InformationWeek
Defining The Business Value Of Technology
December 7, 1998
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Realtor.com uses a three-tier architecture. Microsoft's Internet Information Server software
makes up the Web server tier, which runs on six machines. The DCOM objects and Transaction
Server make up the logic tier, and SQL Server is the data tier. Logic and data run together on 14
servers to reduce network hops. "The major goal is to minimize network traffic going on in any
transaction," says Aleks Kovalchuk, a leader in systems architecture at Scient.The most processor-intensive transactions on Realtor.com are searches, which compare dozens of criteria from home shoppers to 450,000 real estate listings to find matches. Each day, Realtor.com processes 250,000 home searches and serves 2.5 million page views. To distribute the work evenly among its servers, RealSelect uses F5 Labs' BIG/ip load-balancing software, which monitors each server's availability and performance and routes incoming queries to the most available server. "We're going to be in pretty good shape for handling the loads we're expecting to see," says Phil Dawley, VP of technology at RealSelect.
Spread The Work Around
Internet bookstore barnesandnoble.com uses Cisco Systems' LocalDirector load-balancing appliance to monitor the strain on servers and spread the work. If a server fails, LocalDirector detects the crash and takes the failed box out of service. Administrators can disconnect servers without taking down an entire site; LocalDirector automatically routes traffic to the remaining machines. That lets barnesandnoble.com reallocate CPU power where it's most needed. And the site needs power: It received nearly 2 million unique visitors in September, according to Media Metrix.
Barnesandnoble.com manages three kinds of server applications: content, search, and transaction. Each app runs on a separate group of four-way Hewlett-Packard LX Pro machines that run Windows NT. Hosting the applications on different boxes lets administrators take CPU power away from idle apps and give it to overtaxed ones without changing software. "One of the benefits of the three-tier approach is we can apply the horsepower where needed," says John Kristie, VP of IT at barnesandnoble.com.
The bookseller has tuned each of its server apps for speed and performance. The content server, which lets users browse titles and recommendations, serves prebuilt static Web pages. Dynamic pages constructed upon request consume more CPU power. "You want to minimize dynamic content whenever it's not necessary," says Yankee Group's Robins. Barnesandnoble. com built a Java-based authoring tool that uses templates so designers can pump out static pages in short order.
Barnesandnoble.com also built its own search engine, which burns more CPU power than the other server apps, using 60% to 70% of its server capacity. To cut the processing load and speed responses, barnesandnoble.com installed 2 Gbytes of main memory in the servers that run the search engine. The engine scans data cached in memory before querying the database. "The fastest path between the CPU and the data is memory," Kristie says.
For transactions, barnesandnoble.com uses Microsoft Site Server Commerce Edition. Site Server keeps track of the items in users' shopping carts and manages the purchase process. Barnesandnoble.com chose Site Server because it comes with objects that let companies develop their own applications. Purchasing "is a strategic piece where we wanted to have a great deal of development autonomy," Kristie says. Barnesandnoble.com used Site Server to develop its Express Lane ordering application, which lets users enter their credit-card and delivery information once and then buy items by clicking one button.
Site Server connects the barnesandnoble.com Web site to a back-end transaction system based on a four-way HP 9000 Unix server and Informix database. As orders come in through the site, the transaction system sends them to barnesandnoble.com's warehouse system and to distributors' systems in five-minute intervals. Once received, orders are committed immediately and often shipped the same day.
Fast fulfillment is critical to barnesandnoble.com's business strategy. "Near real-time ordering allows us to manage our customer satisfaction process to the highest level," says barnesandnoble.com president Killeen. "And it allows us to source inventory that is closest to the customer to optimize speed of delivery." The bookseller's system is rare among conventional retailers that have extended business to the Web. "A lot of first-round Web sites weren't tightly integrated with back-end systems," says Alexis DePlanque, an analyst at Meta Group Inc. "If something is out of stock, you won't know that right away."
All of this comes at a cost. Barnesandnoble.com's IT staff is separate from its $2.8 billion parent. Barnes & Noble reported an operating loss of $3.4 million during its second quarter this year because of a $23 million operating loss by barnesandnoble.com, which offset a $19.6 million operating profit by Barnes & Noble's retail business. During the first half of this year, barnesandnoble.com spent $10.1 million on capital expenditures. The payoff: The Web site's second-quarter revenue this year rose to $12.5 million, up 470% from the year-ago quarter.
Consolidated Hardware
Another Internet retailer, SpeedServe Inc., integrated its Web site and back-end systems by running them on the same hardware, an IBM System/390 mainframe. The mainframe runs the OS/390 operating system, IBM's DB2 5.0 database, and Lotus Development's Domino Web server. "One of the unique things we're doing is tying the Web site into back-end shipping systems," says Tony McAlister, VP of IT at SpeedServe. The Web site sells books, videos, and computer games. Orders placed through the site ship within 24 hours.
SpeedServe chose to run its site on a mainframe because it's a small company and needs to work closely with its suppliers. The System/390 matched the systems of distributors such as Ingram Entertainment and Ingram Books. The company is small, but its site is growing. It receives 35,000 visitors a day, offers 1.5 million products in its database, and expects to add a million more next year. "With content, shipping, and other activity, the site gets pretty large fast," McAlister says.
With online retail revenue expected to reach $108 billion by 2003, it's only going to get bigger.
--with additional reporting by Martin J. Garvey
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See sidebar stories, "Monster Board Scales Up," and "GeoCities Copes With Rapid Growth."
Illustration by August Stein
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