Enhancing the HP e3000 User Interface

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The three most common ways to generate a simple terminal interface are:
• VPlus. This screen forms-management package, bundled with the MPE/iX operating system,
offers easy availability and high performance. Many applications have been written to use it.
• 4GL. Forth Generation Languages have been available on the HP e3000 since early in the
platform s history. These third-party products provide a terminal interface as part of their
offerings.
• Homegrown. In addition to VPlus and 4GL, users have created their own user interfaces
using the features of the MPE/iX operating system, a 3GL and a HP e3000 terminal.
Style of Access: Desktop-based and Session-based
Before examining the different approaches to the HP e3000 terminal interface, it is useful to
consider two design concepts: desktop-based and session-based. Some user interface
technologies run out of a session, while others connect to a daemon job.
Session-based access style relies on establishing a logon session. In this type of access, the HP
e3000 controls security and program flow, while user interface enhancements are available from
the standard session.
Choosing a session-based access style allows for an easier evolution of the user's environment.
Legacy applications can be accessed as before, and do not need to be migrated to a new access
style. Security and program flow can be the same as they are for users today. Migration of an
application also is simpler because a terminal display is always available if necessary.
On the other hand, by connecting through a daemon job, the user can initiate a connection from
a desktop program without logging on as a session. This desktop-based style of access provides
all interactions with the HP e3000 from a desktop application other than a terminal emulator.
The desktop-based access style requires that users move to a different access paradigm, with
security and program flow controlled from the desktop. The HP e3000 acts only as an
application server, and users may never need to log on directly to it. Migrating an application to
use only desktop-based access requires that all terminal displays be replaced. For example,
error messages could be sent to a log file. Desktop-based access also allows for easier
migration to Web-based access.