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Most applications written for the HP3000 computer require the use of an HP2392A or HP700/92 terminal or terminal emulator. Sometimes it is necessary to access these applications from a device or program that does not have HP terminal emulation available, but supports only DEC VT terminals. Additionaly, it may be necessary to make a connection using the TELNET communications protocol to an HP3000 that does not have TELNET running but only runs the proprietary NS/VT protocol.
Proxy92 is a middleware product designed to translate HP terminal protocols to DEC terminal protocols, and NS/VT sessions to Telnet sessions. It enables users of VT220 and VT320-compatible terminals to run programs on Hewlett Packard HPe3000 computers designed for HP terminals. Proxy92 is written in Java, enabling it to run on a wide variety of hosts - even, where sufficient resources are available, the HPe3000 itself. Java does not have to be available on the end-device or on the HP3000, since Proxy92 can run on an intermediate device for which Java is available.
Some potential applications include the following
Proxy92 acts as a proxy server, listening on a port that you designate. Users or applications that wish to connect to the HP3000 connect via Telnet to the port that Proxy92 is listening on. Proxy92 then makes a connection to the HP3000 using HP's NS/VT protocol. Proxy92 makes all necessary translations between HP700/92 escape sequences and VT320 escape sequences, so that the host screen is displayed on the local VT320 screen and keystrokes entered on the VT320 terminal are handled appropriately. The program does a lot more than simply translating escape sequences: in order to provide block mode emulation it maintains an internal image of the virtual screen and screen memory, field definitions etc. Proxy92 is based on our 15 years' experience of emulating HP terminals.
Proxy92 is written in Java, enabling it to run on the wide variety of platforms for which Java Runtime is available including Windows, UNIX and Linux. Proxy92 has been tested on the version of Java currently available for the HPe3000, but for performance reasons we recommend running Proxy92 on an intermediate computer.
The limitations of Proxy92 result from limitations in the VT320 terminal. Firstly, the HP terminal has a larger screen, consisting of 24 rows of data, 2 rows of function key labels, and a status line. It is not possible to display all this data at once on a standard VT320 terminal. However, many VT320 terminal emulators allow the number of rows to be changed, and provided that 27 rows can be configured an accurate display is possible. Where Proxy92 is under the control of an application program, rather than a real user, this will not normally be an issue. Additionally, the function key label display and status line can be turned off if necessary.
Secondly, the HP terminal has keys that do not exist on the VT320 terminal, and there are some inconsistencies in the way that various terminal emulators handle function keys. We have mapped the special keys to sequences starting with the backslash (\) character, so that \r generates Reset, \0 generates Enter, and \1 though \8 generate F1 through F8. Again, where Proxy92 is under the control of a third party application this won't be an issue.
Proxy92 runs under Java. It must be installed on a computer that has Java 2 installed. This requires either the JDK (Java Development Kit) 1.2 or greater, or a Java Runtime such as JRE which is a free download from Sun Microsystems Limited. Proxy92 will run on the version of Java currently supplied for the HP e3000, but for better performance it is preferable to use an intermediate machine between the HP3000 and the network.
Proxy92 is capable of hosting multiple simultaneous sessions. Some operating systems and Java implementations have a limit on the number of concurrent threads. Proxy92 uses four threads for each session, so please allow for this in calculating how many simultaneous sessions you can run.
Only two files are required: proxy92.jar, and a configuration file (we supply default.j92 as a sample). These need to be in the same directory.
The machine running Proxy92 must be on the network with a static IP address so that it can be reached by the clients. It also must be able to connect through the network to the HP e3000 host computer.
The exact command for running Proxy92 will depend on the requirements of your java runtime software. You need to invoke Java and tell it to run the Proxy92 class, which is contained in the archive file proxy92.jar, with two command line arguments: the name of the configuration file and the port to listen on. Note that Java is case sensitive, and that the jar file starts with a lower case p.
LINUX with JRE 1.2:
/usr/jre1_2/bin/java -cp proxy92.jar; Proxy92 default.j92 1600
Windows with Microsoft's Java Runtime:
jview /cp:a proxy92.jar Proxy92.class default.j92 1600
The first argument passed to Proxy92 is the name of the configuration file. The second argument is the port to listen on. All other parameters, such as the name or address of the host, are contained in the configuration file.
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