Explains why the characteristics of large anc complex software systems mean that agile methods cannot be used without change in their development Accompanies YouTube video https://www.youtube.com/watch?v=L1JcQDHJzHA

1. Agile methods for large systems
Software Engineering 10

2. Factors in large systems

3. Large systems are usually
collections of separate,
communicating systems, where
separate teams develop each
system.

4. These teams may be working in
different places, sometimes in
different time zones.

5. Changing systems that are part of an
SoS may be impossible as this may
affect their principal purpose

6. There can’t be a single stakeholder
representative and many
stakeholders may have to be
involved in requirements refinement

7. Large systems are ‘brownfield
systems’, that is they include and
interact with a number of existing
systems.

8. Many of the system requirements are
concerned with this interaction and
so don’t really lend themselves to
flexibility and incremental
development.

9. Large systems usually have a
diverse set of stakeholders. It is
practically impossible to involve all
of these different stakeholders in the
development process.

10. Large systems and their
development processes are often
constrained by external rules and
regulations limiting the way that they
can be developed.

11. Regulators may be able to stop a
non-compliant system being
deployed and used.

12. Regulation and compliance issues
apply to non-critical as well as
safety-critical systems

13. Following defined processes or
using particular methods may be
required by the regulator

14. Where several systems are
integrated to create a system, a
significant fraction of the
development is concerned with
system configuration rather than
original code development.

15. Partial configuration may be
impossible as it may not implement
the required user functionality

16. Incremental development by
configuration may therefore be
impossible

17. Large systems have a long
procurement and development time.

18. It is difficult to maintain coherent
teams who know about the system
over that period as, inevitably, people
move on to other jobs and projects.

19. Approaches to scaling agile methods
for large systems all focus on
integrating agile methods into plan-
based approaches

20. IBM’s agility at scale model

21. Core agile development.
Maintaining agile principles where
focus is on customer value,
implementation rather than
documentation and team
responsibility

22. Disciplined agile delivery
Elements of plan-based development
introduced. More focus on risk and
recognition of documentation
requirements

23. Agility at scale
Recognition of importance of
complexity and complexity
management
Appropriate mix of plan-based and
agile approaches

24. Team size, geographic distribution,
type of system, organization,
regulation, technical and
organizational complexity

25. A completely incremental approach
to requirements engineering is
impossible.

26. There needs to be a complete overall
picture of the system requirements
that may then be refined by
stakeholder representatives

27. There cannot be a single product
owner or customer representative.

28. For large systems development, it is
not possible to focus only on the
code of the system.

29. Cross-team communication
mechanisms have to be designed
and used.

30. Continuous integration is practically
impossible. However, it is essential
to maintain frequent system builds
and regular releases of the system.

31. Using agile methods for large
systems engineering means
integrating agile practices with the
engineering practices used in large
systems development