CMG experts give Web scalability tips

IT professionals gathered in Anaheim, Calif., for the annual Computer Measurement Group (CMG) conference last week looked mostly for help in measuring Web application performance.

Neil Gunther, a performance analyst who consults with clients including eBay, urged attendees to look beyond number crunching when taking the measure of Internet applications. "Scalability is not a number, it's a function," he told the audience at a panel on Website Scalability. As an example, he pointed to eBay where his early analysis of the site showed that at peak hours it needed 167% of the backend server capacity. What that really meant was that to keep its customers satisfied eBay needed 67% of a server it did not have.

He said his analysis led management to aggressively begin adding server capacity to keep pace with the growing number of users.

Connie Smith, founder of Performance Engineering Service, Santa Fe, NM, said the time to determine if a Web application will have scalability problems is before it is built. She urged developers not to listen to the simplistic argument from anyone that they can "just make the application scale."

She suggested setting objectives for performance of a proposed application and then analyzing it with user scenarios. If analysis shows the application cannot meet the scalability objectives, adjustments must be made.

"Make changes to the application or if it can't reach performance objectives, scale back the objectives," said Smith, who is co-author of a new book titled Performance Solutions: A Practical Guide to Creating Responsive, Scaleable Software.

In the worst-case scenario where analysis shows that a new application simply will not perform at an acceptable level, Smith urged developers to abandon the application as undoable, rather than risk losing customers to more responsive Websites.

In an eCommerce environment where a 30-second delay may send a customer to a competing Website, scalability is definitely more than a number.

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About the Author

Rich Seeley is Web Editor for Campus Technology.