Building Real-Time Applications with Continuous Query Technology

摘要

The client/server development model prevalent in the mid-1990's resulted in extremely easy-to-build rich GUI applications that interacted directly with a relational database. 4GL tools such as Visual Basic and PowerBuilder let even junior developers visually compose both the presentation and most of the backend data binding. While this made for impressive Rapid Application Development (RAD) productivity, the client/server architecture was severely challenged when dealing with real-time environments where the data changes rapidly and applications require visibility to the correct data at all times. As a result, client applications were forced to poll the database continuously to check for changes.