Resumen
The advent of the world-wide-web as a digital distribution mechanism for information has emphasized the need for tools to mediate between browsers, servers and databases. What used to be called three-tier client server architecture has been replaced by the web. The actual means to disseminate information widely is now cheap and reliable. This shift from database and client server architectures to Web-based storage and interaction over more heterogeneous data has increased the need for maintaining comprehensive descriptions of data structure, content and other properties. Distributed dynamic systems, also known as dynamic object-based knowledge systems, are increasingly filling the gap between information source and browser queries. These systems comprise knowledge in the form of objects and methods in object frameworks that constrain and contain the domain knowledge needed to answer queries with responses integrated from multiple data sources. These frameworks are dynamic in that they form rapidly evolvable and extensible systems that take advantage of the changing requirements without having to record existing knowledge.