What's the difference between design patterns and architectural patterns?
It requires a detailed explanation but I will try to sketch the differences to best of my knowledge.
Patterns are distilled commonality that you find in programs. It allows us to deconstruct a large complex structure and build using simple parts. It provides a general solution for a class of problems.
A large complex software goes through a series of deconstruction at different levels. At large level, architectural patterns are the tools. At smaller level, design patterns are the tools and at implementation level, programming paradigms are the tools.
A pattern can occur at very different levels. See Fractals. Quick sort, Merge sort are all algorithmic patterns for organizing a group of elements in a order.
For a most simplistic view:
- Programming paradigms - specific to programming language
- Design patterns - solves reoccurring problems in software construction
- Architectural patterns - fundamental structural organization for software systems
Idioms are paradigm-specific and language-specific programming techniques that fill in low-level details.
Design patterns are usually associated with code level commonalities. It provides various schemes for refining and building smaller subsystems. It is usually influenced by programming language. Some patterns pale into insignificance due to language paradigms. Design patterns are medium-scale tactics that flesh out some of the structure and behavior of entities and their relationships.
While architectural patterns are seen as commonality at higher level than design patterns. Architectural patterns are high-level strategies that concerns large-scale components, the global properties and mechanisms of a system.
How are patterns obtained? Through:
- re-use,
- classification
- and finally abstraction to distill the commonality.
If you have followed the thoughts laid above. You will see that Singleton is a "design pattern" while MVC is one of the "architectural" pattern to deal with separation of concerns.
Try reading on:
- http://en.wikipedia.org/wiki/Architectural_pattern_(computer_science)
- http://en.wikipedia.org/wiki/Design_pattern
- http://en.wikipedia.org/wiki/Anti-pattern
Design Patterns are well known patterns for solving technical problems in a way that has proven itself many times. Design patterns are common design structures and practices that make for creating reusable Object-Oriented software. Design pattern examples are Factory Pattern, Singleton, Facade, State, etc. Design patterns can be used to solve smaller problems throughout the application, and are much easier to inject, change, add than the overall architecture
architecture patterns are well known patterns for solving software application architecture problems. Software application architecture is the process of defining a structured solution that meets all of the technical and operational requirements. Application's architecture is the overall 'organization' of the code. Examples of different Architectures might be MVC, MVVM, MVP, n-layer (i.e. UI-BLL-DAL), etc. The architecture typically needs to be decided up front and often is difficult to change once the application is built.