Information system analysis and design Dr. Dina Tbaishat

Recap Last lecture we discussed the concept of a system and its properties Today we shall highlight the concept of information systems and the need for system development models

Information System Collection of hardware and software for collecting storing and processing data to deliver meaningful information. Information systems manage organizations’ operations Types of information systems: Transaction processing systems (ex: payroll) Operations information systems (ex: sales) information system, an integrated set of components for collecting, storing, and processing data and for delivering information, knowledge, and digital products. Business firms and other organizations rely on information systems to carry out and manage their operations, interact with their customers and suppliers, and compete in the marketplace. For instance, corporations use information systems to reach their potential customers with targeted messages over the Web, to process financial accounts, and to manage their human resources. Governments deploy information systems to provide services cost-effectively to citizens. Digital goods, such as electronic books and software, and online services, such as auctions and social networking, are delivered with information systems. Individuals rely on information systems, generally Internet-based, for conducting much of their personal lives: for socializing, study, shopping, banking, and entertainment.

Computer-based information system An information system that uses computer technology to carry out some or all of its planned functions. Its main components are: Hardware- these are the devices like the monitor, processor, printer and keyboard, all of which work together to accept, process, show data and information. Software- are the programs that allow the hardware to process the data.

Databases- grouping of data into tables, having all related data that describe one entity in one table. Networks- connecting various devices to share resources Procedures- are the commands for combining the components above to process information in attempt to come up with the output

There is always a need to develop information systems that serve different organizations and that can be deployed in various contexts There is also a need to follow certain procedures to enable developers to produce systems that satisfy their intended requirements This will lead us to the concept of system development life cycle and its models…

definitions The following definitions are taken from (Sommerville, 2001): System engineering: it is concerned with all aspects of computer-based systems development (hardware, software and processes) Software: computer programmes and associated documentation, usually a software product is developed either for a customer or for a general market Software engineering: concerned with software production (part of system engineering)

Challenges Facing legacy systems Distributed systems across networks that include different types of computers / support systems Building systems is time consuming Therefore, innovative methods are needed !

Computer-based information system development life cycle This process includes all the stages from specification, design, development, integration to finally testing Specification, the first stage which is intended to decide on the services required from the system and the constraints on its operation  requirements engineering Why is this stage important ??? Because errors can be avoided

This process leads to the production of a requirements document (the specification of the system) This document usually has two levels of detail: the end users and customers need high-level statement of requirements, while developers need a more detailed system specification The requirements document shall be discussed in detail later

Design is the second stage in system development and it refers to the structure of the software to be implemented, the data and the interfaces between the components. Examples of design methods are: data flow model, entity-relation model, object oriented methods (such as class diagram) Development is the third stage and it is concerned with programming, using specific programming language such as java, .Net

Integration is the fourth stage, where bringing the component subsystems together into one system takes place Testing is the last stage of system development, it tests the system upon completion to make sure it satisfies its intended requirements This course focuses on system analysis and design only, it doesn’t consider the rest of the system development stages.