SymfonyLive London 2016 - The Workflow Awakens

It is common having to handle statuses or product states, either on e-commerce or editorial websites. To do that, you can use the classical -manual- way, or get help from libraries covering the basis.

In this talk, we will talk about the state machine concept and definition before considering its usage looking at existing open source libraries. Finally following the Symfony way, we will study the brand-new "Workflow" component.

Transcript

1. The Workflow Awakens
   Tugdual Saunier
   

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2. 2
   Tugdual Saunier
   @tucksaun
   Shipping guy.

   Loves Dev, Ops and
   automation.
   London, UK
   Blackfire.io/SensioLabs
   

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3. 3
   History of the

   Workflow component
   

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4. 4
   Genesis
   

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5. Winter 2013
   5
   

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7. Do we open
   source it?
   7
   

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8. Yes !
   8
   

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9. In Symfony?
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10. Ok, but Greg
    does the PR
    10
    

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12. As usual for @lyrixx
    12
    

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13. September 2014
    13
    

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14. Lack of time
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15. February 2016
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16. Let’s get back to
    work
    16
    

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17. 17
    But was is it?
    

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18. 18
    What problems should it
    address?
    

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19. 19
    On an editorial website, there are several kinds of
    people involved.
    Freelancers, journalists, spellcheckers, chief editor,
    publication director, …
    An article is not published that easily.
    Context
    

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20. 20
    For example, an article must be validated by a
    journalist and a spellchecker.
    Otherwise, the article can not be published.
    Rules exist
    

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21. 21
    The component responsibili﬚ is to ensure the article
    properly goes by all validation steps.
    Welcome Workflow!
    

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22. 22
    Workflow:

    a State Machine
    

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23. 23
    States / Transitions
    state A state B
    Transition T1
    

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24. 24
    Oriented Graph
    A B
    T1
    C
    D
    E
    T2
    T3
    T4
    T5
    

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25. 25
    Get back to the PR
    

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26. Read the code
    one more time
    26
    

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27. Being able to handle article publication process
    There is a serie of steps that must be fulfilled
    Only some users can move from one step to the
    other
    Some steps can be done at the same time
    Define the specs
    27
    

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28. 28
    Example
    

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29. Let’s face it,

    a state machine is
    not appropriate
    29
    

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30. Read some doc
    30
    

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31. Explore existing
    libraries
    31
    

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32. State machine:
    https:/
    /github.com/yohang/Finite
    https:/
    /github.com/winzou/state-machine
    Petrinet
    https:/
    /github.com/florianv/petrinet
    https:/
    /github.com/alterway/component-workflow
    Other
    https:/
    /github.com/vespolina/workflow
    Overview
    32
    

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33. 33
    Let’s move Workflow code
    to a “Workflow net”
    

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34. 34
    What’s this?
    

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35. 35
    This is an extension of Petri networks.
    It looks like state machines.
    But with more features.
    Note: Symfony Workflow component does not implement all the specs.
    Workflow Net
    

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36. 36
    Places / Transitions
    place A place B
    Transition T1
    

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37. 37
    Several Inputs Outputs
    place place
    Transition
    place place
    

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38. 38
    Tokens
    

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39. Schrödinger's cat
    39
    

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40. 40
    Marking
    

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41. 41
    Some Workflow examples
    

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42. 42
    Straight
    

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43. 43
    Round Trip
    

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44. 44
    Or
    

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45. 45
    And / Parallel
    

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46. 46
    Wait, what?
    

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47. 47
    Let’s implement
    

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48. Diff
    48
    

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49. 49
    Workflow::can()
    

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50. 50
    Workflow::can() example
    

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51. 51
    Workflow::apply()
    

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52. 52
    Workflow::apply() example

    Before
    

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53. 53
    Workflow::apply() example

    After
    

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54. 54
    Workflow::getEnabledTransitions()
    

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55. 55
    Definition class : Places
    

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56. 56
    Definition class : Transitions
    

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57. 57
    Definition class : Transitions
    

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58. 58
    Definition class : Transitions
    

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59. 59
    Definition class : Transitions
    

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60. 60
    Graphviz dumper
    

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61. 61
    The EventDispatcher has been plugged into the
    Workflow !
    Events are dispatched each time:
    • a place is leſt
    • a transition is fired
    • a place is reached
    Events
    

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62. 62
    plus one : GuardEvent
    

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63. 63
    What about Symfony?
    

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64. 64
    It is always recommended to first draw your workflow
    on paper first to try it beforehand.
    Definition - By Hand
    

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65. 65
    Definition - YML
    

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66. 66
    Definition - YML - Supports
    

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67. 67
    Definition - YML - Places
    

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68. 68
    Definition - YML - Transitions
    

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69. 69
    What does it look like?
    

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70. 70
    The view
    

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71. 71
    The view
    

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72. 72
    The controller
    

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73. 73
    What about guard?
    

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74. 74
    What about guard?
    

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75. 75
    What about guard?
    

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76. 76
    Demo ?
    

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77. @blackfireio #blackfireio
    

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