introducing sociotechnical systems

Introducing sociotechnical systems, 2013 Slide 1

Introducing socio-technical systems

Ian Sommerville

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What is a system?

A system is a purposeful collection of inter-related components working together to achieve a common objective.

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Image credit: http://www.nagsma.nato.int/

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• A system may include software, mechanical, electrical and electronic hardware. People are responsible for its installation and operation.

• Systems are procured, owned and operated by organizations.

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• The properties and behaviour of system components are inextricably inter-mingled. This leads to complexity.

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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.

– Example: A word processor used to write a book.

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Sociotechnical systems• Sociotechnical systems

– Systems that include technical systems but also operational processes and people who use and interact with the technical system.

– Example: A publishing system to produce a book.

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An automated weather station is part of broader sociotechnical weather recording and forecasting systems

These include hardware and software, forecasting processes, system users, the organizations that depend on weather forecasts, etc.

Introducing sociotechnical systems, 2013 Slide 10Image credit: http://cimss.ssec.wisc.edu/

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The socio-technical systems stack

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Layers in the STS stack

• Equipment– Hardware devices, some of which may

be computers. Most devices will include an embedded system of some kind.

• Operating system– Provides a set of common facilities for

higher levels in the system..

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• Communications and data management– Middleware that provides access to

remote systems and databases.

• Application systems– Specific functionality to meet some

organization requirements

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Layers in the STS stack

• Business processes– A set of processes involving people

and computer systems that support the activities of the business.

• Organizations– Higher level strategic business

activities that affect the operation of the system.

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• Society– Laws, regulation and culture that

affect the operation of the system.

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Layer interdependencies

• There are interactions and dependencies between the layers in a system

• Many changes are cross-cutting so that changes at one level ripple through the other levels

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Changing banking regulations

• Society changes banking regulations to allow greater control of risky lending

• This requires changes to bank’s business processes

• Application systems have to be changed to support this

• Databases may have to record more information

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• For dependability, a systems 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.

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• A system is a purposeful collection of inter-related components working together to achieve a common objective.

Introducing sociotechnical systems, 2013 Slide 20

•Sociotechnical systems are systems that include technical systems but also operational processes and people who use and interact with the technical system.

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• To achieve dependability, we need to contain failures within technical systems and not let these spread to the broader socio-technical system.