AJAX - Web Performance

Load Testing Blog

Generating Dynamic UUID with a Javascript Data Source

We recently had a customer question on how to dynamically generate UUIDs during a load test, and the answer illustrates two interesting techniques in Load Tester:

How to use javascript to dynamically generate data during a test.
How to make call outs to the more extensive Java functions within javascript.

In this example let’s assume the UUID is being used as a path element that you want to dynamically replace during a test like this:
Like much of the test case configuration in Load Tester, the process to edit the dynamic behavior starts in the Fields View.   Click on the URL to select … Continue reading »

Understanding Web Pages in Modern Web Apps

With the advent of AJAX and one-page applications, the concent of a “web page” as a single file with HTML is antiquated. A simple website where the user navigates from page to page has morphed into a web-based application, with complicated user interface elements that aren’t web pages in the traditional sense.
And yet for testing purposes, we need to separate the different stages of a workflow for a web-based application. In Load Tester, then, the concent of a “page” could be anything from a traditional HTML file to a single asynchronous AJAX call. The common denominator is each “page” is … Continue reading »

How to Handle a Website where Cookies are set via Javascript

The process instead is to locate where the cookie value is set in javascript, parse the value, and set the cookie value inside the cookie store. The new cookie value is then updated in every subsequent transaction automatically.

Introducing Web Performance Legion

I want to introduce you to something new: Web Performance Legion. Legion is a new open-source research product. It’s an attempt to create a powerful load testing tool that can handle difficult and or esoteric use cases while still being easy-to-understand at its core. It’s still in the early phases of development, but if you happen to love working with Node, or you need to test a complex RESTful API, Legion might be the tool for you.

Handling Javascript and AJAX Callbacks

AJAX technologies present some special challenges for testing software – since it blurs the distinction between a traditional page-based web application and a rich client-server application. Most testing tools are specific to one or the other – and for very good reasons. This tutorial demonstrates one approach to handling AJAX callbacks in an AJAX-enabled web application using Web Performance Load Tester.
Prerequesites: This guide assumes a solid understanding of the Load Tester product. The Load Tester videos are a good introduction to the main features. It is assumed can record a testcase and exeute load tests using some of the … Continue reading »

Load Testing an Javascript or AJAX Application

Most of us are relieved that web applications are starting to behave more like desktop applications – i.e. smarter and easier to use. A little wow factor here and there doesn’t hurt either. Ease of use always has a cost, so it should come as no surprise that the AJAX applications are more difficult to develop. But you may be surprised that they can also be more difficult to load test.
The reason is fairly simple. Traditional web applications are relatively easy to model and simulate. The state of a user session, at any given time, is a combination of the … Continue reading »

Javascript/JSON Support in Load Tester 4.3

Over the last year, Web Performance engineers have been working to make Load Tester smarter and easier to configure.  Load Tester 4.2 introduced the new Fields View, which allows test case developers to write out HTTP requests using a flexible and composable assortment of data sources.
Starting with Load Tester 4.3, Load Tester will automatically recognize JSON content in any HTTP request.  As a consequence, each JSON element will become a configurable name-value pair field in the Fields View.  We believe this will make it much easier to configure complex AJAX and RESTful style test cases.

Furthermore, whenever Load Tester’s Application … Continue reading »

New JavaScript optimizer

From a load testing perspective, we are not generally concerned with Javascript performance – since it affects client-side rendering time and therefore has little relationship to load. However, we do see a lot of sites that could benefit greatly from improved Javascript performance – especially reducing the size of their Javascript files. Google has a relatively new project, Closure Compiler, that optimizes JavaScript code to reduce size and improve performance.
If you’ve tried the Closure Compiler, give us a shout. We’d love to hear about your results!
Chief Engineer

How-To: Dynamic Field Names and Multi-Variable Extractors

You’re recording test cases, configuring them, replaying them, and running load tests.  One day, you attempt to test a new web application.  However, every time you attempt to run a replay, the replay throws an extractor error; it is unable to find a field in the page content of the replay to extract.  ASM configured this field automatically, so why isn’t it working?  You look at the replay content … and the field name isn’t there.
The usual culprit that causes this problem is a dynamic field name: a variable in a dynamic web page that not only changes in value, … Continue reading »

Performance Impacts of AJAX Development

Using AJAX to Improve the Bandwidth Performance of Web Applications
Being a performance company, we are always interested in the impact of new development techniques on the performance of web applications. We have numerous customers who have performance problems due primarily to the size of their web pages. Put another way – the pages are simply too big to achieve the desired performance goals with the available bandwidth. In some cases, the page consists primarily of content that is common between many pages. For instance, a header, footer and navigation menu that change infrequently, if at all, during the use of … Continue reading »


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