Load Testing Technologies

AJAX Load Testing

More than 20 years ago, there was no way to update a web page without displaying a boring white screen while reloading of the whole page. Thankfully, AJAX has closed this gap and introduced asynchronous data load concept, which enables user to interact with the page while data loads in the background. Nowadays, this concept is the foundation of our content rich and interactive web applications.

AJAX is an abbreviation for Asynchronous JavaScript and XML and it’s more than a technology because it consists of HTML, CSS, JavaScript, XMLHttpRequest and a server-side scripting language such as PHP. An AJAX request consists of the following 6 steps:

1. A web page fires a content change event
2. The handler of this web page creates an XMLHttpRequest object
3. The XMLHttpRequest object requests a document from the server
4. The Server retrieves appropriate data and sends it back
5. The XMLHttpRequest fires an event to notify the web page the data has arrived
6. The handler processes the data and displays it

The flipside from a performance engineer’s perspective is that automation of such asynchronous communication is tricky. Consider load testing a web application which has to serve 100 concurrent users and 10000 searches per hour. You are tasked to validate if the average response time of this application is within the boundaries of 3 seconds.

Basically, you have the following two options for a load test scenario:

1. Protocol-based simulation
2. Browser-based simulation

Let’s compare protocol level with browser level load simulation. The table below reflects the results of this experiment:

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AngularJS Load Testing

Front-end developers love AngularJS because it helps to simplify complex code. This simple and powerful framework solves the error prone DOM manipulation issues with its declarative description of the UI flow. AngularJS is an open source JavaScript Framework and can be added to a page with a simple script tag such as:

<script src=”https://ajax.googleapis.com/ajax/libs/angularjs/1.6.4/angular.min.js”>
</script>

It supports separation of concern and brings dynamic elements to static HTML. Like any other application, also AngularJS-based systems can quickly be impacted by performance issues. Here are a few steps you can take to speed things up on your next NG load testing project:

• Reduce the number of DOM operations to the minimum
• Reduce the total elements of your DOM tree
• Use Chrome profiler to check the memory footprint
• Reduce the activities in your watcher

LoadView gives you everything you need when it comes to accurate AngularJS load testing.

The example below uses a message input based on AngularJS. The screenshot below contains its source code on the left side and the app on the right side.

Flash Load Testing

Flash is an authoring software and is used to create vector graphic-based animations. It’s a platform independent technology and runs on any machine where a Flash player is installed. Due to security concerns, companies often ban Flash from their infrastructure. However, you can build nice applications with Flash, as the overhead is low. However, the one small disadvantage of Flash is that it won’t run without an enabled Flash player plugin.

LoadView gives you everything you need when it comes to accurate FLASH load testing. I’ve used a simple Flash-based Calculator: https://www.dotcom-tools.com/samples/Calculator.html. My load test scenario executes a simple 1 + 2 = 3 calculation.

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HTML5 Load Testing

HTML5 is the fifth version of the HTML, standard, which is still the backbone of our web applications. The ingredients of HTLM5 are:

• HTML which provides the structure
• CSS which takes care for the presentation
• JavaScript which makes things happen

HTML5 gives you everything required to implement beautiful applications running in your browser without the need of any plugins. Such applications are known as cross-platform based applications. They run on any device if your browser supports HTML5. The following is an example of load testing HTML5 with LoadView.

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JavaScript Load Testing

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JSON Load Testing

JSON is an abbreviation for JavaScript Object Notation and is quite similar to XML. It’s a very common data format and used for all kind of browser-server communication. Simplicity, broad programming language support and low overhead are the reason for its popularity.

Some JSON specific performance hotspots include the following:

• Download of large files takes too long
• Memory utilization is too high

In comparison with SOAP XML, the footprint of JSON is lower and it’s easier to read. The example below illustrates JSON load testing with LoadView.

We use JSON in the search functionality on our website. This is the corresponding JSON source code:

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Single-Page Application Load Testing

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SOAP Load Testing

Simple Object Access Protocol (SOAP) is a much more than a programming language. Contrary to JavaScript, which is a development language, SOAP enables communication across any device and operating system. The basic building block of SOAP is XML. SOAP has introduced a format for sending and receiving messages.

Some of the most popular performance hotspots related to SOAP are the following:

• Chatty application
• Wrong or no caching strategy
• Serialization causes high overhead
• No input validation on consumer-side or inefficient web method processing

SOAP-based web services provide a description of their services in WSDL. This web service description language can be used for manual our automated testing. In our showcase below, I will demonstrate how to set up load tests of a SOAP-based application.

This simple CurrencyConverter will be used in our sample load test setup:

https://www.webservicex.net/CurrencyConvertor.asmx?WSDL

The following steps outline how to perform SOAP load testing with LoadView.

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Web API REST Load Testing

REST is a widely used communication standard that stands for Representational State Transfer. It structures data in machine-readable format and makes use of XML or JSON. Contrary to SOAP, which is highly function-driven oriented, REST very data driven. RESTful API and RESTful services are two often used terms in this discipline but they mean nothing more than REST services.

Performance testing of REST services is all about sending data to services or verifying response from it. Some most common REST performance hotspots include the following:

• Chatty services
• Too much or not required data transmitted
• No reuse of TCP connections

Developer communities don’t often agree whether to implement web services in SOAP or REST. From a performance perspective, REST-based services are designed for speed. Their protocol overhead is lower and there is no XML parsing required. The case study below illustrates how Web API REST testing can be done with LoadView.

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WebSockets Load Testing

WebSockets are designed to enable two-way communication between client and server, which means both parties communicate and exchange data at the same time. True concurrency and performance optimization are the two key points of WebSockets.

Advantages of using WebSockets include the following:

• Bidirectional
  • No predefined message pattern, client or server can send a message to the other party
• Full Duplex
  • Independent communication between client and server
• Single TCP Connection
  • Upgrade HTTP connection, client and server communicate over the same TCP connection

If we compare WebSockets with REST or SOAP-based communications patterns, response times of the former are much better because WebSockets enable reuse of the same TCP connection. Research has shown that WebSocket based services are up to 10 times faster.

For this test, we’ll use a ChatBot which answers some basic questions.

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Load Testing with the LoadView Plugin for Jenkins