In today's software development landscape, monolithic applications can present a range of challenges, especially when it comes to scalability and maintainability. As applications grow and domains become more complex, it's crucial to consider more flexible and modular architectures to ensure long-term success. One such solution is Hexagonal Architecture, which separates the domain language from the rest of the application, allowing for increased flexibility, modularity, and ease of maintenance. Transforming a monolithic application into a hexagonal architecture may be challenging, but with the right expertise and guidance, it can lead to significant benefits down the line.
In this post, we explored the challenges of monolithic applications, the advantages of Hexagonal Architecture, and the process of transforming a monolith into a more flexible and scalable system.
What is a Monolith?
A monolith application is a software system that is built as a single, indivisible unit, with all of its components and functionalities tightly coupled together, in the world of software development. While this approach is useful in the initial stages of development, it can lead to a slew of issues as the project grows in various aspects.
Let's look at an example to see why. Building an application is similar to constructing a complex house with various pieces from various manufacturers that do not always fit together perfectly. As a result, the house may include many simplifications and connections that are fragile and prone to errors. In other words, while the finished product may have the desired functionality, the underlying architecture may be problematic, resulting in bugs, maintenance, and scalability issues. This is why skilled architects and knowledge of proper design patterns are needed to ensure the application is built in a modular and scalable manner.
As the codebase of an application grows, adding new features may necessitate changes to existing libraries or the incorporation of ready-made components that may not be ideal for the project. While this method is faster than creating custom parts from scratch, it can lead to a fragile and difficult-to-maintain structure. Our project will eventually become a monolith.
Adding New Features
Adding new features becomes more difficult as the project progresses, as each addition must be carefully considered to avoid disrupting the overall structure. The finished product may function as intended, but its shaky construction may cause problems when changes are made. In essence, extending a monolithic application's capabilities can be a delicate balancing act between speed, adaptability, and long-term stability.
When Modularity is Insufficient: The First Step Towards Hexagonal Architecture
Managing applications as they grow and become more complex can be a time-consuming task. One approach to easing the process is to split the monolith into modules, resulting in reusable components that can be used across the application. However, while modularity can help to some extent, it is not a silver bullet that solves all the problems associated with building large-scale software.
Modularity refers to the concept of breaking down an application into smaller, more manageable components, or modules. Each module can be developed and tested independently, making overall application maintenance and modification easier. These modules are analogous to reusable manufactured building components such as walls, windows, roofs, and floors. Modules, like building blocks, can be assembled in a variety of ways to create a variety of applications.
However, modularity is only useful up to a point. As applications grow in complexity, a specific domain language emerges, causing confusion in development teams, misusing components, and resulting in sophisticated bugs. Consider how the meaning of a single word changes depending on the context in which it is used. Consider the term "customer."
The term "customer" in an IT helpdesk department refers to an employee who is having a technical problem with the company's services. The helpdesk team's priority is to resolve the technical issue as quickly as possible so that the customer can use the company's services effectively.
In a marketing department, a "customer" is someone who has purchased a product from the company, but it also includes people who have interacted with the company in some way, such as those who have subscribed to the company's newsletter or engaged with the company on social media. The marketing team's primary goal is to establish and maintain positive relationships with all types of customers in order to generate new business and retain current customers.
These are just a few examples of how domain-specific language can have different meanings depending on the context. Working on a monolithic application can make it difficult, if not impossible, to ensure that everyone in different teams is using the same terminology and understands the domain model. This can lead to application confusion, misunderstandings, and bugs.
Hexagonal Architecture: Increase Codebase Flexibility
Hexagonal Architecture, also known as Ports and Adapters, is an architectural pattern that gives your codebase flexibility. Interfaces, also known as ports, are at the heart of Hexagonal Architecture and serve as the boundaries between different functionalities of the application.
The concept behind Hexagonal Architecture is to separate the domain, with its own language, from the rest of the application. Adapters convert one part language to another. The domain language is used to describe the business problem that is being solved. By separating the domain core functionality from the rest of the application, developers can concentrate on solving the business problem without having to worry about implementation details or misleading vocabulary in the rest of the application, as long as those implement the communication interface. This necessitates the use of adapters that translate one domain language to another that the port can understand.
One of the key advantages of Hexagonal Architecture is the ability to change external components without having to adjust the core domain. For example, if the application uses a relational database, it can easily be replaced with a NoSQL database if the external component implements the same interface.
This also means that once the interfaces and ports are defined, the domain objects can be designed and tested independently of the rest of the application. This promotes application modularity by allowing different teams to communicate in different domain languages in their core functionality, and it makes the application easier to develop and maintain over time.
How To Transform a Monolithic Application to a More Flexible One
Transforming a monolithic application into a more modular architecture using ports and adapters is a challenging task that demands a thorough understanding of both the application's architecture and the business domain. It's not something that can be carried out by simply following a set of instructions.
A successful transformation is only possible with the assistance of a company with the necessary expertise and skilled architects.
Furthermore, while the benefits of a more modular architecture can be significant, such as the ability to extract microservices and scale specific parts of the application as needed, it's critical to carefully weigh the costs and benefits before embarking on such a transformation.
Nevertheless, the first step in converting a monolithic application to a hexagonal architecture is always to determine which parts of the application must be separated. This includes a session with system architects and a thorough examination of the application domain.
This step is critical because it defines the complex boundaries between application domains, allowing the monolith to be further broken down into smaller standalone pieces and finding areas where dependencies exist between them. We also must ensure that each module can be developed and maintained independently, eliminating the possibility of conflicting domain models.
The process of extracting the domain from the monolith can be complex, time-consuming, and tedious. However, once this is carried out, scaling and expanding the application to meet new requirements becomes much easier. Individual domains, for example, can be divided into separate microservices and deployed independently, allowing for more efficient scaling by scaling only specific domain functionalities and limiting the increase in resources required.
If you believe you need help in achieving modularity through hexagonal architecture, please contact us.