Software Architecture and Design – Goals, Principles plus some Key Considerations
Philippe Kruchten, Grady Booch, Kurt Bittner, and Rich Reitman derived and refined a definition of architecture predicated on work by Mary Shaw and David Garlan (Shaw and Garlan 1996). Their definition is:
“Software architecture encompasses the group of significant decisions concerning the organization of a software system including the selection of the structural elements and their interfaces by which the system is composed; 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, in the end, architecture boils Down to whatever the important stuff is.”
Software application architecture is the process of defining and creating a solution that is well structured and meets all 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. Selecting 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.
Prior to starting the architecting of any software, there are a few basic questions that we should make an effort to get answers for. They are as follows:
How the users of the machine will be interacting with the system?
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 over time?
What are the architectural trends that may impact your application now or after it’s been deployed?
Goals of Software Architecture
Building the bridge between business requirements and technical requirements is the main goal of any software architecture. The purpose of architecture is to identify the requirements that affect the essential structure of the application form. Good architecture reduces the business enterprise risks associated with creating a technical solution while a good design is flexible enough in order to handle the changes that will occur over time in hardware and software technology, as well as in user scenarios and requirements. An architect must consider the overall aftereffect of design decisions, the inherent tradeoffs between quality attributes (such as for example performance and security), and the tradeoffs required to address user, system, and business requirements.
Principles of Software Architecture
The essential assumption of any architecture should be the belief that the design will evolve as time passes and that one cannot know everything one need to know up front. The design will generally have to evolve during the implementation stages of the application as one learn more, so when one tests the design against real world requirements.
Keeping the above statement at heart, let’s try to list down a number of the Architectural principles:
The system should be created to change instead of building to last.
Model the architecture to investigate and reduce risk.
Use models and visualizations as a communication and collaboration tool.
The key engineering decisions should be identified and acted upon upfront.
Architects should consider using an incremental and iterative approach to refining their architecture. Focus on baseline architecture to find 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 all right the first time-design as much as you can to be able to start testing the design against requirements and assumptions. Iteratively add details to the look over multiple passes to make sure that you get the big decisions right first, and then focus on the details. A common pitfall is to dive in to the details too quickly and get the big decisions wrong by making incorrect assumptions, or by failing woefully to evaluate your architecture effectively.
When testing your architecture, consider the following questions:
What were the main assumptions that were made while architecting the system?
What are the requirements both explicit and implicit this architecture is satisfying?
Do you know the key risks with this particular architectural approach?
What countermeasures are in spot to mitigate key risks?
In what Fort Lauderdale architects is this architecture a noticable difference over the baseline or the last candidate architecture?
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 main element principles of any Software Design are:
Separation of concerns: The key factor to be considered is minimization of interaction points between independent feature sets to accomplish high cohesion and low coupling.
Single Responsibility principle: Each component or module ought to be independent in itself and responsible for just a specific feature or functionality.
Principle of Least Knowledge: A component or object should not find out about internal information on other components or objects.
Don’t repeat yourself (DRY): The intent or implementation of any feature or functionality should be done of them costing only one place. It will never be repeated in some other component or module
Minimize upfront design: This principle can be sometimes referred to as YAGNI (“You ain’t gonna need it”). Design only what is necessary. Especially for agile development, you can avoid big design upfront (BDUF). If the application form requirements are unclear, or when there is a possibility of the look evolving over time, one should avoid creating a large design effort prematurely.
Keep design patterns consistent within each layer.
Do not duplicate functionality in a application.
Prefer composition to inheritance. When possible, use composition over inheritance when reusing functionality because inheritance escalates the dependency between parent and child classes, thereby limiting the reuse of child classes. This also reduces the inheritance hierarchies, which can become very difficult to handle.
Establish 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 for example dependency analysis and static code analysis, during development
Not only development, also consider the operation of your application. Determine what metrics and operational data are needed by the IT infrastructure to guarantee the efficient deployment and operation of one’s application.
Application Layers: While architecting and designing the system, one needs to carefully consider the various layers into that your application will be divided. There are some key considerations that need to be kept in mind while doing that:
Separate the areas of concern. Break the application into distinct features that overlap in functionality less than 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 one another.
Abstraction should be used to implement loose coupling between layers.
Do not mix various kinds of components in the same logical layer. For instance, the UI layer should not contain business processing components, but rather should contain components used to handle user input and process user requests.
Keep the data format consistent inside a layer or component.