Contents
Figure 1
Whereas in traditional development
methodologies, functionality is fixed, and time and resources are variable, in
DSDM, time is fixed, and functionality are variable.
Dynamic Systems Development Method (DSDM) is an organized, common-sense
process focused on delivering business solutions quickly and efficiently. It is
similar in many ways to SCRUM and XP, but it has its best uses where the time
requirement is fixed.
DSDM focuses on delivery of the business solution, rather than just team
activity. It makes steps to ensure the feasibility and business sense of a
project before it is created. It stresses cooperation and collaboration between
all interested parties. DSDM makes heavy use of prototyping to make sure
interested parties have a clear picture of all aspects of the system.
Why DSDM?
- Results of development are directly and promptly visible
- Since the users are actively involved in the development of the system, they
are more likely to embrace it and take it on.
- Basic functionality is delivered quickly, with more functionality being
delivered at regular intervals.
- Eliminates bureaucracy and breaks down the communication barrier between
interested parties.
- Because of constant feedback from the users, the system being developed is
more likely to meet the need it was commissioned for.
- Early indicators of whether project will work or not, rather than a nasty
surprise halfway through the development
- System is delivered on time and on budget.
- Ability of the users to affect the project's direction.
How Does DSDM Help to Overcome Development Pitfalls?
Many systems fall short of meeting the needs of the users and purpose they
were designed for, causing the system to either be abandoned or overhauled.
There are a number of ways this may happen:
- Failure to meet the purpose / solve the problem it was designed for -
DSDM allows for user testing all through the development process, thus allowing
developers to get prompt feedback on the usability and suitability of the
product.
- Cost outweighs benefits, or cost is too high altogether - In DSDM, a
Business Study is done at the beginning of the project, greatly decreasing the
likelihood of late surprises in the financial realm.
- Poor communication between involved parties - DSDM stresses
communication and collaboration between all interested parties - developers,
users, etc.
- The users finds the program either too hard to use that it does not work
as expected - DSDM allows for user testing all through the development
process, thus allowing developers to get prompt feedback on the usability and
suitability of the product.
- Hidden flaws surface in the system due to poor design or
implementation - In DSDM, prototyping helps to ensure that the system is
designed correctly and that everyone knows how it will work. Unit testing helps
to uncover hidden bugs, and incremental development allows for user testing all
through the development process.
- Users resist the instantiation of the system, either for political
reasons, or a lack of commitment to it - In DSDM, since the users are
actively involved in the development of the system, they are more likely to
embrace it and take it on.
- The system is in-flexible and/or un-maintainable, and unable to adapt to
change - Since DSDM emphasizes flexibility in design, this is not likely to
happen with DSDM.
Core Concepts in DSDM
The following bullet list describes the core concepts of DSDM.
The people who will be using the product must be actively involved in its
development. This important in order for the product to end up being useful to
the people who will be using it.
- The Team Must Be Empowered to Make Decisions
The team should be able to make rapid and informed decisions, without having
to cut through red tape to get those decisions approved.
DSDM focuses on frequent releases. Frequent releases allow for user input at
crucial stages in the product's development. They also ensure that the product
is able to be released quickly at all times.
- Iterative Development, Driven by User Feedback
The development is the system is done in iterations, which allows for
frequent user feedback, and a partial but prompt solution to immediate needs,
with more functionality being added in later iterations.
- Changes Must Be Reversible
All products should be in a fully known state at all times. This allows for
backtracking if a certain change does not work out well.
- Requirements are Initially Defined at a High Level
High-level requirements are worked out at the beginning of the project,
before any coding, leaving the details to be worked out during the course of the
development.
- Fitness for Business Purpose is the Goal
Meeting the business need is more important than technical perfection.
Testing is done at every step of the way, to ensure that the product being
developed is technically sound and does not develop any technical flaws, and
that maximum use is made of user feedback.
- Collaboration and Cooperation are Essential
Collaboration and cooperation between all interested parties are essential
for the success of the project. All involved parties (not just the core team)
must strive together to meet the business objective.
DSDM assumes that 80% of the solution can be developed in 20% of the time
that it would take to produce the total solution. DSDM focuses on this 80%,
leaving another 20% for later revisions. DSDM assumes that not all of the
requirements for the final solution are known to begin with, so it is likely
that the final 20% of non-essential features are likely to be flawed anyway.
(See MoSCoW Prioritization.)
The DSDM Development Process
The DSDM development process consists of 7 phases. The first one is before
the project has officially started. Then there are the project studies, which in
this document are considered to be one phase. Then there are three more phases
that consist of iterative cycles, which are repeated as necessary to complete
the project. Then there is the post-project phase, where the project is
maintained. The project flow may move between the different phases in the
directions indicated by the arrows above.
The dark blue arrows in the
diagram indicate the normal forward direction of project flow.
The green
arrows indicate directions that may be taken as necessary under normal
circumstances. For example, if the team has finished a "Design and Build"
iteration, but the system cannot be released until another area's functionality
has been defined and it has been built, the project flow may go back to the
"Functional Model" iteration to complete that area.
The light red arrow
represents a direction that is only taken if the project has been found to not
meet the required functionality.
Pre-Project
The pre-project phase is not strictly defined. It occurs before the project
officially begins. In this stage, the project is conceptualized, and the
decision is made to start the project.
Feasibility Study - Finding out if and how the project will work out
In this phase, the team researches the question: Can it be done within the
constraints of time and resources? This phase is done as quickly as possible,
because DSDM is best used where time is short, and therefore the product needs
to be delivered quickly.
Business Study - Studying the business aspects of the project
In this phase, the team researches the business aspects of the project.
- Does it make good business sense?
- Who are the participants and interested parties?
- What is the best work plan? What is needed to:
- Build it
- Test it
- Deploy it
- Support it?
- What technologies will we be using to build and deploy it?
The model is also worked out in this phase.
Functional Model
In this stage, functional prototypes of the system are made and reviewed. A
functional prototype is a prototype of the functions the system should perform
and how it should perform them.
Prototyping follows these steps:
- Investigate
- Refine
- Consolidate
Prototypes cover many different aspects of the system:
- Business -
- Usability - how easy is it to use?
- Performance and Capacity - can it handle the volume and frequency of use
that it will receive?
- Technique - What's the best way of going about solving the problem?
Design And Build
In this stage, the product is designed and developed in iterations. In each
iteration a design model is made of the area being developed, and then that area
is coded and reviewed.
Implement/Deploy/Maintain
In the last phase, the product is wrapped up, documentation is written, and a
review document is drawn up, comparing the requirements with their fulfillments
in the product. The users are trained in how to use the system, and the users
give approval to the system.
Post-Project - Maintenance
After the product is created, maintenance will inevitably need to be
performed. This maintenance is generally done in a cycle similar to the one used
to develop the product.
DSDM FAQ
Is DSDM suitable for all projects?
No. Even diehard proponents of DSDM agree that DSDM will not work for all
projects. (But of course, nor will other methodologies.) More often than not, if
full-on DSDM doesn't work, you'll end up using some DSDM concepts and
principles, but not others. It is important to analyze the nature of the project
at hand, and decide which concepts and principles will help you out, and which
will not.
What are the basic criteria for the success of DSDM?
To use DSDM, there must be full management commitment, the team must be able
to meet together easily, and the team must be able to work together easily.
How widely is DSDM used?
1 out of 5 developers in the UK use DSDM, and more than 500 major companies
have adopted it.
DSDM Roles
DSDM defines several key roles that should be filled by members of the team:
- Ambassador - The person who acts as a go-between between the
customer(s)/users and the development team. He coordinates the development team,
and should have a good overall understanding of how the system will work.
- Visionary - The driving force behind the project - keeps the project steered
on course towards the business goals. Often is the person who started/thought of
the project.
- Advisers - People who have practical knowledge in area(s) of the business
that need to be automated, and/or in the technologies needed to automate these
areas.
There are also other roles that are defined by DSDM:
- Technical Coordinator - The technical coordinator coordinates the various
technical aspects of the system, and ensures that they interact smoothly and
correctly.
- Executive Sponsor - A strong proponent of the system, who has the ability to
contribute funds and resources to the project.
- Project Manager - oversees the development and prototyping.
- Team Manager - Manages the people aspects of the team, and ensures that the
team functions smoothly as a whole.
- Senior Developer - a senior developer who has the knowledge and expertise to
turn the plans and requirements into deliverable code.
- Facilitator - Facilitates in the practical areas of the team's work.
- Scribe - The person in charge of documenting decisions, discussions, and
plans made by the team.
Tools and Techniques
MoSCoW Prioritization
Functionality is categorized according to its importance:
- Must Have - the things that are absolutely essential, and are fundamental to
the system.
- Should Have - things that are important for the business solution.
- Could Have - things that are useful, but can be done without for a short
while.
- Won't Have This Time Around - things that can easily wait until later.
Prioritization is important because there is not enough time to do
everything, and those things that are essential must be put before things that
are not.
Prototyping
Prototypes are used heavily in DSDM. They ensure that all interested parties
have a clear picture of the various aspects of the system.
Facilitated Workshops
Facilitated workshops allow for these benefits:
- Ideal environment for the formation of ideas and quick and balanced growth
of those ideas.
- All interested parties are aware of decisions made by other interested
parties
- Decisions can be made by a wider range of stakeholders.
- Decisions are made quickly and accurately.
TimeBoxing
Fixed time periods ensure that:
- Product delivery stays being the focus
- Concentration is on the top priorities
- All members know where each other is at and how long to expect each other to
take
Links
DSDM Consortium - The official consortium
for DSDM. Has a large number of articles and white papers on DSDM, plus DSDM
certification, discussion groups, etc.
ProcessWave
DSDM Articles
SurgeWorks DSDM Resources
Agile
Alliance DSDM Articles - Articles about DSDM on Agile Alliance's website.
Especially focuses on intermixing DSDM and other Agile methodologies.
DSDM Manual -
A DSDM manual, with poor layout, but some good insights.
Articles
Introducing
DSDM into an Organization
Top Ten DSDM Problems
To
DSDM Or Not To DSDM?
DSDM
Overview - A PowerPoint presentation outlining DSDM.
Books
DSDM:
The Method in Practice by Jennifer Stapleton
DSDM:
Business-Focused Development by Jennifer Stapleton
