Week 1 Flashcards
Information System
A system integrating IT, BUSINESS & PEOPLE
brings business functions and information modules -> effective communication channels => timely and accurate decisions -> organisational productivity and competitiveness
What does an Information System Consists Of
Interrelated computer components for
- collecting
- storing
- processing
- analysing data
to produce information to meet business needs
Why Use Information System
Manage information for an organisation
-> provides functionalities
better systems = more productive = more profits
What is to be considered when designing a system
Information
Functions
Actions perform by the system on data
CRUD Create Read Update Delete
Deep structure
Core representation of the world in the system
Objects represented by data and state transitions and managed through system functions
Surface structure
Information presented at the surface or interface of the system
i.e. printed report versus display on smartphone
User interface
Physical structure
Physical elements of technology (hardware)
3 Levels of Representation
Deep, surface and physical
Logical separation of Information system (architecture)
Resource management (data layer)
Business application (logic layer)
Presentation (user interface) layer
Separated as tiers
1 Tier
3 layers running in one machine i.e. mainframes
- centralised (no distribution)
- layers tightly connected
- difficulty with scalability and portability
2 Tier
Client server architecture
presentation layer runs on client machine
data layer on the server
Thick/Thin client
3 Tier
Each layer almost independent and running on a separate tier
-Middleware platforms supporting access through the WEb aka application servers
N-tier architecture
Incorporating web servers
scalable, portable, easy to manage
System Development Life Cycle (SDLC)
Includes detailed plan of all the activities needed for building, developing, modifying and maintaining an information sys
Stages in the SDLC
- Planning
- Analysis
- Design
- Implementation
SDLC: Planning
Feasibility study Project plan Structure Timeline Budge Why?
SDLC: Analysis
Understanding the business needs and requirements and documenting the requirements using a set of models and specifications
Identifying solution to the problem
SDLC: Design
Design database (database structure, internal properties, security and encryption, distribution and fragmentation, intergration)
Design application architecture and software (partitioning software into subsystems, infrastructure, layers and distribution, detailed desing)
Design user interfaces (prototypes)
Design system interfaces (the interface that enables a new IS to share information with others)
Design the environment (all technology, hardware, software, operating systems, DBMS, communication protocols, software applications)
Design system controls and security (limiting access to authorised users
SDLC: Implementation
Testing, deployment, intergration and maintenance of the developed system
Methodologies
Guidelines for carrying out all of the activities of each core process of the SDLC
Includes
Models, techniques & tools
Modelling approaches (structure (ER) or object oriented (UML)
Thick Client
2 tier architecture
Presentation needs additional software
Thin Client
2 tier architecture
Presentation is done lightly
