Fundamentals of Information Technology Lecture 6 : Systems Concepts

Transcription

1 Fundamentals of Information Technology Lecture 6 : Systems Concepts

2 Session Structure Session Objectives Information Systems Roles Information Systems Definition Designing an Information System Systems Analysis Information Engineering SSADM Client Service Cycle Key Concepts Summary Discussion Questions

3 Session Objectives Understand The concept of an Information System How to analyse an Information System How information is organised & processed in Information Systems Some other key IS Concepts

4 Information Systems Roles Information systems perform three vital roles in business firms. They support: Business processes and operations Business decision making Strategic competitive advantage Major application categories of information systems include: Operations Support Systems Management Support Systems Enterprise Management Systems

5 Information Systems A number of components related to each other in a definable way Components can be created separately then assembled into more complex structures Relationships can be altered depending on how components are arranged or need to interact The definition of processes can be altered depending on the business needs

6 What is an Information System? Control of ofsystem Performance Input of of Data Resources Processing Data Output of of Information Products Storage of ofdata Resources

7 Designing an Information System Define content of each of the 5 elements Data Processing steps Define the relationships between the 5 elements Information flows

8 Systems Analysis Systems analysis is an in-depth study of end user information needs that produces functional requirements. 3 examples of Systems Analysis methodologies: Information Engineering Structured Systems Analysis & Design (SSADM) Client Service Cycle Model

9 Systems Analysis Traditionally involves a detailed study of Information needs of the company & end users Activities, resources, & products of one or more of the present information systems The IS capabilities required to meet information needs of the company, the end users, and all business stakeholders that may use the system

10 Systems Analysis Organizational analysis Study Management structure The people Business activities Environmental systems The current information system

11 Systems Analysis Analysis of the present system Analyze how the present system.. Uses hardware Uses software Is networked Uses people resources to convert data resources into information products. How the IS activities of input, processing, output, storage, and control are accomplished.

12 Systems Analysis Functional requirements analysis What type of information does each business activity require? Format, volume, frequency, response times What are the information processing capabilities required? Input, processing, output, storage, control

13 Systems Analysis Functional requirements analysis (continued) Finally, develop functional requirements End user information requirements that are not tied to the hardware, software, network, data, and people resources Goal identify what should be done identify what should be done, not how to do it.

14 Information Engineering 3 key techniques : Functional Decomposition Show the various functions in the organisation Entity Relationship Models Show the relationship between each user of information Function/Entity Matrix Show the interaction between functions and entities See IPA diagrams - pages 80-82

15 SSADM 3 key techniques : Dataflow diagrams Show the movement of data through an organisation Logical Data Structures Identify the different data stores, and relationships between them (like entity models) Entity Life History Shows activities which impact on an entity See IPA diagrams - pages 83-84

16 Client Service Cycle Concept developed by Karl Albrecht Views organisations as Service Systems Service Management Quality is the #1 driver for success Cycle of Service Continuous chain of events providing service Moments of Truth Interaction points with customers Departmental Hand-Offs Moments in cycle where control passes from 1 dept to another See IPA page 85

17 Key Concepts - Processing Batch Processing Transactions are logged and stored, then processed in batches Example banks logging cheques through the day then processing them all into the system for clearing overnight Older concept now becoming less common, as data is always out of date Online Processing Transactions occur and are processed in realtime at the moment they happen Keeps systems bang up to date

18 Key Concepts - Processing Centralised Processing Data is transferred to a central point, then processed there Puts all processing eggs in 1 basket Distributed Processing Processing can be done at several points geographically spread Data may well be brought together to a central master system later More fault tolerant the idea on which the Internet is based

19 Key Concept - Logical Data Elements Name Field Payroll Record Payroll File Personnel Database

20 Key Concepts File Types Master File Basic information file, updated by input data Transaction File Temporary collections of input records e.g. new orders used to update Master Files. Report Files Temporary outputs from a system, may be produced on paper or screen Backup Files Copies of files kept for security purposes Library Files Collections of computer programs

21 Summary We ve covered The concept of an Information System How to analyse an Information System How information is organised & processed in Information Systems Some other key IS Concepts

22 Discussion Questions Name and describe 3 ways to perform Systems Analysis Explain how data is logically broken down in any IT system What issues should managers understand when thinking about creating a new Information System?