Testing Tips For Today’s Tech: HTML5, WebSockets, RTMP, Adaptive Bitrate Streaming

One of the most dangerous things that can happen to a development team is complacency. The modern world moves so fast, and new technologies are coming out all the time. If you stop innovating and stop adapting, you’ll be sunk. It’s critical for web developers to be continuously responding to the changes around them.

The web community is constantly churning out new technologies that make it easier to develop the applications that savvy users are demanding. It may be obvious, but new technologies often require new ways of thinking about testing – sometimes new tools, other times entirely new testing methods. You just can’t rely on the same old same old when things change as much as the web does.

This means that you, as a performance tester, must constantly be preparing for the latest the web has to offer. We thought we’d provide some tips on how to conduct performance testing on newer technologies, so you can stay one step ahead of the curve.


HTML5 and CSS3 together were one of of the biggest transformations to happen to web development in the past decade. With the introduction of these W3C specifications, finally a common standard for rich media and web interactivity was put in place that applied across all browsers on desktops, laptops, set-tops, and mobile devices.

Since most of what happens in an HTML5 application takes place on the client, much of the performance testing job comes in the form of end-user experience testing. You want to know that your client devices can handle all the processing involved in a high fidelity HTML5 app. For example, here’s a processor-heavy client-side HTML5 app that you can use for benchmarking the client-side experience across different devices.

There are, however, some implications of HTML5 that do matter when viewed through the lens of server-side scalability and load testing. These are:

  • The complexity of the app. HTML5 apps are often very dynamic, so they don’t necessarily all load at once. Make sure your test scenarios fetch all the necessary sub-components, are running correlated scripts, and are exercising AJAX calls appropriately. These will matter under load.
  • HTML5 also supports server-sent events, so you’ll want an infrastructure that can support these events with a normalized method for receiving various types of push notifications and server-sent messages.
  • Finally, you’ll want a good way to record traffic back and forth from the server and then replay those communications as a scalable series of simulated users, with the ability to insert randomized dummy data into each app instance. The richness of an HTML5 app can make these traffic patterns more complicated than a legacy app would typically be. You’ll want the flexibility in your testing infrastructure and scenario design to fully exercise HTML5 as a realistic simulation of load.

Ultimately, HTML5 has new communication features that you need to accommodate and a higher degree of potential complexity in the apps that are built on the platform. But you’ll still want to see all the performance metrics and insights that you do with classic HTML application performance tests.


WebSockets is actually part of the HTML5 specification, but nonetheless it deserves its own callout. WebSocket technology creates a persistent connection between the client and the server. That way a server can push info to a client without waiting to piggy-back on an incoming HTTP request.

As the web grew more and more interactive, companies started using browsers as a platform for low-latency and real-time apps, like running a game, or real-time communications, or notifications. However, since HTTP required every communication to start with a client request, this forced developers and toolkits to create workarounds that simulated server-pushed events, while still fitting in the request-response framework. These solutions worked well, but were inefficient.

With HTML5 and WebSockets, that process became highly efficient. So WebSockets became a great way to push information from the server to the client. However, because they are so speedy and don’t require a new connection to be established any time information needs to be communicated in either direction, web developers often use WebSockets as a way of maintaining a fast channel between client and server, even for traditional request-response purposes.

When it comes to performance testing, the key to testing WebSockets is simulating the bi-directional nature of your app. Test scenarios aren’t always one-way. They aren’t always request-response. They aren’t always server-pushed. Applications that employ WebSockets often contain a mix of communication patterns. To build your load test scenarios you’ll want to record and playback WebSocket communications with your app to create realistic testing scenarios. You’ll also need to handle messages pushed over WebSockets just like you would handle messages pushed using a traditional request-response, piggy-back architecture. Load test variables should include the time it takes to establish a WebSocket connection, as well as the time it takes to send a request over that connection. Finally don’t forget to include tests for both text and binary data.

One more thing to keep in mind – a lot of tools designed to test WebSockets are only built to handle push notifications, but the way modern apps are developed, a lot of request-response apps leverage WebSockets anyway. Make sure your load testing tool can deal with both communication protocols.

If your application doesn’t take advantage of WebSockets, and if you care about performance, consider checking the technology out. WebSockets are a great way to boost your interactive applications.

Real-Time Messaging Protocol (RTMP)

RTMP was originally developed for streaming audio, video, and data over the Internet, between a server and a Flash player. It was created by Macromedia (now part of Adobe) and was later released as an open specification that’s commonly used for Flash and Flex/Air applications. The protocol supports AMF, SWF, FLV, and F4V file formats.

Today, most people agree that the video support included within HTML5 will reduce the need for these file formats. However, because there is so much video out there, and much of it is not HTML5-compliant yet, these traditional formats still carry a lot of weight.

Like WebSockets, RTMP creates persistent connections between a server and a client application written in Flash or Flex/Air. The technology is used to reduce the overhead involved in establishing and tearing down connections for low-latency or highly-interactive apps. Also like WebSockets, performance testing for RTMP is typically focused around the optimizing data that’s pushed from the server to the client.

What’s unique when testing RTMP apps is that you need testing tools that have the RTMP standard built-in. If your app employs this protocol, you’ll want to develop test scenarios that really exercise it. However, RTMP isn’t part of the native HTML5 package the way WebSockets is. Your load testing solution should incorporate RTMP directly, and provide a lightweight way of creating virtual users, recording RTMP traffic, processing it appropriately, and playing it back in a realistic way. Your test scenarios will also need to be able to understand and process events that come from the server in order to simulate a diverse and active user population.

Adaptive Bitrate Streaming

All the technologies listed above focus primarily on interactive apps and bi-directional communications between servers and clients. Adaptive bitrate streaming is altogether different. Built directly on HTTP, adaptive streaming detects a user’s bandwidth and CPU capacity in real-time, and adjusts the quality of the video stream accordingly. That means you get a different data stream if you are watching a movie on your 4” phone than you would get on a 27” monitor at your desk.

Bitrate streaming has become important because it’s a way to reduce buffering and load times for videos. It’s all about being able to serve video content immediately, the moment the user asks for it. That’s the reason you no longer get those annoying “waiting for video to buffer” messages any more.

The thing about adaptive bitrate streaming is that the interaction between the client and server is very complex, so that makes it a difficult thing to simulate in load tests. Plus there are a lot of different kinds of streaming – that adds a whole other layer of complexity. So you need a load testing tool that first can handle a wide variety of streaming technologies like MPEG/DASH, Adobe Dynamic Streaming for Flash, Apple HTTP Live Streaming, and Microsoft Smooth Streaming.

Second, your testing software should be able to handle a large library of videos. Usually streaming apps involve users accessing a broad set of content. To accurately simulate their behavior, you want to avoid having the same videos get served over and over again. You need to be able to fully exercise the behavior of the population as a whole.

Finally, video streaming is very demanding for a server, but it’s not the only thing going on. Apps continue to function in other ways, concurrently while video is streaming. For example, ads get served, related content is browsed, or transactions get executed – all while that video is playing. You’ll need to build this into your test scenarios as part of a realistic media load test.


We all know how important it is to stay on top of the latest trends in technology. At Neotys this is something we take very seriously. That’s why our team is always looking to see what technologies web developers are using and building those capabilities directly into our products. Have questions about testing a particular technology? We’d love to hear from you.

Photo Credit: Susanne Nilsson

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  1. November 10, 2015

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