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expangine-workflows

A service and UI for creating and running user-designed workflows.

A workflow is a sequence of user interactions or automatic processes through which a piece of work passes from initiation to completion.

A workflow more specifically is a collection of steps. Each step has zero or more outcomes, each followed by another step. A workflow is only valid when all outcomes are followed by a step.

Steps

  • Execute: change the state of the workflow
  • Email: send an email to one or more emails
  • API call: make a HTTP call to an outside service and process the response
  • Branch: analyze the state of the workflow to generate possible outcomes
  • Pause: wait until a given date before resuming the workflow
  • Finish: the workflow is done
  • Goto: goto a specfic step next
  • Throttle: control how frequently a step can be ran, to avoid running it too often
  • Fork: start another workflow and keep going
  • Sub: start another workflow and wait until it completes, analyze the completed state to generate possible outcomes
  • User Decision: a user manually picks an outcome
  • User Input: a user manually enters data and the data is used to update the state of the workflow
  • Access: change who can view or perform actions on the workflow instance
  • Multiple: execute multiple steps and wait until all or one has processed

Workflows can be developed for commonly performed actions (tweeting) and then invoked as a sub-workflow.

API

Workflow:

  • start: Step
  • steps: Step[]
  • logs: Workflow Log[]
  • infos: Workflow Info[]
  • watchers: Watcher[]
  • visibility: what parts of the system can see the workflow
  • name: the name of the workflow
  • type: one of TRIGGER, STANDARD
  • input: the (readonly) input type given when the workflow was created
  • temp: the temporary type used while the workflow is in a non-FINISHED status
  • output: the output type
  • trigger: the type for the old/new value for a trigger

Workflow Info: (ex: priority, due)

  • workflow: Workflow
  • label: the label of the info
  • order: the order of the info
  • type: a system type that describes how this info is used
  • visibility: where is this info displayed
  • getData: Expression

Workflow Instance:

  • type: Workflow
  • status: one of WAITING, RUNNING, PAUSED, SUCCESS (completed), ERROR, FAILED (completed)
  • completed_at: the date it finished
  • current: Step
  • input: the input data given when the workflow was created
  • temp: the temporary data used while the workflow is in a non-FINISHED status
  • output: the output data
  • cache: cached data used by steps
  • updated: when workflow last ran
  • created: when workflow was created
  • scheduled: the next time this workflow should run

Step:

  • type: Step Type
  • name: the name of the step
  • icon: an icon of the step
  • color: the color of the step
  • outcomes: Step Outcome[]

Step Outcome:

  • step: Step
  • outcome: string
  • next: Step

Step Type:

  • name: the name of the step type
  • icon: the default icon
  • color: the default color
  • isAsync (workflow: Workflow, step: Step): boolean
  • getOutcomes (workflow: Workflow, step: Step): string[]
  • getOutcomeScope (workflow: Workflow, step: Step, outcome: string): Type
  • getExpressions (workflow: Workflow, step: Step): Expression[]
  • execute (workflow: Workflow, step: Step, instance: WorkflowInstance): Promise<string>

Watcher: (run concurrently for conditions outside the normal workflow)

  • schedule: how often the watcher runs
  • step: the step to run each time a watcher is ran

Actor:

  • name: the name of the actor
  • type: the actor type (user, role, group, workflow, system, watcher)

Workflow Log:

  • workflow: Workflow Instance
  • index: the index of this log in the list of things done to the workflow
  • actor: Actor
  • from: Step
  • outcome: string
  • to: Step
  • created: when the log was created

Step Types

Execute: (run a transactional program)

  • program: Expression (Any)
  • outcomes: [success, error]
  • outcomeScope: result

Email: (send an email)

  • protocol: Email Protocol
  • to: Expression (Text, Text[])
  • cc: Expression (Text, Text[])
  • bcc: Expression (Text, Text[])
  • subject: Expression (text)
  • body: Expression (Text, Element)
  • attachments: Expression (File, File[])
  • outcomes: [sent, error]

API call: (call another service over HTTP(s))

  • url: Expression (Text)
  • method: Expression (Enum: GET/POST/DELETE/PUT)
  • query: Expression (Object)
  • data: Expression (Any)
  • headers: Expression (Object)
  • timeout: Expression (Number)
  • outcomes: [success, error]
  • outcomeScope: response, status, responseHeaders, timedout

Branch: (evaluate state and return possible outcomes)

  • program: Expression (Enum)
  • outcomes: determined by program

Pause: (wait until workflow evaluates further)

  • resume: Expression (Date)
  • outcomes: [elapsed]

Finish: (stop workflow)

  • outcomes: []

Goto: (go to step)

  • step: Expression (Enum: steps)
  • outcomes: []

Throttle: (don't execute too often, max per frequency OR getNextTime)

  • frequency: Expression (Number)
  • max: Expression (Number?)
  • getNextTime: Expression (Date?)
  • outcomes: [run, throttled]

Fork: (create a new workflow)

  • workflow: Expression (Enum: workflows)
  • getInput: Expression
  • outcomes: [created, error]

Sub: (create a workflow and wait for it to finish)

  • workflow: Expression (Enum: workflows)
  • getInput: Expression
  • outcomes: [success, error]
  • outcomeScope: output

User Decision: (user must click a button)

  • due: Expression (Date)
  • outcomes: [...user-defined, elapsed]

User Input: (user must enter data)

  • due: Expression (Date)
  • input: Type
  • submitted: Expression
  • outcomes: [submitted, elapsed]
  • outcomeScope: result

Access: (who can see or act on workflow instance)

  • actor: Expression (List of Enum: user/role/group)
  • rights: Expression (Enum: View, Act, Pause, Resume, Stop, Delete)
  • type: ADD, REMOVE, REPLACE
  • outcomes: [granted]

Multiple: (execute multiple steps and wait until all or one has processed)

  • type: ALL, ONE
  • steps: Step[]
  • mapping: each step outcome is mapped to a new outcome
  • outcomes: determined by mapping