Outline Context for database development Goals of database development Phases of database development

Intro to Information Systems Concepts Feedback Control Products Manufacturing Raw materials

What is an information system? An information system is a system that accepts data resources as input, and processes them into information products as output. To understand an information system let us begin by understanding what a system is? A system

Information system model All information systems use people, hardware, and software to perform input, processing output storage and control activities that transform data resources into information products

Hardware resources ( Machines and media) Components of an Information System Hardware resources ( Machines and media) The concept of hardware resources include all physical devices and materials used in information processing. Specifically it does not include computers and calculators only but also all data media ie all tangible media where data is recorded. Give examples on the slide

Components of an Information System Data resources Databases Knowledge bases Software resources Programs procedures Data are raw facts or observations of a particular phenomenon. It can take many forms e.g alphanumeric consiting of nubers and letters of the alphabet. Text consisting of words or even paragraphs, image such as graphics and shapes Audio such as human voice and other sounds etc. Data resources are organised into two: Databases that hold organised and processed data Knowledge bases that hold knowledge in a variety of forms such as facts and inference rules for a various subjects. Software resources include all sets of information processing instructions. These encompas computer programs that direct and control computer hardware (Operating systems), and sets of information instructions needed by the people (procedures) System software Operating system which supports and controls the operations of a computer system. Application Software: Programs that direct information processing for a particular by End-Users e.g. NFEMIS Proceduers which are oparating instructions for the people who will use the system. E.g. instructions for filling in a form or how to use computer software.

People Resources (End users and IS specialists) Components of an Information System People Resources (End users and IS specialists) People are required for the operation of information systems. These people include end-users and information systems specialists. End users or clients are the people who use an information system or the information it produces These can be people like ministers, Ps’s clerks, Information system specialists are people who develop and operate information systems. These include Systems analysts, programmers, computer operators and other managerial, technical and clerical users. Systems analysts design information systems based on information requirements of end-users, and programmers develop computer programs base on the on the specifications of systems analysts

Roles in the Database Environment Data and database administrators Database designers Application programmers One of the components of the DBMS environment is people. There are four distinct types of people that participate in the DBMS environment. These are data and data administrators, Database designers, application programmers, and the end users. Data and Database Administrators Many organisations view data and the DBMS as corporate resources that must be managed like any other resources. Data and database administration are roles associated with the management of and control of a DBMS and its data. The Data Administrator (DA) is responsible for the management of the data resource including planning, development and maintenance of standards, policies and procedures and conceptual and logical/ database design. The DA consults with and advises senior management ensuring that database development supports corporate objectives. The Database Administrator (DBA) is responsible for the physical realisation of the database i.e. physical database design, implementation, security and integrity control, maintenance of the operational system and ensuring satisfactory performance of the applications and the users. The role of DBA is more technically oriented than that of a DA because it requires knowledge of the target DBMS and the system environment. In some organisations there is no differentiation between these roles and in others teams are dedicated to each of these roles. Database Designers Database designers are responsible for the identification of data (entities and their attributes), the relationships between the data, and the constraints on the data that has to be stored in the database. Database designers must have a thorough understanding of the organisation’s data and its business rules. Business rules describe the characteristics of the organisation’s data as viewed by the organisation. For an effective design the designers must involve the users in the development of the data model and the process should begin as early as possible. Database design can be done in three stages Conceptual database design, which is independent of the implementation details such as the target DBMS, application programs, programming languages, and any other physical consideration. Logical database design which is targeted at a particular data model such as relational, network, or hierarchical Physical design that takes the logical data model and decides how it is to be physically realised. This involves: Mapping the logical data model into a set of tables and integrity constrains Selecting specific storage structures and access methods for the data to achieve good performance for the database activities. Defining any security measures required on the data Application Programmers A database needs application programs that provide required functionality for the end-users. This is the responsibility of the application programmers. The programmers work from the specifications produced by the systems analysts. Each program statement contains an instruction to the DBMS that request it to perform some operation on the database. This could be record insertion, updating or deleting. End-Users End users are the clients for the database. End-user can be classified according to the way they use the system: Naïve users are unaware of the DBMS. They access the database through application programmes that are specifically written and will attempt to make the operation as simple as possible. They invoke database operations by entering simple commands or choosing options from a menu. A specific program instruction will be invoked to perform the required operation. Sophisticated users Sophisticated users on the other hand are familiar with the structure of the database and facilities offered by the DBMS. They can use high level query languages such as SQL to perform operations on the database and may even write application programs for their own use. End-Users

Data Administration Develop and maintain policies governing data access and ownership. Conduct organizational data resource requirements Develop organizational data models and architectures Prepare strategic and technical database plan Identify potential for data sharing and potential database applications Set and enforce operational procedures and standards

Database Administration Conduct physical design Conduct database tuning and capacity planning Establish and maintain a data dictionary Evaluate and select database hardware and software

Database designers Identification of data and the relationships between the data, and the constraints on the data that has to be stored in the database. Conceptual database design Logical database design Physical design Defining any security measures required on the data

Management Information Systems Types of Information Systems Decision Support Systems Management Information Systems TPS :Computerized system that performs and records the daily routine transactions necessary to conduct the business MIS: Information system … that serves the functions of planning, controlling, and decision making by providing routine summary and exception reports. These systems serve middle management and can include on demand "standard" reports. MIS systems normally draw data from TPS. DSS – Decision Support Systems " Information system … that combines data, analytical tools, and models to support semistructured and unstructured decision making. Primary focus is on semistructured decision making with models that either make a preliminary recommendation or project "what if" scenarios. Used by all levels in the organization. DSS systems may be stand-alone or they may draw data from TPS and/or MIS systems. Transaction Processing Systems

Traditional Life Cycle Figure 2 shows the phases of the traditional systems development life cycle. The particular phases of the life cycle are not standard. Different authors and organizations have proposed from 3 to 20 phases. The traditional life cycle is often known as the waterfall model or methodology because the result of each phase flows to the next phase. The traditional life cycle is mostly a reference framework. For most systems, the boundary between phases is blurred and there is considerable backtracking between phases. But the traditional life cycle is still useful because it describes the kind of activities and shows addition of detail until an operational system emerges.