A couple of weeks ago, I used this space to answer the question of how front-end web performance optimization (WPO) solutions complement CDNs. Today, I’m going to talk about ADCs and WPO as complementary solutions, by explaining how WPO picks up where your ADC leaves off.
What does an ADC do?
An ADC is an appliance (such as Radware’s Alteon appliance) or software (such as our virtual Alteon VA) that sits in front of your web servers in your datacenter. It sees all of the traffic to and from your web servers and takes care of a number of mission-critical tasks, the most important being:
- Load balancing
- Managing server availability and fault tolerance
- Providing security services
From a performance perspective, a typical ADC helps mostly with back-end performance. Back-end performance optimization means optimizing how data is processed on your server before it’s sent to the user’s browser. ADCs provide most of their benefit by offloading jobs from the web server, which in turn allows the web server to focus all of its energy and horsepower on serving pages.
Do ADCs provide acceleration benefits?
From an end-user perspective, improving back-end performance doesn’t have an appreciable impact on perceived application speed. However, while ADCs were not designed with front-end acceleration as a primary goal, your ADC does offer the ability to take advantage of a small handful of basic front-end performance best practices, including:
- Basic text and image compression, reducing overall payload
- Object and page caching on the ADC, which relieves some of the latency involved in retrieving resources from the server
- TCP optimization — enabling keep-alives, a core performance technique that reduces the number of TCP connections
Properly implemented via your ADC, these best practices can deliver some front-end acceleration benefit, but they’re just the first step in fully optimizing your pages.
What acceleration benefits does an advanced front-end WPO solution provide?
A front-end WPO solution, such as our FastView technology, applies a host of additional advanced front-end web performance optimization techniques to your web pages or application.
These techniques include:
- Resource consolidation — Bundles page resources so that fewer server round trips are required, thereby reducing latency
- Predictive browser cache — Intelligently predicts where users are likely to go next, and preloads resources into the browser cache so that they’re on standby
- Progressive image rendering — Gives users the perception of faster page load by loading a low-resolution version of an image first, then gradually loading the higher-resolution version.
- Deferral — Delays the execution of non-essential scripts until the rest of the page has rendered
- Mobile-specific techniques — Image resizing, redirect suppression, touch event conversion, leverage localStorage
It’s important to note that these techniques don’t just improve total page load time: they also significantly improve perceived load time by creating the illusion that page load is complete while the browser continues to render the page in the background.
Application delivery controllers and advanced front-end WPO are highly complementary solutions for ensuring the highest level of performance — in terms of availability, security, and speed — for your applications and websites.