Benefits
Monolith applications are defined as Single Integrated Applications. Adding new features to monolithic applications makes them more complex and harder to change. These and some additional challenges of Monolithic Architecture helped Microservices Architecture to gain popularity in software development, as microservice architecture spreads integrated features into a network of different services. This makes microservices smaller than monoliths. Let's review some of the key reasons that make microservices popular:
Independent Deployment: Changes in microservices are deployed independently without causing downtime in other services. It's not necessary to orchestrate discrete services while deploying.
Technology Independent: A microservices architecture can contain individual services written in a variety of languages and tools.
Specialized & Autonomous Teams: By splitting the application into feature-based pieces, instead of working on the entire context of a monolith application, technicians and developers can acquire deep specialized knowledge, enabling them to be more responsive and productive in that smaller scope by developing more expertise. It can also be easier to onboard new developers into smaller application scopes, as they can learn and adapt faster. Teams with isolated domains of responsibility can easily make independent decisions and self-organize which increases motivation and productivity (Daniel Pink's theory of motivation).
Low Cycle-Time: While it may take weeks to complete a release cycle for a monolith, especially considering the effort spent on executing regression tests for the entire monolithic application, microservices, being smaller, can provide a shorter cycle time with high automation.
Performance & Scalability: When functionality is distributed in a network of microservices, it can be easier to isolate performance issues and bottlenecks to a single microservice. Scaling a microservice due to a performance issue would be more cost-effective than scaling a whole monolithic application.
Fault Isolation & Resilience: When an isolated service fails, it doesn't bring down the whole system. This way it becomes easier to address and fix possible issues.
Challenges
The advantages of microservices come with a cost: they are significantly more complex than monoliths, and we can categorize this cost as complexity. As microservices can be considered distributed systems, running and maintaining them can be challenging. Some of the key challenges of using microservices include:
Communication Performance: Every communication between microservices involves a network call, whereas every call between modules of a monolith application is in-process communication, which is almost instantaneous. A well-designed microservices architecture, being prepared for network failures and latency issues, and avoiding chatty behavior between services may help overcome network performance issues.
Security: Implementing security in a microservices environment can be complex because all security measures must be layered throughout the system to minimize security risks and eliminate exploitable vulnerabilities.
Observability: In a microservices architecture, as services are distributed across various servers and containers, monitoring and debugging become more complex and require specialized telemetry and analysis tools.
Automation: All repetitive tasks, such as tests, deployments, monitoring, and scaling, must be automated when working in a microservices architecture. This can add some additional complexity compared to a monolith architecture.
Coordination: All services must be organized to work harmoniously together to execute tasks. Configuring and managing dependencies of services can be challenging and may require extra expertise.
Data Governance: Acquiring data from a monolithic database and creating reports with it is pretty straightforward, but obtaining the same data from a variety of distributed services, each with its own data stores, can be complex.
Deployment & Versioning: Deploying multiple services with different versions, ensuring backward compatibility, and transitioning to newer versions can be complicated.
While microservices offer significant advantages, organizations must engage in careful architectural planning, adopt strong development practices, and possess an understanding of how to address the complexities that come with distributed systems when adopting a microservices architecture.