Microservice Communication: A Complete Guide 2024

If you are considering developing a web application using Microservice architecture, you're on the right track to building a robust and scalable system. In this guide, we'll explore the key ways microservices communicate with each other. By using the communication approach, you can benefit from improved flexibility, maintainability, and fault tolerance in your development process.

Learning Microservice Communication

For a system of microservices to work together, communication between them is essential. Two primary categories of communication techniques exist:

• Synchronous Communication: This type of communication is direct, in which the customer waits for a service response. Here, HTTP/HTTPS is the most regularly used protocol, which is frequently implemented via gRPC or RESTful APIs.
• Asynchronous Communication: The client doesn't have to wait for a prompt answer while using this technique. Messages are instead transmitted to an event bus or message broker, which forwards them to the relevant services. Typical protocols are MQTT, AMQP, and Kafka.

What are microservices?

Microservices are a modern architectural approach to developing applications by breaking them down into small, independent services that can be developed, deployed, and scaled independently. Each microservice is designed to perform a specific business function and communicates with other services through well-defined APIs. 

Advantages of Microservices Architecture

• Scalability and Flexibility:

Microservices allow applications to scale specific services independently based on demand. This modular approach enables developers to add or modify features without affecting the entire application, making it highly adaptable to changing requirements.

• Improved Maintainability:

With each service being separate, the codebase becomes more manageable, making it easier to understand, update, and debug. Teams can work on individual services simultaneously, promoting faster development and deployment.

• Fault Isolation and Resilience:

In a Microservices architecture, if one service fails, it doesn't bring down the entire system. Services are isolated, ensuring that failures are contained and the application remains resilient.

• Technology Diversity:

Microservices allow for the use of different technologies for different services, enabling developers to choose the best tools for each task. This flexibility encourages innovation and allows leveraging the most suitable technology stacks.

• Continuous Deployment:

Microservices promote continuous integration and continuous deployment (CI/CD) practices. Small, independent services can be deployed quickly, reducing the time to market for new features and updates.

What are the 4 ways in which microservices communicate?

Microservices have become increasingly popular due to their ability to improve scalability, maintainability, and overall development agility. One of the key factors that enable microservices to function effectively is their communication mechanism. Let's explore the four ways in which microservices communicate:

• Communication with Clients through RESTful APIs:

Microservices interact with clients through ‘RESTful APIs,’ providing a standardized and platform-independent approach. Clients can make HTTP requests to specific endpoints exposed by microservices to retrieve the required data or perform actions. 

Read our blog: Why Your Enterprise Applications Need A Microservice Architecture?

This decoupled communication enables smooth integration with various client applications.

• Communication between Microservices:

For complex business processes, microservices often need to communicate with each other. This inter-service communication can be achieved through various protocols, such as ‘HTTP,’ ‘gRPC,’ or message queues like ‘RabbitMQ. By communicating directly, microservices can collaborate adeptly to provide a cohesive application experience.

• Communication with Data Stores:

Microservices typically have their own databases or data stores. For data consistency, microservices communicate with their respective data stores when they need to read or write data. This approach ensures that each service can manage its data independently without interfering with other services.

• Communication with Infrastructure:

Microservices rely on infrastructure components like service discovery, load balancers, and ‘API gateways.’ Service discovery helps in locating and connecting with other microservices dynamically. Load balancers distribute incoming requests across multiple instances of a service to achieve high availability and scalability. API gateways act as intermediaries between clients and microservices, handling tasks like authentication, rate limiting, and caching.

Microservices Communication Types

When developing a web application using Microservice architecture, understanding the different types of communication between microservices is crucial for a successful implementation. Let's explore two essential types of microservices communication:

• Synchronous Microservices Communication:

In synchronous communication, the client sends a request to a microservice and waits for a response before proceeding. This type of communication is akin to a traditional client-server model. ‘RESTful APIs’ are commonly used for synchronous communication, where the client makes an HTTP request to the microservice, which then processes the request and sends back a response. While this approach simplifies development, it can lead to performance bottlenecks and potential cascading failures if a microservice experiences downtime.

• Asynchronous Microservices Communication:

Asynchronous communication, on the other hand, allows the client to send a message to a microservice without waiting for an immediate response. Instead, the microservice processes the message and sends a response later, or it may not send a response at all, depending on the situation. Asynchronous communication is often achieved through message brokers like ‘RabbitMQ or Kafka.’ This approach improves system resilience, as services can continue to function independently, even if one or more services are temporarily unavailable. However, it introduces complexities in handling eventual consistency and message processing.

• Data Sharing

Microservices occasionally require direct data sharing.

Shared Databases: Although they can result in tight coupling, shared databases are generally discouraged but can occasionally be used with proper planning. Ideally, every service should have its own database.

Use Case: A straightforward content management system in which several microservices require read access to a common database holding articles and user profiles. For instance, to show user-specific material, the profile and article services both read from a shared database.

Data Replication: Updated by events or data synchronisation procedures, services keep their own copies of shared data.

Use Case: A distributed CRM system with local copies of client data kept by each microservice. Events are issued to synchronise data across services upon updating client information, guaranteeing consistency while maintaining decoupling.

• Service Discovery

Microservices must find each other in the architecture using service discovery.

Service Registries: Apps such as etcd, Eureka, Consul, etc. They keep a list of all the services that are offered along with their locations.

Use Case: Consul is used for service discovery by an e-commerce application built on microservices. A newly launched microservice instance registers with Consul. After then, other services might ask Consul to locate any instances of the inventory or payment services.

DNS-Based Discovery: This method, which is frequently employed with container orchestration systems like Kubernetes, allows services to be found using DNS.

Use Case: Kubernetes-based application in which Kubernetes-provided DNS names are used by microservices to find each other.

• Service Mesh

A specific infrastructure layer for controlling communication between services.

Sidecar Proxies: Applications such as load balancing, encryption, and observability are managed by programs like Istio, Linkerd, or Envoy.

Use Case: Istio is used to handle retries, manage traffic between services, and implement circuit breaking to increase the robustness and observability of the game services in this microservices architecture for a large-scale online game.

Traffic Management: Manages the flow of traffic and puts regulations like circuit breaking and retries into effect.

Use Case: A financial trading platform where requests are routed based on policies that can dynamically alter in response to load and performance needs. Traffic flow between microservices is managed by a service mesh such as Linkerd.

Read our blog: What is The Role of Microservices in DevOps: Better Together

How Do Microservices Interact With Each Other?

Microservices interact via various network protocols and messaging systems. Some common methods include:

• HTTP/HTTPS: Microservices frequently communicate using RESTful APIs over HTTP or HTTPS protocols. Each microservice exposes endpoints, allowing other services to request or modify data. This is a simple and widely adopted method, making it ideal for many applications.

• Messaging Queues: Asynchronous communication between microservices can be achieved through messaging queues like RabbitMQ, Apache Kafka, or Amazon SQS. In this model, services publish messages to a queue, and other services consume them, allowing for loose coupling and support for event-driven architectures.

• RPC (Remote Procedure Calls): RPC mechanisms, such as gRPC or Thrift, allow microservices to invoke methods on remote services as if they were local, simplifying the communication process. gRPC, in particular, provides efficient communication using protocol buffers and HTTP/2.

• Event Streaming: In some architectures, microservices use event streaming platforms like Apache Kafka or Amazon Kinesis for communication. This allows services to produce and consume events in real-time, which is especially valuable for asynchronous and distributed event processing.

• Service Mesh: Service meshes provide added functionality for microservices communication, including service discovery, load balancing, encryption, and monitoring, enhancing both reliability and security.

What are some best practices for designing microservice communication?

Best practices for designing microservice communication include defining clear service boundaries and APIs, using lightweight protocols for communication, implementing idempotent and resilient endpoints, monitoring and logging communication patterns for debugging and troubleshooting, and considering the trade-offs between synchronous and asynchronous communication based on application requirements. Additionally, ensure robust security measures to prevent threats like SMS spoofing and other forms of cyber attacks.

Another key best practice is implementing a circuit breaker pattern in microservices communication. This pattern helps prevent service failures from cascading across the system by detecting when a service is unresponsive or slow, and temporarily "breaking" the connection to prevent overload. By doing so, the circuit breaker improves system resilience, ensuring that failures in one service don't impact the entire architecture. When combined with other practices like monitoring, idempotent endpoints, and security measures, the circuit breaker helps maintain stability and reliability in distributed microservices environments.

Summary

By adopting Microservices architecture, your web application development process can be revolutionized and will be cost-effective. Microservices communicate effectively through ‘RESTful APIs,’ with each other, data stores, and various infrastructure components. This approach improves scalability, maintainability, and fault tolerance. With SayOne Tech's expertise in Microservices development, you can unlock the full potential of this architecture for your business. 

Contact SayOne Tech developers today for top-notch Microservices development services.