How can you design software architecture for maximum modifiability?

Abstraction and modularity are indeed pivotal in software architecture. Abstraction allows developers to focus on interfaces rather than internal workings, simplifying understanding and maintenance. Modularity breaks the system into smaller, independent units, enhancing manageability, reusability, and issue isolation. However, balance is crucial; over-abstraction can add complexity, and excessive modularity can lead to fragmented systems. Properly implemented, these principles lead to code that's easier to test, maintain, and extend, aligning well with agile and CI/CD practices.

Modularity is important here, but often it is not taken to the extremes you really need for maximum modifiability as described here. Optimising for deletability as presented by Greg Young in his "The Art of Destroying Software," is an interesting concept that focuses on replacing complete modules or parts of software when needed by designing in a way to eliminate the fear of "starting over" if the world around changes

Designing software architecture is crucial for long-term maintainability.?Here are some practices to consider: - Separation of concerns: divide the application into well defined modules with clear?responsibilities. The complexity of the application should be split vertically to define?what is high level and what is low level, and horizontally when two components are not related to each other.? It is called layers of abstraction.? - Loose coupling: design the communication between system components in an asynchronous manner and minimize the direct communication. - Encapsulation:?Encapsulation is a technique that can be used to achieve separation of concerns. By encapsulation we hide internal implementation details from external components.

Abstraction in the case of modifiability can be thought from the perspective of improving cohesion and reducing tight couplings of the components in an application. An idea on how to do this is to consider interface based design and making of use of dependency injection to provide the concrete implementations where its required. With modularity the idea is to have cohesive groups that addresses a particular responsibility. This allows us to be able to organize the code in ways to better manage and understand the complex processes and behaviors in a system. Which in turn helps when it comes to future changes and enhancements.

Abstraction simplifies complexity by hiding internal workings and exposing only interfaces, much like knowing how to drive a car without understanding its engine mechanics. Modularity involves dividing software into smaller, independent units, enabling easier maintenance and development, akin to building with Lego blocks where each piece can be individually managed and assembled. Together, these principles reduce software complexity, coupling, and dependency, making it more comprehensible, testable, and adaptable.

Design patterns and principles serve as guidelines to create flexible and adaptable structures that can accommodate changes efficiently. One such principle is the Single Responsibility Principle (SRP), which advocates that a class should have only one reason to change. By adhering to SRP, each class is focused on a specific responsibility, making it easier to modify without affecting other parts of the system. Additionally, the use of design patterns, such as the Observer pattern, can enhance modifiability by decoupling components. For instance, in an e-commerce application, the Observer pattern can be employed to notify various modules about changes in product availability without directly coupling them.

Existem inúmeros Design Patterns que nos ajudam a deixar o código mais fácil para modifica??es e manuten??es. O próprio SOLID, mencionado nesse artigo, deixa a nossa arquitetura organizada e aberta para receber atualiza??es, melhorias e novos recursos sem afetar outras partes do código. A reutiliza??o de código, evitando redundancia também ajuda a deixar nossa arquitetura mais fácil de manuten??o. Princípios como o DRY (Don't repeat yourself) nos ajudam a abstrair nossas implementa??es em métodos e classes genéricas e métodos de extens?o, por exemplo.

?? Coupling and cohesion must be understood to create a scalable, maintainable, and modifiable application. To be able to modify existing components, you need to make sure those are appropriately coupled to other components. Modifications in a tightly coupled scenario (see Connascene) can cause harmful side effects or make it impossible to perform changes. Another way to describe the ability to modify safely is substitutability. If we can exchange a component easily, we can also change it. Optimizing for loose coupling and high cohesion when necessary is critical to understanding.

Design patterns are good but not every pattern fit everywhere. Recognize what you need. Factory and IOC are common use. builder and adapter also have use cases. as Mentioned, SOLID provide good detailing how the design should flow. use Interfacing and abstract classes for contractual binding

Make the architecture as simple as possible. 1. Having plug and play will pay back in long run. For example: Notification system (SNS) integration with third parties(i.e. SaaS) will allow the whole design to change the vendor whenever required. 2. Try to avoid using SaaS provided attributes in bespoke applications, it introduces more dependency and needs more engineering efforts when changing the SaaS platform.

In Kotlin and Java, achieve runtime flexibility without recompiling through dynamic class loading, configurable components through external files, reflection, and annotations. There's things to consider: - Store settings externally in configuration files (properties, YAML) and load them dynamically at runtime. - Swap entire components dynamically using dynamic class loading, allowing seamless replacement of functionality. - Use reflection for runtime access and modification of class elements, enabling adaptable behavior without altering source code. You can even recompile your program internally at the runtime (for example, DCEVM). But without overengineering of course. - Java's Service Provider Interface should be also considered ??

Have 0 hard coded values and comparisons in code. if a value need to be compared, it should be compared with a config based value so that it can be modified at runtime without redeploying IL files or compiled files. Also separate debug files are a good idea.

Adopt methods like Scrum, prioritizing valuable features and gaining frequent stakeholder feedback. Utilize refactoring to enhance code quality and readability. Implement continuous integration and delivery for automated testing and deployment, ensuring a reliable and adaptable software architecture. Modifiability is an ongoing process involving meticulous planning, design, and testing.

Prototype is a great SDLC if you want to test a theory on a small scale. I always use it for my expectation with system and to recognize moving parts.

Additionally to the mentioned methods, it's also important to see features and complexity as a living process. Develop only the features and methods you need right now. Then the second person/team to reuse the code is responsible for refactoring and abstractions. You don't have to think about "what could be" from the get go if you are in the habit of regularly refactoring what you come across. This way your code base is a living thing and adpats to your needs without getting overly bloated with "oh this could've been this feature but we never got around to it" complexity.

En mi opinión y en mi experiencia el software componible es mejor que el uso excesivo de microservicios. Dejaría los Microservicios solo para los diferentes dominios del negocio, todo lo demás que sea transversal lo dejaría como librerías y las subiría a algún regitry, npm, github Package etc etc. Además aplicaría Arquitectura Hexagonal en Backend. En Frontend nada de microfrontend, aplicaría Software Componible con Bit.dev por ejemplo lo que disminuiría la complejidad cognitiva muchísimo.

Using a layered architecture and testing each class in each layer independently with unit tests ensures that you can easily swap out any of the dependencies/ units as you will need to mock these if you want to test the layers in isolation. This automatically leads to a modular architecture with well defined interfaces.

There are some additional and important concepts we can use to design software architecture for maximum modifiability: 1. Service-Oriented Architecture (SOA) 2. Leveraging the middlewares 3. Strong CI/CD (includes code reviews, code refactoring) 4. Container based software (makes it easier to debug and fix bugs, develop new features becomes easier and faster due to minimal dependency on other containers of the application)

Especially chiding the correct layers and decoupling the architecture into components which can be mixed&matched can make it a lot easier to maintain. Additionally it would pay a lot on to the maintainability to have the components auto-tested by CI/CD.

In every decision that you take, remember that your architecture must be designed to be able to change easily. Architectures are not easy to define, and it takes time to build something stable and robust. Build something that you and your team are comfortable working with; and be ready to change a lot of things in the beginning of the process. Although the analysis part must be long and well-thought, in my opinion it's impossible to design an architecture perfect from the first design. You will always look in the direction of abstraction, but there will be always some details that will block your view. Don't hesitate to refactor your architecture once designed. That's what agile methodologies and complex architectures are about: refinement.