Chapter 12 Design and Implementation 2024 PDF

Chapter 12 Design and Implementation INF112 Principles  Designing new systems or modifying existing ones should always help an organisation achieve its goals  The primary emphasis of systems implementation is to make sure that the right information is delive...

Chapter 12 Design and Implementation INF112 Principles  Designing new systems or modifying existing ones should always help an organisation achieve its goals  The primary emphasis of systems implementation is to make sure that the right information is delivered to the right person in the right format at the right time  Maintenance and review add to the useful life of a system but can consume large amounts of resources. These activities can benefit from the same rigorous methods and project management techniques applied to systems development  Systems design  Answers the question: how will the information system solve a problem?  Results in a technical design  Details system outputs, inputs, and user interfaces  Specifies hardware, software, databases, telecommunications, personnel, and procedures  Shows how these components are related Logical and Physical Design Logical design: description of functional requirements of a system Output, input, process, file, and database Telecommunications, procedures, controls, and security Personnel and job requirements Physical design: specification of characteristics of system component necessary to put logical design into action Characteristics of hardware, software, database, telecommunications, and personnel Procedure and control specifications Interface design and controls Characteristics of how users access and interact with system Sign-on procedure Interactive processing Menu-driven system Help facility Lookup tables Restart procedure Good interactive design 6 Design of system security and controls  Preventing, detecting, and  Systems controls: rules and procedures to correcting errors maintain data security  Disaster planning and recovery  Deterrence controls: rules and procedures to prevent problems before they occur Disaster planning: process of anticipating and providing  Closed shops: only authorised operators can run computers for disasters  Open shops: other personnel, such as Disaster recovery: programmers and analysts, may also run implementation of disaster computers plan Approaches Hot site Cold site Incremental backup Generating systems design alternatives  Consider many factors when selecting a vendor >> Reliability, stability, services, reviews, etc.  Request for proposal (RFP): document that specifies required resources such as hardware and software in detail  Financial options: consider scalability Purchase Lease Rent Generating systems design alternatives Evaluating and selecting a systems design Preliminary evaluation To dismiss unwanted proposals Begins after all proposals have been submitted Final evaluation Detailed investigation of proposals remaining after preliminary evaluation Acquiring software: Make or buy? Bespoke versus off-the-shelf software Bespoke: High cost Software should exactly match needs Quality can vary depending on the programming team Can take years to develop Can develop a competitive advantage with good software Off the shelf: Lower cost Might not exactly match needs Usually high quality Can acquire it now Other organisations will have the same software and therefore it won’t give anyone an advantage  Acquiring database & telecommunications systems  Databases are a blend of hardware and software  Telecommunications systems require a blend of hardware and software  Earlier discussion on acquiring hardware and software also applies to acquisition of: Database systems Telecommunications hardware and software User preparation  Readying managers, decision makers, employees, other users, and stakeholders for new systems  Training users IS personnel: Hiring and training  Personnel that might be needed for new system  IS manager  Systems analysts  Computer programmers  Data-entry operators  Training programs should be conducted for IS personnel who will be using the system Site preparation  Preparation of the location of a new system  May involve: Making room for a computer in an office Special wiring and air conditioning Renovation of entire room Special floor Additional power circuits Data preparation  Ensuring all files and databases are ready to be used with new computer software and systems  Also called data conversion Installation  Process of physically placing computer equipment on the site and making it operational  Normally, manufacturer is responsible for installing computer equipment  Someone from the organisation (usually IS manager) should oversee the process  Unit testing: testing of individual programs System testing: testing entire system of programs Volume testing: testing the application with a large amount of data Testing Integration testing: testing all related systems together Acceptance testing: conducting any tests required by user Alpha testing: testing an incomplete or early version of system Beta testing: testing a complete and stable system by end users 17 Start-Up  Process of making the final tested information system fully operational  Approaches Direct conversion (big bang, plunge, direct cutover) Phase-in approach (piecemeal) Pilot start-up Parallel start-up User acceptance  User acceptance document: formal agreement signed by user that states that a phase of installation or the complete system is approved Legal document that removes or reduces IS vendor’s liability  Systems operation and maintenance Systems operation: Use of a new or modified system Help desk provides support Systems maintenance: Types of maintenance: Checking, changing, and enhancing  Slipstream upgrade: minor upgrade the system to make it more useful in  Patch: fix a problem or make small achieving user and organizational enhancement goals Difficult and costly for legacy systems  Release: significant program change requiring new documentation Autonomic computing allows computers to manage themselves  Version: major program change with new features The financial implications of maintenance  Total maintenance expenditures increase in time and money as programs age For older programs, total cost of maintenance can be System Review up to five times greater than total cost of development  Analysis of systems to make sure that they are operating as intended  Determining factor in decision to replace a system  Often compares performance and Costs more to fix than benefits of designed system with replace system actual performance and benefits of operational system Factors to consider during systems review  Mission  Training  Organisational goals  Costs  Hardware and software  Complexity  Database  Reliability  Efficiency  Telecommunications  Response time  Information systems personnel  Documentation  Control  Systems design answers the question: “How will the information system solve a problem?”  Logical design: description of functional requirements of a system  Physical design: specification of characteristics of the system components necessary to put the logical design into action  Steps of systems implementation: hardware acquisition, software acquisition, user preparation, personnel hiring and training, site preparation, data preparation, installation, testing, start-up, and user acceptance  Systems operation: use of a new or modified system  Systems maintenance: checking, changing, and enhancing the system to make it more useful in achieving user and organisational goals