Large-Scale ASP Replication of Database-Driven Portals

Web portal applications that dynamically generate results in response to user requests are more popular than ever. Such portal applications usually consist of a business logic component and a very large database, or databases that hold the portal’s content. Despite efforts to speed up response generation, ever-rising user demand means that replication of a portal’s logic and database will be needed at some point as other methods to keep up with demand (faster databases and content caching for example) have limits. This article explains issues surrounding the replication of a single full-scale database-driven portal application. In addition to the issues of replicating a single, unsophisticated application, it also anticipates a future in which portal applications offer multiple levels of service to users, and large application service providers (ASPs) host and replicate many portal applications on networks of servers. An ASP must replicate complex portal applications in order to satisfy user demand while minimizing operating costs. ASPs will need mature tools for making replication decisions and deploying and otherwise managing their replication system. To that end, this article highlights two prototype software packages, ACDN and DATE/DASIM, that address some aspects of replica management by ASPs. Using the two prototypes as a starting point and recalling single portal replication issues, a set of features for a mature ASP replication management systems are proposed.