The Complete Guide to Microservices and Microservice Architecture

The Complete Guide to Microservices and Microservice Architecture

In this article, you will learn about the following: Why Microservices, What Is Microservices, Features Of Microservice Architecture, Advantages Of Microservice Architecture, Best Practices To Design Microservices, Companies Using Microservices and more

This Microservices tutorial starts by helping you understand microservices architecture and best practices for designing them.

*Have you ever wondered, ****What is *Microservices and how the scaling industries integrate with them while building applications to keep up with their client expectations?

To get an idea of What is Microservices, you have to understand how a monolithic application is decomposed into small tiny micro applications which are packaged and deployed independently. This tutorial will clear your understanding of how developers use microservices to scale their applications according to their need.

In this tutorial, you will learn about the following:
Why Microservices?What Is Microservices?Features Of Microservice ArchitectureAdvantages Of Microservice ArchitectureBest Practices To Design MicroservicesCompanies Using Microservices## Why Microservices?

Now, before I tell you about microservices, let’s see the architecture that prevailed before microservices i.e. the Monolithic Architecture.

In layman terms, you can say that its similar to a big container wherein all the software components of an application are assembled together and tightly packaged.

Listed down are the challenges of Monolithic Architecture:

Figure 1: What Is Microservices – Challenges of Monolithic Architecture
Inflexible – Monolithic applications cannot be built using different technologies Unreliable – Even if one feature of the system does not work, then the entire system does not workUnscalable – Applications cannot be scaled easily since each time the application needs to be updated, the complete system has to be rebuiltBlocks Continous Development – Many features of the applications cannot be built and deployed at the same timeSlow Development – Development in monolithic applications take lot of time to be built since each and every feature has to be built one after the other**Not Fit For Complex Applications – **Features of complex applications have tightly coupled dependencies
The above challenges were the main reasons that led to the evolution of microservices.

What Is Microservices?

Microservices, aka Microservice Architecture, is an architectural style that structures an application as a collection of small autonomous services, modeled around a business domain.

** Figure 2**: What Is Microservices – Microservices Representation

In Microservice Architecture, each service is self-contained and implements a single business capability.

Differences Between Traditional Architecture and Microservices

Consider an E-commerce application as a use-case to understand the difference between both of them.

Figure 3: What Is Microservices – Differences Between Monolithic Architecture and Microservices

The main difference we observe in the above diagram is that all the features initially were under a single instance sharing a single database. But then, with microservices, each feature was allotted a different microservice, handling their own data, and performing different functionalities.

Now, let us understand more about microservices by looking at its architecture. Refer the diagram below:

**Microservice Architecture **

Figure 4: What Is Microservices – Microservice Architecture
Different clients from different devices try to use different services like search, build, configure and other management capabilitiesAll the services are separated based on their domains and functionalities and are further allotted to individual microservicesThese microservices have their own load balancer and execution environment to execute their functionalities & at the same time captures data in their own databasesAll the microservices communicate with each other through a stateless server which is either REST or Message BusMicroservices know their path of communication with the help of **Service Discovery **and perform operational capabilities such as automation, monitoringThen all the functionalities performed by microservices are communicated to clients via API GatewayAll the internal points are connected from the API Gateway. So, anybody who connects to the API Gateway automatically gets connected to the complete system
Now, let us learn more about microservices by looking at its features.

Microservices Features

Figure 5: What Is Microservices – Features Of Microservices
Decoupling – Services within a system are largely decoupled. So the application as a whole can be easily built, altered, and scaledComponentization – Microservices are treated as independent components that can be easily replaced and upgradedBusiness Capabilities – Microservices are very simple and focus on a single capability Autonomy – Developers and teams can work independently of each other, thus increasing speedContinous Delivery – Allows frequent releases of software, through systematic automation of software creation, testing, and approval Responsibility – Microservices do not focus on applications as projects. Instead, they treat applications as products for which they are responsible Decentralized Governance – The focus is on using the right tool for the right job. That means there is no standardized pattern or any technology pattern. Developers have the freedom to choose the best useful tools to solve their problems Agility – Microservices support agile development. Any new feature can be quickly developed and discarded again## Advantages Of Microservices

Figure 6: What Is Microservices – Advantages Of Microservices
Independent Development – All microservices can be easily developed based on their individual functionalityIndependent Deployment – Based on their services, they can be individually deployed in any application Fault Isolation – Even if one service of the application does not work, the system still continues to functionMixed Technology Stack – Different languages and technologies can be used to build different services of the same applicationGranular Scaling – Individual components can scale as per need, there is no need to scale all components together## Best Practices To Design Microservices

In today’s world, complexity has managed to creep into products. Microservice architecture promises to keep teams scaling and function better.

The following are the best practices to design microservices:

Figure 7: What Is Microservices – Best Practices To Design Microservices

Now, let us look at a use-case to get a better understanding of microservices.

Use-Case: Shopping Cart Application

Let’s take a classic use case of a shopping cart application.

When you open a shopping cart application, all you see is just a website. But, behind the scenes, the shopping cart application has a service for accepting payments, a service for customer services and so on.

Assume that developers of this application have created it in a monolithic framework.Refer to the diagram below:

Figure 8: What Is Microservices – Monolithic Framework Of Shopping Cart Application

So, all the features are put together in a single code base and are under a single underlying database.

Now, let’s suppose that there is a new brand coming up in the market and developers want to put all the details of the upcoming brand in this application.

Then, they not only have to rework on the service for new labels, but they also have to reframe the complete system and deploy it accordingly.

To avoid such challenges developers of this application decided to shift their application from a monolithic architecture to microservices.Refer to the diagram below to understand the microservices architecture of shopping cart application

Figure 9: What Is Microservices – Microservice Architecture Of Shopping Cart Application

This means that developers don’t create a web microservice, a logic microservice, or a database microservice. Instead, they create separate microservices for search, recommendations, customer services and so on.

This type of architecture for the application not only helps the developers to overcome all the challenges faced with the previous architecture but also helps the shopping cart application to be built, deployed, and scale up easily.

Companies using Microservices

There is a long list of companies using Microservices to build applications, these are just to name a few:

Figure 10: What Is Microservices – Companies Using Microservices

Java Fundamentals: Learn Java for absolute beginners |Simpliv

Java Fundamentals: Learn Java for absolute beginners |Simpliv

Java Fundamentals: Learn Java for absolute beginners

Description
This is the best course to learn to program in Java in Spanish from scratch and without any experience in this fabulous programming language. This is the first course where we will study the Fundamentals of Java, and we will take you step by step until you acquire the bases of the Java language and you can start to study more advanced Java topics.

The content is divided into perfectly structured levels, each level supported by the previous one, with the aim of adding Java knowledge incrementally and so you can focus on mastering the issues little by little and gradually. So ensure the success of your Java training.

We will also offer support for any doubts about the didactic material included in this Java Fundamentals course.

We manage a new teaching methodology that we have called Speed ​​Learning. This methodology consists of concise videos that go directly to the point to be studied, complemented by eBooks with explanations and step-by-step images (which you can print, or search for any text you need, or use for your offline study), since As we know we can not do text search within a video. In addition, our methodology includes perfectly structured and very didactic exercises that will allow you to accelerate your eLearning learning. No loss of time in videos where you have to watch the instructor codify an exercise, too much theory, little practice or anything like that. Our Speed ​​Learning methodology guarantees that in the shortest possible time you will acquire the necessary knowledge for the Java professional and working world.

The Java Fundamentals course includes the following topics for study:

Lesson 1 - Starting with Java Technology

The amazing world of Java programming

What is Java technology (from a practical approach)

Our first Java program from scratch

Lesson 2 - Variables and Operators in Java

Use of Variables in Java and what we use them for

Types of Data in Java and how they are classified

Management and Classification of operators in Java

Lesson 3 - Control statements in Java

Using the if-else structure and where to use it

Handling the switch structure and when applying it

Lesson 4 - Handling Loops in Java

Use of the for loop and its use

Using the while loop and how to apply it

Use of the do-while loop and when to use it

Lesson 5 - Object Oriented Programming

Introduction to Object Oriented Programming (OOP)

Handling Classes in Java

Use of Objects in Java

Lesson 6 - Functions in Java

Declaration of Methods or Functions in Java

Use and call of functions in Java

Lesson 7 - Data Management in Java

Using Arrays in Java

Management of Matrices in Java

Lesson 8 - Inheritance in Java

Inheritance Management in Java

Use of superclasses and subclasses in Java

Final Level Laboratory

Final Exercise where everything learned in this Level is integrated

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Passion for Java Technology

Who this course is for:

Anyone who wants to learn how to program in Java
Basic knowledge
Basic knowledge of PC use
Basic management of an operating system such as Windows, Mac or Linux
It is not necessary to know how to program, we will start from scratch !!!
The attitude and desire to start coding and learning Java once and for all from scratch!
What will you learn
Have the basics of the programming language with Java
You will know the basic syntax of the Java language
Manage the concept of Variables and Operators in Java
We will study Object Oriented Programming with Java
You will learn the Control Statements and Loops in Java
We will see the concept of Functions with Java
We will study the concept of Inheritance in Java
We will learn to use Arrays in java
We will handle the concept of Matrices in Java
We will learn to Design Classes in Java
We will make a final application with everything learned in the course
To know more:

Java Microservices: Code Examples, Tutorials, and More

Java Microservices: Code Examples, Tutorials, and More

Microservices are replacing monoliths every day. So, let's explore how Java devs can put them to work with the help of their favorite frameworks

Originally published by Angela Stringfellow https://dzone.com

Microservices are 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 larger, application-wide functionality. Tools 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.

What Are Microservices?

Microservices are a form of service-oriented architecture style (one of the most important skills for 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 and may be created using different coding or programming languages. Big and complicated applications can be made up of simpler and independent programs that are executable by themselves. These smaller programs are grouped together 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?” It is usually developed by an engineering team with only a few members and can be written in any programming language as well as utilize any framework. 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 the Benefits of Microservices?

There are several benefits to using microservices. For one, because these smaller applications are not dependent on the same coding language, the developers can use the programming language that they are most familiar with. That helps developers come up with a program faster with lower costs and fewer bugs. The agility and low costs can also come from being able to reuse these smaller programs on other projects, making it more efficient.

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 own 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 Dropwizard application using Maven. How?

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

<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
    @JsonProperty
    private String template;
    @NotEmpty
    @JsonProperty
    private 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 does not matter if you are writing apps for security, configuration, or big data; there is a Spring Boot project for it.

Spring Boot projects include:

  • Spring IO Platform: Enterprise-grade distribution for versioned applications.
  • Spring Framework: For transaction management, dependency injection, data access, messaging, and web apps.
  • Spring Cloud: For distributed systems and used for building or deploying your microservices.
  • Spring Data: For microservices that are related to data access, be it map-reduce, relational or non-relational.
  • Spring Batch: For high levels of batch operations.
  • Spring Security: For authorization and authentication support.
  • Spring REST Docs: For documenting RESTful services.
  • Spring Social: For connecting to social media APIs.
  • Spring 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
@EnableAutoConfiguration
public 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 that it has great documentation that is filled with examples. It 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 found here.

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. Play 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. It has good routing and filtering, and available for Java SE/EE, OSGi, Google AppEngine (part of Google Compute), Android, and other major platforms.

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:

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

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Further reading

An Introduction to Microservices

What is Microservices?

Build Spring Microservices and Dockerize Them for Production

Best Java Microservices Interview Questions In 2019

Build a microservices architecture with Spring Boot and Spring Cloud

Java and MicroProfile: Building microservices in style

Java and MicroProfile: Building microservices in style

Learn the steps required to design, build, deploy, and orchestrate a cloud native microservice architecture using Java and Eclipse MicroProfile. We’ll use Red Hat’s MicroProfile (former WildFly Swarm) implementation known as Thorntail, optimized for deployment to OpenShift and integrated with Azure services.




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Java In-Depth: Become a Complete Java Engineer!

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