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 based on work by Mary Shaw and David Garlan (Shaw and Garlan 1996). Their definition is:

“Software architecture encompasses the set of significant decisions concerning the organization of a software system like the collection of the structural elements and their interfaces where the system is composed; behavior as specified in collaboration the type of 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 a system into its parts; the decisions that are Hard to change; you can find 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 creating a solution that is well structured and meets all the technical and operational requirements. The architecture will be able to consider and improve upon the normal quality attributes such as for example performance, security, and manageability.

The main focus of the program 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. The selection 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.

Prior to starting the architecting of any software, there are some basic questions that people should strive to get answers for. They are as follows:

How the users of the system will be interacting with the machine?

How will the application 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 be designed to be flexible and maintainable as time passes?

Do you know the architectural trends that might impact your application now or after it’s been deployed?

Goals of Software Architecture

Building the bridge between business requirements and technical requirements may be the definitive goal of any software architecture. The goal of architecture is to identify the requirements that affect the essential structure of the application. Good architecture reduces the business risks associated with creating a technical solution while an excellent design is flexible enough in order to handle the changes that may occur over time 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 essential assumption of any architecture should be the belief that the look will evolve over time and that certain cannot know everything one have to know up front. The look will generally have to evolve through the implementation stages of the application form as one learn more, and as one tests the look against real world requirements.

Keeping the above statement in mind, let’s make an effort 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 analyze and reduce risk.

Use models and visualizations as a communication and collaboration tool.

The key engineering decisions should be identified and applied upfront.

Architects should consider utilizing an incremental and iterative method of refining their architecture. Start with baseline architecture to obtain the big picture right, and then evolve candidate architectures as you iteratively test and improve one’s architecture. Do not try to get it fine the first time-design just as much as you can so as 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 focus on the details. A common pitfall is to dive into 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 primary assumptions which were made while architecting the machine?

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 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 take into account 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.

Fort Lauderdale architects of Least Knowledge: A component 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 ought to 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 need it”). Design only what’s 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, one should avoid making a large design effort prematurely.

Design Practices

Keep design patterns consistent within each layer.

Do not duplicate functionality within an 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 also reduces the inheritance hierarchies, which can become very difficult to deal with.

Set up 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 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 required 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 some key considerations that require to be kept in mind while doing that:

Separate the regions of concern. Break your application into distinct features that overlap in functionality less than possible. The main benefit of this approach is that a feature or functionality could 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 various kinds of components in exactly the same logical layer. For instance, the UI layer shouldn’t 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.

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