Abstract: A technique, system, and computer program for maintaining session information among multiple clustered computers for servlets and providing those servlets with various session services. The session services are implemented using a plug-in servlet engine. The session information is preferably maintained without using a persistent data store, to avoid performance penalties associated with storing information in persistent storage such as a database. A locking technique is implemented to prevent servlets from inadvertently overwriting each other's session object data. A registration process is preferably used, to optimize communication of configuration property changes. Non-proprietary interfaces are used, allowing for scalability, portability, and maximum industry acceptance of this solution.

Abstract: A technique, system, and computer program for using servlets to isolate the retrieval of data from the rendering of the data into a presentation format. Data retrieval logic is isolated to a data servlet, and presentation formatting is isolated to a rendering servlet. Servlet chaining is used to send the output of the data servlet to the rendering servlet. The data servlet formats its output data stream for transfer to a downstream servlet. This data stream may be formatted using a language such as the Extensible Markup Language (XML), according to a specific Document Type Definition (DTD). The rendering servlet parses this XML data stream, using a style sheet that may be written using the Extensible Style Language (XSL), and creates a HyperText Markup Language (HTML) data stream as output.