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 like the selection of the structural elements and their interfaces by which 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 typically common recurring themes when explaining architecture He identifies these themes as "The highest-level breakdown of a system into its parts; the decisions which are Hard to change; there are multiple architectures in a system; 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 is the process of defining and coming up with a solution that is well structured and meets all of the technical and operational requirements The architecture should be able to consider and improve upon the normal quality attributes such as for example performance, security, and manageability The main focus of the Software architecture is how the major elements and components within an application are used by, or interact with, 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 people should make an effort 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 What are the various non-functional requirements for the application, such as for example security, performance, concurrency, internationalization, and configuration How can the application form be designed to be flexible and maintainable as time passes 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 goal 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 a good design is flexible enough to handle the changes which will occur as time passes in hardware and software technology, as well as in user scenarios and requirements An architect must consider the overall effect of design decisions, the inherent tradeoffs between quality attributes such as for example performance and security, and the tradeoffs necessary to address user, system, and business requirements Principles of Software Architecture The basic assumption of any architecture ought to be the belief that the look will evolve as time passes and that one cannot know everything one have to know up front The look will generally need to evolve during the implementation stages of the application form as one learn more, so when one tests the look against real world requirements Keeping the above statement in mind, let's try to list down a number of the Architectural principles The system should be created to change rather than 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 ought to be identified and acted upon upfront Architects should consider utilizing an incremental and iterative method of refining their architecture Start with baseline architecture to have the big picture right, and evolve candidate architectures as you iteratively test and improve one's architecture Usually do not try to get it all right the first time-design just as much as you can so that you can start testing the design against requirements and assumptions Iteratively add details to the look over multiple passes to make sure that you obtain the big decisions right first, and focus on the details A common pitfall is to dive in to the details too quickly and obtain the big decisions wrong by making incorrect assumptions, or by failing 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 What are the requirements both explicit and implicit this architecture is satisfying What are the key risks with this architectural approach What countermeasures are in place to mitigate key risks In what ways is this architecture an improvement over the baseline or the final candidate architecture Design Principles When getting started off 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 key factor to be kept in mind 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 in charge of just a specific feature or functionality Principle of Least Knowledge A component or object should not know 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 of them costing only one place It should never be repeated in a few other component or module Minimize upfront design This principle is also sometimes known as YAGNI "You ain't gonna require it" Design only what is necessary Especially for agile development, one 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, you need to avoid making a large design effort prematurely https//hackmdio/faVVCq1WTnSU4_a-tOjx4g/H1zuGzCGA Keep design patterns consistent within each layer Do not duplicate functionality within an application Prefer composition to inheritance When possible, use composition over inheritance when reusing functionality because inheritance increases the dependency between parent and ***** classes, thereby limiting the reuse of ***** 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 and 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 Know what metrics and operational data are needed by the IT infrastructure to ensure the efficient deployment and operation of one's 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 the application into distinct features that overlap in functionality less than possible The advantage of this approach is a feature or functionality could be optimized independently of other features or functionality Be explicit about how layers communicate with one another Abstraction should be used to implement loose coupling between layers Do not mix different types of components in exactly 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 within a layer or component