28-07-2012, 02:49 PM
Evolution & Impact of Software engineering & Socio-technical Systems
[attachment=29397]
Topics covered
Evolution & Impact of Software engineering
Emergent system properties
Systems and their environment or Systems engineering
The system design process
System Procurement
Evolution & Impact of Software engineering
Evolved over the past 50 years
Early Programmer used an exploratory programming style
Programmer developed software techniques guided by his own intuition, experience etc..
It was an art
Esoteric use of past experience
Then changed from an esoteric art to craft form & slowly emerged as an engineering discipline
Software Engineering
Software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance & refinement of software.
Engineering approach to develop software
Systematic collection & use of past experience
Why Study Software Engineering
To acquire skills to develop large programs
Ability to solve complex programming problems
Learn techniques of specification, design, user interface development, testing, project management etc
To acquire skills to be a better programmer
What is a system?
A purposeful collection of inter-related components working together towards some common objective.
A system may include software, mechanical, electrical and electronic hardware and be operated by people.
System Engineering : It is the activity of specifying, designing, implementing, validating, deploying & maintaining systems as awhole
Emergent properties
Properties of the system as a whole rather than properties that can be derived from the properties of components of a system
Emergent properties are a consequence of the relationships between system components
They can therefore only be assessed and measured once the components have been integrated into a system
Examples of emergent properties
The overall weight of the system
This is an example of an emergent property that can be computed from individual component properties.
The reliability of the system
This depends on the reliability of system components and the relationships between the components.
The usability of a system
This is a complex property which is not simply dependent on the system hardware and software but also depends on the system operators and the environment where it is used.
Types of emergent property
Functional properties
These appear when all the parts of a system work together to achieve some objective. For example, a bicycle has the functional property of being a transportation device once it has been assembled from its components.
Non-functional emergent properties
Examples are reliability, performance, safety, and security. These relate to the behaviour of the system in its operational environment.
Systems and their environment
Systems are not independent but exist in an environment
System’s function may be to change its environment
Environment affects the functioning of the system e.g. system may require electrical supply from its environment
The organizational as well as the physical environment may be important
Human and organisational factors
Process changes
Does the system require changes to the work processes in the environment?
Job changes
Does the system de-skill the users in an environment or cause them to change the way they work?
Organisational changes
Does the system change the political power structure in an organisation?
System architecture modelling
An architectural model presents an abstract view of the sub-systems making up a system
May include major information flows between sub-systems
Usually presented as a block diagram
May identify different types of functional component in the model
Intruder alarm system
Sensor
Movement sensor
door sensor
Actuator
Siren
Communication
Telephone caller
Co-ordination
Alarm controller
Interface
Voice synthesizer
The system engineering process
Usually follows a ‘waterfall’ model because of the need for parallel development of different parts of the system
Little scope for iteration between phases because hardware changes are very expensive. Software may have to compensate for hardware problems
Inevitably involves engineers from different disciplines who must work together
Much scope for misunderstanding here. Different disciplines use a different vocabulary and much negotiation is required. Engineers may have personal agendas to fulfil
[attachment=29397]
Topics covered
Evolution & Impact of Software engineering
Emergent system properties
Systems and their environment or Systems engineering
The system design process
System Procurement
Evolution & Impact of Software engineering
Evolved over the past 50 years
Early Programmer used an exploratory programming style
Programmer developed software techniques guided by his own intuition, experience etc..
It was an art
Esoteric use of past experience
Then changed from an esoteric art to craft form & slowly emerged as an engineering discipline
Software Engineering
Software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance & refinement of software.
Engineering approach to develop software
Systematic collection & use of past experience
Why Study Software Engineering
To acquire skills to develop large programs
Ability to solve complex programming problems
Learn techniques of specification, design, user interface development, testing, project management etc
To acquire skills to be a better programmer
What is a system?
A purposeful collection of inter-related components working together towards some common objective.
A system may include software, mechanical, electrical and electronic hardware and be operated by people.
System Engineering : It is the activity of specifying, designing, implementing, validating, deploying & maintaining systems as awhole
Emergent properties
Properties of the system as a whole rather than properties that can be derived from the properties of components of a system
Emergent properties are a consequence of the relationships between system components
They can therefore only be assessed and measured once the components have been integrated into a system
Examples of emergent properties
The overall weight of the system
This is an example of an emergent property that can be computed from individual component properties.
The reliability of the system
This depends on the reliability of system components and the relationships between the components.
The usability of a system
This is a complex property which is not simply dependent on the system hardware and software but also depends on the system operators and the environment where it is used.
Types of emergent property
Functional properties
These appear when all the parts of a system work together to achieve some objective. For example, a bicycle has the functional property of being a transportation device once it has been assembled from its components.
Non-functional emergent properties
Examples are reliability, performance, safety, and security. These relate to the behaviour of the system in its operational environment.
Systems and their environment
Systems are not independent but exist in an environment
System’s function may be to change its environment
Environment affects the functioning of the system e.g. system may require electrical supply from its environment
The organizational as well as the physical environment may be important
Human and organisational factors
Process changes
Does the system require changes to the work processes in the environment?
Job changes
Does the system de-skill the users in an environment or cause them to change the way they work?
Organisational changes
Does the system change the political power structure in an organisation?
System architecture modelling
An architectural model presents an abstract view of the sub-systems making up a system
May include major information flows between sub-systems
Usually presented as a block diagram
May identify different types of functional component in the model
Intruder alarm system
Sensor
Movement sensor
door sensor
Actuator
Siren
Communication
Telephone caller
Co-ordination
Alarm controller
Interface
Voice synthesizer
The system engineering process
Usually follows a ‘waterfall’ model because of the need for parallel development of different parts of the system
Little scope for iteration between phases because hardware changes are very expensive. Software may have to compensate for hardware problems
Inevitably involves engineers from different disciplines who must work together
Much scope for misunderstanding here. Different disciplines use a different vocabulary and much negotiation is required. Engineers may have personal agendas to fulfil