Prof. Dr. Bettina Kemme

"Adaptable Multi-Tier Architectures"

Many application domains such as e-commerce, life-sciences, and banking deploy information systems that are built within a multi-tier framework. A multi-tier architecture typically consists of a client-tier, a web-tier, an application server tier, and a database backend tier. Each of these tiers provides different functionality. From the user perspective, however, the system should appear as a single unit. Adaptability plays a crucial role in providing the user with the desired quality of service. It means that the system tolerates faults of individual components, and is able to dynamically adjust to variations and increase of the load submitted. This talk presents replication as a natural way to provide fault-tolerance and scalability for both the application server and database tiers. The load can be distributed across the replicas of a tier, and in case a replica fails, other replicas can serve as backups. The challenge is that the execution of a client request spans several tiers, hence, interaction between the tiers needs to be taken into account.

This is joint work with the Technical University of Madrid