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Workflows

A workflow defines sequences of states in which the instances of a Data Type go through.

More generally it's the sequence of steps involved in moving from the beginning to the end of a working process.

info

Synonyms of state could be: step, phase, activity, etc.

(depending of your business logic)

Features and constraints

Workflows at Olympe support a number of features and impose some constraints on them for better design.

  • On Workflows:
    1. Always have an Initial State
    2. Are associated to one Data Type
    3. Historize all transitions and initializations
  • On States:
    1. Have a unique name for each State
    2. Are not limited in number
  • On Transitions:
    1. Have a unique name for each Transition leaving a given State.
      A State can transition to multiple States, in which case, each Transition must have a unique name. Transition Unique Name
    2. Must be unique between a pair of origin/destination States
    3. Can have the same State as the origin and destination
    4. Can have an optional Process function called when the Transition is triggered
  • On object states (history):
    1. Contain the name of the Workflow, of the State and of the assignee (User)
    2. Contain the date and time of the transition/initialization
    3. Optionally contain the serialized object's properties as a JSON string

Workflow examples

Let's take a look at some examples.

To-do list task

A very simple example to start with: the workflow of a task in a To-do list.

The task starts in the To Do state, then moves to Doing and then to Done when finished.

todo_list_example

Fishing license validation

A bit more complex one: a fishing license application to request and accept/refuse fishing licenses.

The license starts in the To Validate state, then it can go to the Validated or the Refused states.

If some information is missing, the license can go back and forth to the Waiting For Info state.

fishing_license_example

Online shopping cart

Here we have the steps for an online shopping cart.

The cart can go back and forth until the Payment is Done.

Note also the self transition of the state Shopping, that we can use when adding or removing items to/from the cart.

Note also the optional Discount step used if the user has a voucher for example.

online_shop_basket_example

Game server room state

One last example from a project done sometime ago. It was about an online game in which players could create rooms, wait for players to join and then start the game.

The started room (in the Closed phase) was then processed by the game server to handle all game logic. The players also always knew in which phase the server room was (Setup, Running, etc).

game_server_room_example

Create a Workflow

Create one by drag-and-dropping the Workflow component from the Marketplace on the right side of the screen into the main editor:

create_workflow

You can then rename it and double-click on it to open the workflow editor:

rename_workflow

The Workflow editor looks like this the first time you open it. The State in blue represents the Initial State of your Workflow. There is always one so it is automatically created for you:

empty_workflow_editor

In the Spec & Doc tab you can give some information about your Workflow.

There is some configuration of the Workflow you need to do:

  1. Since Workflows are always associated to a specific Data Type, you must specify it
  2. You can or not enable the serialization of the Data Type instances when using the Workflow
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Even if the serialization of objects is disabled the Workflow will still historize the object's states, just without the object's values.

workflow_spec_doc

Define the States

You can now start creating and defining your Workflow States. Simply drag & drop them from the Marketplace:

create_state

To rename your State, you can select its name and give it the name you want:

rename_state

To delete the State or find its usages, just hover your mouse over it and you will see the options at the top-right corner:

state_hover

Define the Transitions

Now that we have our States, we can start creating Transitions between them.

To do that follow those steps:

  1. Hover your mouse over the State from which the Transition starts
  2. Click on the arrow icon in the top-right corner and keep your button pressed
  3. Move your mouse to the destination State and release your mouse button
  4. The Transition is created!

transition_created

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  • The default Transition name is always To <destination state name>. That's why renaming the States before creating Transitions may gain you some time.
  • You must hover the Transition to see its name. You can also hover the origin or destination State to see it.

To rename the Transition, delete it or find its usages, simply hover the Transition and click on it:

transition_popup

Self-transition

A Workflow in DRAW allows the creation of a self-transition, which is a transition with the same origin and destination State.

To create such Transition, follow the same steps as for creating a normal Transition but release your mouse button when it's on the same State:

self_transition

Transition process function

You can define an optional process function on your transitions. This is useful to add logic on transitions, like sending an email, changing the object's properties, do some verifications, etc.

To do so click on the f(x) button in the transition popup we saw above. It will create an anonymous function following this signature:

process_function

The inputs are:

  1. Control Flow: triggered when the transition is triggered (but not done yet)
  2. Object: the object on which the transition was triggered
  3. User: the user triggering the transition
  4. Data Map: an optional Map of data passed to the process function

The outputs are:

  1. Control Flow: trigger it to finalize the transition
  2. Error Flow: trigger it to cancel the transition
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When a process function is set on a transition, the little dot on the transition arrow appears in blue to quickly see it.

Using Workflows in DRAW

Below we show some very useful bricks when it comes to manipulate Workflows in DRAW.

All those bricks are defined in the Marketplace extension extensions/workflow, where you can find also another useful bricks.

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All workflow-related bricks start with Workflow: to simplify search in the Marketplace.
The Marketplace content being editor specific, these bricks are available from the Function Editor or Action Editor.

Initialization of a Workflow

When creating an instance of a model associated with a Workflow, the Workflow is not automatically initialized on the instance.

To do that, you must explicitly use the brick Workflow: Initialize:

workflow_initialize

It takes the instance as an input and the workflow to initialize (since multiple workflows could be associated with the instance Data Type).

info

Once the Workflow is initialized on the instance, its current state is the Workflow's Initial State.

Transitioning from one State to another

To trigger a Transition (transitioning from one State to another), you can use the brick Workflow: Trigger Transition:

workflow_trigger_transition

You must specify which Transition since the current State may have multiple outgoing transitions.

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If the Transition has a Process function, it's automatically called by the brick before executing the Transition. If the Process function returns an Error Flow, the Transition will fail and the error will be forwarded by the brick.

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Note that you can pass an optional Map of data to the Process function.

Retrieving the current object state

To get the current object state information of an instance for a specific Workflow, use the brick Workflow: Get Object State:

workflow_get_object_state

You get in output an object of type Workflow Object State on which you can get further information but also directly the different properties that can be extracted of this Workflow Object State instance as a shortcut.

Check if an object is in a specific State

Often you just want to know if an instance is in a specific State. To do that use the brick Workflow: Is Object In State:

workflow_is_object_in_state

Get an object history

If you want not just the current object state but all the history, you can use the brick Workflow: Get Object History:

workflow_get_object_history

It will return a Query Result of Workflow Object State ordered by datetime (descending).

Using workflows in CODE

You can manipulate workflows in CODE too. This is very useful if you want to do complex logic on them or some logic very specific to your use cases.

To do that CODE exposes all workflow-related models in the Public API:

export class Workflow extends CloudObject {
static serializationEnabledProp: Property<boolean>;
static dataTypeRel: Relation<Workflow, CloudObject>;
static statesRel: Relation<Workflow, WorkflowState>;
static initialStateRel: Relation<Workflow, WorkflowState>;
}

export class WorkflowState extends CloudObject { /* empty */ }

export class WorkflowTransition extends CloudObject {
static processRefProp: Property<Brick>;
static fromStateRel: Relation<WorkflowTransition, WorkflowState>;
static toStateRel: Relation<WorkflowTransition, WorkflowState>;
}

export class WorkflowObjectState extends CloudObject {
static workflowProp: Property<string>;
static stateProp: Property<string>;
static assigneeProp: Property<string>;
static dateTimeProp: Property<Date>;
static serializedObjectProp: Property<string>;
static objectRel: Relation<WorkflowObjectState, CloudObject>;
static currentObjectRel: Relation<WorkflowObjectState, CloudObject>;
}

You can find the full documentation in the file cloud.d.ts.

Data Model

Here is a diagram of each type and their properties and relations, as defined in the Public API above:

workflow_data_model