Elective 4: Week 1 - 3

Information System

Information System

Is an interconnected set of components used to collect, store, process and transmit data and digital information

Information System

At its core, it is a collection of hardware, software, data, people and processes that work together to transform raw data into useful information.

Hardware

Networks

Software

Data

People

Processes

Typical Components of Information System

Hardware

An IS includes computers and servers

Computer hardware

Is essential for providing users with access to the system

Servers

Provide storage space for data, programs and applications that make up the system

Networks

Such as local area networks (LANs), wide area networks (WANs), intranets and cloud networks are important for interconnecting different components and allowing user access from anywhere in an organization.

Software

Is an integral part of an IS

Operating systems

Provide underlying platforms, while databases allow users to store and retrieve large amounts of data

software packages

An enterprise may run on hundreds of different software applications, as well as large _____ that integrate multiple applications

Data

This includes structured data stored in databases, as well as unstructured data such as text documents, images or audio files. Users can access this data through various applications within the system for reporting or analysis purposes.

People

Play a key role in any IS, from administrators who manage the system itself to users who interact with it daily.

People

End users must become familiar with interfaces and learn to perform tasks within the system to get work done.

Processes

Governing how components work together within an IS are critical. I

Processes

IT leaders must define procedures for everything from setting up secure user accounts to creating emergency backup plans.

Processes

Understanding how all these pieces fit together is essential for an IS to meet a company's needs effectively.

Input

Processing

Output

Feedback

Basic process of an IS

Input

This phase involves gathering raw data from both internal and external sources.

Processing

Raw input is transformed into a meaningful and usable format during this stage.

Output

Processed information is then delivered to individuals or activities within the organization for their use.

Feedback

Which is essentially output that is sent back to the organization's members

Systems analysts

Serve as intermediaries between users and developers, gathering and analyzing requirements, and designing system solutions.

INFORMATION SYSTEMS ANALYSIS AND DESIGN

Is a complex process for creating and maintaining computer-based systems that enhance an organization's products and services. It's driven by an organization's needs and involves a team of professionals

Methodologies

Techniques

Tools

ELEMENTS OF SYSTEMS ANALYSIS AND DESIGN

Methodologies

Are structured approaches to system development that impact the final product, aligning with an organization's management style and usually integrating various development techniques.

Techniques

Are specific processes used by analysts to ensure thorough and comprehensible work. They aid in tasks such as conducting interviews, project planning, system logic diagramming, and report design within systems development projects

Tools

Often computer programs, streamline the use of techniques and ensure adherence to the development methodology. It's essential that both techniques and tools align with the organization's chosen methodology, simplifying the process for developers

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 (SDLC)

The traditional methodology used to develop, maintain, and replace information systems.

Planning

Analysis

Design

Implementation

Maintenance

PHASES OF SYSTEMS DEVELOPMENT LIFE CYCLE

Planning

The first phase of the SDLC in which an organization’s total information system needs are identified, analyzed, prioritized, and arranged.

Analysis

The second phase of the SDLC in which system requirements are studied and structured.

Design

The third phase of the SDLC in which the description of the recommended solution is converted into logical and then physical system specifications.

Logical Design

Physical Design

Type of Design in SDLC

Logical design

The part of the design phase of the SDLC in which all functional features of the system chosen for development in analysis are described independently of any computer platform.

Physical design

The part of the design phase of the SDLC in which the logical specifications of the system from logical design are transformed into technology-specific details from which all programming and system construction can be accomplished.

Implementation

The fourth phase of the SDLC, in which the information system is coded, tested, installed, and supported in the organization

Maintenance

The final phase of the SDLC, in which an information system is systematically repaired and improved.

Software

Is a program or set of programs containing instructions that provide desired functionality

Engineering

Is the process of designing and building something that serves a particular purpose and finds a cost-effective solution to problems.

Software Engineering

Is the process of designing, developing, testing, and maintaining software. It is a systematic and disciplined approach to software development that aims to create high-quality, reliable, and maintainable software.

Origin of Software

The evolution of software can be traced back to the invention of the first programmable computers in the mid-20th century, such as the ENIAC and UNIVAC

Software Process

Is a set of related activities that leads to the production of a software product.

Software Process

These activities may involve the development of software from scratch in any standard programming language.

Software specification

Software design and implementation

Software validation

Software evolution

Four activities that are fundamental to software engineering:

Software specification

The functionality of the software and constraints on its operation must be defined.

Software design and implementation

The software to meet the specification must be produced.

Software validation

The software must be validated to ensure that it does what the customer wants.

Software evolution

The software must evolve to meet changing customer needs

Products

Roles

Pre-and post-conditions

Process descriptions may also include:

Products

Which are the outcomes of a process activity. For example, the outcome of the activity of architectural design may be a model of the software architecture.

Roles

Which reflect the responsibilities of the people involved in the process. Examples of roles are project manager, configuration manager, programmer, etc.

Pre- and post-conditions

Which are statements that are true before and after a process activity has been enacted or a product produced.

Software process models

Are simplified representations of software processes that provide partial information about the process from a particular perspective.

Software process models

They are abstractions of the process that can be used to explain different approaches to software development.

Waterfall Model

Incremental development

Reuse-oriented software engineering

Some commonly used process models include:

Waterfall Model

Which represents the fundamental process activities as separate process phases such as requirements specification, software design, implementation, and testing .

Waterfall Model

Is a plan-driven process that requires planning and scheduling all process activities before starting work on them.

Requirements analysis and definition

System and software design

Implementation and unit testing

Integration and System Testing

Operation and Maintenance

The principal stages of the waterfall model directly reflect the fundamental development activities

Requirements analysis and definition

Define the System’s specification and its goals through consultation with system users.

System and software design

Allocate requirements to hardware and software, establish system architecture, and design software components.

Implementation and unit testing

Turn designs into programs and verify each unit meets its specifications.

Integration and System Testing

Combine and test program units to ensure all requirements are met before customer delivery

Operation and Maintenance

Deploy the system, address errors, enhance components, and adapt to new requirements over time.

Formal System Development

Is ideal for systems with stringent safety, reliability, or security requirements. It simplifies the creation of safety or security cases to demonstrate compliance with these requirements.

Formal System Development

A variation of the Waterfall Model

Incremental Development

Involves developing an initial implementation, evolving it through several versions based on user feedback.

Reduced cost for accommodating changing customer requirements

Easier customer feedback on development progress

The possibility of delivering useful software earlier

Incremental development offers three key advantages over the waterfall model

lack of visibility and degradation of system structure over time

making further changes difficult and costly

The incremental approach in software development has two management problems

Incremental development

Is complex for large, multi-team systems, necessitating a stable architecture and well-defined roles

Reuse-oriented software engineering

Software reuse is common in software projects, both informally and through reuse-oriented approaches

Reuse-oriented software engineering

Rely on a large base of reusable software components and an integrating framework.

requirement specification

component analysis

requirements modification

system design with reuse

development and integration

system validation

The process model for reuse-based development includes stages such as

Component Analysis

Requirements Modification

System Design with Reuse

Development and Integration

Reuse-based development stages

Component Analysis

Identify components for requirements implementation, which may only partially match the needs.

Requirements Modification

Adjust requirements based on component insights, revisiting the component analysis if necessary.

System Design with Reuse

Design the system framework, incorporating reusable components and creating new ones if needed.

Development and Integration

Develop non-reusable software components and integrate them with Commercial Off-The-Shelf systems. Integration is often part of the development process.

Web services that are developed according to service standards and which are available for remote invocation.

Collections of objects that are developed as a package to be integrated with a component framework such as .NET or J2EE.

Stand-alone software systems that are configured for use in a particular environment.

Three types of software component that may be used in a reuse-oriented process

Software specification

Software design and implementation

Software validation

Software evolution

Process activities

Process activities

Real software processes involve technical, collaborative, and managerial activities, utilizing various tools to specify, design, implement, and test software systems.

Process activities

These processes can be organized sequentially or interleaved, depending on the development approach, and may include activities like specifying requirements, creating preprogramming tests, and system restructuring during evolution

Software specification

Is the process of understanding and defining the required services and constraints for a system

CASE tools

Support the software engineering process by automating activities such as graphical system modeling, code generation, user interface creation, program debugging, and program translation.

Feasibility study

Requirements elicitation and analysis

Requirements specification

Requirements validation

There are four main activities in the requirements engineering process

Feasibility Study

Assesses if user needs can be met within budget and technology constraints.

Requirements Elicitation and Analysis

Involves deriving system requirements from observations, discussions, and may include creating models

Requirements Specification

Translates gathered information into a document that defines user and system requirements.

Requirements Validation

Ensures requirements are realistic, consistent, and complete, correcting any errors in the document.

Software design and implementation

The implementation stage of software development involves converting a system specification into an executable system, which includes software design and programming.

architectural design

interface design

component design

database design

The design process for information systems includes

Architectural Design

Defines the overall system structure, key components, their relationships, and distribution

Interface Design

Specifies unambiguous interfaces between components, enabling concurrent development.

Component Design

Involves designing individual components, which may include functionality statements or detailed design models.

Database Design

Focuses on data structures and their representation in the database, whether reusing an existing one or creating a new database.

Software validation

Also known as verification and validation (V&V), ensures that a system conforms to its specification and meets customer expectations.

component testing

system testing

acceptance testing

The stages in the testing process

Component testing

Involves testing individual system components independently.

System testing

Integrates components to create a complete system and checks for errors and interface problems

Acceptance testing

Is the final stage before operational use and tests the system with real customer data.