An instance handle (similar in concept to a file handle) represents a program's access to the API, and distinguishes the program-specific resources and settings used within the API. This identification is necessary for DLLs, which may be accessed by several different programs simultaneously. When a program initializes the API by calling EsbInit(), an instance handle is returned.
Using Instance Handle in Applications
An instance handle is declared as type ESB_HINST_T in Visual Basic programs.
The instance handle must be passed to the EsbLogin() call, which returns a context handle, and also to the API terminate function EsbTerm() to free any program-specific resources used within the API.
Instance handles may be passed to other programs, child processes, or threads, which can then log in independently of the original using the same API resources and settings. Make sure that all programs, processes or threads using the same instance handle log out before they terminate the API.
Note: | A thread may require its own instance handle (phInstance) to avoid overwriting another thread's networking status information. |