What is Software Architecture and why is it Important?

Pinning down exactly what ‘software architecture’ actually is can be a tricky task. Renowned computer scientist Ralph E Johnson once described it as thus: “Architecture is about the important stuff. Whatever that is.”

While there is no universally accepted detailed definition of what software architecture means, most can agree on its fundamental principles. In its most basic form, it can be described as the design and structure of complex IT systems. It is the blueprint for how individual software components should be organized and connected in a robust structural system that meets the business requirements.

Just as in a building construction project, software architecture decisions are typically high-level design choices - what tools, standards and frameworks should be used and how all the elements will interact with each other. These decisions are made at the start of a project and are crucial to its success. After all, the way in which software systems are designed and put together will impact performance, security, reliability, and scalability.

Who is the software architect?

The role of a software architect can sometimes be blurred with that of an engineer or developer, especially when working on smaller and structurally simple systems.

However, there are some important distinctions: at the very start of a software development life cycle, a software architect needs to be able to understand what elements are fundamental and how they need to be deployed, connected, and controlled. The architect’s vision, which will guide software engineers and developers, will layout optimal design solutions for a business’s requirements (functionality, performance etc), while taking into account all the relevant constraints (time, budget, existing infrastructure).

To do this successfully, a software architect needs to have a detailed understanding of how the different tools available at the time can solve the problems they are tackling in the most efficient and effective manner. This includes knowing when the latest and most powerful technology isn’t appropriate to use in a certain system.

Why is software architecture important?

Put simply, without robust software architecture shaping your IT system, you run the risk of ending up with a “big ball of mud.” Some key benefits of good software architecture include:

• A unifying vision: The software architecture can provide a basis for communication and understanding across all stakeholders. It gives developers, users, managers, testers, etc. a common language with which they can debate ideas, prioritize concerns, and make more effective decisions.
• A solid foundation: The earliest decisions of a software system are the most important. This is when the basic structures and standards are laid out - once they are in place and the project moves forward it quickly becomes difficult and costly to change them.
• Scalability: If the building blocks of a system are well-defined and stable, and it is functioning as intended, the model can be easily expanded or re-used elsewhere. A clear and well-understood structure will also make it cheaper and easier to detect and fix any bugs in the existing software.

Common software architecture patterns

Established software architecture patterns are design structures that are known to work. The range of architecture patterns continues to grow and evolve, but experienced software architect Mark Richards outlines five common patterns that are used to design and organize software systems.

• Layered Pattern: Probably the most well-known pattern, this involves dividing code into layers. Each layer has a specific responsibility and provides a call or service to the next layer. A key feature is the separation of the functions of each component - the presentation layer only needs to present the relevant information in an accessible format, while the ‘data access’ layer is only concerned with storing the information securely in the database.
• Event-Driven Pattern: In this pattern, software components are decoupled and set up to asynchronously identify, process, and respond to ‘events’, such as a mouse click or keystroke. For example, with an online purchase the ‘event producer’ component would detect the initial event (a customer placing the order) and send on the information to ‘event consumer’ modules that perform specific functions in response (e.g. calculate VAT, notify client). Typically a central unit will act as a ‘mediator’, receiving information from event producers and assigning it to the relevant event consumers. It is used commonly in apps due to its flexibility and scalability.
• Microkernel Pattern: This system is made up of a core unit (the ‘microkernel’), which is the entry point for data, and a number of independent plug-in components with specific functions. The core unit takes care of routine functions and data flow while plug-in modules have specialized, stand-alone responsibilities. A benefit of this pattern is that you can continue integrating new plug-in modules to add more business capabilities or adapt to changing system requirements.
• Microservices Pattern: This pattern has become more popular after being used by Netflix to great success. Rather than a monolithic application this involves building a system of multiple applications (‘microservices’) that work with each other. Each microservice has distinct responsibilities and can be built, tested, and deployed independently of other units, providing greater flexibility and scalability.
• Space-Based Pattern: Also known as ‘cloud architecture’, this pattern addresses issues of scalability and bottlenecks with high user volumes by removing the central database and splitting processing and storage across multiple servers.

The right architecture pattern for your IT system will depend on numerous factors, including project timeframe, budget, and the skill set of the developers involved. It’s also possible to combine several different patterns if the need arises. There is no one pattern or solution that will work everywhere, and that’s why software architects can earn their stripes getting these decisions right at the start of a project.

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