1. Developing Information Systems
Chapter: FOUR
Lecture: Eleven
Developing Information Systems
This lecture will cover following topic:
Developing Information Systems (SDLC)
-System Analysis
-System Design
-System Implementation and Maintenance

2. System Analysis The System Development Cycle (SDLC)
Systems analysis is not a preliminary study, it is an in-depth study of end-user information needs that produces functional requirements that are used as the basis for the design of a new information system.
Systems analysis traditionally involves a detailed study of:
The information needs of the organization and end users.
The activities, resources, and products of any present information systems.
The information system capabilities required meeting your information needs, and those of other end users.

3. System Analysis The System Development Cycle (SDLC)
a. Organizational Analysis: An organizational analysis is an important first step in system analysis. How can you improve an information system if you know very little about the organizational environment in which that system is located? You can’t. That’s why you have to know something about the organization, its management structure, its people, its business activities, the environmental systems it must deal with, and its current information systems. You must know this information in more detail for the specific end user departments that will be affected by the new or improved information system being proposed. For example, you cannot design a new inventory control system for a chain of department stores until you learn a lot about the company and the types of business activities that affect its inventory.

4. System Analysis The System Development Cycle (SDLC)
b. Analysis of the Present System: Before you design a new system, it is important to study the system that will be improved or replaced (if there is one). You need to analysis how this system uses hardware, software, and people resources to convert data resources, such as transaction data, into information products, such as reports and displays. Then you should document how the information system activities of input, processing, output, storage, and control are accomplished. For example, you might note the format, timing, volume, and quantity of input/output activities that provide user interface methods for interaction between end users and computers. Then, in the systems design stage, you can specify what the resources, products, and activities should be in the system you are designing.

5. System Analysis The System Development Cycle (SDLC)
c. Functional Requirements Analysis:
This step of system analysis is one of the most difficult. You need to work with systems analysis and other end users to determine your specific information needs.
For example, you need to determine what type of information you required; what its format, volume and frequency should be; and what response times are necessary.
Second, you must try to determine the information processing capabilities required for each system activity (input, processing, output, storage, control) to meet these information needs. Your main goal should be to identify what should be done, not how to do it.

6. System Analysis The System Development Cycle (SDLC)
Finally, you should try to develop functional requirements. Functional requirements are end user information requirements that are not tied to the hardware, software, and people resources that end users presently use or might use in the new system. That is left to the design stage to determine. For example, figure 4.8, outlines some of the key areas where functional requirements should be developed.

7. System Analysis The System Development Cycle (SDLC)
User interface requirements. The input/output needs of end users that must be supported by the information system, including sources, formats, content, volume, and frequency of each type of input and output.
Processing requirements. Activities required to convert input into output. Includes calculations, decisions, decision rules, and other processing operations, and capacity, throughput, turnaround time, and response time needed for processing activities.
Storage requirements. Organization, content, and size of databases, types and frequency of updating and inquiries, and the length and rationale for record retention.
Control requirements. Accuracy, validity, safety, security, and adaptability requirements for system input, processing, output, and storage functions.
Figure 4.8 : Functional requirements specify information system capabilities required to meet the information needs of users.

8. System Design The System Development Cycle (SDLC)
System analysis describes what a system should do to meet the information needs of users.
System design specifies how the system will accomplish this objective.
System design consists of design activities that produce system specifications satisfying the functional requirements developed in the systems analysis stage.
These specifications are used as the basis for software development, hardware acquisition, system testing, and other activities of the implementation stage.

9. System Design The System Development Cycle (SDLC)
User Interface Design
Data Design
Process Design
Screen, Form, Report, and Dialog Design
Data Element Structure Design
Program and Procedure Design
Systems Design
Figure: Systems design can be viewed as the design of user interfaces, data, and processes.

10. System Design The System Development Cycle (SDLC)
(i) User Interface Design: The user interface design activity focuses on designing the interactions between end users and computer systems. Designers concentrate on input/output methods and the conversion of data and information between human-readable and machine-readable forms. User interface design produces detailed specifications for information products such as display screens, interactive user/computer dialogues (including the sequence or flow of dialogue), audio responses, forms, documents, and reports.

11. System Design The System Development Cycle (SDLC)
(ii) Data Design: The data design activity focuses on the design of the structure of databases and files to be used by a proposed information system. Data design frequently produces a data dictionary, which catalogs detailed descriptions of:
The attributes of characteristics of the entities (objects, people, places, events) about which the proposed information system needs to maintain information.
The relationships these entities have to each other.
The specific data elements (databases, files, records, etc) that need to be maintained for each entity tracked by the information system.
The integrity rules that govern how each data element is specified and used in the information system.

12. System Design The System Development Cycle (SDLC)
(iii) Process Design:
The process design activity focuses on the design of software resources, that is, the programs and procedures needed by the proposed information system.
It concentrates on developing detailed specifications for the program modules that will have to be purchased as software packages or developed by custom programming.
Thus, process design produces detailed program specifications and procedures needed to meet the user interface and data design specifications that are developed.

13. System Design The System Development Cycle (SDLC)
b. System Specifications:
The design of user interface methods and products, database structures, and processing and control procedures results in hardware, software, and personnel specifications for a proposed system.
The final design must specify what types o hardware resources (machine and media), software resources (programs and procedures), and people resources (end user and information systems staff) will be needed.
It must specify how such resources will convert data resources (store in files and databases they design) into information products (display, reports, and documents).
These specifications are the final product of the systems design stage, and are called the systems specifications.

14. System Design The System Development Cycle (SDLC)
User Interface specifications: The content, format, and sequence of user interface products and methods such as display screens, interactive dialogues, audio responses, forms, documents, and reports
Database specifications: Content, structure, distribution, and access, response, maintenance, and retention of database.
Software specifications: The required software package or programming specifications of the proposed system, including performance and control specifications.
Hardware and facilities specifications: The physical and performance characteristics of the equipment and facilities required by the proposed system.
Personal specifications: Job descriptions of persons who will operate the system.
Figure : System specifications specify the details of a proposed information system.

15. Implementation and Maintenance
The System Development Cycle (SDLC)
The systems implementation stage involves hardware and software acquisition, software development, testing of programs and procedures, development of documentation, and variety of installation activities.
It also involves the education and training of end users and specialists who will operate a new system.
Finally, implementation involves converting from the use of a present system to the operation of a new or improved system. This may involve operating both new and old systems in parallel for a trial period, operation of a pilot system on a trial basis at one location, phasing in the new system one application or location at a time, or an immediate cutover to the new information system.

16. Implementation and Maintenance
The System Development Cycle (SDLC)
Systems maintenance involves the monitoring, evaluating, and modifying of a system to make desirable or necessary improvements.
This may include a postimplementation review process to ensure that the newly implemented system meets the functional requirements established for it.
Systems maintenance includes making changes to tax computations in the payroll systems and tax-accounting systems of a business.
However, it is vital in ensuring the success of any newly developed system because well-designed system will fail if it is not properly implemented.