Application Architecture Guide 2.0 BETA 1 - Willy .Net

Chapter 1 - Fundamentals of Application Architecture
Objectives
• Learn the fundamentals of application architecture.
• Understand key application architecture terms and principles.
• Learn the key forces shaping today’s architectural landscape.
Overview
This chapter lays a foundation for practical application architecture. It starts by describing
architecture and design at a high level and then dives deeper into specific aspects of application
architecture and design. The remainder of the guide follows the same approach. Finally, this
chapter defines key terms and principles. Understanding these will help you to gain the most
benefit from this guide, and be more successful as an application architect.
What Is Application Architecture
Software architecture is often defined as the structure or structures of a system. Several wellknown
industry experts have expanded that definition with information on the decisions that
must be made related to architecture. Here we look at a somewhat formal definition of
architecture, and then take a more informal view.
Kruchten, Booch, Bittner, and Reitman on Architecture
Philippe Kruchten, Grady Booch, Kurt Bittner, and Rich Reitman derived and refined a definition
of architecture based on work by Mary Shaw and David Garlan (Shaw and Garlan 1996). Their
definition is:
“Software architecture encompasses the set of significant decisions about the organization of a
software system including:
• Selection of the structural elements and their interfaces by which the system is composed.
• Behavior as specified in collaboration among those elements.
• Composition of these structural and behavioral elements into larger subsystems.
• Architectural style that guides this organization.
Software architecture also involves functionality, usability, resilience, performance, reuse,
comprehensibility, economic, and technology constraints, tradeoffs and aesthetic concerns.”
Fowler on Architecture
In Patterns of Enterprise Application Architecture, Martin Fowler outlines some common
recurring themes when explaining architecture:
• The highest-level breakdown of a system into its parts.
• The decisions that are hard to change.
• There are multiple architectures in a system.
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