Web apps are not scalable

By Candice Jones, ITWeb online telecoms editor

Johannesburg, 14 May 2008

While HTTP has become the application deployment of choice in an age of Web services, it does not scale well.

"As a new global trend, delivering applications through HTTP can be great. Users are now able to access full enterprise applications through a Web browser. However, in terms of infrastructure and bandwidth, scalability becomes problematic," says Citrix country manager Nick Keene.

Web applications are straining traditional load balancers and data centres with the integration of rich media capabilities, service-oriented architectures and interactive Web 2.0 capabilities, he says.

"These applications are significantly more complex and resource-intensive, yet they must still be delivered with the fastest performance, best security and lowest total cost of ownership."

On Web servers, HTTP must create a session for every object that is requested on a given page and must subsequently drop that request. "Servers are controlling connection sessions instead of serving Web pages to clients, which creates overhead and, in turn, poor application performance."

To resolve these issues, many businesses will throw more servers at the situation, or allow more users to connect to applications by increasing bandwidth, he says. "With everyone in SA trying to do their part to curb the electricity crisis, this is not the way to tackle the problem. It just creates a server sprawl, which most data centres are now trying to avoid."

NetScaler MPX debuts

The company says its NetScaler appliance could help alleviate the strain that Web applications create. The high-end version of the product, NetScaler MPX, was released this week.

According to Keene, the MPX can process 375 000 HTTP requests per second and up to 750 000 transactions per second. "By analysing the traffic, it determines which server or service should complete any given HTTP request, which will minimise overhead on Web servers delivering applications."

NetScaler creates a pre-established connection with Web servers in a data centre and builds a front for the applications that need to be served. "The applications are then delivered to the client in a compressed form. The established connection effectively cuts out the need to add servers to load balance larger request volumes," he adds.

While he agrees the high-end version of the technology may not suit the South African situation, since few companies actually process large numbers of transactions per second, the appliance's lower end offerings may well provide the acceleration the business needs.

Entry-level appliances have a recommended retail price of around R17 000, while the MPX version will retail at R100 000. Keene says cost will vary according to client needs.