PSS - OpenVMS Performance Simulation System

Overview: PSS v3.4

PSS, Performance Simulation System, is a software package which allows a user to monitor and record a terminal session and then replay that session on one or more real or pseudo terminals. The software can also provide response time measurements of on-line application systems while they are running. Three main services are provided: Performance Simulation, Application Reliability and Testing, and Security.

Performance Simulation

PSS provides you with the ability to load any interactive application for the purposes of determining its performance and reliability. This is a Loading Terminal Emulator. This means that the software can drive one or more real terminals as though actual people were entering data. This facility becomes more important, when combined with its pseudo-terminal capabilities. This feature allows you to generate terminal loading, greater than the number of real, physical terminals available to your system(s).

Typically, a user measures an interactive application performance through the primary metrics of response time. The service-level method of determining response time is used by our software. That involves beginning response-time measurement from the completion of a Read QIO until a new Read QIO is posted. This more rigorous view of response-time measurement ensures that various response-time placebos (such as EDT's working message) do not interfere with the response time captured. You can use PSS with Digital's SPM or VPA products to determine the technical impact of an application's performance characteristics.

When the simulation is complete, response-time statistics for one or more terminals can be obtained. By comparing the initial time, a "delimiter" was entered during the input phase with the time an output sequence was sent to the terminal. This elapsed time is the response time, which is saved during the simulation. In addition PSS allows you to enter your own response-time checkpoints via the conversion utility. In this way response-time measurements are of special interest to you.

Application Reliability and Testing

During the recording phase, logs are created capturing all output per terminal. You can TYPE or EDIT this data so that you can view all of the output, generated by the session (including input character echo). By comparing the two files for differences (via DIF), you can generate an automated-audit trail. This is particularly useful for project work, when you must ensure regression testing and reliability before implementing your system.


Since records are kept of all input and/or output of any selected-terminal session, a side application of this product is system security. You can use the software to monitor both local and dial-in terminal sessions. This feature allows you to monitor highly sensitive applications for unauthorized access. In addition by monitoring the VMS system console, a complete log of system events is available, including everything the operator entered. This feature is useful for monitoring operator interaction on production machines, when a complete record of events is necessary for determining problems.

Minimum Hardware Supported

This product runs under the OpenVMS operating system under all standard, VAX or AXP hardware configurations. The software driver requires approximately 3Kb of physical memory. Each monitored/playback terminal also requires approximately 3Kb of memory. All terminals which use the OpenVMS class-terminal driver are supported.

Prerequisite Software

Any VAX or AXP processor, using OpenVMS VAX V5.5-2 (or later) or OpenVMS Alpha V6.1 (or later). PSS is able to monitor/play back any terminal device which uses the OpenVMS Terminal Class Driver (such as the DZ, DMF, or DMZ), the Terminal Server (LAT), or the X.25 PSI device.

Optional Software

The External Performance Simulation System, EPSS, is optionally available for those users who want to run the terminal-loading aspects of PSS on another computer system. EPSS is a Remote Terminal Emulator, capable of testing other computer systems on an Ethernet.

Software Installation

Installation of this software product is subject to the terms of the ASCI Standard Software Product License Agreement. This software is Customer installable and uses Digital's VMSINSTAL facility.

Warranty Information

This software is sold through ASCI's Software Product License Agreement, which warrants the product for ninety (90) days from the date of purchase. Warranty services include telephone- remedial support and product upgrades. Additional maintenance services after the warranty period---as well as any consulting or product training---are available and are separately priced.

Maintenance Information

After the initial product warranty expires, ASCI offers a twelve-month maintenance plan. This includes telephone-remedial support, product upgrades, and enhancements, as they become available. The annual maintenance plan is separately priced.

Ordering Information

ASCI distributes all product downloads and documentation via the web. Current prices are available upon request. Multi- CPU and Educational Institutions discounts are available.

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