What are Microservices? Code Examples, Tutorials & More (2022)

Microservicesare increasingly used in the development world as developers work to create larger, more complex applications that are better developed and managed as a combination of smaller services that work cohesively together for more extensive, application-wide functionality.

Tools such as Service Fabric are rising to meet the need to think about and build apps using a piece-by-piece methodology that is, frankly, less mind-boggling than considering the whole of the application at once.

Today, we’ll take a look at microservices, the benefits of using this capability, and a few code examples.

(Video) What are microservices really all about? - Microservices Basics Tutorial

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What are Microservices? Code Examples, Tutorials & More (1)

What are Microservices?

Microservices are an architectural style that develops a single application as a set of small services. Each service runs in its own process. The services communicate with clients, and often each other, using lightweight protocols, often over messaging or HTTP.

(Video) What are Microservices?

Microservices can be thought of as a form of service-oriented architecture (one of the most critical skillsfor Java developers) wherein applications are built as a collection of different smaller services rather than one whole app.

Instead of a monolithic app, you have several independent applications that can run on their own. You can create them using different programming languages and even different platforms. You can structure big and complicated applications with simpler and independent programs that execute by themselves. These smaller programs are grouped to deliver all the functionalities of the big, monolithic app.

Microservices captures your business scenario, answering the question, “What problem are you trying to solve?”

Instead of large teams working on large, monolithic projects, smaller, more agile teams develop the services using the tools and frameworks they are most comfortable with. Each of the involved programs is independently versioned, executed, and scaled. These microservices can interact with other microservices and can have unique URLs or names while being always available and consistent even when failures are experienced.

What are Microservices? Code Examples, Tutorials & More (2)

What are the Benefits of Microservices?

There are many benefits to using microservices. Some of them are related to how they allow your developers to write code. Other influence your architecture.

Microservices are small applications that your development teams create independently. Since they communicate via messaging if at all, they’re not dependent on the same coding language. Developers can use the programming language that they’re most familiar with. This helps them come work faster, with lower costs and fewer bugs

Since your teams are working on smaller applications and more focused problem domains, their projects tend to be more agile, too. They can iterate faster, address new features on a shorter schedule, and turn around bug fixes almost immediately. They often find more opportunities to reuse code, also.

Microservices improve your architecture’s scalability, too.

With monolithic systems, you usually end up “throwing more hardware” at the problem or purchasing expense and difficult-to-maintain enterprise software. With microservices, you can scale horizontally with standard solutions like load balancers and messaging.

Also, as more and more enterprises embrace the cloud, you’re probably looking that way, too. Microservices are a great way to get there.

What are Microservices? Code Examples, Tutorials & More (3)

Cloud platforms lend themselves to newer technologies like containerization. Microservices lend themselves to containerization too, since they already are small applications with a limited set of dependencies. This means you can scale your services horizontally with technologies like Docker and Kubernetes without writing any customized code.

Examples of Microservices Frameworks for Java

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

  • 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.
  • Jersey. This open-source framework supports JAX-RS APIs in Java is very easy to use.
  • Swagger. Helps you in documenting API as well as gives you a development portal, which allows users to test your APIs.

Others that you can consider include: Dropwizard, Ninja Web Framework, Play Framework, RestExpress, Restlet, Restx, and Spark Framework.

How to Create Using Dropwizard

DropWizard pulls together mature and stable Java libraries in lightweight packages that you can use for your applications. It uses Jetty for HTTP, Jersey for REST, and Jackson for JSON, along with Metrics, Guava, Logback, Hibernate Validator, Apache HttpClient, Liquibase, Mustache, Joda Time, and Freemarker.

You can setup a Dropwizard application using Maven. How?

In your POM, add in a dropwizard.version property using the latest version of DropWizard.

(Video) Microservices Basics Tutorial Part 1 || Spring boot Microservices || Code Decode

<properties><dropwizard.version>LATEST VERSION</dropwizard.version></properties>Then list the dropwizard-core library:<dependencies><dependency><groupId>io.dropwizard</groupId><artifactId>dropwizard-core</artifactId><version>${version}</version></dependency></dependencies>

This will set up a Maven project for you. From here, you can create a configuration class, an application class, a representation class, a resource class, or a health check, and you can also build Fat JARS, then run your application.

Check out the Dropwizard user manual at this link. The Github library is here.

Sample code:

package com.example.helloworld;import com.yammer.dropwizard.config.Configuration;import com.fasterxml.jackson.annotation.JsonProperty;import org.hibernate.validator.constraints.NotEmpty;public class HelloWorldConfiguration extends Configuration {@NotEmpty@JsonPropertyprivate String template;@NotEmpty@JsonPropertyprivate String defaultName = "Stranger";public String getTemplate() {return template;}public String getDefaultName() {return defaultName;}}

Microservices with Spring Boot

Spring Boot gives you Java application to use with your own apps via an embedded server. It uses Tomcat, so you do not have to use Java EE containers. A sample Spring Boot tutorial is at this link.

You can find all Spring Boot projects here, and you will realize that Spring Boot has all the infrastructures that your applications need.

It doesn’t matter if you are writing apps for security, configuration, or big data; there is a Spring Boot project for it.

Spring Boot projects include:

  • IO Platform: Enterprise-grade distribution for versioned applications.
  • Framework: For transaction management, dependency injection, data access, messaging, and web apps.
  • Cloud: For distributed systems and used for building or deploying your microservices.
  • Data: For microservices that are related to data access, be it map-reduce, relational, or non-relational.
  • Batch: For high levels of batch operations.
  • Security: For authorization and authentication support.
  • REST Docs: For documenting RESTful services.
  • Social: For connecting to social media APIs.
  • Mobile: For mobile Web apps.

Sample code:

import org.springframework.boot.*;import org.springframework.boot.autoconfigure.*;import org.springframework.stereotype.*;import org.springframework.web.bind.annotation.*;@RestController@EnableAutoConfigurationpublic class Example {@RequestMapping("/")String home() {return "Hello World!";}public static void main(String[] args) throws Exception {SpringApplication.run(Example.class, args);}}

Jersey

Jersey RESTful framework is open source, and it is based on JAX-RS specification. Jersey’s applications can extend existing JAX-RS implementations and add features and utilities that would make RESTful services simpler, as well as making client development easier.

The best thing about Jersey is its exceptional documentation. It’s filled with excellent examples. Jersey is also fast and has extremely easy routing.

The documentation on how to get started with Jersey is at this link, while more documentation can be foundhere.

A sample code that you can try:

package org.glassfish.jersey.examples.helloworld;import javax.ws.rs.GET;import javax.ws.rs.Path;import javax.ws.rs.Produces;@Path("helloworld")public class HelloWorldResource {public static final String CLICHED_MESSAGE = "Hello World!";@GET@Produces("text/plain")public String getHello() {return CLICHED_MESSAGE;}}

Jersey is very easy to use with other libraries, such as Netty or Grizzly, and it supports asynchronous connections. It does not need servlet containers. It does, however, have an unpolished dependency injection implementation.

Play Framework

Play Framework gives you an easier way to build, create, and deploy Web applications using Scala and Java. This framework is ideal for RESTful application that requires you to handle remote calls in parallel. It is also very modular and supports async. Play Framework also has one of the biggest communities out of all microservices frameworks.

Sample code you can try:

package controllers;import play.mvc.*;public class Application extends Controller {public static void index() {render();}public static void sayHello(String myName) {render(myName);}}

Restlet

Restlet helps developers create fast and scalable Web APIs that adhere to the RESTful architecture pattern. The framework has good routing and filtering. It’s available for Java SE/EE, OSGi, Google’s AppEngine (which is part of Google Compute), Android, and many other Java platforms. It’s a self-sufficient framework that even ships with its own webserver.

Restlet comes with a steep learning curve that is made worse by a closed community, but you can probably get help from people at StackOverflow.

Sample code:

(Video) Microservices explained - the What, Why and How?

package firstSteps;import org.restlet.resource.Get;import org.restlet.resource.ServerResource;/*** Resource which has only one representation.*/public class HelloWorldResource extends ServerResource {@Getpublic String represent() {return "hello, world";}}

Best Practices for Microservices

You should be able to tell by now that making the shift to microservices creates a lot of benefits for development, operations, and the business. They create opportunities for increased scalability, greater reliability, and cost savings. But, there’s no such thing as a free lunch. Microservices come with pitfalls of their own.

Here are some best practices that will help your migration.

Each of your microservices should use their own data store. You want the development (and dev-ops) team to choose the database for each of their service. They should have an opportunity to choose the data store that best suits their project. At the same time, if teams share a database, it’s too easy for them to share a schema, creating a monolithic service under a different name.

What are Microservices? Code Examples, Tutorials & More (4)

Deploying microservices in containers isn’t just a good idea. It’s a best practice, too. I’ve mentioned several times that microservice teams should choose their own tools. How do operations and dev-ops manage the chaos this creates? By using containers, so you can deploy and orchestrate your system with a single set of tools.

There’s a reason why RESTful services and microservices are often associated with each other. It’s because the best microservices architectures treat their services as stateless. REST’s state transfer that pushes state down to the clients means that you can treat your servers as stateless, and run your code as interchangeable parts of a whole. You only need to worry about making sure that there are enough services available to handle the load. And, if one fails, another can pick up the slack.

Additional Resources and Tutorials on Microservices

For further reading and information on microservices, including some helpful tutorials, visit the following resources:

  • How To Build Microservices With Java EE And JBossForge
  • Microservice Logging
  • Microservice Communication

In this article, we’ve discussed what microservices are, and how they can help you improve your enterprise architecture. After defining what these services are, we covered their major benefits. Then we looked at some of the most popular microservice APIs for Java. Then, we wrapped up with a look at microservices best practices and a list of resource here on Stackify’s website.

Microservices are a great addition to your enterprise. But, it helps to have a tool like Retrace to help you monitor them.

Retrace is a code-level APM solution that can manage and monitor your app’s performance throughout the entire development lifecycle. Plus, it offers many other features, such as error tracking, log management, and application metrics.

Start your trial today.

Try Stackify’s free code profiler, Prefix, to write better code on your workstation. Prefix works with .NET, Java, PHP, Node.js, Ruby, and Python.

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(Video) Microservices Full Course - Learn Microservices in 4 Hours | Microservices Tutorial | Edureka

FAQs

What are microservices for example? ›

Examples of Microservices

Netflix has a widespread architecture that has evolved from monolithic to SOA. It receives more than one billion calls every day, from more than 800 different types of devices, to its streaming-video API. Each API call then prompts around five additional calls to the backend service.

What is microservice code? ›

Microservices are small applications that your development teams create independently. Since they communicate via messaging if at all, they're not dependent on the same coding language. Developers can use the programming language that they're most familiar with.

How many lines of code are in a microservice? ›

Microservices are self-contained software components that are no more than 100 lines of code.

Is REST API a microservice? ›

Microservices: The individual services and functions – or building blocks – that form a larger microservices-based application. RESTful APIs: The rules, routines, commands, and protocols – or the glue – that integrates the individual microservices, so they function as a single application.

What are types of microservices? ›

What you'll learn
  • Explore the three types of microservices: stateless, data centric, and aggregator.
  • Understand which patterns to employ to ensure stability and resilience and when to apply each type to solve the problem at hand.
30 Oct 2018

How do you write microservices code? ›

Creating a Simple Microservice
  1. Step 1: Create a Maven project using Spring Initializr https://start.spring.io/
  2. Step 2: Choose the Spring Boot version 2.2. ...
  3. Step 3: Provide the Group name. ...
  4. Step 4: Provide the Artifact id.

Which language is used in microservices? ›

Primary languages among microservices developers

The 3 most popular languages for microservices development are Java (41%), JavaScript (37%), and Python (25%).

What are the 12 factors of microservices? ›

The Twelve Factors
  • I. Codebase. One codebase tracked in revision control, many deploys.
  • II. Dependencies. Explicitly declare and isolate dependencies.
  • III. Config. Store config in the environment.
  • IV. Backing services. ...
  • V. Build, release, run. ...
  • VI. Processes. ...
  • VII. Port binding. ...
  • VIII. Concurrency.

How many endpoints are in a microservice? ›

The number of endpoints is not really a decision point. In some cases, there may be only one endpoint, whereas in some other cases, there could be more than one endpoint in a microservice. For instance, consider a sensor data service, which collects sensor information, and has two logical endpoints--create and read.

What is the size of a microservice? ›

The name “microservices” conveys the fact that the size of the service matters; obviously, microservices are supposed to be small. One way to define the size of a microservice is to count the lines of code (LOC). However, such an approach has a number of problems: It depends on the programming language used.

What protocol is most common for a microservice? ›

The most common type is single-receiver communication with a synchronous protocol like HTTP/HTTPS when invoking a regular Web API HTTP service. Microservices also typically use messaging protocols for asynchronous communication between microservices.

How many types of microservices are there? ›

Broadly speaking, there are two types of microservices: Stateless microservices. Stateful microservices.

What is an API gateway in microservices? ›

The API Gateway offers a reverse proxy to redirect or route requests (layer 7 routing, usually HTTP requests) to the endpoints of the internal microservices. The gateway provides a single endpoint or URL for the client apps and then internally maps the requests to a group of internal microservices.

What are steps to make microservice? ›

The following are the key points to think about at that time.
  1. Keep communication between services simple with a RESTful API. ...
  2. Divide data into bounded contexts or data domains. ...
  3. Build your microservices architecture for failure. ...
  4. Emphasize monitoring to ease microservices testing.

Is Netflix a microservice? ›

Some critical part of Netflix' backend comprises of: AWS EC2, which are scalable computing instances. AWS S3, which is a scalable storage. Business logic microservices, which are custom-built, and task-oriented frameworks.

Is Facebook a microservice? ›

Just like Lyft, Facebook knows microservices.

Is Docker a microservice? ›

Docker is the world's leading software containerization platform. It encapsulates your microservice into what we call as Docker container which can then be independently maintained and deployed. Each of these containers will be responsible for one specific business functionality.

Is microservices same as API? ›

Here are the main differences between APIs and microservices: An API is a contract that provides guidance for a consumer to use the underlying service. A microservice is an architectural design that separates portions of a (usually monolithic) application into small, self-containing services.

Is Google a microservice? ›

Google App Engine has a number of features that are well-suited for a microservices-based application. This page outlines best practices to use when deploying your application as a microservices-based application on Google App Engine.

Can Python be used for microservices? ›

Advantages of Python for microservices development

Developers can also reuse the same code within a single application or across several modules, using built-in functions. Python's advanced scripting capabilities also allow developers to automate systems provisioning and configurations for microservices.

Is microservices frontend or backend? ›

The microservices expose APIs to be used by the frontend. However, the data returned to the frontend by the Microservices may not be formatted or filtered according to the exact way the frontend needs to represent them. In that case, the frontend needs to have some logic on its own to re-format these data.

Can frontend be a microservice? ›

Micro-frontend architecture is a design approach in which a front-end app is decomposed into individual, semi-independent “microapps” working loosely together. The micro-frontend concept is vaguely inspired by, and named after, microservices.

Which database is used in microservices? ›

Relational databases

You'll have to start building microservices with what you have – a relational database, such as DB2, MS SQL Server, MySQL, PostgreSQL, and gradually split it into several small services. On top of that, you can use a relational database in microservices if you apply polyglot persistence.

What are microservices patterns? ›

Branch microservice design pattern is a design pattern in which you can simultaneously process the requests and responses from two or more independent microservices.

What are the key principles of a microservices? ›

For object-oriented design we follow the SOLID principles. For microservice design we propose developers follow the “IDEALS”: interface segregation, deployability (is on you), event-driven, availability over consistency, loose-coupling, and single responsibility.

What skills are needed for microservices? ›

Here are the essential skills which microservices developers need:
  • Architecture Knowledge: In simple words, microservices are architectural patterns. ...
  • Domain Modelling: ...
  • DevOps and Containers. ...
  • Security: ...
  • Testing: ...
  • Continuous integration: ...
  • Language. ...
  • Back-End Development.

Which API Gateway is best for microservices? ›

Why NGINX Plus Is the Best API Gateway for Both Traditional Apps and Microservices
  • NGINX and NGINX Plus are already the industry's most pervasive API gateway. ...
  • NGINX is also the pioneer in developing microservices reference architectures.
10 Jan 2019

Is Load Balancer a microservice? ›

Server side load balancer acts as a single point of failure as if it fails, all the instances of the microservice becomes inaccessible as only load balancer has the list of servers. Since each microservice will have a separate load balancer, the overall complexity of the system increases and it becomes hard to manage.

Does every microservice have an API? ›

While microservices let users access API, not every microservice has to be part of an API. Microservices break large applications into independent parts, giving developers more flexibility to create lean, performant applications.

Does every microservice need a database? ›

You do not need to provision a database server for each service. For example, if you are using a relational database then the options are: Private-tables-per-service – each service owns a set of tables that must only be accessed by that service.

Can one microservice call another? ›

One microservice can easily expose a REST endpoint for other microservices to call it. Integration via RESTful endpoints is typically implemented when a microservice needs to call another and receive an immediate (synchronous) response.

Which architecture is used in microservices? ›

Containers are a well-suited microservices architecture example, since they let you focus on developing the services without worrying about the dependencies. Modern cloud-native applications are usually built as microservices using containers.

How do I connect two microservices? ›

The synchronous call is the simplest way to communicate two services. It also bonds them together, since the calling microservice needs to wait for a response from remote. This kind of coupling can sometimes be prevented by using asynchronous communication.

How do you communicate between two microservices? ›

There are two basic messaging patterns that microservices can use to communicate with other microservices.
  1. Synchronous communication. In this pattern, a service calls an API that another service exposes, using a protocol such as HTTP or gRPC. ...
  2. Asynchronous message passing.

How does 2 microservices communicate with each other? ›

The two commonly used protocols are HTTP request/response with resource APIs (when querying most of all), and lightweight asynchronous messaging when communicating updates across multiple microservices.

Is Google a microservice? ›

Google App Engine has a number of features that are well-suited for a microservices-based application. This page outlines best practices to use when deploying your application as a microservices-based application on Google App Engine.

Is Netflix a microservice? ›

Some critical part of Netflix' backend comprises of: AWS EC2, which are scalable computing instances. AWS S3, which is a scalable storage. Business logic microservices, which are custom-built, and task-oriented frameworks.

Why microservices are used? ›

Microservices allow developers to become language and technology agnostic. Different team members can use different programming languages and technologies when debugging and coding. Monitoring microservices lets you check your architecture for service and performance and identify future debugging problems.

What is microservices spring boot example? ›

Microservices means many small services, building small, self-contained, ready to run applications. In monolithic architecture, a combination of many components in an application becomes a large application that has many disadvantages. For example, if a monolithic application down, the entire application will be down.

Is every API a microservice? ›

Microservices is an approach to building an application that breaks its functionality into modular components. APIs are part of an application that communicates with other applications. So, APIs can be used to enable microservices.

Is Facebook a microservice? ›

Just like Lyft, Facebook knows microservices.

Is Docker a microservices? ›

Docker is the world's leading software containerization platform. It encapsulates your microservice into what we call as Docker container which can then be independently maintained and deployed. Each of these containers will be responsible for one specific business functionality.

Is Kafka a microservice? ›

Apache Kafka architecture for microservices utilizes an application setup where Microservices communicate with each other through Kafka. This is made possible by the publish-subscribe approach of Apache Kafka for handling record writing and reading.

Is MVC a microservice? ›

MVC is way of designing as service where we have model view and controller. In Microservices architecture we can use MVC in one way where each component will be distributed . 1. Answer to your question yes your application can be Microservices if it followed the 12 factors as mentioned in the website .

Is Maven a microservice? ›

Microservices are so well-known in the IT industry right now that they don't require a special introduction. If you've worked with monolithic programs before, you'll understand how difficult it is to deploy them.

How do you write a microservice? ›

The following are the key points to think about at that time.
  1. Keep communication between services simple with a RESTful API. ...
  2. Divide data into bounded contexts or data domains. ...
  3. Build your microservices architecture for failure. ...
  4. Emphasize monitoring to ease microservices testing.

What skills are needed for microservices? ›

Here are the essential skills which microservices developers need:
  • Architecture Knowledge: In simple words, microservices are architectural patterns. ...
  • Domain Modelling: ...
  • DevOps and Containers. ...
  • Security: ...
  • Testing: ...
  • Continuous integration: ...
  • Language. ...
  • Back-End Development.

How many types of microservices are there? ›

Broadly speaking, there are two types of microservices: Stateless microservices. Stateful microservices.

What are the types of microservices in Java? ›

Here, we are going to create 3 different microservices in Java. First microservice is Discovery Server which is a Eureka server. Second microservice is Authentication Service which is Producer service and Third microservice is Consumer service which is discovery client.

What is an API gateway in microservices? ›

The API Gateway offers a reverse proxy to redirect or route requests (layer 7 routing, usually HTTP requests) to the endpoints of the internal microservices. The gateway provides a single endpoint or URL for the client apps and then internally maps the requests to a group of internal microservices.

Videos

1. What are microservices?!?!? Let’s build one with .NET and Docker!
(dotNET)
2. Microservices for Beginners Tutorial — IBM Developer
(IBM Developer)
3. MICROSERVICES ARCHITECTURE | INTER MICROSERVICES COMMUNICATION | PART - 7
(Tech Dummies Narendra L)
4. Microservices vs API | Differences Between Microservice and API | Edureka
(edureka!)
5. .NET Microservices – Full Course for Beginners
(freeCodeCamp.org)
6. Python Microservices for Beginners
(Scalable Scripts)

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