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Principles
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Comments
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| I. |
Active user
involvement is imperative. |
DSDM is a
user-centred approach. If users are not
closely involved throughout the
development life-cycle, delays will occur
as decisions are made and users may feel
that the final solution is imposed by the
developers and/or their own management.
Users are not outside the development
team acting as suppliers of information
and reviewers of results but are active
participants in the development process. |
| II. |
DSDM teams must be
empowered to make decisions. |
DSDM teams consist
of both developers and users. They must
be able to make decisions as requirements
are refined and possibly changed. They
must be able to agree that certain levels
of functionality, usability, etc. are
acceptable without frequent recourse to
higher level management. |
| III. |
The focus is on
frequent delivery of products. |
A product-based
approach is more flexible than an
activity-based one. The work of a DSDM
team is concentrated on products that can
be delivered in an agreed period of time.
This enables the team to select the best
approach to achieving the products
required in the time available. By
keeping each period of time short, the
team can easily decide which activities
are necessary and sufficient to achieve
the right products.
Note:
Products include interim development
products, not just delivered systems.
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| IV. |
Fitness for
business purpose is the essential
criterion for acceptance of deliverables. |
The focus of DSDM
is on delivering the necessary
functionality at the required time. The
computer system can be more rigorously
engineered later if such an approach is
acceptable. Traditionally the focus has
been on satisfying the contents of a
requirements document and conforming to
previous deliverables, even though the
requirements are often inaccurate, the
previous deliverables may be flawed and
the business needs may have changed since
the start of the project. |
| V. |
Iterative and
incremental development is necessary to
converge on an accurate business
solution. |
DSDM allows systems
to grow incrementally. Therefore the
developers can make full use of feedback
from the users. Moreover partial
solutions can be delivered to satisfy
immediate business needs. Iteration is
inherent in all software development.
DSDM recognises this and, by making it
explicit, uses iteration to continuously
improve the system being developed.
When
rework is not explicitly recognised in a
development life-cycle, the return to
previously "completed" work is
surrounded by controlling procedures that
slow development down. Since rework is
built into the DSDM process, the
development can proceed more quickly
during iteration.
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| VI. |
All changes during
development are reversible. |
To control the
evolution of all products (documents,
software, test products, etc.),
everything must be in a known state at
all times. This means that configuration
management must be all-pervasive. Backtracking is a
feature of DSDM. However in some
circumstances it may be easier to
reconstruct than to backtrack. This
depends on the nature of the change and
the environment in which it was made.
The
ability to reverse changes is limited to
within the development of an increment.
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| VII. |
Requirements are
baselined at a high level. |
Baselining
high-level requirements means
"freezing" and agreeing the
purpose and scope of the system at a
level which allows for detailed
investigation of what the requirements
imply. Further, more detailed baselines
can be established later in the
development, although the scope should
not change significantly. |
| VIII. |
Testing is
integrated throughout the life-cycle. |
Testing is not
treated as a separate activity. As the
system is developed incrementally, it is
also tested and reviewed by both
developers and users incrementally to
ensure that the development is moving
forward not only in the right business
direction but is technically sound. Early
in DSDM, the testing focus is on
validation against the business needs and
priorities. Towards the end of a project,
the focus is on verifying that the whole
system operates effectively. |
| IX. |
A collaborative and
co-operative approach between all
stakeholders is essential. |
The nature of DSDM
projects means that low-level
requirements are not necessarily fixed
when the developers are originally
approached to carry out the work. Hence
the short term direction that a project
takes must be quickly decided without
recourse to restrictive change control
procedures. The stakeholders include not
only the business and development staff
within the project, but also other staff
such as Service Delivery or resource
managers.
When
development is procured from an external
supplier, both the vendor and the
purchaser organisations should aim for as
efficient a process as possible while
allowing for flexibility during both the
pre-contract phase and when the
contracted work is carried out.
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DSDM 
