This document discusses sociotechnical systems and introduces their key concepts. It defines a system as a purposeful collection of interrelated components working towards a common goal. Sociotechnical systems specifically include both technical systems (e.g. software, hardware) as well as the operational processes and people interacting with the technical systems. These systems have a layered "stack" structure with different levels including equipment, operating systems, applications, business processes, organizations, and broader society. Changes at one level can ripple through other levels due to interdependencies between layers. Achieving dependability requires containing failures within layers and understanding how adjacent layers may be affected.

1. Introducing socio-technical
systems
Ian Sommerville
Introducing sociotechnical systems, 2013
Slide 1

2. What is a system?
A system is a purposeful collection of
inter-related components working
together to achieve a common
objective.
Introducing sociotechnical systems, 2013
Slide 2

3. Image credit: http://www.nagsma.nato.int/
Introducing sociotechnical systems, 2013
Slide 3

4. • 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.
Introducing sociotechnical systems, 2013
Slide 4

5. • The properties and behaviour of system
components are inextricably intermingled. This leads to complexity.
Introducing sociotechnical systems, 2013
Slide 5

6. Introducing sociotechnical systems, 2013
Slide 6

7. 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.
Introducing sociotechnical systems, 2013
Slide 7

8. 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.
Introducing sociotechnical systems, 2013
Slide 8

9. 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 9

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

11. The socio-technical systems
stack
Introducing sociotechnical systems, 2013
Slide 11

12. 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..
Introducing sociotechnical systems, 2013
Slide 12

13. • Communications and data management
– Middleware that provides access to remote
systems and databases.
• Application systems
– Specific functionality to meet some
organization requirements
Introducing sociotechnical systems, 2013
Slide 13

14. 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.
Introducing sociotechnical systems, 2013
Slide 14

15. • Society
– Laws, regulation and culture that
affect the operation of the system.
Introducing sociotechnical systems, 2013
Slide 15

16. 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
Introducing sociotechnical systems, 2013
Slide 16

17. 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
Introducing sociotechnical systems, 2013
Slide 17

18. • 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.
Introducing sociotechnical systems, 2013
Slide 18

19. • A system is a purposeful collection of
inter-related components working
together to achieve a common
objective.
Introducing sociotechnical systems, 2013
Slide 19

20. •Sociotechnical systems are systems
that include technical systems but also
operational processes and people who
use and interact with the technical
system.
Introducing sociotechnical systems, 2013
Slide 20

21. • To achieve dependability, we need to
contain failures within technical systems
and not let these spread to the broader
socio-technical system.
Introducing sociotechnical systems, 2013
Slide 21