Slide 1 Ch 13 Application architectures Generic architectures that can be configured and adapted to create a system that meets specific requirements Can be used as a starting point for architectural design design checklist way of organizing the work of the development team means of assessing components for reuse vocabulary for talking about application types Read this chapter to help structure your project Some repetition

Slide 2 Application types 1. Data processing data driven applications that process data in batches without explicit user intervention during the processing billing systems, payroll systems 2. Transaction processing data-centered applications that process user requests and update information in a system database e-commerce, reservation systems 3. Event processing system actions depend on interpreting environmental events word processors, games 4. Language processing user intentions are specified in a formal language that is processed and interpreted by the system compilers, command interpreters

Slide 3 1. Data processing systems Data-centered Databases usually larger than the software Data input and output in batches input: customer #s and associated readings of an elec. meter output: one bill for each customer # Typical structure.

Slide 4 2. Transaction processing systems Process user requests for information from or to update a database From a user perspective: any coherent sequence of operations that satisfies a goal e.g. find the times of flights from London to Paris Users make asynchronous requests which are processed by a transaction manager

Slide 5 ATM (transaction processing) System organization: Transaction management:

Slide 6 Information systems (transaction processing.) Usually layered Generic: Library information system

Slide 7 Resource allocation systems (transaction processing) Systems that manage a fixed amount of some resource airspace in air traffic control systems rooms in a hotel tickets on Ticketmaster books in a library Usually layered

Slide 8 3. Event processing systems These systems respond to events in the system’s environment. Their key characteristic is that event timing is unpredictable so the architecture has to be organised to handle this. Many common systems such as word processors, games, etc. are event processing systems.

Slide 9 Editing systems (event processing) Characteristics: single user must provide rapid feedback to user actions transactions may be long and need recovery facilities Naturally object-oriented screen event command editor data ancillary data file system display

Slide Language processing systems Natural or artificial language input Output is some other representation of that language May include an interpreter to act on the instructions in the language being processed

Slide 11 Data-flow model of a compiler

Slide 12 Repository model of a compiler

Slide 13 To think about How do editing and language processing systems differ? How does your project fit any of these models?