Serves as the root container for state machine workflows. Contains event-driven activities and states.
Assembly: System.Workflow.Activities (in System.Workflow.Activities.dll)
'Declaration <ComVisibleAttribute(False)> _ <ToolboxBitmapAttribute(GetType(StateMachineWorkflowActivity), "Resources.StateMachineWorkflowActivity.png")> _ <ActivityValidatorAttribute(GetType(StateActivityValidator))> _ Public Class StateMachineWorkflowActivity _ Inherits StateActivity 'Usage Dim instance As StateMachineWorkflowActivity
The is an activity container used to create workflows that follow a state machine model.
The is a CompositeActivity, which means the can contain other activities. The and the EventDrivenActivity activities are the only permitted child activities of the . EventDrivenActivity activities are permitted because the root activity itself behaves like a state. Therefore, you can have EventDrivenActivity activities at the root level that are used by all the State activities in the . EventDrivenActivity activities at this level provide a global mechanism for processing workflow events and automate state transitions. StateActivity activities provide a mechanism to define the various stages in the model.
The InitialStateNameProperty of the state machine is the state in which the state machine is when an instance of the state machine is created. The InitialStateNameProperty property is mandatory and must be provided when a is created. The InitialStateNameProperty of the state machine is like any other state activity that is contained within the state machine. The state activity can be a direct child of the root activity and a can have only one InitialStateNameProperty.
The CompletedStateNameProperty of the is a StateActivity activity that is designated as the end state of the . When a transition is made to the CompletedStateNameProperty, the workflow execution is completed. The CompletedStateNameProperty is not mandatory. This means that you can have a that is not completed. This does not mean that the state machine workflow is always active in memory. The might be unloaded as it waits for an event.
activities that never complete are especially useful in processing long running business transactions, as in the case of a purchase order received by a supplier. The fact that the purchase order was fulfilled does not mean that the purchase order process is over. The goods that are part of the purchase order might be returned or the purchase order might be amended and have additional items added to it after the fulfillment. Sometimes there might be a requirement to keep the purchase order records for an extended period of time for legal or other purposes. The fact that a workflow does not finish just means that the workflow remains in an unloaded state. There may be a case for retiring the workflows, which means that after a set period of time the workflow instance may be forced to shut down.
The following code example shows how to create a new instance of the class and use it to implement a basic state machine to transition between three states. This code example is part of the SimpleStateMachineWorkflow SDK sample from the StateMachineWorkflow.cs file. For more information, see Simple State Machine.
Me.WhileLoop = New System.Workflow.Activities.WhileActivity() Me.Parallel = New System.Workflow.Activities.ParallelActivity() Me.Sequence1 = New System.Workflow.Activities.SequenceActivity() Me.Sequence2 = New System.Workflow.Activities.SequenceActivity() Me.ConsoleMessage1 = New System.Workflow.Activities.CodeActivity() Me.ConsoleMessage2 = New System.Workflow.Activities.CodeActivity() ' ' WhileLoop ' Me.WhileLoop.Activities.Add(Me.Parallel) AddHandler codecondition1.Condition, AddressOf Me.WhileCondition Me.WhileLoop.Condition = codecondition1 Me.WhileLoop.Name = "WhileLoop" ' ' Parallel ' Me.Parallel.Activities.Add(Me.Sequence1) Me.Parallel.Activities.Add(Me.Sequence2) Me.Parallel.Name = "Parallel"
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.