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The last topic I want to cover in

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this lesson is architectural styles. So, let's see

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what those architectural styles are. There are certain

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design choices that when applied in a given context

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regularly result in solutions with superior properties. What

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this means is that, compared to other possible alternatives,

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these solutions are more elegant, effective, efficient, dependable,

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evolve-able, scale-able, and so on. Architectural styles capture exactly

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these solutions. They capture idioms that we can

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use when designing a system. For a more formal

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definition, let's look how Mary Shaw and David Garlan

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define a architectural style. They say that an architectural

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style defines a family of systems in terms

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of a pattern of structural organization; a vocabulary of

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components and connectors and constraints on how these components

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and connectors can be combined. So in summary we

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can say that an architectural style is a named collection

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of architectural design decisions applicable in a given context. And I

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want to stress that it is important to study and

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know these architectural styles for several reasons. Because knowing them allows

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us to avoid reinventing the wheel. It also allows us

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to choose the right solution to a known problem and in

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some cases it even allows us to move on and

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discover even more advanced styles if we know the basic ones.

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So we should be familiar with architectural styles, what

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they are, and in which context they work, and

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in which context they do not work. So as

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to be able to apply them in the right situations.