Social-Technical Systems Flashcards
• Socio-technical systems include computer hardware, software and people and are designed to meet some business goal. • Human and organisational factors, such as the organisational structure, have a signicant effect on the operation of socio-technical systems. • Failure and success are not always absolute - they are always a judgement made from outside the system
Recap (What is a System, ICSE)
A system is a construct or collection of different elements that together produce results that are not obtainable by the elements alone.
Extra Notes on Systems
- Software engineering is not an isolated activity but is part of a broader systems engineering process.
- Software systems are therefore not isolated systems but are essential
components of broader systems that have a human, social or organisational purpose. - An embedded weather recording system is part of broader weather recording and forecasting systems.
- These include hardware and software, forecasting processes, system users, the organisations that depend on weather forecasts, etc.
The properties and behaviour of system components are inextricably (impossible to disentangle) intermingled (connected together). This leads to complexity.
Name all parts of the Socio-Technical System Stack?
Society
Organisation
Business Processes (System Engineering)
Application Systems (System Engineering / Software Engineering)
Communication and Data Management (System Engineering / Software Engineering)
Operating System (System Engineering / Software Engineering)
Equipment (System Engineering)
Describe each layer of the Socio-Technical Systems Stack
Equipment
- Hardware devices, some of which may be computers. Most devices will include an embedded
system of some kind.
Operating Systems
- Provides a set of common facilities for higher levels in the system.
Communications and Data Management
- Middleware that provides access to remote systems and databases
Application Systems
- Specific functionality to meet some organisation requirements
Business Processes
- A set of processes involving people and computer systems that support the activities of the business
Organisations
- Higher level strategic business activities that affect the operation of the system
Society
- Laws, regulation and culture that affect the operation of the system
What is a Socio-Technical system
A system, that includes hardware and software components, that has defined operational processes followed by human operators and which operates within an organisation. It is therefore influenced by organisational policies, procedures and structures.
Note on System Design
- There are interactions and dependencies between the layers in a system and changes at one level ripple through the other levels
- Example: Change in regulations (society) leads to changes in business processes and application software.
- For dependability, a system’s perspective is essential
- Contain software failures within the enclosing layers of the STS stack.
- Understand how faults and failures in adjacent layers may affect the
software in a system.
Name two system categories?
Technical Computer-Based Systems
- Systems that include hardware and software but where the operators and operational processes are not normally considered to be part of the system. The system is not self aware.
Socio-Technical Systems:
- Systems that include technical systems but also operational processes and people who use
and interact with the technical system.
- Socio-Technical Systems are governed by organisational policies and rules.
- Example: A publishing system to produce a book., Technological companies (Facebook, Twitter, WhatsApp)
Name three general characteristics of a Socio-Technical System?
Emergent Properties:
- Properties of the system as a whole that depend on the system components and their
relationships.
Non-Deterministic:
- They do not always produce the same output when presented with the same input because the system’s behaviour is partly dependent on human operators.
Complex Relationships with Organisational Objectives:
- The extent to which the system supports organisational objectives does not just depend on the system itself.
Explain in more detail about 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
An example of this is a fighter jet.
Name and describe some examples of emergent properties
Volume
- The volume of a system (the total space occupied) varies depending on how the component assemblies are arranged and connected.
Reliability
- System reliability depends on component reliability but unexpected interactions can cause new types of failures and therefore affect the reliability of the system.
Security
- The security of the system (its ability to resist attack) is a complex property that cannot be easily measured. Attacks may be devised that were not anticipated by the system designers and so may defeat built-in safeguards.
Repairability
- This property reflects how easy it is to x a problem with the system once it has been discovered. It depends on being able to diagnose the problem, access the components that are faulty, and modify or replace these components
Usability
- This property reects how easy it is to use the system. It depends on
the technical system components, its operators, and its operating environment.
What are the two types of emergent properties?
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. They are often critical for computer-based systems as failure to achieve some minimal
defined level in these properties may make the system unusable.
Note on Reliability of an Emergent Property
- Because of component interdependencies, faults can be propagated through the system.
- System failures often occur because of unforeseen inter-relationships between components.
- It is practically impossible to anticipate all possible component relationships.
- Software reliability measures may give a false picture of the overall system reliability
Name three influences on the reliability of a component.
Hardware Reliability
- What is the probability of a hardware component failing and how long does it take to repair that component?
Software Reliability
- How likely is it that a software component will produce an incorrect output. Software failure is usually distinct from hardware failure in that software does not wear out.
Operator Reliability
- How likely is it that the operator of a system will make an error?
Note: Failures are not independent and they spread from one level to another.
What is meant by the term ‘non-deterministic’ in relation to Socio-Technical Systems.
They do not always produce the same output when presented with the same input because the system’s behaviour is partly dependent on human operators.
People do not always behave in the same way, when using software systems.
System Behaviour can become unpredictable because of frequent changes to hardware, software and data.
How can we determine the success of a system?
A success of a system is a judgement and cannon be objectively measured.
Success in this case is judged by the effectiveness of the system when deployed.
Different stakeholders have their own views about whether or not a system is ‘successful’.
Note: Different stakeholders see the problem in different ways and each has a partial understanding of the issues affecting the system.
