The WebTerm java applet is a terminal emulator implemented in Java, which can be used to provide TELNET sessions from within Web browsers or other applications which use Java. License WebTerm was written by Dianne Hackborn and Melanie Johnson. The design and implementation of WebTerm are available for royalty-free adoption and use for non-commercial purposes, by any public or private organization. Copyright is retained by the Northwest Alliance for Computational Science and Engineering and Oregon State University. Redistribution of any part of WebTerm or any derivative works must include this notice. Please address correspondence to nacse-questions@nacse.org. If you find WebTerm useful and/or wish to receive notification of future releases, please let us know! Use the form at url: http://www.nacse.org/web/webterm/feedback.html or send mail to nacse-questions@nacse.org. Building WebTerm After you've downloaded the WebTerm distribution, unload it using the command zcat | tar -xvf - If you have the binary (byte-compiled) distribution, this will create a number of *.class files, which are ready to run. If you've downloaded the source distribution, it will create a number of *.java files, which you must then compile using javac (from the Java Development Kit), using the command javac WebTerm.java VT200.java This will create the *.class files. Using WebTerm To use WebTerm, include a link to it in an html file:

Your Web browser is decaf-only (no java)!

 The width and height specifications are kludges to tell Netscape to make it approximately the right size; unfortunately, there's currently no way to specify an absolute size in characters. The second line will be printed, as you would expect, by browsers that don't support java. Though WebTerm provides a means of specifying the computer to which you wish to connect, the security restrictions of most web browsers will not allow you to make a connection to any machine other than the one from which the applet was loaded (ie, the machine running the httpd server). Parameters The "WebTerm.class" applet recognizes the following parameters: HOST Name of initial host machine. Default is the machine the applet was retrieved from (for most browsers, this is the only useful value). PORT Number of port for connection. Default is 23, the standard Telnet port. PROMPT#, REPLY#, ENDPROMPTS# A set of parameters for specifying automatic replies to incoming text. The '#' represents the prompt number -- prompts should start at 1, and be consecutively numbered. 'PROMPT' is the trigger text, 'REPLY' is the text to send when the trigger is encountered, and if 'ENDPROMPTS' is true then this will turn off all prompts for the rest of the telnet session. See the section "Automatic Setup" for an example. The supplied strings may contain standard Java escape sequences, including \n, \r, \t, \b, \f, \###, \u####, and \x##. Some Missing Features There is no cut-and-paste mechanism. Resizing of the terminal is not well supported. Automatic Setup WebTerm provides an automatic setup feature, utilizing a simple expect-reply sequence. For instance, to have WebTerm automatically login as user "guest" with password "foobar" (on a system which prompts with "login: " and "password: "), you might use the following code after the tag and before the tag: Security Note that use of the automatic setup feature as described will invite everyone in the world to login to your system as "guest" without requiring the password. If you use this feature, you should do so only: 1. on a login with a highly restrictive shell, 2. or in an html file which is readable only by the owner, owned by whatever user your httpd server runs as (usually the user "nobody"), and protected by whatever form of access control your httpd server provides. 3. or in an html file which is readable only by the owner and owned by a regular user (in which case it cannot be opened as a url, but must be opened as a file, and will be accessible only on the local system). Implementation classes The following is a brief description of the java classes included in the WebTerm distribution. WebTerm A full applet, which combines the below classes to provide an actual VT100 terminal emulator. It includes controls for select a host and port, opening and closing the network connection, and the actual terminal screen. Telnet Implements a complete Telnet session client. As far as we know, this client implements the Telnet protocol correctly, though fairly minimally; it supports the standard Telnet options TERMINAL TYPE and NAWS (the latter is used to communicate the terminal dimensions to the host). When connecting to a host, it always tries to turn on the host's ECHO option; this must be supported for the client to work correctly. This implementation was based on the March 1995 protocol standards. The Telnet client communicates with the user through an instance of an Emulator class, from which it also receives information about the emulation name and terminal dimensions. PromptInfo A class used to store the information about one prompt which the Telnet class is currently watching for. Parameters An interface used to hand the applet parameters to the Telnet class. Emulator A generic base class for terminal emulations; this implements a set of methods which the terminal uses to send data to the Telnet session, and that the Telnet session uses to send data to the terminal. VT100Emulator A subclass of the Emulator which implements the VT100 control sequences. The following sequences are currently implemented: ESC > Reset ESC 8 Restore cursor position ESC 7 Save cursor position ESC D Index ESC E Next index ESC M Reverse index ESC c Reset to initial state ESC [ A Move cursor up ESC [ B Move cursor down ESC [ C Move cursor right ESC [ D Move cursor left ESC [ E Move to next line ESC [ F Move to previous line ESC [ H Set cursor position ESC [ f Set cursor position ESC [ J Clear in display ESC [ K Clear in line ESC [ L Insert line above cursor ESC [ M Delete line at cursor ESC [ c Terminal type report ESC m Set mode (currently ignored) ESC [ 6 n Cursor position report ESC [ 5 n Terminal status report ESC [r Set scroll region Probably the most important missing sequences are those for horizontal tab stops. Terminal The basic functionality of an ASCII terminal. Implements functions for writing text to the terminal, moving the cursor, scrolling regions of the screen, insert and deleting lines. The class has a small amount of smarts for optimizing redrawing, but could use quite a bit more. RubberTextField A slight variation on the standard TextField, which allows it to shrink down more than usual. ClassRegistry A set of classes for communicating between objects that exist in different applets in different frames, windows, or documents. History Changes in v1.3.1: Added support for multiple terminal types (necessary for netscape 3.0) Changes in v1.3: Added REGISTRY and FONTSIZE parameters. Registers itself with a ClassRegistry, so that other applets can insert text into its input stream with a "send" command. Now correctly handles smaller applet sizes. Cleaned up font allocation, now handles bold and italic fonts. Slight fixes to VT100 emulation. Split source into multiple files. Changes in v1.2: Added support for text styles. Changes in v1.1: Added PROMPT#, REPLY#, and ENDPROMPT# arguments.