ruby
• nicknamed Ruote (keep the ru)

5. sub-projects
• ruote
• ruote-fluo
• ruote-web & ruote-rest

6. sub-projects
• ruote : as a ruby project
• ruote-fluo : how ruote sees processes
• ruote-web & ruote-rest : ruote + web

7. ruote

8. ruote
• open source
• ruby
• workflow engine

9. ruby
• ruby is slow
• yes, but development time is shorter
• yes, but hardware gets faster
• yes, but interpreters get stronger and
faster

10. workflow
• ruote is a workflow engine
• incidentally BPM, BPM the discipline
• do you have the discipline to integrate
such a tool ? (usage cost)
• do you have the discipline to avoid
such a tool ? (non-usage cost)

11. ruby and workflow
• ruby is well-known,
because of Ruby on Rails
• rails people are able to build web
application very quickly
• “workflow” for them is spelled
“act_as_state_machine”

12. act_as_a_state_machine
• ruby on rails plugin
• attach states (and transitions) to rails
entities
• virtual entities representing
business processes
• still 1 web application
• ruote : target is ruby, not just rails

13. ruby and workflow
my endeavour :
• bring a workflow engine to ruby
or
• leverage ruby to write a
better workflow engine
?

14. ruby
• ruby is one of the fastest language
(shortest development time)
• less code to write
• less code to maintain

15. ruby people
• lots of ex-{PHP|Perl|Java} people
• different perspective
(enterprise wide vs web wide)
• true community (not big guns driven)
• ruby people seem to be
going in the right direction (trust)

16. workflow engine
• process definition interpreter
• process definition language ?
• many grails

17. many grails
• visual grail
• “no code” / no programming grail
• standard grail
• (formal grail)

18. visual and standard
• in 2001-2002,
there were XPDL and BPML
• visual is hard, lots of noise info
• trying to come up with a language

19. “no code” grail
• defining a process is not
programming
• redacting a mission statement is not
programming
• specifying a series of task to be
executed by a machine is not
programming

20. programming
• I firmly believe that defining a process is
programming (modeling)
• I firmly believe that issues raised by
process execution are better solved by
people with an understanding of
programming and systems (managing)
• no coder and no admin ?

21. programming
business processes
• building abstractions / raising the
abstraction level
• provide a language
• a process definition language

22. language
• a language and its interpreter
• 4 main constructs
• process-definition
• participant
• sequence
• concurrence

24. language
• conciseness
(process def vs context)
• no “box and arrow position” noise
• graphical representation can be
derived from such a language
• XML parsers were/are available

25. requirements
• the workflow control patterns
• directly and indirectly
• community
• feedback and requests

27. participants
• workflow resource patterns
• orchestrating :
• BPEL and web services
• ruote and ‘participants’
• participants usually change less often
than processes
• users, roles, systems, services, ...

28. workitems
• issuing workitems to participants
• serializable as JSON / XML / YAML
• payload : reference is better than raw
content
• apply / reply workitems as well

29. ruote-fluo

30. ruote-fluo
• is a javascript library
• fluo-can :
renders process definitions graphically
• fluo-tred :
online process definition edition

31. fluo-can

32. fluo-tred

33. formats
• so you have XML, Ruby and this online
tool
• it’s manipulating ASTs
• exp :=
[ exp_name, { attribute* },[ child_exp* ]]

36. languages, trees
• a tree at the heart
• direct interpretation, no compilation
(not so low level interpretation)
• (-) slower
• (+) graspable,
directly modifiable (in-flight)
• (+) easy to add new expressions

37. expressions
• ruote is a very patient (long running)
interpreter
• interprets trees of expressions
• expressions come in two flavour :
raw / applied
• they reply to 3 messages :
apply / reply / cancel

38. a
process-
definition b
0
c
sequence
g participant
0.0
d 0.0.0
quot;alphaquot;
alpha
e
f
apply
participant
0.0.1 quot;bravoquot;
reply
bravo

39. ruote
• simplistic / naive
• that’s a strength when things go wrong
(it should not play tricks on you)
• ...

40. ruote & web

41. ruote & web
• a process definition is a document
• a document, a URI

43. ruote & web
• workflow things as web resources
• processes / errors / workitems
• launch : POST /processes
• cancel : DELETE /processes/3425ba2

46. ruote-rest
• trying to be RESTful
• trying to stick to web standards
• trying hard for connectedness

47. web standards
• HTTP
• XML, JSON
• Atom, RSS
• AtomPub (content oriented maybe)
• iCal, ...

48. ruote-rest
• process server
• embedded vs external
• state machine vs process server

49. next spins

50. next
• better ruote-web2 (2008/11)
• more in-flight edition
• better migrations / batch migrations
• more documentation
• more...