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Korean Solaris System Administrator's Guide

TTY Streams

The data path between a user's shell and the terminal is called a stream. The data on a stream contain characters and control information that affect data handling, such as the control sequences that precede a change in code set or communication protocols. Data entering the stream from the terminal are raw or unprocessed. Data are sequentially processed by STREAMS modules for appropriate use by the shell or an application.

STREAMS provides a way to modularize the processing on a line, allowing processing instructions to be grouped in functional modules. These modules can be added or removed from the line so that different environments can be provided to a terminal according to the user's needs.

Traditional STREAMS

The traditional STREAMS TTY environment contains a raw device driver, a line discipline module, and a stream head. The raw device driver provides an I/O interface between the kernel and the hardware. Because it is closest to the physical hardware, it provides basic communication protocols, baud rate switching, and other low level services. The line discipline module is a set of instructions or disciplines that transforms the raw data to processed data. This includes handling the delete character, line kill character, and others. The stream head provides an interface between the user's process and the stream.

Korean Solaris STREAMS

The Korean Solaris operating environment uses the modular nature of STREAMS to support Korean. In addition to the traditional TTY modules, this product implements code conversion in STREAMS. Hangul-Hanja conversion is typically supplied by many existing Korean TTYs and is not available in the Korean Solaris TTY environment.

The Korean Solaris operating environment enhances the traditional modules. Its line discipline handles proper cursor movement for wide characters as well as normal protocols. The Korean Solaris software code conversion modules convert between two different character code formats such as between Packed (also called Combination code of KS C 5601-1987) and EUC (called Completion code).

Code conversion depends on the appropriate flags or parameters being set. For example, if a Packed code terminal is being used, the input from the terminal is converted to EUC and the output to the terminal is converted to Packed code.

The major modules that can be pushed onto the stream are ldterm, kpack and kjohap: