Spring Web Flow is a framework that introduces the concept of flows to extend the navigation capabilities of the Spring MVC framework. It allows expressing navigation rules and managing conversational state through the use of flow definitions composed of states and transitions. This provides advantages over traditional approaches like JSP, Struts, and JSF by making the navigation logic more modular, reusable, and visually understandable through tools like the Spring Tools Suite flow editor. While it adds capabilities, it also introduces some performance overhead and complexity that may not be suitable for all applications.

1. Spring Web Flow:
A little flow of happiness.
Сергей Моренец, morenets@mail.ru
24 мая 2013 г.

2. About author
• Works in IT since 2000
• 9 year of Java SE/EE experience
• 5 years of Spring (including SWF) usage
• Regular speaker on Java User Group conferences
• Senior Java developer in Provectus

3. Agenda
• Overview of the navigation history
• Basics of SWF
• Practical usage
• Pros & Contras
• Q & A

5. Spring MVC

6. Navigation overview
• JSP
• Spring MVC
• Struts
• JSF

7. JSP

8. Spring MVC

9. Struts
struts-config.xml

10. JSF
faces-config.xml

11. Disadvantages
• Visualizing the flow is very difficult
• Mixed navigation and view
• Overall navigation rules complexity
• All-in-one navigation storage
• Lack of state control/navigation customization

12. What is Spring Web Flow?
• Developed by Erwin Vervaet in 2004
• Initial version released in October, 2006
• Spring MVC extension
• Introduces flows concept
• Extends application scopes
• SWF 2.3.2 released in Jan, 2013

13. Erwin Vervaet
• Belgium citizen
• Holds master's degree in computer science
• Originator of Spring Web Flow Project
• Senior project manager together with Keith Donald
• Speaker on the most Java and Spring related
themes
• Independent consultant www.ervacon.com

14. What is SWF for?
• How do you express page navigation rules?
• How do you manage navigation and conversational
state?
• How do you facilitate modularization and reuse?

15. Use case

16. Request diagram

17. Request diagram

18. Flow definition
• XML document with predefined elements
• Flow definition is composed of a set of states
• Each state has one or more transitions that are used to
move to another state
• A transition is triggered by an event

19. Flow Structure
Flow
Transitions
Data
States

20. State type
State
Action View Subflow Decision End

21. Action state

22. View state

23. Decision state

24. Subflow state

25. End state

26. Start/end activity

27. Transition binding
• JSF
• Spring MVC

28. JSF

29. Spring MVC

30. Post redirect get(PRG)

31. Spring scope
Singleton
Request
Global-
session
Session
Prototype

32. SWF scope
Request
View
ConversationFlow
Flash

33. Request scope
• Tied at the level of a single request
• Not linked to a flow execution by itself

34. Flash scope
• Extended request scope for PRG case
• Useful for rendering error/warning messages

35. View scope
• Can be referenced only within view state
• Useful for storing data required with given view only

36. Flow scope
• Lives within flow session
• Not available inside sub-flows

37. Conversation scope
• Lives within entire flow execution
• Available to all sub-flows

38. Flow scope usage

39. View scope usage

40. Presentation level

41. Flow tracking
Original link http://mysite/site/main?id=1
Target http://mysite.com/site/main?execution=e2s1

42. Flow tracking

43. Flow tracking

44. Flow tracking
Original link http://mysite/site/main?id=1
Target
http://mysite.com/site/main?execution=e2s1&id=1

45. Exception handling
• Transition on exception
• Custom exception handler

46. Transition on exception

47. Exception handler

48. Exception handler

49. Flow inheritance
Parent-flow
Child-flow

50. Shortcuts
• requestParameters
• currentEvent
• currentUser
• messageContext
• resourceBundle
• flowRequestContext

51. Breadcrumbs
• Navigation elements in UI
• Allows to keep track of the documents within
system
• Provide links to move to current, previous or next
step
• Home page > Section page > Subsection page

52. Breadcrumbs

53. Breadcrumbs

54. Breadcrumbs

55. Breadcrumbs

56. Distribution

57. Integration
• Spring MVC/Spring Security
• Apache MyFaces
• JSF 2
• Portlets
• RichFaces
• Struts 2
• Tiles

58. Future
• Suspend/resume functionality
• Backtracking support
• Flows deployment as OSGi bundles
• Native support for Tiles and FreeMarker
• URL rewriting
• Java-based flow definition syntax

59. Pros
• High-level navigation control with clear observable
lifecycle
• Designed to be self contained
• Compile-independent
• Easy to understand and visualize
• Expression language support
• Custom validation (including AJAX)
• Integrates with major web frameworks

60. Cons
• Requires Spring framework
• Separate Spring project
• Additional performance overhead
• Lack of community support
• Not suitable for simple or flow-free applications

61. Spring Tools Suite
• Eclipse development environment for building
Spring-powered enterprise applications
• Visualization of Spring Web Flow
• Flow graph
• Flow editor

62. References

63. Q&A
Сергей Моренец, morenets@mail.ru