Software Architecture and Design-Ch-1.v6

Software Architecture & Design, Chapter I: Introduction
© 2025, UKH, Dr.Ibrahim Ismael Hamarash, ibrahim.hamad@ukh.edu.krd
Software Architecture and Design
Chapter I
Introduction to
Software Architecture and Design
Professor Dr. Ibrahim Ismael Hamarash
ibrahim.hamad@ukh.edu.krd
https://ibrahimhamarash.github.io

Your way in
building software

Architecture Concept: Foundation
Building Architecture: when we build
something, we need to have a foundation for
it. This is the point of contact with the ground,
the surface that supports the building.
Software Architecture: When you write your
software you are building it on top of a
foundation made of software and hardware. It
is important to be aware of the kind of
foundation you select to deploy your software
on.

➢ Even if we don’t usually call it ”software foundation”, there are many different ”platforms” on
which you can deploy and you can write software for.
➢ The latest metaphor to describe a foundation for software is not based on something solid like the
ground, but instead nowadays our software runs in the clouds. For some reason this seems to be a
good way to sell access to so-called ”platforms as a service” (PaaS). You place your software in the
Cloud. And this somehow gives you some stable foundation you can rely on.
➢ Which platforms have you built software for?
Is a programming language like Java a platform? The language can be part of a platform.
➢ Still, while Java was marketed as platform independent, it actually is a special platform to write
software which then can run on multiple platforms. This is where the foundation metaphor starts
to show its limits.

Architecture Concept: Close Architecture
➢ Other metaphors that we use when we talk about architecture is for
example, the notion of boundary. The first thing you should define is
the system’s boundary, for example, by drawing a box delimiting the
inside of your system from the outside, the rest of the world.
➢ This boundary can be closed if your system is isolated and does not
exchange any information with outside. You have complete
knowledge about the state of the system and there is no information
that you have to go somewhere else to get.
➢ Another way to look at the closed metaphor is to consider the
functional requirements that the closed system should satisfy. For
example, let’s consider the game of chess or the game of go. You can
list the rules, you know exactly what they are, and the rules are not
changing. And these rules are limited and well known in advance. This
makes it possible to solve the game.

Architecture Concept: Open Architecture
➢ Your system is no longer closed when there is uncertainty about its boundary.
Not only requirements may be partially known, but they may change in the
future in unexpected ways.
➢ Let’s say you build a application and you publish it on the open Web and it goes
viral. A few days after you launch, you get 2 million users that you did not
anticipate. But what if it never happens? Should every architecture be designed
to scale to ”Web scale”? Or is it more important to be able to grow and adapt
your system when it becomes necessary?
➢ Enter the Internet, every thing becomes connected to everything else. Today
every system is an open system. Whether you want it or not, you cannot build a
wall around your system, it needs to be integrated with other systems to be
useful. Your system becomes interdependent and interconnected to other
systems over which you have no control. Service providers may disappear
without notice or change their terms of service (e.g., switching from a free to a
paid service, or a stiff price increase), making it no longer possible for your
system to work with them.

Architecture Concept: Interface
➢ When we have open systems which connect with other systems, the
points where their boundaries interact become very important. We
call these interfaces and will dedicate some time to dissect the issue of
how to build a good API.
➢ Life has taken a long time to find out how to evolve from single-
celled organisms into multicellular ones. It is not a trivial problem for
heterogeneous, autonomous and distributed systems to
communicate, interact and inter-operate so that you can use them as
building blocks to construct something larger, something whose value
is greater than the sum of its parts.
➢ This becomes particularly difficult when each system is built by
people who do not know one another and are unable to talk
together and have a tendency to apply changes without informing
the others in advance.

Architecture Concept: Quality

Software Development Process

➢ Architects are not concerned with the
creation of building technologies and
materials—making glass with better thermal
qualities or stronger concrete.
➢ Architects are concerned with how building
materials can be put together in desirable
ways to achieve a building suited to its
purpose.
➢ The design process that assembles the parts
into a useful, pleasing (hopefully) and cost-
effective (sometime) whole that is called
“architecture”.

Software Design:
Those development activities that
enable a person to describe in
detail how the resulting Software
will actually be implemented.
Software Design is about design
patterns, classes, interfaces,
modules, functions, …. etc.

Forces
What are the challenges of
designing an architecture that
as an architect you have to
deal with?

Software Architecture: Definition
ISO/IEC/IEEE 42010 standard definition
“Fundamental concepts or properties of a system in its environment embodied in its
elements, relationships, and in the principles of its design and evolution."
The standard makes the following main points:
➢ A software architecture is a fundamental part of a software system.
➢ A software system is situated in an environment, and its software architecture
takes into consideration the environment in which it must operate.
➢ An architecture description documents the architecture and communicates to
stakeholders how the architecture meets the system's needs.
➢ Architecture views are created from the architecture description, and each view covers
one or more architecture concerns of the stakeholders

Another definition:
“The software architecture of a program or computing system is the
structure or structures of the system, which comprise software
elements, the externally visible properties of those elements, and the
relationships among them.”
Software architecture in practice, 2nd ed.
The definition makes the following main points:
➢ A software system contains structure.
➢ A software system is made up of one or more structure.
➢ The combination of all structures forms the overall software
architecture.

Design approaches
✓ Traditional Approaches
✓ Iterative Approaches

Waterfall Software Development Life Cycle
(SDLC)

https://agilemanifesto.org/

SCRUM, an agile framework

Agile Modelling 12 principles

Example:
Service Value as a software project

New developers often ask, “When are these
tasks carried out in a real project?”

What tools and diagrams do you use?
Example: Satzinger, Jackson and Burd book on Systems
Design and Analysis in a Changing World

✓ The formality of a project also affects design.
✓ Formal projects usually require well-developed design documents typically
reviewed in formal meetings.
✓ Developers on informal projects often create their designs with notepads and
pencils and then throw away the design once the program is coded. This kind
of informal design (used in many Agile projects) is merely a means to an end,
which is the actual program code.
✓ A developer who jumps into writing software without carefully thinking it
through—often referred to as cowboy coding—ends up with errors, patches,
and systems that are unreliable and difficult to update.

Why is software architecture important?
Software architecture is the foundation of a software system. A
proper foundation laid down by a software system's architecture
yields a number of benefits, like
➢ Defining a solution to meets the requirements
➢ Enabling and inhibiting quality attributes Giving you the ability
to predict software system qualities
➢ Easing communication among stakeholders
➢ Managing change
➢ Providing a reusable model
➢ Improving cost and effort estimates
➢ Imposing implementation constraints

The need for a common
modeling language
The fundamental driver
behind them all is that
programming languages are
not at a high enough level of
abstraction to facilitate
discussions about design.

Remark
UML is going to be a Visual
Programming Language.

Who are the consumers of software architecture?
➢ End users
➢ Business analysts
➢ Domain experts
➢ Quality assurance personal
➢ Managers
➢ Operations staff
and
The developers

Roles of the Software Architect

Software Architects

Remark
The law of Parsimony
Reduce everything to its essence so that form
harmonizes with function.
or,
YAGNI
You Ain't Gonna Need It!

“Always design a thing by considering it in its
next larger context- a chair in a room, a room
in a house, a house in an environment, an
environment in a city plan”
Eliel Saarenin

“There are three responses to a piece of
design, yes, no and WAW, WAW is the one to
aim for”
Milton Glaser

➢ There exists only a modest body of knowledge about
software architecture•
➢ Scientific and analytical methods are still lacking -
those that do exist are hard to apply in practice.
➢ There is no perfect design: architecture is a wicked
problem involving subjective tradeoffs and the
management of extreme ambiguity and contradiction.
➢ Experience counts: the best architects are grown, not
born.

Resources:
Reading list
Kevin, L., and Sobhan, T., (2023). Introduction to Software Architecture, Springer.
Harry Percival and Bob Gregory., (2020). Architecture Patterns with Python, O’Reilly.
Bass, L., Clements P., Kazman, R. (2022). Software Architecture in practice, Pearson, Adison-Weily.
Joseph, I., (2018). Software Architecture Handbook, PacktPub.
Watching list:
https://www.youtube.com/watch?v=JV8HNsFWHD4
https://www.youtube.com/watch?v=sQCBfuV5qVg
Listening list:
https://softwarearchitecturerad.io/

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