The “All of the Above” Approach to Improving Application Performance

#ado #fasterapp #stirling Carnegie Mellon testing of ADO solutions answers age old question: less filling or tastes great?

You probably recall years ago the old “Tastes Great vs Less Filling” advertisements. The ones that always concluded in the end that the beer in question was not one or the other, but both.

Whenever there are two ostensibly competing technologies attempting to solve the same problem, we run into the same old style argument. This time, in the SPDY versus Web Acceleration debate, we’re inevitably going to arrive at the conclusion it’s both less filling and tastes great.

SPDY versus Web Acceleration

In general, what may appear on the surface to be competing technologies are actually complementary. Testing by Carnegie Mellon supports this conclusion, showing marked improvements in web application performance when both SPDY and Web Acceleration techniques are used together.

That’s primarily because web application traffic shows a similar pattern across modern, interactive Web 2.0 sites: big, fat initial pages with a subsequent steady stream of small requests and a variety of response sizes, typically small to medium in content length. We know from experience and testing that web acceleration techniques like compression provide the greatest improvements in performance when acting upon medium-large sized responses though actual improvement rates depend highly on the network over which data is being exchanged. We know that compression can actually be detrimental to performance when responses are small (in the 1K range) and being transferred over a LAN. That’s because the processing time incurred to compress that data is greater than the time to traverse the network. But when used to compress larger responses traversing congested or bandwidth constrained connections, compression is a boon to performance.

It’s less filling.

SPDY, though relatively new on the scene, is the rising star of web acceleration. Its primary purposes is to optimize the application layer exchanges that typically occur via HTTP (requests and responses) by streamlining connection management (SPDY only uses one connection per client-host), dramatically reducing header sizes, and introducing asynchronicity along with prioritization.

It tastes great.

What Carnegie Mellon testing shows is that when you combine the two, you get the best results because each improves performance of specific data exchanges that occur over the life of a user interaction.

HERE COMES the DATA

The testing was specifically designed to measure the impact of each of the technologies separately and then together. For the web acceleration functionality they chose to employ BoostEdge (a software ADC) though one can reasonably expect similar results from other ADCs provided they offer the same web acceleration and optimization capabilities, which is generally a good bet in today’s market.

The testing specifically looked at two approaches:

Two of the most promising software approaches are (a) content optimization and compression, and (b) optimizing network protocols. Since network protocol optimization and data optimization operate at different levels, there is an opportunity for improvement beyond what can be achieved by either of the approaches individually. In this paper, we report on the performance benefits observed by following a unified approach, using both network protocol and data optimization techniques, and the inherent benefits in network performance by combining these approaches in to a single solution.

-- Data and Network Optimization Effect on Web Performance, Carnegie Mellon, Feb 2012

The results should not be surprising – when SPDY is combined with ADC optimization technologies, the result is both less filling and it tastes great.

When tested in various combinations, we find that the effects are more or less additive and that the maximum improvement is gained by using BoostEdge and SPDY together. Interestingly, the two approaches are also complimentary; i.e., in situations where data predominates (i.e. “heavy” data, and fewer network requests), BoostEdge provides a larger boost via its data optimization capabilities and in cases where the data is relatively small, or “light”, but there are many network transactions required, SPDY provides an increased proportion of the overall boost. The general effect is that relative level of improvement remains consistent over various types of websites.

-- Data and Network Optimization Effect on Web Performance, Carnegie Mellon, Feb 2012

NOT THE WHOLE STORY

Interestingly, the testing results show there is room for even greater improvement. The paper notes that comparisons include “an 11% cost of running SSL” (p 13). This is largely due to the use of a software ADC solution which employs no specialized hardware to address the latency incurred by compute intense processing such as compression and cryptography. Leveraging a hardware ADC with cryptographic hardware and compression acceleration capabilities should further improve results by reducing the latency incurred by both processes.

Testers further did not test under load (which would have a significant impact on the results in a negative fashion) or leverage other proven application delivery optimization (ADO) techniques such as TCP multiplexing. While the authors mention the use of front-end optimization (FEO) techniques such as image optimization and client-side cache optimization, it does not appear that these were enabled during testing.

Other techniques such as EXIF stripping, CSS caching, domain sharding, and core TCP optimizations are likely to provide even greater benefits to web application performance when used in conjunction with SPDY.

CHOOSE “ALL of the ABOVE”

What the testing concluded was that an “all of the above” approach would appear to net the biggest benefits in terms of application performance. Using SPDY along with complimentary ADO technologies provides the best mitigation of latency-inducing issues that ultimately degrade the end-user experience. Ultimately, SPDY is one of a plethora of ADO technologies designed to streamline and improve web application performance.

Like most ADO technologies, it is not universally beneficial to every exchange. That’s why a comprehensive, inclusive ADO strategy is necessary. Only an approach that leverages “all of the above” at the right time and on the right data will net optimal performance across the board.