z/Scope Terminal Emulator

Open Host Interface Objects (OHIO)

OHIO addresses the need for a standardized advanced programming interface that can access host data. OHIO does not modify the TN3270/TN5250 protocol or datastream but instead provides a common access method to host data once it arrives at the client. It uses an Object Oriented approach to divide the data into logical objects, and provides methods on those objects to allow standard access to the host data.


HLLAPI is a standard programming interface that provides access to a host emulator session. Functions are provided for reading host screen data (such as the characters and attributes), for sending keystrokes, and for performing other emulator-related functions. The EHLLAPI interface is a single call-point interface. There is a single callable API through which all EHLLAPI functions are requested. On each call to the interface the application provides a function number which identifies the function requested, a pointer to a data buffer, a pointer to the length of the data buffer, and a pointer to a return code. WinHLLAPI is based on the familiar EHLLAPI.API. It encompasses all of its existing functionality and adds extensions that take advantage of the Windows message-driven environment.

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