Are Microservices Distributed Systems?

A distributed system comprises independent nodes that communicate with each other to accomplish a common goal. The short answer to whether microservices are a distributed system is yes.

Microservices are a type of distributed system,s since the architecture entails decoupling a large application into a suite of small services. These services communicate with each other, often through APIs and are designed to be deployed independently. This approach allows for flexibility, scalability, and ease of maintenance and testing of individual services.

Not all distributed systems are microservices, and there’s a distinct difference between the two architectural concepts. To better understand how microservices are related to distributed systems, we’ll define each and provide some examples you’ll recognize.

The Fundamentals of Distributed Systems: A Deep Dive

There are a few key concepts that are essential to understanding how distributed systems work. At a high level, they are a network of computers that coordinate to perform a common task. The key idea behind a distributed system is to spread the workload across multiple nodes in the network. By distributing the workload, the system becomes more fault-tolerant, as the failure of one node does not necessarily lead to the failure of the entire system.

Some of the characteristics of distributed systems include:

• Concurrent processing

Multiple nodes in the network can process data or perform tasks simultaneously. The system can take advantage of the processing power of multiple machines, achieving more efficient use of resources.

• Shared data

In a distributed system, data can be stored and accessed by multiple nodes in the network. This allows for flexibility regarding where data is stored and how it is accessed. However, it also introduces new challenges related to data consistency and coordination.

• Transparency

The system should hide the complexity of the underlying network and present a simple, unified view to the user. The user is not aware of the underlying complexity of a distributed system.

Examples of distributed systems include:

• Cloud computing platforms like Amazon Web Services, Microsoft Azure, and Google Cloud Platform
• Peer-to-peer networks like BitTorrent
• Distributed databases like MongoDB and Cassandra
• Cluster computing frameworks like Apache Hadoop and Apache Spark

The fundamentals of Microservices

Microservices are a way of structuring an application as a collection of small, independently deployable services that communicate with each other over a network. This is different from the traditional monolithic architecture, where all components of the application are tightly coupled and run as a single unit.

These are the primary characteristics of a microservice:

• Flexibility

Microservices architecture allows individual services to be developed, deployed, and scaled independently, allowing faster development and deployment. In contrast, in a monolithic architecture, changes to the codebase require the entire application to be rebuilt and redeployed, which can be time-consuming and complex.

• Scalability

In microservices architecture, each service can be deployed on different machines or locations, allowing for horizontal scaling. This means that as the load on the system increases, more resources can be added to individual services to handle the load rather than having to scale the entire application.

• Isolated maintenance

Microservices architecture allows for better isolation of bugs and easier troubleshooting. If a bug is found in one service, it can be fixed and deployed without having to deploy changes to the entire application.

Drawbacks of microservices:

• Increased complexity

Microservices architecture involves breaking down a monolithic application into smaller, independent services. While this can provide many benefits, it also increases the overall complexity of the system as a whole. This can make it more difficult to understand and maintain, as well as to troubleshoot and debug issues that may arise.

• Security concerns

Microservices architecture may introduce new security risks, as each service may have its own set of vulnerabilities that must be managed. Additionally, services may need to communicate sensitive information with each other, which can introduce security risks if not properly secured.

• Data consistency

In a microservices architecture, different services may store and manage parts of the application's data. This can make it more difficult to maintain data consistency across the system, as there may be multiple sources of truth for the same data. This can lead to data inconsistencies, conflicts, and other issues.

Distributed monoliths

Although distributed systems are often associated with microservices, it's possible to have a distributed monolith. Usually, this happens when attempting to build a microservice-based app without taking into account microservices architectural principles.

Building microservices is more than simply splitting an application into several entities and implementing CRUD operations using APIs. Each microservice should be able to handle instances independently and synchronously communicate with each other.

You can think of a distributed monolith as a system which resembles a microservice architecture but operates under the principles of monolith architecture.

You know you have distributed monolith if your services:

• It cannot be deployed independently and scale
• Their communication is affected by high latency
• They share the same database or any other resource
• A change in one service collapses the entire system

To avoid ending up with a distributed monolithic, let’s look at how best to implement microservice architecture.

Implementing microservices

Here are some best practices to keep in mind when implementing microservices:

Choose the right technologies for communication and coordination

Microservices communicate with each other through APIs, so it's important to choose technologies that are well-suited for building and consuming APIs. This includes technologies such as REST and gRPC. When deciding on the technology stack, it is important to consider the language, framework, and libraries that are best suited for the problem at hand. Also, consider the scalability of the chosen technologies.

Establish a consistent and reliable service registry

A service registry is a central location where services can register themselves and discover other services. This allows for easy communication between services and allows for service discovery and load balancing. A service registry should be built with reliability and scalability in mind. A clear and consistent naming convention for services is important to keep the architecture organized and easy to work with.

Implement service discovery and load balancing

Service discovery allows services to find and communicate with each other, while load balancing ensures that traffic is distributed evenly among all available instances of a service. This helps ensure the system remains available and responsive even under heavy load. Different load-balancing algorithms can be used depending on the specific use case. For example, Round-robin and Least-connections are some of the popular algorithms.

Monitor and log everything

Monitoring and logging are essential for understanding how your system is behaving and identifying issues when they arise. Use monitoring tools such as Prometheus and Grafana for metrics, and log aggregation tools like Elasticsearch and Kibana for logs. Furthermore, it is important to have a centralized monitoring and logging system to have a centralized view of the entire system.

Implement a circuit breaker pattern

Microservices are distributed systems, and communication between them can fail. A circuit breaker pattern can be implemented to prevent cascading failures by halting communication with a service that is not responding. This pattern can be implemented using libraries like Hystrix and Resilience4j.

Monolith decomposition strategies

When it comes to decomposing a monolithic architecture into a microservices architecture, several strategies can be employed to make the process more manageable. Two popular strategies are the Strangler Fig pattern and Branch by Abstraction.

Strangler fig pattern

The Strangler Fig pattern is a technique for gradually migrating a monolithic application to a microservices architecture. The idea is to create new microservices that gradually "strangle" the functionality of the existing monolithic application. This is done by creating new services that handle specific functionality and gradually routing more and more traffic to the new services until the monolith is no longer needed.

This approach minimizes the risk of disrupting the existing system. This pattern is best used when there is a need to decompose a legacy system and introduce new services incrementally.

Branch by abstraction

Branch by abstraction involves creating an abstraction layer within the monolithic application to allow new services to be developed and deployed independently of the existing system.

The abstraction layer allows the existing monolithic application to continue running while new services are implemented. This pattern is best used when there is a need to introduce new functionalities to the system, but the monolithic architecture doesn't allow for it.

Service decomposition

Service decomposition is a strategy for decomposing a monolithic architecture into a microservices architecture. The process starts by identifying the core business capabilities of the system and grouping them into individual services. Each service should be responsible for specific functionality and should have a clear and well-defined interface for communication with other services. This approach allows for better separation of concerns, making the system more maintainable and easier to understand.

One important aspect of service decomposition is to ensure that the services are loosely coupled, meaning that changes to one service should not have a ripple effect on other services.

While decomposing a monolith architecture, it's a good idea to observe these best practices:

• Identify the boundaries:

The first step is to identify the boundaries of the different services. This is done by analyzing the functionalities of the application and looking for natural groupings of related functionality.

• Start small

Decomposing a monolithic architecture can be a daunting task, so it's important to start small. Begin by identifying a single service that can be extracted from the monolith and focus on that service first. Once that service is up and running, you can move on to the next service.

• Use feature flags

Feature flags allow you to deploy new functionality to a small set of users while keeping the functionality hidden from the majority of users. This allows you to test new functionality in a production environment without the risk of disrupting the entire system.

• Use a phased approach

Decomposing a monolithic architecture can be a complex and time-consuming process, so it's important to take a phased approach. Start by extracting a small number of services, then gradually increase the number of services over time.

• Re-architect as necessary

Decomposing a monolithic architecture often requires re-architecting the system. This may include changes to the data model, the application's infrastructure, and the application's runtime environment.

• Emphasize communication and collaboration

The process of decomposing a monolithic architecture can be challenging, so it's important to emphasize communication and collaboration between the different teams involved in the process. This includes not only the development team but also the operations, testing and security teams.

Frequently Asked Questions

Q: What is microservices architecture?
A microservices architecture is a way of building software applications as a collection of small, independently deployable services. Each service is responsible for a specific functionality and communicates with other services through APIs.

Q: Can microservices architecture be used for small projects?
Microservices architecture can be used for projects of any size, but it may be overkill for small projects. It's important to consider the complexity of the project and the resources available before deciding on an architecture. Microservices may be more appropriate for larger, more complex projects that require high scalability and fault tolerance.

Key Takeaways

Microservices are a type of distributed system. They are an architectural pattern in which an application is broken down into small, independently deployable services that communicate with each other over a network. Each microservice is responsible for a specific business function and can be developed, deployed, and scaled independently. This allows for greater flexibility and scalability compared to a monolithic architecture.

However, implementing microservices also comes with its own set of challenges such as increased complexity, increased operational overhead and increased security risk. To overcome these challenges, it's important to have a good understanding of the best practices for designing and managing microservices in a distributed system.