WF4.0 BASICS (20) ActivityWithResult returned value Activity

This section describes how to use a returned value Activity in WF4.

Download this example:

Http://files.cnblogs.com/foundation/ActivityWithResultSample.rar

 

Examples

ActivityWithResult

Class Name		System. Activities. ActivityWithResult
File		System. Activities. dll
Structure Description		Inherit Activity Is A Pair Ace class   [Result] The attribute type is [System. Activities. OutArgument] [ResultType] the attribute Type is [System. Type]
Function Description		[Result] attribute is returned value [ResultType] attribute is returned value type   Derived class System. Activities. Activity <TResult> Failed from System. activities. activity <TResult> implements custom Activity, because Activity <TResult> does not provide [Execute method], and [InternalExecute method is internal sealed] (For details, refer to [Activity execution principle])   From CodeActivity <TResult> NativeActivity <TResult> AsycCodeActivity <TResult> Implement custom Activity

 

 

CodeActivity <TResult>

Return the value to the [Result] attribute using the override [Execute method] method Return Value

 

For example, Scenario Description: There are two [Int] parameters x and y. the return value is x + y.

Activity		Public Sealed Class MyCodeActivity: CodeActivity <int> { Public InArgument <int> X {get; set ;} Public InArgument <int> Y {get; set ;}     Protected Override Int Execute (CodeActivityContext context) { Int x = X. Get (context ); Int y = Y. Get (context );     Return x + y;   // ----- Or --------- // Context. SetValue (base. Result, x + y ); // Return base. Result. Get (context ); }   }
Workflow
Host	WorkflowInvoker. Invoke (new MyCodeActivityWorkflow ());
Result

 

 

NativeActivity <TResult>

Implemented by assigning values to the [Result] attribute

 

For example, Scenario Description: There are two [Int] parameters x and y. the return value is x + y.

Activity	Public Sealed Class MyNativeActivity: NativeActivity <int> { Public System. Activities. InArgument <int> x {Set; get ;}   Public System. Activities. InArgument <int> y {Set; get ;}     Protected Override Void Execute (NativeActivityContext context) { Int r = (int) x. Get (context) + (int) y. Get (context ); This. Result. Set (context, r );   } }
Workflow
Host	WorkflowInvoker. Invoke (new MyNativeActivityWorkflow ());
Result