Please enable JavaScript.
Coggle requires JavaScript to display documents.
Week Nine: Chapter Twelve: IS development (12.1 What is systems…
Week Nine:
Chapter Twelve: IS development
12.1 What is systems development?
Systems development / systems analysis:
process of creating and maintaining information systems
Requires:
establishing system goals
setting up the project
determining requirements
business knowledge and management skill
requires coordinated team work of both specialists and non- specialists with business knowledge
must construct / adapt procedures to fit your business and people, regardless of how you obtain the computer programs
12.2 Why is systems development difficult and risky?
Major challenges to system development
Difficulty of determining requirements
must create an environment where difficult questions are asked and answered?
what should a system do?
standards and exception reports? what specific features and functions do they have to utilise
Changes in requirements
aims at a moving target
requirements change as the system is developed
Scheduling and Budgeting Difficulties
how long to build it?
how long to create data model?
how long to do testing?
etc
need to answer these to perform a financial analysis
Changing Technology
technologies continue to change - do they stop and switch to new technology?, finish developing according to existing plan?
can they afford to keep changing the project?
Diseconomies of Scale
20 employees = diseconomies of scale
Brooks' Law:
adding more people to a late project make the project later
larger staff requires increased coordination but also need new training
existing team members train and taken off productive task
software development face a dilemma to increase work per employee in a small team & extend project's timeline or reduce timeline by adding staff but cause diseconomies of scale
12.3 What are the five phases of the Systems development life cycle (SDLC)?
12.4 How is a system definition accomplished?
12.5 What is the user's role in the requirements phase?
12.6 How are the five components designed
Systems development life cycle (SDLC):
traditional process used to develop information systems
1. System Definition
developers in this phase use management's statement of the system needs in order to begin to define the new system
2. Requirement Analysis
developers identify the particular features and functions of the new systems
output is a set of approved user requirements
3. Component Design
output is a set of approved user requirements, which become the primary input used to design system components
4. Implementation
developers implement, test and install the new system
5. Maintenance
users will find errors, mistakes and problems
will develop new requirements
description of fixes and new requirements I put into a system maintenance phase
maintenance phase starts the process all over again
12.4 How is Systems Definition accomplished?
the organisation will assign a few employees to define then new system, assess its feasibility and plan the project
1. Define system goals and scope
define the goals and purpose of the new system in terms of the organisation's competitive strategy
defined by specifying business activities and user / processes / locations that will be involved
2. Assess Feasibility
aim to eliminate obviously non-sensible projects before forming a project development team and investing significant labour
cost feasibility:
approximates total cost and compares it to the system value
schedule feasibility:
difficult to determine because it is hard to estimate the time it takes to build the system
technical feasibility:
refers to whether existing information technology can meet the needs of the new system
organisational feasibility:
concerns whether the new system fits within the organisation's customs, culture, charter or legal requirements
3. Form a Project team
typical development team:
systems analyst, managers, programmers, software testers, users, outside contractor
team composition changes over time
user involvement is critical - review and oversight committees that meet periodically, especially at the completion of project phases and other milestones
12.5 What is the user's role in the requirements phase?
aim:
determine and document the specific features and functions of the new system
1. Determine requirements
requirements need to be determined correctly, then design and implementation will be easier
requirements include what is to be produced, frequency and how fast
conduct user interviews to bring requirements to light
2. Approve requirements
users must review and approve them before the project continues
easiest and cheapest time to alter system is now
3. Role of a prototype
needs to work, mockup forms and reports and needs to put the user into the experience of employing the system to do his / her tasks
can be expensive but justified for greater clarity and completeness of requirements
dilemma of funding prototypes
12.6 How are the five components designed?
teams design each component by developing alternatives, evaluating each of those alternatives against the requirements and then selecting among those alternatives
1. Hardware Design
team designs specifications for the hardware it needs and the source of it
purchase, lease or lease time from a hosting service in the cloud
2. Software Design
software design depends on source of programs:
off the shelf software
off the shelf with alteration software
custom developed programs
decide where application processing will occur
mobile devices
processing can occur on cloud servers or a mixture
thin client or native application?
3. Database design
convert data model to database design using techniques
if using off the shelf programs, then little database design needed the programs will handle their own database processing
4. Procedure design
Normal processing:
Users:
procedures for using the system to accomplish business tasks
Operations personnel:
procedures for starting, stopping and operating the system
Backup
Users & operations personnel:
user procedures for backing up data and other resources
Failure recovery
users:
procedures to continue operations when the system fails
procedures to convert back to the system after recovery
operations personnel:
procedures to identify the source of failure and get it fixed
procedures to recover and restart the system
5. Design of job descriptions
teams of systems analysts and users determine job descriptions, functions for users and operations personnel
new IS may create new jobs
12.7 How is an information system implemented?
obtain, install and test new systems
1. System testing
developers need to test all of the components and devise a system to assign fixes to people and to verify that the fixes are correct and complete
test plan:
consists of sequences of actions that users take when using the new system
include normal actions that users will take but also incorrect actions
Product quality assurance (PQA):
construct the test plan with the advice and assistance of users
Beta testing:
process of allowing future system users to try out the new system of their own
products in beta test phase are usually complete and full functioning
2. System conversion approaches
pilot:
implements entire system in limited portion of the business
limits exposure to business if system fails
phased:
system installed in phases or modules
each piece installed and tested
parallel:
complete new and old systems run simultaneously
very safe, but expensive
plunge:
high risk if new system fails
only if new system not vital to company operation
3. Design and implementation for the five components
Hardware:
Design:
determine specification
Implementation:
obtain, install and test hardware
Software
Design:
select off-the-shelf programs, design alterations and custom programs
implementation:
license program and write
alternations
Data
design:
design database and related structures
implementation:
create database. fill and test data
Procedures
design:
design user and operations procedures
implement:
document procedures. create training programs. review and test procedures
people
design:
develop user and operations job descriptions
implementation:
hire and train
12.8 What are the tasks for system maintenance?
either fix the system so that it works correctly or to adapt it to changes in requirements
record requests for change:
failures / enhancements
prioritise requests
fix failures:
patches: software developers group fixes for high priority failures into a patch
service packs: bundle fixes of low-priority problems into larger groups
new releases
12.9 What are some of the problems with the SDLC?
SDLC waterfall method:
processes are supposed to operate in a sequence of non-repetitive phases
Requirements documentation difficult
business requirements change
"analysis paralysis" - spend so much time on documentation, it hampers progress
scheduling and budgeting difficulties
time and cost estimates for a large project way off
people who make initial estimates know little about how much time it will take or cost