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Creating Queuable Components

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A component with at least one queuable interface is a queuable component. For a component to be invoked by a queue, the interfaces must be marked as queuable and the component must be installed in a queued application. However, a queuable component can be a component of a non-queued application.

A queuable interface must contain only in parameters—no out parameters and no return values. These characteristics are verified by analyzing the type information during component installation. If the interface is not queuable, the queue of the application containing the component cannot be activated.

To specify a COM+ interface as queuable, use the following steps:

  1. In the console tree of the Component Services administrative tool, under Component Services, open the COM+ Applications folder associated with the computer you wish to manage.

  2. Open the Interfaces folder of the component of the COM+ application that you want to make queuable.

  3. Right-click the interface that you want to mark as queuable, and then click Properties.

  4. Select the Queuing tab in the properties dialog.

  5. Activate the check box labeled Queued.

    Note

    If the Queued check box is grayed out, the interface does not satisfy the queuable constraints described above.

     

  6. Click OK.

    A queuable component can be identified as such by adding the QUEUEABLE attribute macro to the Interface section of the Interface Definition Language (IDL) source file for all interfaces that are queuable.

    #include "mtxattr.h"
[ object, dual, uuid(), helpstring(IShiphip"), QUEUEABLE ]
interface IShip:IDispatch{
   [propput, id(1)] HRESULT CustomerId ([in] long CustId);
   [propput, id(2)] HRESULT OrderId ([in] long OrderID);
   [id(3)] HRESULT LineItem ([in] long Qty);
   [id(4)] HRESULT Process ();
}

Creating Component Queues

Developing Queued Components