OpenEdge Development:<br />Progress 4GL Handbook Other object types

Memory management is also an issue for other object types that aren’t discussed in this book, but which this section mentions briefly:

MEMPTR — A MEMPTR is a pointer to an area of your computer’s memory that you allocate and use independently of any Progress objects. You are fully responsible for controlling this memory. You allocate memory using the SET-SIZE function. You deallocate it by using SET-SIZE to set the size to zero. There are other functions that manipulate memory allocated with a MEMPTR, but Progress does not recognize the form of the contents in any way.

ActiveX control — You can extend the visual content of your user interface and other aspects of an application that runs on MS Windows using ActiveX controls. You access an ActiveX control through a special handle called a COM-HANDLE. You are responsible for using a special RELEASE OBJECT statement to release memory associated with the object. Because ActiveX controls operate outside the bounds of objects known to Progress, and because they can do so much on their own, they can be a major source of memory leaks. You need to use and test them very carefully.

Socket — A socket is a connection to a process running outside the OpenEdge session, possibly on another machine. OpenEdge provides access to other procedures through its support for sockets. A SOCKET is another kind of dynamic object you can create and use from the 4GL. You must clean up sockets just like any other objects. There is a special SESSION:FIRST-SOCKET attribute that lets you access the head of the chain of all the sockets allocated in your session.

Asynchronous request — You can run a procedure in another OpenEdge session with a special ASYNCHRONOUS keyword to allow your session to continue to run until the other session responds. A procedure run in this way is kept in memory even after the request is complete so that you check the completion status. You must take special care to delete these procedures when you are done with them. There is also a SESSION:FIRST-ASYNC-REQUEST attribute that identifies the chain of all outstanding asynchronous requests in your session.