Caching Protocol to Speed Web Page Access

In an effort to improve Web caching technology, Microsoft Corp. and bitter rivals Sun Microsystems Computer Co. and RealNetworks Inc., ( as well as Inktomi Corp. (, teamed up to write the Web Proxy Autodiscovery Protocol (WPAD).

Drafted for the Internet Engineering Task Force (IETF), the specification enables devices to automatically discover the Web caching nodes on a proxy server, which will result in faster access to Web pages and increased quality of streaming video.

"The protocol is designed to enhance performance for end users and reduce TCO (total cost of ownership)," says John Montgomery, product manager, standards activities group, at Microsoft. "Administrators no longer have to configure client systems, which reduces TCO. And because it’s more simple for clients to find a proxy server’s cache than actually find the Web site itself, the client’s performance is improved."

WPAD is specifically designed for two markets: large enterprises and Internet service providers (ISP). "Whether its for the Internet, corporate intranet or extranet, accessing information as fast as possible is becoming a necessity for large enterprises," says David Baltaxe, research analyst at Current Analysis Inc. (

To that end, WPAD enables administrators to manage bandwidth and control what information employees can access.

ISPs have begun to rely on caching technology to enhance performance as well. For instance, an ISP may store frequently visited pages in a proxy server’s cache so subscribers simply get the page from the proxy server, rather than following the trail of servers all the way to the actual page. That job is currently taken on by routers that support Layer 4 interception and redirection, or by clients connecting directly to a caching server. WPAD will allow ISPs to use caches without requiring routers and switches.

WPAD will also benefit client-side application developers, who will be able to incorporate automatic discovery of a network’s caching servers into new applications.

RealNetworks says future versions of the RealSystem G2 streaming video server product line will support the protocol. Additionally, WPAD, which analysts expect to have a smooth acceptance by the IETF, has surfaced in a beta version of Internet Explorer 5.0. "Future versions of Windows will be likely candidates for WPAD, and that includes IE," Montgomery says.

Sun, on the other hand, is approaching WDAP from a different angle. "Sun got in on this game because down the road the company will probably use the WPAD technology for server-to-server cache autodiscovery," says Martin Marshall, director of Internet services and application development services at Zona Research Inc. (

But in the end, one common goal brought this unlikely mix of partners together. "In this case, the protocol is about bandwidth, and that’s important to all these vendors," Baltaxe says. "Vendors often get together early to form a standard, then once the standard is accepted and adopted the companies start flexing their marketing muscle and offering competing products. Inevitably, that will happen with WPAD."