Beginner's Guide to Workflow. MSDN Library Design Tools Development Tools and Languages Mobile and Embedded Development Online Services patterns & practices Servers and Enterprise Development Web Development Show: © 2014 Microsoft. Tutorials. Hosting Windows Workflow. Programming Windows Workflow Foundation by Scott Allen If you enjoyed this article, you'll enjoy the book even more! Order now from Packt Publishing and save 10%! Windows Workflow is a runtime and not an application.
A host process must load and launch the workflow runtime before starting a workflow. The host process tells the runtime the types of workflows to create, and the runtime manages the lifecycle of the workflows and notifies the host process about important lifecycle events, like workflow completion and termination. The runtime isn't particular about the type of host it lives inside. The host process could be a smart client application running on an office desktop machine, or an ASP.NET worker process running on a server in the rack of a data center.
A host can also customize the workflow runtime by layering additional services on top of the runtime's base feature set. We've used the runtime in previous articles, but let's review what we've learned so far. Instance.Start(); Windows Workflow Persistence Services. Many business processes take long periods of time to complete (up to many months or even years). Holding the workflow in memory is not only impractical (because of memory limitations), but it also prevents scaling because an instance must be processed on a single server. Many of these long-running workflows are not actively executing flow or process logic and are effectively idle, waiting for input from users or other systems. By unloading an idle instance, the host application can save memory and enable scalability across processing servers. When certain conditions occur while a workflow is running, the workflow runtime engine uses a persistence service, if one is loaded in the runtime, to persist state information about the workflow instance.
These conditions include such things as the following: Creating Persistence Services Locking Workflow State Information Persistence Service Batching Behavior Complex Hosting Scenarios See Also. SqlWorkflowPersistenceService Class (System.Workflow.Runtime.Hosting) Represents a persistence service that uses a SQL database to store workflow state information. public class SqlWorkflowPersistenceService : WorkflowPersistenceService, IPendingWork The SqlWorkflowPersistenceService type exposes the following members. The SqlWorkflowPersistenceService class represents a fully-functional persistence service.
You can use this service out-of-box to persist and retrieve workflow state information about a workflow instance when requested to by the workflow runtime engine. The SqlWorkflowPersistenceService supports locking of workflow instances. This feature is used when several workflow runtimes share the same database. .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 Any public static (Shared in Visual Basic) members of this type are thread safe. Windows Workflow SQL Persistence Architecture. Windows Workflow as WCF Service and Workflow Persistence.
Download source - 82.16 KB Introduction Windows Workflow Foundation is a .NET 3.0 and 3.5 feature. In this article, I am trying to explain how workflow can be exposed as WCF web service. Persistence of the workflow is also explained in detail. I took sequential calculator workflow service as an example. Background If you are new to workflow, please refer to this link on MSDN. Using the Code The uploaded zip file contains 4 projects. WorkFlowContracts: Defined a ICalculator Service contract. To set up the whole solution, first you need to create the persistence database. Create database, let's say PersistanceDB in the SQL server. SqlPersistenceService_Schema.sql SqlPersistenceService_Logic.sql After this step, your persistence database is ready for the workflow. Now you need to set the connection string for the persistence database. Open web.config file of workflow service. Build the solution. Let's say by calling StartCalculator() method of the service, you get back the workflow id: History.
When to use it.