Loadrunner Tips

Now we can go further with LoadRunner.Lets take an example to know the importance of LoadRunner better.Consider the client-side application for an automated teller machine (ATM). Although each client is connected to a server, in total there may be hundreds of ATMs open to the public. There may be some peak times — such as 10 a.m. Monday, the start of the work week — during which the load is much higher than normal. In order to test such situations, it is not practical to have a testbed of hundreds of ATMs. So, given an ATM simulator and a computer system with LoadRunner, one can simulate a large number of users accessing the server simultaneously. Once activities have been defined, they are repeatable. After debugging a problem in the application, managers can check whether the problem persists by reproducing the same situation, with the same type of user interaction.
Working in LoadRunner involves using three different tools which are part of LoadRunner. They are Virtual User Generator (VuGen), Controller and Analysis.

1.Virtual User Generator --------------

The Virtual User Generator (VuGen) allows a user to record and/or script the test to be performed against the application under test, and enables the performance tester to play back and make modifications to the script as needed. Such modifications may include Parameterization (selecting data for keyword-driven testing), Correlation and Error handling.
During recording, VuGen records a tester's actions by routing data through a proxy. The type of proxy depends upon the protocol being used, and affects the form of the resulting script. For some protocols, various recording modes can be selected to further refine the form of the resulting script. For instance, there are two types of recording modes used in LoadRunner Web/HTTP testing: URL based, and HTML based.

2.Controller--------------------------

Once a script is prepared in VuGen, it is run via the Controller. LoadRunner provides for the usage of various machines to act as Load Generators. For example, to run a test of 1000 users, we can use three or more machines with a LoadRunner agent installed on them. These machines are known as Load Generators because the actual load will be generated from them (Load Generators were previously known as "Injectors" - the latter term is still widely used).
Each run is configured with a scenario, which describes which scripts will run, when they will run, how many virtual users will run, and which Load Generators will be used for each script. The tester connects each script in the scenario to the name of a machine which is going to act as a Load Generator, and sets the number of virtual users to be run from that Load Generator.
LoadRunner uses monitors during a load test to monitor the performance of individual components under load. Some monitors include Oracle monitors, WebSphere monitors, etc... Once a scenario is set and the run is completed, the result of the scenario can be viewed via the Analysis tool.

3.Analysis--------------------------------

This tool takes the completed scenario result and prepares the necessary graphs for the tester to view. Also, graphs can be merged to get a good picture of the performance. The tester can then make needed adjustments to the graph and prepare a LoadRunner report. The report, including all the necessary graphs, can be saved in several formats, including HTML and Microsoft Word format.

Notes:Testbed----A testbed is a platform for experimentation for large development projects. Testbeds allow for rigorous, transparent and replicable testing of scientific theories, computational tools, and other new technologies.
The term is used across many disciplines to describe a development environment that is shielded from the hazards of testing in a live or production environment.
In software, the hardware and software requirements are known as the testbed. This is also known as the test environment.
Testbeds are also pages on the internet where the public is given the opportunity to test CSS or HTML they have created and are wanting to see the outcome.

Keyword-driven Testing----Keyword-driven testing is a Software testing technique that separates much of the programming work from the actual test steps so that the test steps can be developed earlier and can often be maintained with only minor updates, even when the application or testing needs change significantly.