Database Server Organization for Handling Mobile Clients

The use of mobile computers is gaining popularity. The number of users with laptops, notebooks is increasing and this trend is likely to continue in to the future where the number of mobile clients will far exceed the number of traditional \\xed" clients. Applications running on the mobile clients download information by periodically connecting to repositories of data stored in either databases or le systems. Such mobile clients constitute a new and diierent kind of work load and exhibit a diierent access pattern than seen in traditional client server systems. Though le systems have been modiied to handle clients that can download information, disconnect, and later reintegrate, databases have not been redesigned to accommodate mobile clients. There is a need to support mobile clients in the context of client server databases This paper is about organizing the database server to take into consideration the access patterns of mobile clients. We propose a concept of hoard key which captures these access patterns. Three diierent techniques for organizing data at the server based on the hoard key are presented. We argue that each technique is suited for a particular workload. The workload is a combination of requests from mobile clients and traditional clients. This reorganization also allows us to address issues of concurrency control, disconnection, replica control in mobile databases. We present simulation results that show the performance of server reorganization using hoard keys. We also provide an elaborate discussion of issues resulting from this new reorganization in this new paradigm that includes mobile clients and traditional clients.