SDI (Software Development Interface)

Spyglass SDI (Software Development Interface) is the main competitor to NCSA Mosaic CCI (Common Client Interface). The expectation is that SDI and CCI will eventually converge into a common specification. In addition to what CCI offers, SDI also provides a protocol for initiating messages from the browser to the client application. This protocol causes the application to be informed when the certain events occur on the browser or actually diverts handling of those events to the application. This addition makes SDI an appropriate protocol for invoking a new client application from a browser. The Netscape Navigator web browser supports SDI under Windows and MacOS.

SIMPLE

sh, csh, ksh, bash, tcsh, rc, zsh (Unix shell languages)

In Unix-speak, a shell is the user's command-level interface to the operating system. The Bourne shell (i.e. sh) was the initial Unix shell, and still is the most widely used, but, over the years, other shells were developed, differing primarily in the syntax and semantics of the command languages they implemented. Other Unix shell languages are csh (C shell), ksh (Korn shell), bash (Bourne again shell), tcsh (Tenex C shell), rc, and zsh (Z shell). I won't go into the differences here. See Shells and Shell Programming for a comprehensive comparison. My point here is that these shells are essentially interpreters for scripting languages, and are commonly used on Unix platforms for a variety of programming tasks, especially by system administrators, including web site maintenance chores like CGI scripting. Newer languages used in this context, like Perl and Tcl, were heavily influenced by the shell language forebears, and were generally developed to deal with the ever increasing complexity of scripting tasks, and the desire to apply such high-level languages to somewhat different tasks. Perl is a case of the former, Tcl a case of the latter, with the new task being quick development of GUI interfaces.