Prof. Dr.-Ing. Stefan Deßloch AG Heterogene Informationssysteme Geb. 36, Raum 329 Tel. 0631/205 3275
[email protected] Chapter 11 Web-based Information Systems TP Application Architecture client n Front-end program n interacts with (possibly wide range of) display devices front-end n gathers and validates input, displays output n constructs and forward request (e.g., as a RPC Front-end or asynchronous message) Program è provides device-independence for server n Request controller server n guides the request execution Request Controller n determines required steps, then executes them by invoking transaction servers Transaction Transaction Transaction n usually runs as part of an ACID transaction ... Server Server Server n Transaction server n process that runs application programs doing the actual work of the request DBMS n almost always runs within the scope of an Database Database ACID transaction System System n typically interacts with a DBMS n simple applications can be composed into more complex ones (using local proc. call, TRPC, asynch. messaging, …) DB DB n makes difference to req. controller fuzzy Middleware for Heterogeneous and 2 © Prof.Dr.-Ing. Stefan Deßloch Distributed Information Systems Front-end Program Functions n Gather input and display output (user interaction) n form and menu concepts n user selects a menu item to identify the type of transaction to be executed n front-end program display a (series of) form(s) for gathering input data n input data is validated by the front-end program n goal: avoid calling