The concept of systems development
• A modern approach to system
analysis and design
• Types of Information System and
System development
• System development life cycle
•A complex, challenging, and stimulating organizational process that a team of business and systems professionals uses to develop and maintain computer-based information systems.
•System analysis and design techniques provide the analyst with a systematic procedure for analyzing data input, data flow, and information output; furthermore, the techniques can improve the functioning of business.
-An information system (IS) is an arrangement of people, data, processes, communications, and information technology that interact to support and improve day-to-day operations in a business, as well as support the problem-solving and decision-making needs of management and users.
-Information technology is a contemporary term that describes the combination of computer technology (hardware and software) with telecommunications technology (data, image, and voice networks).
The concept of systems development
• information system and design
• application software
• software engineering processes
• methodologies
• techniques
• tools
•Application software -Computer software designed o support organizational functions or processes.
•Methodologies – comprehensive, multiple-step approaches to systems development that will guide your work and influence the quality of your final product.
•Techniques-The particular processes that an analyst will follow to help ensure that his work is complete, well-done, and understood by project team members .
•Tools –computer programs that make it easy to use and benefit from techniques and follow the guidelines of the overall development methodology.
A Modern Approach to System Analysis and Design
• Separating data and processes that handle data
3 components of IS :
i. Data
ii. Data flow
iii. Processing logic
* Process-oriented approach v.s. data-oriented approach
•Data- Raw facts that describe people, objects, and events in an organization
•Information-Data that have been processed and presented in a form suitable for human interpretation, often with the purpose of revealing trends or patterns
•processing logic -The steps by which data are transformed or moved and a description of the events that trigger the occurrence of these steps
•A process-oriented approach is defined as an overall strategy to information systems development that focuses on how and when data are moved through and changed by an information system.
•data-oriented approach -An overall strategy to information systems development that focuses on the ideal organization of data, rather than where and how data are used
• Team - IS manager, system analyst
(SA), programmers,
end-users, supporting end-user,
business managers,
other IS Managers/Technicians
Types of IS and System development
• Management Information system
• Decision support system (DSS)
• Expert systems
-Transaction processing systems automate the handling of data about business activities or transactions.
==>
- automate the handling of data about business activities or transactions
- data for each transaction are captured, verified, accepted or rejected.
- Reports may be produced immediately.
- The analysis & design of TPS focuses on the firm’s
current procedures for processing transactions.
- takes the relatively raw data through a TPS and converts them into a meaningful form.
- Often requires data from several transaction processing systems.
- Must be able to develop a comprehensive and
accurate model of data in building an MIS.
-Decision support systems are designed to help organizational decision makers make decisions by providing an interactive environment that uses data and models.
==>
- designed to help organizational decision makers make decisions
- provides an interactive environment in which decision makers can manipulate data and models of business operations
- concentrates on 3 main components:
• database
• model base
• user dialogue
-Expert systems represent attempts to codify and manipulate knowledge rather than information by mimicking experts in particular knowledge domains.
- used if-then-else rules or other knowledge representation forms that can describe the way an
expert would approach situations in a specific domain of problems.
- Need to acquire the knowledge of the expert in the particular problem domain.
-Systems development methodology
A standard process followed in an organization to conduct all the steps necessary to analyze, design, implement, and maintain information systems.
•Systems Development Life Cycle
The traditional methodology used to developed, maintain, and replace information systems.
What is methodology?
•The word Methodology is used in several ways.
•Methodology can refer to the science that studies the methods of problem solving. Most sciences have their own specific methodology.
•Methodology is sometimes used synonomously with "method," particularly a complex method or body of methods, rules, and postulates employed by a discipline. Some usage arbiters regard this usage as pretentious and questionable.
•In software engineering and project management, a methodology is a codified set of recommended practices, sometimes accompanied by training materials, formal educational programs, worksheets, and diagramming tools.
System development life cycle
•During the project identification and selection phase, an organization’s total information system needs are identified, analyzed, prioritized, and arranged.
•During the project initiation and planning phase, a potential IS project is explained, and an argument for continuing or not continuing with the project is made.
• During the analysis phase, the current system is studied, and alternative replacement systems are proposed.
•During the design phase, the description of the recommended solution is converted into logical and then physical system specifications.
• During the implementation phase, the information system is coded, tested, installed, and supported in the organization.
•During the maintenance phase, the system is systematically repaired and improved.
Other Approaches to Development
* Prototyping
an iterative process of systems development in which requirements are converted to a working system.
It will continually revised through close work between an analyst and users.
* Joint application design
a structured process in which users, managers, and analysts work together for several days in a series of intensive meetings to specify or review system requirements.
* Participatory design
focus on users and the improvement in their work lives.
*Rapid Application Development (RAD)
–Systems development methodology created to radically decrease the time needed to design and implement information systems. RAD relies on extensive user involvement. JAD sessions, prototyping, integrated CASE tools, and code generators.
Other Approaches to Development
CASE Tools
Computer Aided Software Engineering tools
-Software tools that provide automated support for some portion of the systems development process.
-an automated software tools used by systems analysts to develop information systems.
- It can be used to automate or support activities throughout the systems development process.
Agile Methodologies
•A more incremental process approach, called agile development, does much less up-front requirements analysis, but instead develops requirements in small increments as the process proceeds.
•The Agile Methodologies share three key principles:
–A focus on adaptive rather than predictive methodologies
–A focus on people rather than roles
–A focus on self-adaptive processes.
•Fowler(2003) recommends agile or adaptive process if the project involves:
–Unpredictable or dynamic requirements
–Responsible and motivated developers
–Customers who understand the process and will get involved
Comparing traditional and agile software processes.
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