Software Processes

Question 1

what is a process

Answer 1

series of activities

Question 2

Name some characteristics of processes

Answer 2

pescribes all major activities.
Has entry and exit criteria
organized in a sequence
contraints may apply

Question 3

what is a life cycle

Answer 3

process involves the building of some product.

Question 4

What is the software process

Answer 4

structured set of activities require to develop a software system consisting of specification, design and implementation, validation and evolution.

Question 5

What is a software process model

Answer 5

abstract representation of a process.

Question 6

What is the waterfall problem

Answer 6

seperate and distinct phases of specification and development

Question 7

Problems with waterfall problem

Answer 7

difficult of accomodating change after the process is underway - inflexible partioning. static view of requirements so ignores changing needs. Lack of user involvement. Problems arent detected until late in the process.

Question 8

Where is the waterfall model used in?

Answer 8

military and aerospace industries

Question 9

When is it appropriate to use the waterfall model?

Answer 9

when the final requirements are well understood which is rare

Question 10

Advantages of waterfall model

Answer 10

easy to remember
each step is an important step in software development
squence is important. Design before code.

Question 11

What is evolutionary development

Answer 11

based upon the idea of developing an initial implementation, exposing to user and refining it based on their response.

Question 12

what is throw away prototyping

Answer 12

understand system requirements. Start with poorly understood requirements. Develop quick and dirty system, expose to user comment, refine.

Question 13

Problems with evolutionary development

Answer 13

lack of process visibility, systems are sometimes poorly structred, special skills may be required. Used in all types of system but rare in safety critical.

Question 14

What is formal systems development?

Answer 14

based on the transformation of a mathematical specification.

Question 15

what does correctness preserving mean in terms of transformation?

Answer 15

program conforms to its specification. Embodied in the ‘cleanroom’ approach.

Question 16

Problems with formal system development

Answer 16

need for specialised skill and training. (higher inital cost).
can be difficult to formally specify aspects of the system like user interface
can be more time consuming
Used in critical systems

Question 17

what is incremental development?

Answer 17

development and delivery is broken down into increments. User requirements are prioritised and once development is started the requirements are frozen so later increments continue to evolve.

Question 18

name some advantages of increment development

Answer 18

customer value
early increments
lower risk of overall project failure
highest priority system services tend to recieve more testing

Question 19

In reality, which method of development to software use and why?

Answer 19

Prototyping and iterative buiding as it reduces the risk of making wrong product, allows the software to undergo more testing, less chance of inventory loss.

Question 20

what is the software specification

Answer 20

process of establishing what services are required and the constraints.

Question 21

Name some design process activities

Answer 21

architectural design (sub systems)
abstract specification
interface design
component design
data structure design
algorithm design

Question 22

what is a model

Answer 22

graphical view of the operation/structure of the system. Can be dynamic or static.

Question 23

Why have models?

Answer 23

formalises the type and format of require info.
easier to get a big picture than text
do not rely on natural language.

Question 24

what is verification, validation and system testing

Answer 24

verification - systems conforms to its specifications
validation - meets the requirements of the user
system testing involves executing the system with test cases

Question 25

name some testing stages

Answer 25

unit testing, module testing, sub system testing, system testing, acceptance testing.

Question 26

What is CASE?

Answer 26

software to support software development and evolution process. Doesnt support teach activities.