Application: Intermittently Synchronized Databases

• In some of the applications, a server or a group of servers manages the central database and the clients carry laptops or palmtops with a resident DBMS software to do “local” transaction activity for most of the time.
• The clients connect via a network or a dial-up connection (or possibly even through the Internet) with the server, typically for a short session—say, 30 to 60 minutes.
• They send their updates to the server, and the server must in turn enter them in its central database, which must maintain up-to-date data and prepare appropriate copies for all clients on the system.
• Thus, whenever clients connect—through a process known in the industry as synchronization of a client with a server—they receive a batch of updates to be installed on their local database.
• The primary characteristic of this scenario is that the clients are mostly disconnected; the server is not necessarily able to reach the client. This environment has problems similar to those in distributed and client-server databases, and some from mobile databases, but presents several additional research problems for investigation.
• We refer to this environment as Intermittently Synchronized Database Environment (ISDBE), and the corresponding databases as Intermittently Synchronized Databases (ISDBs).