Replication in service oriented architectures

Multi-tier architectures have become the main building block in service-oriented architecture solutions with stringent requirements on performance and reliability. Replicating the reusable software components of the business logic and the application dependent state of business data is a promising means to provide fast local access and high availability. However, while replication of databases is a well explored area and the implications of replica maintenance are well understood, this is not the case for data replication in application servers where entire business objects are replicated, Web Service interfaces are provided, main memory access is much more prevalent, and which have a database server as a backend tier. In this paper, we introduce possible replication architectures for multi-tier architectures, and identify the parameters influencing the performance. We present a simulation prototype that is suitable to integrate and compare several replication solutions. We describe in detail one solution that seems to be the most promising in a wide-area setting.