Using microservices means creating applications from loosely coupling services. The application consists of several small services, each representing a separate business goal. They can be developed and easily maintained individually, after what they are joint in a complex application.
Microservices is an architecture design model with a specific bounded context, configuration, and dependencies. These result from the architectural principles of the domain-driven design and DevOps. Domain-driven design is the idea of solving problems of the organization through code.
The business goal is important to the business users, with a clear interface and functions. This way, the microservice can run independently from other microservices. Moreover, the team can also work on it independently, which is, in fact, the point of the microservice architecture.
Many developers claim microservices have made them more efficient. This is due to the ability to work in small teams. This allows them to develop different small parts that will later be merged as a large app.
They spend less time coordinating with other developers and more time on developing the actual code. Eventually, this creates more value for the end-user.
The Complexity Challenge
Complexity is a relative term. What’s complex for one person is simple for another. However, complexity is the problem that domain-driven design should solve. In this context, complexity means interconnectedness, many different data sources, different business goals, etc.
The domain-driven approach is here to solve the complexity of software development. On the other hand, you can use emergent design when the challenge is simple. However, when your application is complex, the complexity will only grow, and so will your problems.
Domain-driven design bases on the business domain. Modern business environments are very complex and wrong moves can lead to fatal outcomes. Domain-driven design solves complex domain models, connecting to the core business concepts.
Eric Evans, introduced the concept in 2004, in his book Domain-Driven Design: Tackling Complexity in the Heart of Software. According to the book, it focuses on three principles:
- The primary focus of the project is the core domain and domain logic.
- Complex designs are based on models of the domain.
- Collaboration between technical and domain experts is crucial to creating an application model that will solve particular domain problems.
Important Terms in Domain-Driven Design
In DDD, it’s important to pay attention to the following terms:
Domain logic
Domain logic is the purpose of your modeling. Most commonly, it’s referred to as the business logic. This is where your business rules define the way data gets created, stored, and modified.
Domain model
Domain model includes the ideas, knowledge, data, metrics, and goals that revolve around that problem you’re trying to solve. It contains all the rules and patterns that will help you deal with complex business logic. Moreover, they will be useful to meet the requirements of your business.
Subdomain
A domain consists of several subdomains that refer to different parts of the business logic. For example, an online retail store could have a product catalog, inventory, and delivery as its subdomains.
Design patterns
Design patternsare all about reusing code. No matter the complexity of the problem you encounter, someone who’s been doing object-oriented programming has probably already created a pattern that will help you solve it. Breaking down your problem into its initial elements will lead you to its solution. Everything you learn through patterns, you can later use for any object-oriented language you start to program in.
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