The Open Host Interface Objects (OHIO) implementation provided in this product is a prototype of a new, cross-vendor host access programming interface currently under development in the Internet Engineering Task Force. This implementation represents the state of the OHIO API as defined in the second draft of the Open Host Interface Objects Internet Draft. Note that definition of the OHIO API has not been completed and the final version of the OHIO API might differ from what is presented in this implementation.
The Open Host Interface Objects (OHIO) provides a core set of classes and methods that allow the development of platform independent applications that can access host information at the data stream level. OHIO implements the core host access function in a complete class model that is independent of any graphical display and only requires a Java-enabled browser or comparable Java environment to operate. The class library represents an object-oriented abstraction of a host connection that includes reading and writing the host presentation space, enumerating the fields in the presentation space, reading the operator information area (OIA) for status information, and performing asynchronous notification of significant events.
With OHIO, application developers can write Java applets that manipulate data from the host presentation space without requiring the users to have the applets residing on their machines. The presentation space represents a virtual screen that contains both data and associated attributes presented by host applications. OHIO Java applets can open a session to the host, wait for incoming host data, get specific strings from the virtual screen, get associated attributes of the strings, set new string values, send function keys back to the host, and wait for the next host response. After an interaction is complete, the applet can switch to other tasks or simply close the session. The entire operation can be done without ever showing host screens.
OHIO is a significant improvement over traditional emulator programming interfaces such as EHLLAPI. These improvements include:
Host
On-Demand's OHIO implementation provides the following additional
benefits:
In addition, applications or applets written to work with the OHIO API are portable between any OHIO implementation, including both Host On-Demand and Personal Communications.
See "Open Host Interface Objects for Java" for details on specific classes.
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