The software architecture of a program or computing system is a depiction of the system that aids in the understanding of how the system will behave. The architecture is the primary carrier of system qualities such as performance, modifiability, and security, none of which can be achieved without a unifying architectural vision.
Is the process of defining a structured solution that meets all of the technical and operational requirements, while optimizing common quality attributes such as performance, security, and manageability. It involves a series of decisions based on a wide range of factors, and each of these decisions can have considerable impact on the quality, performance, maintainability, and overall success of the application.
The Principles of Architecture Design
Your design will generally need to evolve during the implementation stages of the application as you learn more, and as you test the design against real world requirements. Create your architecture with this evolution in mind so that it will be able to adapt to requirements that are not fully known at the start of the design process.
Consider the following questions as you create an architectural design:
- What are the foundational parts of the architecture that represent the greatest risk if you get them wrong?
- What are the parts of the architecture that are most likely to change, or whose design you can delay until later with little impact?
- What are your key assumptions, and how will you test them?
- What conditions may require you to refactor the design?
Key Architecture Principles
- Build to change instead of building to last. Consider how the application may need to change over time to address new requirements and challenges, and build in the flexibility to support this.
- Model to analyze and reduce risk. Use design tools, modeling systems such as Unified Modeling Language (UML), visualizations where appropriate to help you capture requirements and architectural and design decisions, and to analyze their impact. However, do not formalize the model to the extent that it suppresses the capability to iterate and adapt the design easily.
- Use models and visualizations as a communication and collaboration tool. Efficient communication of the design, the decisions you make, and ongoing changes to the design, is critical to good architecture. Use models, views, and other visualizations of the architecture to communicate and share your design efficiently with all the stakeholders, and to enable rapid communication of changes to the design.
- Identify key engineering decisions. Use the information in this guide to understand the key engineering decisions and the areas where mistakes are most often made. Invest in getting these key decisions right the first time so that the design is more flexible and less likely to be broken by changes.
Characteristics
Multitude of stakeholders: Software systems have to cater to a variety of stakeholders such as business managers, application owners, developers, end users and infrastructure operators. These stakeholders all have their own concerns with respect to the system. Balancing these concerns and demonstrating how they are addressed is part of designing the system.
Separation of concerns: The established way for architects to reduce complexity is to separate the concerns that drive the design. Architecture documentation shows that all stakeholder concerns are addressed by modeling and describing the architecture from separate points of view associated with the various stakeholder concerns.
Quality-driven: Classic software design approaches were driven by required functionality and the flow of data through the system, but the current insight is that the architecture of a software system is more closely related to its quality attributes such as fault-tolerance, backward compatibility, extensibility, reliability, maintainability, availability, security, usability, and other such –ilities.
Recurring styles: Like building architecture, the software architecture discipline has developed standard ways to address recurring concerns. These “standard ways” are called by various names at various levels of abstraction.
Conceptual integrity: A term introduced by Fred Brooks in The Mythical Man-Month to denote the idea that the architecture of a software system represents an overall vision of what it should do and how it should do it.
info:
http://www.ibm.com/developerworks/rational/library/feb06/eeles/
https://msdn.microsoft.com/en-us/library/ee658098.aspx
https://en.wikipedia.org/wiki/Software_architecture
http://www.sei.cmu.edu/architecture/
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