When testing or monitoring an environment, you need to emulate the true behavior of users on your system. HP testing tools emulate an environment in which users concurrently work on, or access your system.

To do this emulation, the human was replaced with a virtual user, or a Vuser. The actions that a Vuser performs are typically recorded in a Vuser script. The primary tool for creating Vuser scripts is the Virtual User Generator, VuGen.VuGen not only records Vuser scripts, but also runs them. Running scripts from VuGen is useful for debugging. It enables you to emulate how a Vuser script will run when executed as part of a larger test.When you record a Vuser script, VuGen generates various functions that define the actions that you perform during the recording session. VuGen inserts these functions into the VuGen editor to create a basic Vuser script.

Vuser Technology Overview

Vusers emulate the actions of human users by performing typical business processes in your application. The actions that a Vuser performs during the recording session are described in a Vuser script.

HP's tool for creating Vuser scripts is the Virtual User Generator, VuGen. You use VuGen to develop a Vuser script by recording a user performing typical business processes on a client application. VuGen records the actions that you perform during the recording session, recording only the activity between the client and the server. Instead of having to manually program the application's API function calls to the server, VuGen automatically generates functions that model and emulate real world situations.

During recording, VuGen monitors the client and traces all the requests sent to and received from the server.

During playback, Vuser scripts communicate directly with the server by executing calls to the server API. When a Vuser communicates directly with a server, system resources are not required for the client interface. This lets you run a large number of Vusers simultaneously on a single workstation, and enables you to use only a few testing machines to emulate large server loads.

In addition, since Vuser scripts do not rely on client software, you can use Vusers to check server performance even before the user interface of the client software has been fully developed.Using VuGen, you can run scripts as standalone tests. This is useful for verifying the script's functionality and it enables you to see how a Vuser will behave during a test run.To effectively use the Vuser scripts, you add them to a scenario using the LoadRunner Controller. While running the Vusers, you gather information about the system's response. Afterwards, you can view this information with the Analysis tool.

For example, you can observe how a server behaved when one hundred Vusers simultaneously withdrew cash from a bank's ATM.

VuGen records Vuser scripts on Windows platforms only. However, a recorded Vuser script can be run on both Windows and Linux platforms.

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