Microservices is a service-oriented architecture pattern that builds applications as a collection of various smaller independent service units. Microservices is a software engineering approach that focuses on breaking down an application into single-function modules having well-defined interfaces. These modules can be deployed independently and operated by small teams that own the service’s entire lifecycle.

‘Micro’ refers to the size of a microservice that needs to be manageable by a single development team of 5 to 10 developers. In this way of looking at application architecture, big applications are divided into small independent units. This article will demonstrate microservices tutorials using examples, and also tell you about the different tools and architecture styles you need to know about.

What is Monolithic Architecture?

Every e-commerce application has a set of standard features like Search, Review, Payments etc. Customers can access these features using their browsers and dedicated platform apps. Simply put, monolithic architecture can be seen as a large container within which all the software components of an application are combined into a single package. When the developer deploys the application, it is a single Monolithic unit. The code for each different feature is on the same server. To scale the application, you will need to run multiple instances or servers of these applications. There are, however, several challenges to Monolithic architecture.

Challenges of Monolithic architecture

Scalability

There are multiple music apps in use today. Take Spotify as an example. Assume the developers want to update a Top Hits playlist according to the newest song ratings and listings. They cannot scale the application simultaneously using Monolithic architecture. New instances of the same application must be created every time a new feature or change has to be developed or deployed.

Agility

Consider that developers want to make immediate changes within the application. Monolithic architecture and applications can accommodate these changes, but the problem is that the developers will have to rebuild the code from scratch for every small change.

Hybrid Technologies

Now consider the developers of the application, Spotify in this case, are comfortable using technologies like Java, C++, NET, or C#. Even though they don’t have a problem using these technologies, Monolithic architecture will require them to build large and complex applications using a single technology.

Fault Tolerance

Suppose one application feature stops working. The entire application will go down as a result. To overcome this problem, the application has to be created once again. It needs to be tested once again and finally re-deployed.

With so many challenges and complexities, developers have re-designed monolithic applications and have broken them down into multiple individual components that can be managed and deployed piece by piece. This is what we know today as microservices.

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What is Microservice Architecture?

Microservice architecture allows developers to build applications as a collection of small autonomous services developed for a business domain. It is an application architectural development style, a variant of structural style architecture that helps arrange applications as a coupled collection of services. The Microservice architecture contains fine-grained services and lightweight protocols.

Consider an e-commerce application developed using microservice architecture. Each microservice is focused on a single business capability. Each feature like Search and Rating have their individual instances (server) and communicate with each other.

Advantages of Microservice Architecture

Multiple programming languages

There are many benefits to using microservices. Since they communicate using messaging if at all, they don’t depend on a single coding language. Developers can choose the programming language they are most comfortable with. This helps work move faster and reduce costs and bugs.

Agility

Since your team of developers will work on smaller applications and more focused problems, your projects will be more agile as a result. Your team will be able to iterate faster, address new features on tight deadlines and fix bugs almost immediately. They will also find more ways to reuse code.

Scalability

Unlike Monolithic architecture, Microservices help improve the scalability of your architecture. When there is a problem with a Monolithic application, you tend to solve it by purchasing and adding new hardware or complicated enterprise software. With Microservices, you can scale horizontally or laterally with standard solutions such as load balancers and messaging.

Cloud Compatibility

Cloud platforms evolve and adapt to accommodate newer technologies. Microservices comprise smaller applications with limited dependencies. Both cloud platforms and Microservices lend themselves to containerisation. This means organisations can scale services horizontally with services such as Docker and Kubernetes without having to write any customised code.

 

Examples of Microservices Frameworks for Java

There are many Microservice frameworks that you can use while developing applications for Java. Some of these are mentioned below.

Microservices with Spring Boot

Arguably the best Java microservices framework. Spring Boot works over languages for Inversion of Control, Aspect-oriented Programming and the like. It gives you a Java application to use with your own apps via an embedded server. It also uses Tomcat, therefore you don”t need to use Java EE Containers. Spring Boot has all the infrastructures that your applications need. Whether you are writing apps for security, configuration or Big Data, you will find a Spring Boot project to help you achieve your goal.

 

A typical Spring Boot project includes

  • IO Platform - Enterprise-grade distribution for versioned applications
  • Framework - Helps with transaction management, dependency injection, data access, messaging and web applications.
  • Cloud - For distributed systems. The cloud is used to build and deploy Microservices
  • Data - This is useful for microservices that are related to data access, whether it’s map-reduce, relational or non-relational.
  • Batch - For high levels of batch operations
  • Security - This is needed for authorisation and authentication support
  • REST Docs - This helps to document RESTful services
  • Social - Connects you to social media APIs
  • Mobile - For mobile web apps

Microservices with Jersey

This is an open-source framework. It supports JAX-RS APIs in Java and is very easy to use. Jersey’s applications can extend existing JAX-RS implementations. They can also add features and utilities that can make RESTful services simpler and make client development easier.

Jersey offers exceptional documentation capabilities, which makes it stand out from other frameworks. It has several excellent examples, is very fast and has very easy routing.

Jersey is very easy to use with other libraries like Netty and Grizzly and also supports asynchronous connections. It doesn’t require servlet containers. Its only drawback is that it has an unpolished dependency injection implementation.

Microservices with Swagger

Swagger helps you to document APIs and also gives you a development portal to allow testing of your APIs. It is an open-source toolset that can be easily integrated into your application or solution. Even people who don’t have technical knowledge can easily use the Swagger Microservice framework.

Microservices with Dropwizard

Dropwizard helps you to combine and access mature and stable Java libraries in lightweight packages that are easy to use for your applications. It uses Jetty for HTTP, Jersey for REST and Jackson for JSON. Dropwizard also uses Metrics, Guava, Logback, Hibernate Validator, Apache HttpClient, Liquibase, Mustache, Joda Time and Freemarker.

A Dropwizard application can easily be set up using Maven. In your POM, add a dropwizard.version property using the latest version of DropWizard. Simply doing this sets up a Maven project for you. Then you can create a configuration class, an application class, representation class, resource class or a health check. You can also build Fat JARS and then run your application.

Microservices with Play

Play is a framework that lets you build, create and deploy web applications easily using Scala and Java. This framework works great for RESTful applications that require handling remote calls parallelly. It is a highly modular framework and supports async. Of all the Microservices frameworks, Play has one of the largest communities.

Microservices with Restlet

The Restlet framework helps developers to create scalable and efficient web APIs that comply with the RESTful architecture pattern and style. This framework displays good routing and filtering. It is available for Java SE/ EE, OSGi, Google’s AppEngine (a part of Google Compute), Android and many other Java platforms. It is a self-reliant framework that comes with its own webserver.

One of the limitations of Restlet is that the framework comes with a steep learning curve. This is only made worse by its closed community, although you can get help from different platforms around the world.

SOA (Service Oriented Architecture) Principles

A service-oriented architecture (SOA) is an architectural pattern in computer software design where a communications protocol is used by application components over a network to provide service to other components. The principles of service-orientation are independent of products, vendors and technology. SOA makes it easier for software components to work with each other even over various networks.

SOA services are maintained by a registry that acts as a directory listing. Applications must look up the services in the registry to invoke each service.

Microservices are a form of the service-oriented architecture style, in that applications are built as a collection of smaller services instead of a single application or software.

Additional Read: What are Microsoft Azure Cloud Services?

Microservice Tools

There are several Microservice tools that can make your team’s life easier.

1. Wiremock: Testing Microservices

Wiremock is a flexible library of sorts, for stubbing and mocking web services. Wiremock can configure responses returned by the HTTP API when a specific request is received. It is also used for testing microservices.

2. Docker

Docker is an open-source project that allows you to create, deploy and run applications by using containers. These containers allow developers to run an application as a single package. They also allow you to transfer libraries and other dependencies in a single package.

3. Hystrix

Hystrix is a fault tolerance Java library. It is a tool designed to separate access points to remote services, systems and third-party libraries within a distributed environment such as that of Microservices. Hystrix improves your overall application system by isolating the failing services and preventing consequent service failures.

 

Best Practices for Microservices

Making the shift to Microservice architecture applications has many benefits, as you must have realised by now. These benefits extend to business, development and operations. Microservices create opportunities for increased stability, scalability, agility, reliability and higher cost savings.

Like every good or service, Microservices too have limitations. If you are looking to migrate to Microservices, there are some industry-recognised practices to help overcome pitfalls.

  1. Each Microservice you use should have its own data store. If teams share databases, a monolithic service comes up which limits agility.
  2. Keep and use code of a similar maturity level. This helps the developer smoothly align their flow while creating or modifying code.
  3. Use containers, so that you can deploy and orchestrate your system using a single set of tools. This helps operations and dev-ops manage the chaos.
  4. Always treat your server as stateless.

Microservices Certification

As more apps migrate to Microservices, there is a growing demand for Microservice developers and experts. As of February 2021, job portal Naukri.com showed more than 45000 vacancies for Microservice professionals. Be the first among your peers, enroll in a Microservices course today.

Armin Vans
Aarav Goel has top education industry knowledge with 4 years of experience. Being a passionate blogger also does blogging on the technology niche.

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