Selection of Process Types

In-Process and out-of-process servers provide differing services, especially regarding the user interface of your application.

User Interfaces

Although earlier versions of Visual FoxPro make it possible for you to use forms as output-only elements in an Automation server application, the two run-time libraries in Visual FoxPro handle this situation differently for out-of-process and for in-process servers.

In-Process Servers

Apartment-model threading support requires that in-process .dll Automation servers not have user interfaces. In Visual FoxPro 5.0, it was possible (though not recommended) to create an in-process .dll Automation server that had a user interface such as a form. You could use the form only for display because the form events were not supported. Since Visual FoxPro 6, if you attempt to create a user interface in an in-process .dll, Automation generates an error. This is referred to as unattended mode.

Out-of-Process Servers

An out-of-process (.exe) Automation server can have a user interface. The Visual FoxPro function SYS(2335) enables you to disable UI and modal events for an out-of-process .exe Automation server so they can be handled remotely without user intervention. Modal events are created by user-defined modal forms, system dialogs, the MESSAGEBOX( ) function and the WAIT command, and so on and normally require user input.

See Also

Server Design Considerations and Limitations | Control of Call Blocking | Selection of a Run-Time Library | Language Supported in Run-Times | Automation Server Programming Notes