Content Delivery for Distributed Sites
By John N. Stewart
This article is the second in a series on the evolving strategy for distributed Web site design. The first installment (in the October issue) introduced the five main challenges of creating a distributed Web site: content management, content distribution, distributed monitoring, site development, and security models.
In managing distributed sites, it isn't enough to simply distribute the content to multiple locations. As the Web site administrator, you need to design the techniques by which users will access content on the "closest" machine. This ensures that a Web page is delivered as quickly as possible, increasing customer satisfaction with the site. The key to this speedy delivery is Best Site Selection (BSS).
As the industry changes, so does terminology. BSS has come to describe the method used to move a consumer (or any end user) to the best available server to handle their requests. Although it's still a maturing discipline, BSS techniques range from the most primitive scripts to complex systems that make decisions based on near-realtime information about Internet behavior.
In its current incarnation, BSS sends a user to the best site through DNS requests and responses. To use a BSS system, one must construct Web pages with BSS servers in mind. Most documents in a distributed system aren't dispersed from a single server, but rather from many distributed machines. The documents are typically referenced with URLs that reflect this distributed architecture. For example, references that are usually written as http://www.m
