Week 2 Flashcards
In 2005 what percentage of projects were delivered on time and in budget?
34%
How much did the FBI spend on it’s project and how long did it last before they declared they were not even close to a working system?
$M170
2001-2005
What was project Everest?
Ford Motors
$M200 over budget, abandoned softare project to buy supplies and replace legacy software
What was project Innovate?
McDonalds
$1B budget to monitor all aspects of operations
1999-2002, killed off after $170M wasted by no progress
What are 3 problems often occurring with software development?
Unreliable products - crashes, unexpected behaviour, etc
Expensive Maintenance - usually exceed estimates, often over 90% of effort on maint
Incorrect - bad communication means all parties have a different idea in their head about final product
What are some of the underlying difficulties of software development?
Complexity - programs get very complex very quickly, no two are quite alike
Changeability - operating environment is constantly changing, client’s system may be completely different to users, different platforms etc.
Invisibility - software is not a physical thing - difficult to see progress sometimes
What is software engineering?
application of engineering to software
branch of compsci dealing with large, complex software built by teams to last many years and undergo changes
Involves formal procedures and techniques
What 6 properties does every system have?
Input/Output
A purpose
A boundary and Environment
Subsystems and interfaces
Control with feedback/feedforward
Some emergent property - greater than sum of parts
What elements must every information system have?
Human activity that needs information
Stored data
Input method
Process that turns data into information
output method
In addition to the required properties of information systems, what other properties may information systems have?
Subsystems
Interfaces with other systems
What are 3 types of software?
Custom (bespoke) software
Commercial/Off-the-shelf software
Embedded software
What is bespoke software?
Made for one particular client
Developed in-house or outsourced
Usually unique to the client - i.e. particular set of requirements
What is commercial/off the shelf software?
Software sold on the open market
Often cheaper and more reliable than custom software, but less customisable/flexible
May not fit all client’s needs
Not unique to the client
What is embedded software?
Made for and runs on a particular piece of hardware
User may not even be aware of it
e.g. software inside dvd player or washing machine
What do requirement analysts do?
Work with the customers to identify and document the requirements
what do designers do?
generate a system-level description of what the system is supposed to do
What do programmers do?
Write the lines of code to implement the design
