Glossary

Assertion

Validates a server response during a test by defining and asserting a condition that must be met. Validation can be based on the response content, size or duration. NeoLoad and NeoLoad Design Studio can be configured to throw assertion errors when the conditions defined by an assertion are not met. Other than clearly pointing out unexpected or faulty behavior in load scenarios, assertions and assertion errors also reveal functional issues.

Count

Count statistics are the number of full executions of an element of a User Path. If the element is interrupted (because of error or end of test), then the count number is not incremented.

Counter

See Performance counter.

HTTP request

The HTTP request is the request sent to the server to retrieve an HTML page, image or CSS file. Requests are grouped within pages.

Requests are the messages sent by the client to a server which emits a response

HTTP response

The HTTP response is the Web server answer to an HTTP request.

Load Generator

The Load Generator is a program piloted by the Controller, which plays a scenario while simulating a predefined number of users. A Load Generator is started by its Load Generator Agent for each User Path validation. NeoLoad Web has an agent and Load Generator built in for ease of use. Load Generator may refer either to the program simulating the users, or to the machine on which it is installed.

Load testing

Load testing consists in simulating real-life workload conditions for the tested web application. It helps determine if the application works fine with the loads that result from large numbers of simultaneous users, transactions and to determine whether it can handle peak usage periods.

Monitor

A Monitor observes the behavior of a component part of a monitored machine (web server, application server, operating system, database, etc.). A Monitor groups together several performance counters and indicators.

Monitored machine

A monitored machine is a server, or other device in the infrastructure, that is to be monitored. A monitored machine may be a physical machine or a network device. A monitored machine groups together several Monitors.

Page

See Web page.

Performance counter

The last element of the monitoring infrastructure which retrieves the numeric values on a Monitor.

Population

A Population is a group of Virtual User types which allows the application to be tested using different business actions. One typical example is when testing an e-business website with 90% of users browsing the catalog and 10% making an on-line purchase.

Response times

NeoLoad response times are calculated from the time the first byte of a request is sent, until the time the last byte of the response is received, namely including network time to send request and receive response.

Scenario

A scenario sets out all the test parameters: duration, load policy (constant, ramp-up, peak or custom), number of Virtual Users to be generated, and so on. NeoLoad can manage several scenarios for each project.

Transaction

A Transaction groups the different web pages that make up a "business transaction". In other words, a Transaction is a set of web pages that carry out a business exchange. A typical example is the set of pages used to connect to an application. Transactions are clearly marked in the Test Results to make analyzing download times easier.

TTFB (Time to First Byte)

The time taken, in seconds, before receiving the first byte of the response. This is the time taken by the server to start sending its response, excluding the download time. It includes the time to create the connection to the server, the time to send the request and the time for the server to generate the response. This indicator is sometimes useful in detecting network bottlenecks. If the TTFB is short, but the response time long, it may indicate a network delay issue.

User Path

A User Path is a set of Transactions, web pages, requests and/or logical actions that describes the browsing actions performed on an application or a website. It can be recorded or manually defined in order to be replayed by n number of Virtual Users performing the same actions.

Virtual User

A Virtual User simulates a user by executing a User Path. A typical load test can contain one or several User Paths, each User Path being executed by several Virtual Users.

Virtual User instance

A Virtual User instance is a specific execution of a User Path. During a load test, several User Paths are running at the same time, each of them being a Virtual User instance.

Web page

Page as rendered by a web browser. It consists in the HTML page and all its sub-components, such as image files and CSS style sheets.