How to Design a Robust Microservices Architecture: Top 4 Decisions
Here is a short checklist of four essential elements of microservices you should be prepared to implement in microservices adoption.
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More than 60% of enterprises are adopting a microservices architecture (MSA), yet they often fail at designing, building, and managing it. Implementing a successful MSA is more complex than monolithic application architectures, as it demands more discipline and effort on the part of IT professionals. Remember moving from a monolith architecture to a microservices architecture is a key task in building an application architecture distributed globally and being a challenging task, brings inevitable backfires. You require a versioning strategy for interfaces and services.
In the words of Gary Olliffe, Research Vice President of Gartner, “The superpowers of MSA can, in large part, be attributed to the benefits of loose coupling and decomposing systems into component services that can be developed, deployed, and operated independently of each other.” Having said that, technical professionals need to stay focused on loose coupling systems and thus make design decisions to accomplish their MSA goals.
1. Dependency Management
Dependencies emerge to be one of the biggest problems of distributed architectures. Though in a microservice-based architecture, services are designed as isolated units managing a minimized set of problems, MSA may rely on the integration and cooperation of these units. This is when it becomes the most important to define your strategy for dependency management.
You need to decouple services from the environment through distributed configuration. A runtime platform or simply a standalone solution helps to offer distributed configuration management. The configuration information consists of a topic, database, and queue names, including other environmental data. Service discovery also enables technical professionals to decouple services from one another. Through a service registry application programming interface (API), a service provider can register its availability. Consumers can thus discover and connect to service endpoints via the service registry. Resolutions into a service endpoint become manageable on the client as well as the service side.
2. Iteration is the Key
Iterate, iterate, iterate to recognize and extract smaller services adopting the microservices approach. MSA supports fluid, faster iteration of application delivery, which is why you should focus on iterations from the beginning. Functionalities are isolated in smaller services to ensure scalability leading to each service scaling independently.
And then you should use decomposition strategies. Apply the decomposition patterns to decompose an application into services. You can either decompose by business capability or by subdomain. Make the process of decomposition easier and simplify the data by using the bounded context concept from domain-driven design (DDD).
In the context of DDD, the anti-corruption layer (ACL) helps to maintain the sanity even where there is a change in the dependent external systems. This layer aims to hide the internal domain models of the IT legacy and prevents them to pollute the domain models of new services (microservices). Design an abstraction layer to decouple the new service from the legacy one, where there are dependencies on pre-existing features or data.
3. Building a Versioning Strategy
Implementing a coherent versioning strategy is crucial to achieving your MSA goal. You need to have this strategy in place for your services and interfaces, as microservices architecture supports and manages change at a rapid pace. You should be clear about how to recognize and deploy new versions. At the time of breaking changes, support transition periods where the previous version of the interface and the latest one is supported in parallel.
An ideal and widely adopted approach here is better known as semantic versioning. With a three parts string, the MAJOR version should increment when the changes are breaking the clients, while the MINOR version should increment when the changes are not breaking the clients. The PATCH version change indicates bug fixes.
As architects and service developers, you need to check which services are using business capabilities and on which capabilities these services rely, which is why you need to execute a service dependency tracking mechanism.
4. Loose Coupling of Services
One of the major design decisions you need to make is to design your interfaces for loosely coupled consumption. Separating services into self-contained deployment units is the best practice here. When you set of services grows, you surely must deal with multifarious relationships among those, and this demands you to keep the service composition loosely coupled.
A loosely coupled architecture is made up of independent elements that are resilient to changes in the behavior of components with whom they collaborate. An asynchronous channel is used to bring about communications between components. Components can thus process messages and events on their terms, without affecting operations.
Besides, it is considered to decouple data ownership, data persistence, access, and reporting. You can deliver a higher level of agility and independence only when data is decoupled. There can thus be no referential integrity between data owned by one service and that owned by the other.
Is Your MSA Design in Place?
Now that you have learned how to make the right decision decisions that help to deliver a robust microservices architecture and implement it successfully, get ready to achieve your MSA goals. As you effectively implement these decisions, you notice the reduced design and build times, as well as lesser runtime dependencies between services and their consumers.
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