Windows Workflow Foundation

introduction

A workflow and a host application can pass data between them by using parameters. On the workflow side, a parameter is a simple property that is defined in your workflow class. If a set method is defined for the property, the host application can set that property before the workflow executes by passing in a parameters collection during the CreateWorkflow method call. To return parameters back to the host application after it finishes executing, you can define a get method for the property.

in this artical, create an string property named FirstName, LastName and Age as Integer. this property is passed to workflow when the report is submitted.

whats the windows workflow foundation engine?

The Windows Workflow Foundation runtime engine is responsible for creating and maintaining running workflow instances. To accomplish this, the runtime engine needs a host process that includes console applications, Windows Forms-based applications, ASP.NET Web sites, and Web services. Additionally, workflow-enabled applications that host the Windows Workflow Foundation runtime engine can further refine the behavior of the workflow runtime engine by using services. The base services in Windows Workflow Foundation can be configured to support transactions, persistence, tracking, threading, and scheduling. For application-specific functionality, your application can also define custom services that can be added to the runtime engine.

Creating a Workflow Host

The host interacts with Windows Workflow Foundation through the WorkflowRuntime class, or a custom class that inherits from it. You create a WorkflowRuntime object and populate it with the services that you will use during the execution of your workflows.

Host Responsibilities

Host responsibilities are as follows:

• Create one or more processes and one or more application domains.

• Provide isolation mechanisms as needed.

• Marshal calls between application domains as needed.

• Start workflow instances.

• Create custom and local services.

Additionally, a host might do the following:

• Control the loading and unloading of workflows from memory.

• Listen for specific events and communicate them to a user or administrator.

• Set time-outs and retries for each workflow.

• Expose performance counters.

• Write log information for debugging and diagnostics.

• Provide custom service implementations.

• Create localized services to meet language requirements of the hosting application and user base.