Philippe Kruchten, Grady Booch, Kurt Bittner, and Rich Reitman derived and refined a definition of architecture based on work by Mary Shaw and David Garlan (Shaw and Garlan 1996). Their definition is:
“Software architecture encompasses the set of significant decisions about the organization of a software system including the selection of the structural elements and their interfaces where the system is made up; behavior as specified in collaboration among those elements; composition of the structural and behavioral elements into larger subsystems; and an architectural style that guides this organization. Software architecture also involves functionality, usability, resilience, performance, reuse, comprehensibility, economic and technology constraints, tradeoffs and aesthetic concerns.”
In Patterns of Enterprise Application Architecture, Martin Fowler outlines some common recurring themes when explaining architecture. He identifies these themes as:
“The highest-level breakdown of something into its parts; the decisions which are Hard to change; there are multiple architectures in something; what is architecturally Significant can change over a system’s lifetime; and, ultimately, architecture boils Down to whatever the important stuff is.”
Software application architecture may be the process of defining and coming up with a solution that is well structured and meets each of the technical and operational requirements. The architecture should be able to consider and improve upon the normal quality attributes such as performance, security, and manageability.
The main focus of the Software architecture is the way the major elements and components within an application are employed by, or connect to, other major elements and components within the application form. contemporary houses of data structures and algorithms or the implementation details of individual components are design concerns, they are not an architectural concerns but sometimes Design and Architecture concerns overlap.
Before starting the architecting of any software, there are several basic questions that we should strive to get answers for. They’re as follows:
How the users of the machine will be interacting with the machine?
How will the application form be deployed into production and managed?
Do you know the various non-functional requirements for the application, such as for example security, performance, concurrency, internationalization, and configuration?
How can the application be made to be flexible and maintainable as time passes?
Do you know the architectural trends that may impact the application now or after it has been deployed?
Goals of Software Architecture
Building the bridge between business requirements and technical requirements is the definitive goal of any software architecture. The purpose of architecture is to identify certain requirements that affect the basic structure of the application form. Good architecture reduces the business enterprise risks associated with creating a technical solution while an excellent design is flexible enough to be able to handle the changes that will occur as time passes in hardware and software technology, in addition to in user scenarios and requirements. An architect must consider the overall effect of design decisions, the inherent tradeoffs between quality attributes (such as performance and security), and the tradeoffs necessary to address user, system, and business requirements.
Principles of Software Architecture
The basic assumption of any architecture should be the belief that the design will evolve over time and that one cannot know everything one have to know up front. The design will generally need to evolve through the implementation stages of the application form as one learn more, so when one tests the design against real world requirements.
Keeping the above statement at heart, let’s make an effort to list down a few of the Architectural principles:
The system should be built to change rather than building to last.
Model the architecture to analyze and reduce risk.
Use models and visualizations as a communication and collaboration tool.
The key engineering decisions ought to be identified and applied upfront.
Architects should consider utilizing an incremental and iterative approach to refining their architecture. Focus on baseline architecture to obtain the big picture right, and then evolve candidate architectures as one iteratively ensure that you improve one’s architecture. Usually do not try to get it fine the first time-design as much as you can so that you can start testing the design against requirements and assumptions. Iteratively add details to the design over multiple passes to ensure that you obtain the big decisions right first, and then focus on the details. A standard pitfall is to dive in to the details too quickly and obtain the big decisions wrong by making incorrect assumptions, or by failing woefully to evaluate your architecture effectively.
When testing your architecture, think about the following questions:
What were the main assumptions which were made while architecting the machine?
Do you know the requirements both explicit and implicit this architecture is satisfying?
What are the key risks with this particular architectural approach?
What countermeasures are in spot to mitigate key risks?
In what ways is this architecture a noticable difference over the baseline or the last candidate architecture?
Design Principles
When getting started with Software design, one should bear in mind the proven principles and the principles that adheres to minimizes costs and maintenance requirements, and promotes usability and extensibility. The key principles of any Software Design are:
Separation of concerns: The main element factor to be kept in mind is minimization of interaction points between independent feature sets to attain high cohesion and low coupling.
Single Responsibility principle: Each component or module should be independent in itself and in charge of just a specific feature or functionality.
Principle of Least Knowledge: An element or object should not find out about internal details of other components or objects.
Don’t repeat yourself (DRY): The intent or implementation of any feature or functionality should be done at only one place. It should never be repeated in some other component or module
Minimize upfront design: This principle is also sometimes referred to as YAGNI (“You ain’t gonna require it”). Design only what’s necessary. Specifically for agile development, one can avoid big design upfront (BDUF). If the application requirements are unclear, or if you have a possibility of the look evolving over time, you need to avoid creating a large design effort prematurely.
Design Practices
Keep design patterns consistent within each layer.
Do not duplicate functionality in a application.
Prefer composition to inheritance. If possible, use composition over inheritance when reusing functionality because inheritance increases the dependency between parent and child classes, thereby limiting the reuse of child classes. This reduces the inheritance hierarchies, which can become very difficult to handle.
Set up a coding style and naming convention for development.
Maintain system quality using automated QA techniques during development. Use unit testing along with other automated Quality Analysis techniques, such as dependency analysis and static code analysis, during development
Not only development, also think about the operation of your application. Determine what metrics and operational data are required by the IT infrastructure to guarantee the efficient deployment and operation of your application.
Application Layers: While architecting and designing the machine, one needs to carefully think about the various layers into that your application will be divided. There are a few key considerations that need to be kept in mind while doing that:
Separate the areas of concern. Break your application into distinct features that overlap in functionality as little as possible. The advantage of this approach is that a feature or functionality can be optimized independently of other features or functionality
Be explicit about how exactly layers communicate with each other.
Abstraction should be used to implement loose coupling between layers.
Do not mix different types of components in the same logical layer. For example, the UI layer shouldn’t contain business processing components, but instead should contain components used to take care of user input and process user requests.
Keep the data format consistent inside a layer or component.