How Microservices Communicate with Each Other
Microservices are a great framework for any enterprise, but it is of no use if they cannot communicate with each other smoothly.
Let us dig into the details of microservices and how they are associated with cloud native applications.
Every enterprise emphasizes building scalable applications. It is a fact that cloud-native approach is the best to overcome scalability challenges. One of the fundamental principles of cloud native is microservices.
What are Microservices?
Microservices are an architectural style and comprises of small modules/elements which are independent of each other. At times they are interdependent on other microservices or even a database. Breaking down applications into smaller elements brings scalability and efficiency to the structure.
Every microservice is deployed independently and presented in a different repository. There will an independent continuous delivery pipeline allocated to each microservice.
How do Microservices work?
Cloud microservices further break down the SOA (Service Oriented Architecture) strategy into smaller functional services. A collection of microservices becomes macro services where code updates or changes happen quickly and smoothly without interrupting the workflow.
A microservice task is to address one concern at a time. This helps in scalability, for example, if there are any code changes then updating the code of a single function is possible. There is no need to refactor or re-deploy rest of the framework of microservices. Even in the case of failures, the services are independent of each other thereby creating a reliable environment.
Another best part about microservices is that they are self-sustaining.
For example, consider a microservice in one of the clusters that have four subfunctions and one of the subfunctions fails. With lots of orchestration tools available in market today, self-healing can occur without human intervention. It happens without impacting the functioning of the framework and workflow. It is automatic and transparent to the end-user.
Microservices architectures are used along with Docker containers (packaging and deployment set-up). VM images were used for deployment until recently. But over time, developers have realized that containers are more efficient than VMs. With containers, the code (and required code libraries) can be deployed on any Linux system (or any OS that supports Docker containers). Containers are the perfect integration practice for microservices. The speed at which it can be launched or re-deployed helps during the events of migration or system failure.
Since containers are native to Linux, commodity hardware can be applied to a huge collection of microservices in any data center, private cloud, or hybrid multi-cloud.
Microservices and cloud-native architecture have always been associated together almost from the beginning, so it is common that the user community looks at it as similar practices. Microservices and containers can be run on any compatible OS (generally Linux). The OS can be present in the public cloud, on-premises, or in a virtual hypervisor.
Today with more development happening in the cloud, cloud-native architectures and practices have migrated back to on-premises data centers. A lot of enterprises are building their own local environs where they share the same primary characteristics as the cloud. The purpose is to enable a single development practice across any location. Popularity and more and more adoption of microservice frameworks and container technologies have e made cloud-native practice appealing and a necessity for companies.
How do They Communicate?
In the world of a microservice framework, any application is built through a collection of services. But each service in that collection has to meet the following guidelines:
- Loosely coupled
- Manageable and testable
- Ability to deploy independently
Task of each service in a microservice framework is to solve a business problem in the application or to support one. A single team will be assigned to look into the services and functionality of the application.
Benefits of Microservice architecture that are making it a popular service are:
- Easy to build and manage
- Services are classified around business issues
- Scalable and fast
- Scope for autonomous and independent teams
Let us look at some of the ways in which services can communicate in a microservices architecture.
- HTTP communication
- Message communication
- Event-driven communication
HTTP has the total control while choosing how services should communicate with each other. HTTP calls between services is a feasible approach for service-to-service communication.
In such cases when one service is dependent on another service, the services complete their task cycle and then meet the requests received from another service. This is called Synchronous HTTP calls between services. There is no coupling between services here. But those services that placed requests have to wait till they get the response, in order to perform any action.
HTTP asynchronous call is another option between two services. Here, the service takes request from the first service in case of multiple requests and immediately responds with a URL. This URL is used to check on the progress of the request. The services need not wait for their response as this happens instantly as coupling is loose. The services are isolated.
In message communication, the participating services do not communicate directly with each other. The services push messages via message broker in order to reach out to other services. The message broker is the point of contact between all services. This reduces complexity and increases efficiency.
However, there is still some coupling between services using this approach. Both or all the services must agree on the message structure and components involved before the workflow.
An event-driven pattern is another asynchronous approach where coupling between services is completely removed. In an event-driven approach the services need not know about any common message structure. Communication happens through events that individual services generate.
A message broker is still needed here as individual services will write their events to it. However, the participating services need not know the details of the event. They only respond to the event that is happening and not any message that the event would deliver.
There are many communication patterns for microservices out there that are doable in a microservice-based architecture. It can be achieved in both synchronous and asynchronous pattern.
Implementation of the microservice looks easy at the onset. The size and focus of these smaller elements simplify the tasks and are much better than the archetypal monolith architecture. But in the case of multiple services that are interdependent, things can get quite challenging. The distributed nature of the system can lead to technical glitches. It will be better to deploy them as independent entities. However, you cannot do this at all times. You might need the help of another service to activate business logic. We at Embitel have been a successful service provider in this sector. Reach out to industry experts today.