City University of Hong Kong

Mobile and Real-time Computing

The importance of real-time computing in a large number of applications, such as avionics and defense systems, industrial automation and air traffic control, has resulted in an increased research effort in this area.

In particular, in recent years, the research on real-time database systems (RTDBS) has received a lot of interest. A RTDBS is a database whose transactions and data objects are associated with timing constraints. Transactions are defined with deadlines on their completion times and data objects are defined with temporal constraints on their validity. To commit a transaction, it has to be completed on or before its deadline and also all its accessed data objects have to be valid at its committed time.

In a RTDBS, a number of factors can affect the predictability of system performance such as transaction scheduling, concurrency control, disk I/O scheduling and buffer management. The mission of the research on real-time database systems in our department is to identify and solve important problems in the design of time-critical and safety-critical database applications. Some of the current research work are:

  1. real-time active database systems
  2. concurrency control protocols for RTDBS mixed transactions
  3. commitment in distributed real-time database systems
  4. mobile computing systems for time-critical applications