What are Microservices?

While building an application, one has to keep many factors in mind to make the application efficient and effective. Several services are performed while building an application. So, what are microservices? Microservice is one such service that is responsible for software development. It helps you to identify future debugging problems and allows you to check architecture for service and performance. 

Also, the major advantage we have using microservice is that even if one component fails, the entire software system will not break. Since microservice divides the app into sub-components. Using a common toolset for microservice in DevOps, both the development and operations can be handled smoothly. In this article, each and every detail about microservice is explained such as microservice – characteristics, architecture, examples, etc. 

What are Microservices?

Microservice is a small, loosely coupled distributed service. Microservice architecture evolved as a solution to the scalability, independently deployable, and innovation challenges with Monolithic architecture (Monolithic applications are typically huge – more than 100,000 lines of code). It allows you to take a large application and decompose or break it into easily manageable small components with narrowly defined responsibilities. It is considered the building block of modern applications. Microservices can be written in a variety of programming languages, and frameworks, and each service act as a mini-application on its own. Microservice can be considered as the subset of SOA(Service Oriented Architecture). 

Reasons for Using Microservice

In monolithic applications, there are a few challenges:

• For a large application, it is difficult to understand the complexity and make code changes fast and correctly, sometimes it becomes hard to manage the code
• Applications need extensive manual testing to ensure the impact of changes
• An application typically shares a common relational database to support the whole application
• For small changes, the whole application needs to be built and deployed
• The heavy application slows down start-up time

Benefits of Microservices

1. Small Modules – The application is broken into smaller modules that are easy for developers to code and maintain.
2. Easier Process Adaption – By using microservices, new Technology & Process Adaption becomes easier. You can try new technologies with the newer microservices that we use.
3. Independent scaling – Each microservice can scale independently via X-axis scaling (cloning with more CPU or memory) and Z-axis scaling (sharding), and Y-axis scaling (functional decomposition) based on their needs.
4. Removes dependency – Microservice eliminates long-term commitment to any single technology stack.
5. Unaffected – Large applications remain largely unaffected by the failure of a single module.
6. DURS – Each service can be independently DURS (deployed, updated, replaced, and scaled).
7. Increased Security: –Microservices enable data separation. Each service has its own database, making it harder for hackers to compromise your application.
8. Open Standards: –APIs enable developers to build their microservices using the programming language and technology they prefer.

Limitations of Microservices

1. Configuration Management – As it becomes granular the headache comes with configuring the services and monitoring those. You need to maintain configurations for hundreds of components across environments.
2. Debugging – Tracking down the service failure is a painstaking job. You might need to look into multiple services across different components. Centralized Logging and Dashboards are essential to make it easy to debug problems.
3. Automation – Because there are a number of smaller components instead of a monolith, you need to automate everything – Builds, Deployment, Monitoring, etc.
4. Testing – Needs a greater effort for end-to-end testing as it needs all the dependent services to be up and running.
5. Coordination – While handling requests across multiple independent services there is a requirement for proper workflow management.

Examples of Microservices

Organizations experienced a massive change while using microservice in their application, and that’s where the transition from monolithic to microservice came. You can go through some of the real-life examples in applications that use microservice are:

• Amazon – Initially, Amazon was a monolithic application but when microservice came into existence, Amazon was the first platform to break its application into small components, thereby adapting microservice. Due to its ability to change individual features and resources, the site’s functionality improved to a massive extent. 
• Netflix – Netflix is one such company that uses microservices with APIs. In 2007, when Netflix started its move towards movie-streaming service, it suffered huge service outages and challenges, then came the microservice architecture which was a blessing to the platform. 
• Uber – When uber switched from monolithic nature to a microservice, it experienced a smooth way. Using microservice architecture, the webpage views and searches increased to a greater extent. 

Characteristics Of Microservices

• The application will be divided into micro-components
• Each service has a separate database layer, independent codebase, and CI/CD tooling sets
• Can also use different languages, frameworks, and technologies
• Well-understood Distribution Transaction Management
• Presents API and is a decentralized app
• Easy routing process
• Robust and failure-resistant
• Decentralized operations
• Stateless and stateful services
• Designed for business
• Each service is independent
• Autonomous and specialized
• Each Service can implement an independent security mechanism

Components of Microservice Architecture

Microservices were introduced to update the requirement in the application (components) without affecting the entire application. Microservice architecture is a type of application architecture where the application is developed as a collection of services. It helps in providing a framework used to develop, deploy, and maintain microservices architecture diagrams and services independently. Each service can be changed according to the need of the application without affecting the rest of the application.

The components of microservice architecture include:

• Identity Providers – This service allows users to access and identify data. It creates applications using a collection of loosely coupled services. You can redirect users to the IAM for authentication, i.e., set up a user database and define permissions for user-facing microservices. 
• Databases – It owns a private database to access data and it is also updated through its service API. It supports inter-process communication for a different technology to any remote service. 
• Containers – These are software packages that operate independently to avoid any disturbance in the other components. Containers are efficient since they rely on specific dependencies and the underlying code. Also, container orchestration tools like Kubernetes provide automated scaling and container management. 
• Service Discovery – It manages deployment and distributes the load evenly, it features a service consumes, service registry, and service provider.
• API Gateway – It serves as an essential part of communication in the system between the client and microservices.

Microservice Pros and Cons

As every coin has two sides, each system has pros and cons as well. Microservices too have some pros (benefits) and cons as well. Let’s have a look at them:

Pros

• Can independently develop and deploy services
• Dynamically scalable and quickly functioning
• Integration with third-party dependencies
• Has an independent manageable deployment module
• Different services may use different languages

Cons

• Multiple services mean multiple resources (difficult to handle)
• Different services using different languages makes testing difficult
• Debugging issues
• Increase in effort while handling it
• Challenges in deployment
• Communication between services isn’t easy

Design Patterns of Microservices

When a problem occurs while working on a system, there are some practices that are to be followed and in microservices, those practices are Design Patterns. Design patterns are such practices which when followed lead to efficient architectural patterns resulting in overcoming challenges such as inefficient administration of these services and also maximizing performance. While working on an application, one must be aware of which design pattern to be used for creating an efficient application.

1. Aggregator – It invoked services to receive the required information (related data) from different services, apply some logic and produce the result. The data collected can be utilized by the respective services. The steps followed in the aggregator pattern involve the request received by the service, and then the request made to multiple other services combines each result and finally responds to the initial request. 
2. API Gateway – API Gateway acts as a solution to the request made to microservices. It serves as an entry point to all the microservices and creates fine-grained APIs for different clients. Requests made are passed to the API Gateway and the load balancer helps in checking whether the request is handled and sent to the respective service. 
3. Event Sourcing – This design pattern creates events regarding changes (data) in the application state. Using these events, developers can keep track of records of changes made. It is generally used with the CQRS pattern to decouple read and write commands. 
4. Strangler – Strangler is also known as a Vine pattern since it functions the same way vine strangles a tree around it. For each URI (Uniform Resource Identifier) call, a call goes back and forth and is also broken down into different domains. Here, two separate applications remain side by side in the same URI space, and here one domain will be taken into account at a time. Thus, the new refactored application replaces the original application.
5. Decomposition – decomposition design pattern is decomposing an application into smaller microservices, that have their own functionality. Based on the business requirements, you can break an application into sub-components. For example, Amazon has separate services for products, orders, customers, payments, etc. 

There are other design patterns as well, but the above-mentioned are some of the majorly used ones. 

SOA vs Microservices

SOA (Service Oriented Architecture) is a collection of services that communicate with each other for passing data. Whereas Microservices are such architectures in which the application is broken into smaller components to serve only one function. The main difference between SOA and microservices lies in their architecture. 

• In SOA, you need to modify the monolith whereas microservice lets you create a new service.
• SOA uses message protocols whereas microservice uses HTTP, REST
• SOA shares the data storage whereas microservice has independent data storage.
• Communication is done using ESB in SOA where through an API layer in microservices.
• SOA is less scalable while microservices involve highly scalable architecture.

If you want to know more, do read Difference between Service-Oriented (SOA) and Micro Service Architecture (MSA)

Microservice Frameworks for Java

There are several microservices frameworks that you can use for developing Java. Some of these are:

1. Spring Boot – This is probably the best Java microservices framework that works on top of languages for Inversion of Control, Aspect-Oriented Programming, and others.
2. Dropwizard – Dropwizard pulls together stable, mature libraries from the Java ecosystem into a simple, lightweight package that lets you focus on getting things done.
3. Restlet – Restlet Framework helps Java developers build better web APIs that follow the REST architecture style.
4. Spark – A micro-framework for creating web applications in Kotlin and Java 8 with minimal effort.

Others that you can consider include Ninja Web Framework, Play Framework, RestExpress and Restx Framework.

Final Verdict

Now that you know “What are microservices”, it’s very important to have a practical idea about them by working hands-on on them. This article entirely answers all your doubts about microservices, their architecture, working, features, real-life applications, etc. Microservices are a must-known term in the case while building an application. Thus, it’s very important to have a good command of it. 

FAQ’s

Q1. What is meant by microservices?

Microservices are an architectural way of software development where the application is divided into small components (service). It allows the application to break into small parts which helps in solving debugging issues. Thus, it saves from crashing the entire system as you’ve to just focus on the small component. 

Q2. What are the 3 components of a microservice?

The three main components of a microservice include:

• Containers
• API Gateway
• Database

Q3. Is an API a microservice?

APIs combine separate microservices to perform an operation. Microservice breaks the application into small components to ease the operation and debugging issues whereas APIs are solely responsible for communication. For more details, please refer to the article – Difference between Microservice and API.