Key Principles for Software Architecture and Design

Defining the Architecture is a challenging job. However by focusing on few Key Design Principles, we can make it easy and even interesting. Here are few Key Principles for Architecture and Design:
  • Separation of concerns: Each component in the system should be assigned a specific responsibility. It means that features should not be overlapped among the components and the users should be very clear about where to go for a certain feature. It avoids interdependency of system components, and make the system easy to maintain. Suppose in future, you find scope of improvement for this feature, then you need not to make the changes at multiple places. But you will make the changes in the specific component, owner of the feature, and all other components will get the benefits as they must already be using this for that specific feature. This approach also makes the application easier to understand for a user.
  • Principle of Single Responsibility: Every component should own one specific and distinguished feature. It helps in defining the responsibilities clearly, helps the user to understand the system easily and also help in integration of component with other components. 
  • Don't Repeat Yourself: This principle states that one functionality and hence the piece of code should be implemented in one component only. It should not be repeated across the components. Uses are that the code will be very maintainable. If you find any error, or you want to optimize the code, there is always one place where you can do it. Otherwise there will be a search in whole code to find out the places where similar code has been done for a feature.

Application Architecture and Design

Application Architecture is the structure of the whole system which describes the important component/objects of a system, various interfaces and that how these interact with each other. It also defines how system will be accessible to external world and how it will integrate with other third party services. So it is a high level structuring of the system, which might not have the detailing at object level; but will describes various layers, what kind of components/objects these layers will have and how these different layers will interact with each other.

Now if we need detailing at next level i.e. objects and their relations then we should proceed for designing of the system. To understand the difference between architecture and design, consider the Architecture may define a layer where all request processor/handlers should resides. Further design can describes various kind of actual request processors based on system and business need.