As Client-Server Style Applications Resurface Performance Metrics Must Include the API

Mobile and tablet platforms are hyping HTML5, but many applications are bound to a traditional client-server model, making API performance a top concern for organizations.

I recently received an e-mail from Strangeloop Networks with a subject of: “The quest for the holy grail of Web speed: 2-second page load times". Being focused on optimizing the user-interface, they appropriately quoted usability expert Jakob Nielsen, but also included some interesting statistics: 

  • 57% of site visitors will bounce after waiting 3 seconds or less for a page to load.
  • Aberdeen Group surveyed 160 companies and discovered that, on average, slowing down a site by just one second results in a 7% reduction in conversions.
  • Shopzilla accelerated its average page load time from 6 seconds to 1.2 seconds and experienced a 12% increase in revenue and a 25% increase in page views.
  • Amazon performed its own page speed optimization and announced that, for every 100 milliseconds of improvement, revenues increased by 1%.
  • Microsoft slowed down its Bing site by two seconds, which led to a 4.3% loss in revenue per visitor.

The problem is not that this information is inaccurate in any way. It’s not that I don’t agree that performance is a top concern for organizations – especially those for whom web applications directly generate revenue. It’s that “applications” are quickly becoming a mash-up of architectural models, not all of which leverage the ubiquitous web browser as the client. It is particularly true on mobile and tablet platforms, but increasingly true of web-delivered applications, as well.

Too, many applications are dependent upon third-party services via the use of Web 2.0 APIs that can compromise performance of any application, browser-based or not.


I was browsing Blackberry’s App World on my Playbook with my youngest the other day, looking for some games appropriate for a 3-year old. He was helping, navigating like a pro, and pulling up descriptions of applications he found interesting based on their icon.

When the application descriptions started loading slowly, i.e. took more than about 3 seconds to pop up on the screen, he started hitting the “back” button and trying another one. And another one. And another one. Ultimately he became quite frustrated with the situation and decided his Transformers were more interesting as they were more interactive at the moment. Turns out I was having some connectivity issues that, in turn, impacted the Playbook’s performance.

I took away two things from the experience:

1. A three-year old’s patience with application load times is approximately equal to the “ideal” load time for adults. Interesting, isn’t it?

2. These mobile and tablet-deployed “applications” often require server-side, API, access. Therefore, API performance is critical to maintaining a responsive application.

It is further unlikely that all applications will simply turn to HTML5 as the answer to address the challenges inherent in application platform deployment diversity. APIs have become a staple traffic on the Internet as a means to interconnect and integrate disparate services and it is folly to think they are going anywhere.  What’s more, if you know a thing or three about web applications, APIs are enabling real-time updating in record numbers today, with more and more application logic responsible for parsing and displaying data returned from those API calls residing on the client.

Consider, if you will, the data from the “API Billionaires Club” presented last year in “Open API Madness: The Party Has Just Begun for Cloud Developers

These are not just API calls coming from external sources; these are API calls coming from each organization’s own applications as well as integrated, external sources. These APIs are generally calls for data in JSON or XML formats, not pre-formatted user interface markup (HTML*).

No amount of HTML manipulation is likely to improve the performance of API calls because there is no HTML to optimize. It’s data, pure and simple, which means the bulk of the responsibility for ensuring wicked fast performance suitable to a three-year old’s patience is going to land squarely on the application delivery chain and the application developer.

That means minimizing processing and delivery time through carefully optimizing code (developers) and the delivery chain (operations).


When the web first became popular any one who could use a scripting language and spit out HTML called themselves “web developers.” The need for highly optimized code to support the demanding performance requirements of end-users means that it’s no longer enough to be able to spit out HTML or even JSON.

It means developers need to be highly skilled in optimizing code on the server-side such that processing times are as tight as can be.  Calculating Big (O) may become a valued skill once again.

But applications are not islands and even the most highly optimized function in the world can be negatively impacted by factors outside the developer’s control. The load on the application server – whether physical or virtual – can have a deleterious effect on application performance. Higher loads, more RAM, fewer CPU cycles translates into slower executing code – no matter how optimized it may be.

Processing cryptographic operations of any kind, be it for compression or security purposes, can consume resources and introduce latency into processing times when performed on the server. And the overhead from managing connections, usually TCP, can take as much time as processing a request. All those operations add up to latency that can drive the end-user response time over the patience threshold that results in an aborted transaction. And when I say transaction I mean request-reply transaction, not necessarily those that involve money. Aborted transactions are also bad for application performance because it’s wasting resources. That connection is held open based on the web or application server’s configuration, and if the end-user aborted the transaction, it’s ignoring the response but tying up resources that could be used elsewhere.

Application delivery chain optimization is a critical component to improving response time. Offloading cryptographic processing and protocol management can alleviate much of the load that negatively impacts application processing times and shifts the delivery-time component of application performance  management from the developer to operations, where optimization and acceleration technologies can be applied regardless of data format. Whether it’s HTML or JSON or XML is irrelevant, compression, caching and cryptographic offload can benefit both end-users and developers by mitigating those factors outside the developer’s demesne that impact performance negatively.

THE WHOLE is GREATER than the SUM of its PARTS

It is no longer enough to measure the end-user experience based on load times in a browser. The growing use of mobile devices – whether phones or tablets – and the increasingly interconnected web of integrated applications means performance of an application is more complicated than it was in the past.

The performance of an application today is highly dependent on the performance of APIs, and thus testing APIs specifically from a variety of devices and platforms is critical in understand the impact high volume and load has on overall application performance.  Testing API performance is critical to ensuring the end-user experience is acceptable regardless of the form factor of the client. 

If you aren’t sure what acceptable performance might be, grab the nearest three-year old; they’ll let you know loud and clear.


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    Published May 23, 2011
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