To illustrate several different workflow strategies, here are diagrams of each of the workflows that ship with the Kaleo Web plugin. You’ll find these definitions in the directory
Think of workflow as a state machine made up of nodes. A node can be a state, a task, a condition, a fork, a join, or a timer. Transitions are used to move from one node to another. Each type of node has different properties. For example, states execute actions automatically and require no user input. Tasks block until user input completes a transition to another state. The transition then moves the workflow to the next task or state. This cycle continues until the end Approved state is reached. For example, you could create a workflow which goes through two approvers. Initiating the workflow puts it in the In Review state and then transitions to a task which requires user input. Users approve or reject the asset as part of the task. When the first user approves the asset in the workflow, a condition checks to see if there are two approvals. Since there is only one, workflow transitions back to the task. When the second user approves the asset, the condition finds there are two approvers and it triggers a different transition to the Approved state.
Transitions connect one node to another. On exiting the first node, processing follows the transition to the node it points to. Selecting a Transition turns your pointer into a connector; you connect the starting end of a transition to one node and the other end to the next node in your process.
In addition to Start and End node types, there are five node types you can use in your workflow:
- Condition: Directs workflow execution to an appropriate transition based on conditional logic of the node’s script.
- Fork: Forks the workflow execution into two parallel threads.
- Join: Joins parallel workflow threads.
- Join XOR: Joins parallel workflow threads, but only needs to receive workflow execution from one of them.
- State: Represents a workflow state.
- Task: Represents a task that can be assigned.
Drag and drop any nodes you need onto the Kaleo Workflow Designer for Java workflow diagram. Each node type supports execution of scripted actions and sending notifications that can use templates.
For the ticket-process-definition workflow diagram, there’s a simple
StartNode State node, followed by the
Developer Task node, followed by the
EndNode State node. There are two transitions, from
Developer and from
Here’s the idea behind the Ticket Process Workflow definition. A developer should approve his fix and send it for quality assurance to QA, where it must pass testing by a QA engineer. Then it’ll go to QA Management, where it must be approved by a QA manager. Let’s use a Fork node to accurately depict these parallel approval tasks.
Drag and drop a Fork node onto your workflow diagram. A wizard helps you create your node. Click the green plus symbol to select new or existing nodes to process in parallel threads. A drop-down menu gives you options to select tasks to be done in your fork threads. In addition, a checkbox lets you indicate whether to automatically add a corresponding join node to your workflow.
On finishing your fork node in the wizard, Kaleo Designer places your new nodes onto the workflow diagram’s canvas. If you’re not happy with the location of your new nodes, drag them to place them where you want on your canvas. Our ticket process workflow now looks something like this:
Why is there a red “X” in the bottom left of multiple nodes within our workflow? These are error markers! Errors indicate something is specified incorrectly or is missing from your nodes. If you click on an error marker, Developer Studio displays hints on resolving the problem. Don’t worry, we’ll address these error markers momentarily.
Clicking on a node brings up a floating palette; use it to make quick, convenient customizations to a node.
The floating palette has several features you can use:
- Add (green cross): Add an action or notification on the node. To edit the added action or notification, bring up Designer’s Properties view.
- Edit Actions (paper with arrow): Edit the node’s existing actions.
- Edit Notifications (envelope): Edit existing notifications on the node.
- Edit Script (pencil): Edit the script of the condition node. This feature only applies to the condition node.
- Change Assignments (person): Assign or reassign a task. This feature only applies to the Task node type.
- Delete (red “X”): Delete the node.
- Show in Source (paper with folded corner and arrow): Show the node specified as as a model element in the workflow definition’s XML source and switches the main editor to Source mode.
- Start Transition (black arrow): Change the pointer to transition mode letting you create a workflow transition from the current node to another node.
Obviously, there is still work to be done in our workflow definition. We have multiple error markings and the fork and join nodes aren’t connected to anything. Let’s change the assignments for our two new task nodes, QA and QA Management, by clicking the Change Assignments icon from the floating palette for each node. The Choose Assignment Type menu appears for each node, letting you choose their assignment type. After we assign the QA and QA Management task nodes, the error markers disappear.
For the QA tasks in our
ticket process workflow, let’s assign someone other than the asset creator. Realistically, each of these tasks would be assigned to different site roles. For simplicity, lets assign both the QA and QA Management tasks to the same user. If you have a user in mind, specify that user. Otherwise, create a user named “Joe Bloggs” with screen name “joe”. For the user to receive emails, he must be registered within Liferay Portal. If you haven’t registered Joe Bloggs (“joe”) already, see the Discover documentation on Adding and Editing Users. To configure the user’s email, login to the user’s account and visit Control Panel → Server Administration → Mail for setup options.
Select the Change Assignments icon from the floating palette for each QA task node. Then, select Assign to a specific user from the Choose Assignment Type menu and click Next. You have options to enter the user’s User-id, Screen name, or Email address. Enter the user’s screen name and click Finish.
Assigning the QA and QA Management task nodes resolved their error markings (no more red “X”!). The join node’s error marking won’t disappear until you connect the join node to another task.
Let’s take a moment to consider the XML code of the ticket process workflow definition in its current state.
It specifies its XML version, encoding, and its document root element called
workflow-definition. Nested within the
workflow-definition element are its name, description (optional), version, and its nodes: 1 fork, 1 join, a start and end state. Here’s the general overview of our workflow definition:
<?xml version="1.0" encoding="UTF-8"?> <workflow-definition xmlns="urn:liferay.com:liferay-workflow_6.2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:liferay.com:liferay-workflow_6.2.0 http://www.liferay.com/dtd/liferay-workflow-definition_6_2_0.xsd"> <name>Ticket Process</name> <version>1</version> <!-- fork node --> <!-- join node --> <!-- start and end state nodes --> <!-- task nodes --> </workflow-definition>
We’ll describe each of our workflow definition’s nodes, starting from top to bottom, left to right.
Our start state node, named StartNode, simply transitions the flow of execution to our Developer task. Here is this state node (note, we left off the optional
<metadata>...</metada> elements to shorten the code snippets):
<state> <name>StartNode</name> <initial>true</initial> <transitions> <transition> <name>Developer</name> <target>Developer</target> <default>true</default> </transition> </transitions> </state>
The Developer task is assigned to the creator and transitions to the EndNode state node upon approval. Each workflow instance is associated with an asset. By default, a task is associated with the asset creator.
<task> <name>Developer</name> <assignments> <user></user> </assignments> <transitions> <transition> <name>approved</name> <target>approved</target> </transition> <transition> <name>EndNode</name> <target>EndNode</target> </transition> </transitions> </task>
The ending state node is named EndNode. It specifies that an Approve action is to be executed on entering this node.
Our workflow definition has one fork node named Pass to QA. It forks the process to the QA and QA Manager task nodes:
<fork> <name>Pass to QA</name> <transitions> <transition> <name>QA</name> <target>QA</target> </transition> <transition> <name>QA Management</name> <target>QA Management</target> </transition> </transitions> </fork>
Both the QA-related task nodes are assigned to the user with screen name joe.
<task> <name>QA</name> <assignments> <user> <screen-name>joe</screen-name> </user> </assignments> <transitions> <transition> <name>Pass to QA Join</name> <target>Pass to QA Join</target> </transition> </transitions> </task> <task> <name>QA Management</name> <assignments> <user> <screen-name>joe</screen-name> </user> </assignments> <transitions> <transition> <name>Pass to QA Join</name> <target>Pass to QA Join</target> </transition> </transitions> </task>
Lastly, the QA and QA Manager task nodes transition into the Pass to QA Join join node:
<join> <name>Pass to QA Join</name> </join>
Now you know what the resulting XML is like for your workflow definition. You can check your definition’s source code anytime from within Liferay Studio or your favorite XML editor. To learn more on the different workflow nodes available to use in Liferay workflow definitions, see the Discover documentation on Creating New Workflow Definitions.
Since we’ve been using Designer’s Workflow Diagram mode, let’s go over some of its features.
Workflow Diagram Features
Developer Studio provides you with additional features within the workflow diagram. Below we list some of these features; they can greatly enhance your workflow designing experience.
Workflow Diagram Actions are available via the toolbar in the upper right corner of the Workflow Diagram:
- Zoom In
- Zoom Out
- Zoom Actual
- Save as Image
These toolbar icons are shown in the figure below.
More Workflow Diagram Actions are accessible by right clicking on the Workflow Diagram’s canvas:
- The Layout feature lets you arrange nodes vertically or horizontally, so it’s easy to organize your workflow quickly without having to touch a node.
- The Rename feature lets you rename a node or transition; select by double clicking its current name and typing in a new name.
- The Surveyor’s Level feature helps you center a node, vertically or horizontally, with respect to another node.
You’ve probably noticed the Properties and Outline views below your workflow diagram. Let’s explore them next.
Properties View and Outline View
The Properties and Outline views contain more cool features you can use to customize your workflow; they’re located on the bottom and bottom right of Developer Studio, respectively.
The Properties view lets you edit the current node’s properties. If no node is selected or you select the workflow canvas, the Properties view displays your workflow’s general properties; you can edit these, too. Once you click on an individual node, its properties appear.
Node properties are grouped as follows:
- Actions: Execute scripts with respect to your node. Each action has a Name, Script Language, Execution Type, and a Priority (optional). Clicking Edit Script brings up the script in the default editor for the Script Language you specified.
- Notifications: Notify users with respect to your node. Each notification has a Name, Template Language, Execution Type, and one or more Notification Types.
- Assignments: Assign tasks to users or roles. Click Change Task Assignments to specify or change the assignment.
- Task Timers: Name timers for a task and whether the timers are blocking. Each task timer has a Name and Blocking indicator.
- Script: Edit a script for your condition node. Clicking Edit Script brings up the script in the default editor for the Script Language you specified.
- Other: Edit miscellaneous properties like Name and Description, applicable to your node’s type.
Here’s what the Properties view looks like in Developer Studio:
Workflows frequently become too large to view in entirety on the workflow diagram screen; the Outline view is a huge asset when this happens. It’s a top level view that displays your entire workflow definition, no matter how large it becomes. In addition, it highlights what you’re currently viewing on your Workflow diagram, giving you a picture of where you’re located in the broader picture of your workflow. You can use the Outline view to change your position in the Workflow Diagram by dragging the highlighted box where you’d like to focus.
Developer Studio’s Properties and Outline views make customizing your workflow easier than ever!
Viewing Workflow Definition XML Source
The workflow diagram view of your workflow definition is convenient; sometimes you’ll also want to edit and review your workflow definition’s XML source code. Selecting the Source tab next to the Diagram tab in the main editor view takes you to the XML, and you can easily switch contexts as you need.
Source mode offers you its own cool features:
- Section Highlighting: Shows XML source code for the node or transition currently selected in the workflow diagram. Click the document icon in an entity’s floating palette or right click the entity and select Show in source.
- Editor Validation: Displays an error marking in the editor’s gutter if your code is invalid. Click the error marking to see hint for resolving the error.
- Content Assist: Suggests language specific functions and variables as you edit code. When you’re inserting variables, it also lists all available variables that are a part of the Kaleo workflow.
With the Source view, you can keep track of your edits while using Developer Studio’s powerful graphical features.
Designing a workflow is good. Creating nodes and transitions is good, too. But there’s more you can do with it; keep reading to learn about creating workflow scripts, or making your notifications more interesting using Freemarker templates.