What Is Software Architecture?
1. What Is Software Architecture?
Writing and reading a book about software architecture, which distills the experience of many people, presupposes that
1. having a software architecture is important to the successful development of a software system and
2. there is a sufficient, and sufficiently generalizable, body of knowledge about software architecture to fill up a book.
One purpose of this book is to convince you that both of these assumptions are true, and once you are convinced, give you a basic knowledge so that you can apply it yourself.
Software systetns are constructed to satisfy organizations' business goals. The architecture is a bridge between those (often abstract) business goals and the final (concrete) resulting system. While the path from abstract goals to concrete systems can be complex, the good news is that software architectures can be designed, analyzed, documented, and implemented using known techniques that will support the achievement of these business and mission goals. The complexity can be tamed, made tractable.
These, then, are the topics for this book: the design, analysis, documentation, and implementation of architectures. We will also examine the influences, principally in the form of business goals and quality attributes, which inform these activities.
In this chapter we will focus on architecture strictly from a software engineering point of view. That is, we will explore the value that a software architecture brings to a development project. (Later chapters will take a business and organizational perspective.)
Discussion Questions ·
1. Software architecture is often compared to the architecture of buildings as a conceptual analogy. What are the strong points of that analogy? What is the correspondence in buildings to software architecture structures and views? To patterns? What are the weaknesses of the analogy? When does it break down?
2. Do the architectures you've been exposed to document different structures and relations like those described in this chapter? If so, which ones? If not, why not?
3. Is there a different definition of software architecture that you are familiar with? If so, compare and contrast it with the definition given in this chapter. Many definitions include considerations like "rationale" (stating the reasons why the architecture is what it is) or how the architecture will evolve over time. Do you agree or disagree that these considerations should be part of the definition of software architecture?
4. Discuss how an architecture serves as a basis for analysis. What about decision-making? What kinds of decision-making does an architecture empower?
5. What is architecture's role in project risk reduction?
6. Find a commonly accepted definition of system architecture and discuss what it has in common with software architecture. Do the same for enterprise architecture.
7. Find a published example of an architecture. What structure or structures are shown? Given its purpose, what structure or structures should have been shown? What analysis does the architecture support? Critique it: What questions do you have that the representation does not answer?
8. Sailing ships have architectures, which means they have "structures" that lend themselves to reasoning about the ship's performance and other quality attributes. Look up the technical definitions for barque, brig, cutter,frigate, ketch, schooner, and sloop. Propose a useful set of "structures" for distinguishing and reasoning about ship architectures.