RESTful web services for a kanban-style factory workflow using the Play Framework.
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README.md

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Playflow Web Services

Playflow defines RESTful web services for a kanban-style factory workflow using the Play Framework, version 2.4.2.

Install

  1. install java 1.8
  2. install Play Framework activator 2.4.2 http://www.playframework.com/
  3. cd to playflow project directory
  4. do activator test to run tests
  5. do activator run to run the application
  6. go to http://localhost:9000/api to view the api

Motivation

There are many open source factory workflow projects, but they are complex and difficult to adapt to specific projects. Playflow is basic enough to be easily adaptable to any workflow where users complete work at a given set of stations. Work items are moved from state to state and from station to station using RESTful API calls. An auditing trail is automatically recorded for all state transitions. This project provides a serious head-start for projects with these kinds of workflow requirements, and, since it is implemented in Play Framework, it is also fun and good for your health.

Definitions

  • Kanban workflow: a style of workflow where workers can choose what they want to work on from a 'free queue' (see below).

  • Project: Has a set of Work Items to be processed.

  • Work Item: a piece of work that is completed via the set of stations in a factory. It may, but doesn't need to be, part of a project.

  • Work Item History: an auditing record of a work item's State transitions. A transition is added to the history every time a work item is processed, changes assignee, or moves to a different station (service calls assign, process, and next--see below-- all invoke state transitions).

  • Work Item State: Can be INITIAL (not yet in a factory), UNASSIGNED (at a a factory station but not yet assigned to station worker), IN_PROCESS (being worked on by station worker), PROCESSED (work completed by a station worker), or COMPLETED (all work at at all stations in the factory has been completed).

  • Project State: Can be INITIAL (at least one project work item not yet in a factory), IN_PROCESS (no initial work items and at least one work item still being worked on at factory stations), or COMPLETED (all work items in the project have been completed). Note that projects do not have a separate audit history as project history is just the sum of all the histories of its work items.

  • Factory: Has an assembly line for processing a project's work items.

  • Assembly Line: Has a set of stations in which work items are processed.

  • Station: Has workers that process work items.

  • Worker: a user that processes work items at a particular station.

  • Free Queue: a station's work items that have not yet been claimed by a Worker (i.e. work items without an assignee)

  • Project assign Service Call: service call that assigns a project to a factory (puts the project's work items into the first station in the factory's assembly line).

  • Work item assign Service Call: service call that assigns a work item to a worker (assignee).

  • Work item process Service Call: service call that indicates that a work item has been processed by a worker at a station.

  • Work item next Service Call: service call that transitions a work item to the next station.

USE CASES

Admin needs to see all the factories, with all the stations, with all the work items at those stations:

  • use GET:/api/factories service to get all factories
  • use GET:/api/stations?factoryId=<factoryId> service to get the stations at each of those factories
  • use GET:/api/workItems?stationId=<stationId> to get the list of work items at each station.

Admin needs to create a new factory:

  • use POST:/api/factories service with factory payload to create a factory
  • use POST:/api/stations service with station payload specifying previously created factory

Admin needs to see which projects are complete:

  • use GET:/api/projects?state=completed

Admin needs to check which stations a project is at:

  • use GET:/api/stations?projectId=<projectId>

Admin needs to create a new project with work items:

  • use POST:/api/projects service with project payload to create a project.
  • use POST:/api/workItems service with work item payload specifying previously created project.

Admin needs to move a project into a factory:

  • use POST:/api/projects/<projectId>/assign?factoryId=<factoryId>

Admin needs to move a project out of all factories:

  • use POST:/api/projects/<projectId>/assign service without specifying a factoryId

Worker needs to see work items he has been assigned but has not completed:

  • use GET:/api/workItems?state=in_process&assigneeId=<userId>

Worker needs to see which stations she is responsible for and process work at one of those stations:

  • use GET:/api/stations?workerId=<userId> to get the list of user stations
  • use GET:/api/workItems?stationId=<stationId>&state=unassigned to get the list of unassigned items at a particular station.
  • use POST:/api/workItems/<workItemId>/assign?assigneeId=<userId> to assign one of those unassigned work items to the worker.
  • use POST:/api/workItems/<workItemId>/process service to indicate item has been processed.
  • use GET:/api/stations/<stationId> to get the nextStationId.
  • use POST:/api/workItems/<workItemId>/next?nextStationId=<nextStationId> service to move the item to the next station.

Admin needs to move a worker's items back to the station's free queue because the worker is sick.

  • use GET:/api/workItems?assigneeId=<userId> to get all the sick worker's work items.
  • use POST:/api/workItems/<workItemId>/assign service without specifying an assigneeId to move them back to an unassigned state at the current station.

FAQ

Which databases are compatible with playflow?

  • An in-memory H2 database is built-in for testing. Your application can use any SQL database. Just configure play with the jdbc driver and url.

Can a Factory have QA?

  • Yes, just add a station for QA directly after the station that needs to be QAed. From the QA station, use the next service with the previous station's ID specified as a parameter to reject a Work Item to the previous station.

Can a Factory have a gating Station before Work Items enter an Assembly Line or before Work Items are released from the factory?

  • Yes, a factory manager, for example, can be assigned as the sole worker in the first Station. He can then be the one to gate work for the rest of the assembly line. Likewise, a factory manager can be assigned as the sole worker in the last station gating release of the project.

Do stations in an assembly line need to be ordered?

  • No. A station object may or may not specify a next station and even if it does specify a next station, nothing enforces this ordering (your application can either use or ignore this information when specifying a nextStationId parameter for the next service call).

Can a Factory have branching and merging stations?

  • Yes. The branch stationId must be specified in the parameters of next service call. Merging is handled in the same way (by specifying the merge stationId in the next service call).

Can a Factory have two assembly lines?

  • No. A factory has only one assembly line, but you can simulate the presence of multiple assembly lines by branching (see above).

Can work items be transfered to a different factory?

  • Yes. Any stationId at any factory can be specified in the next service call.

Can a project be split between two or more factories?

  • Yes. Any work item can be assigned to any station at any factory via the next service call. The project assign convenience method, however, assigns the entire project to a single factory.

Can work items be reassigned to a different worker?

  • Yes. Use the assign service to reassign Work Items.

Do projects move sequentially or concurrently through the assembly line?

  • Concurrently (they move at whatever pace the workers at the various stations finish the project's work items). This means that a single worker at a single station may simultaneously have work items from several different projects in his or her work queue. Use projectId to distinguish the different projects returned from the Work Items services.

Are any of the objects validated? For example, does a Factory need to be created with a first and last station? Or do Work Items need to have a particular state before they can be the subject of an assign, process or next service call?

  • No, objects are not validated at creation time, nor at any other time excepting when a project is assigned to a factory that doesn't have a first station or a service is being called for an object that doesn't exist. Your application can add additional validation.

Where are completed work items stored?

  • A workItem can only be completed after being processed in a factory's last station(s) so completed work items will always be stored at that last station(s).

Routes

(Services expect and return JSON. Specifics at http://localhost:9000/api)

Projects:

  • GET /api/projects
  • GET /api/projects/<projectId>
  • POST /api/projects
  • PUT /api/projects/<projectId>
  • DELETE /api/projects/<projectId>
  • POST /api/projects/<projectId>/assign

Work Items:

  • GET /api/workItems
  • GET /api/workItems/<workItemId>
  • POST /api/workItems
  • PUT /api/workItems/<workItemId>
  • DELETE /api/workItems/<workItemId>
  • POST /api/workItems/<workItemId>/assign
  • POST /api/workItems/<workItemId>/process
  • POST /api/workItems/<workItemId>/next

WorkItemHistory:

  • GET /api/workItems/<workItemId>/history

Factories:

  • GET /api/factories
  • GET /api/factories/<factoryId>
  • POST /api/factories
  • PUT /api/factories/<factoryId>
  • DELETE /api/factories/<factoryId>

Stations:

  • GET /api/stations
  • GET /api/stations/<stationId>
  • POST /api/stations
  • PUT /api/stations/<stationId>
  • DELETE /api/stations/<stationId>

Users

  • GET /api/users
  • GET /api/users/<userId>
  • POST /api/users
  • PUT /api/users/<userId>
  • DELETE /api/users/<userId>