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WorkflowPersistenceService Class

The abstract base class from which all persistence services are derived.

Namespace:  System.Workflow.Runtime.Hosting
Assembly:  System.Workflow.Runtime (in System.Workflow.Runtime.dll)

public abstract class WorkflowPersistenceService : WorkflowRuntimeService

The WorkflowPersistenceService type exposes the following members.

Protected methodWorkflowPersistenceServiceWhen implemented in a derived class, initializes a new instance of the WorkflowPersistenceService class.

Protected propertyRuntimeGets the WorkflowRuntime for this service. (Inherited from WorkflowRuntimeService.)
Protected propertyStateGets the state of the WorkflowRuntimeService. (Inherited from WorkflowRuntimeService.)

Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Protected methodStatic memberGetDefaultSerializedFormRetrieves the serialized default form of the Activity.
Public methodGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Protected methodStatic memberGetIsBlockedIndicates whether the given activity is blocked.
Protected methodStatic memberGetSuspendOrTerminateInfoRetrieves the termination or suspend information of the given activity.
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodStatic memberGetWorkflowStatusRetrieves the status of the workflow.
Protected methodLoadCompletedContextActivityWhen implemented in a derived class, loads the specified completed scope back into memory.
Protected methodLoadWorkflowInstanceStateWhen implemented in a derived class, loads the specified state of the workflow instance back into memory.
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodOnStartedWhen overridden in a derived class, represents the method that will be called when the workflow runtime engine raises the WorkflowRuntime.Started event. (Inherited from WorkflowRuntimeService.)
Protected methodOnStoppedWhen overridden in a derived class, represents the method that will be called when the workflow runtime engine raises the WorkflowRuntime.Stopped event. (Inherited from WorkflowRuntimeService.)
Protected methodRaiseServicesExceptionNotHandledEventRaises the WorkflowRuntime.ServicesExceptionNotHandled event. (Inherited from WorkflowRuntimeService.)
Protected methodStatic memberRestoreFromDefaultSerializedFormRestores the Activity from its serialized form.
Protected methodSaveCompletedContextActivityWhen implemented in a derived class, saves the specified completed scope to a data store.
Protected methodSaveWorkflowInstanceStateWhen implemented in a derived class, saves the workflow instance state to a data store.
Protected methodStartWhen overridden in a derived class, starts the service and changes the State to Starting. (Inherited from WorkflowRuntimeService.)
Protected methodStopWhen overridden in a derived class, stops the service and changes the State to Stopping. (Inherited from WorkflowRuntimeService.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Protected methodUnloadOnIdleDetermines whether a workflow should be unloaded when idle.
Protected methodUnlockWorkflowInstanceStateWhen overridden in a derived class, unlocks the workflow instance state.

When certain conditions occur while the workflow is running, the workflow runtime engine persists state information about the workflow instance. Persistence can occur, for example, when an atomic transaction finishes, when the workflow instance becomes idle, when the host calls WorkflowInstance.Unload on the workflow instance, or when a workflow instance is terminated or finishes. When the workflow runtime engine semantics dictate that persistence should occur, the workflow runtime engine calls methods that are supplied by a persistence service to save state information about the workflow instance. Likewise, when the workflow runtime engine needs to restore a previously persisted workflow instance, it calls methods that are supplied by the persistence service to load this state information. The workflow runtime engine handles all the semantics regarding when to perform persistence. The persistence service handles actually saving and loading the workflow state information to or from a data store.

You can create a persistence service by deriving a class from the WorkflowPersistenceService class. You can add your persistence service to the workflow runtime engine by calling AddService or by making an appropriate entry in the application configuration file. The WorkflowRuntime should only contain one persistence service. Windows Workflow Foundation provides the SqlWorkflowPersistenceService class, an out-of-box persistence service, which you can use as is or extend.

The workflow runtime engine has semantics for locking workflow state information for use in environments where persistence services that run in different processes might have access to a single data store. The WorkflowPersistenceService class provides the capability to support this functionality of the workflow runtime engine by providing a parameter to SaveWorkflowInstanceState that specifies whether the state information of a workflow instance should be unlocked in the data store, and by providing a method UnlockWorkflowInstanceState to unlock previously locked workflow state information. In a persistence service that implements locking, a call to LoadWorkflowInstanceState should lock the state information for a workflow instance.

Your persistence service should throw a PersistenceException if it fails to save state information to its data store or load state information from its data store. The workflow runtime engine expects this behavior.

A batching mechanism is provided for services that use a durable store to save workflow state information. It is important in these cases to maintain consistency between the durable store that is used by the persistence service and the internal state of the workflow runtime engine. You can add functionality defined by the IPendingWork interface to your service, and then participate in workflow transaction batching provided by the WorkflowCommitWorkBatchService by adding changes to your data store as work items to the WorkBatch. The durable store itself should implement the IEnlistmentNotification interface, so that workflow information is not persisted incorrectly in the event of a transaction rollback. For more information, see SaveCompletedContextActivity or SaveWorkflowInstanceState.

.NET Framework

Supported in: 4, 3.5, 3.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.