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What are Microservices?
This Microservices tutorial on What are Microservices gives you an introduction to microservices and also shows the practical implementation of microservices with a demo.
What are Microservices | Microservices Introduction
Microservices - also known as the microservice architecture - is an architectural style that structures an application as a collection of services that are.
Topics Covered:
00:00:00 Introduction
00:00:51 Before Microservices - Monolithic Architecture
00:02:14 Monolithic Architecture - Example
00:03:40 Monolithic Architecture - Challenges
00:07:26 What Is Microservice Architecture?
00:08:20 Microservice Architecture - Example
00:11:44 Features Of Microservice Architecture
00:12:57 Advantages of Microservice Architecture
00:14:20 Companies Using Microservices
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 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.
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.
Microservices can be thought of as a form of service-oriented architecture (one of the most critical 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. 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 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.
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.
<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.
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
@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 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 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. 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:
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";
}
}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.
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.
#microservices
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1599055326
Testing Microservices Applications
The shift towards microservices and modular applications makes testing more important and more challenging at the same time. You have to make sure that the microservices running in containers perform well and as intended, but you can no longer rely on conventional testing strategies to get the job done.
This is where new testing approaches are needed. Testing your microservices applications require the right approach, a suitable set of tools, and immense attention to details. This article will guide you through the process of testing your microservices and talk about the challenges you will have to overcome along the way. Let’s get started, shall we?
A Brave New World
Traditionally, testing a monolith application meant configuring a test environment and setting up all of the application components in a way that matched the production environment. It took time to set up the testing environment, and there were a lot of complexities around the process.
Testing also requires the application to run in full. It is not possible to test monolith apps on a per-component basis, mainly because there is usually a base code that ties everything together, and the app is designed to run as a complete app to work properly.
Microservices running in containers offer one particular advantage: universal compatibility. You don’t have to match the testing environment with the deployment architecture exactly, and you can get away with testing individual components rather than the full app in some situations.
Of course, you will have to embrace the new cloud-native approach across the pipeline. Rather than creating critical dependencies between microservices, you need to treat each one as a semi-independent module.
The only monolith or centralized portion of the application is the database, but this too is an easy challenge to overcome. As long as you have a persistent database running on your test environment, you can perform tests at any time.
Keep in mind that there are additional things to focus on when testing microservices.
- Microservices rely on network communications to talk to each other, so network reliability and requirements must be part of the testing.
- Automation and infrastructure elements are now added as codes, and you have to make sure that they also run properly when microservices are pushed through the pipeline
- While containerization is universal, you still have to pay attention to specific dependencies and create a testing strategy that allows for those dependencies to be included
Test containers are the method of choice for many developers. Unlike monolith apps, which lets you use stubs and mocks for testing, microservices need to be tested in test containers. Many CI/CD pipelines actually integrate production microservices as part of the testing process.
Contract Testing as an Approach
As mentioned before, there are many ways to test microservices effectively, but the one approach that developers now use reliably is contract testing. Loosely coupled microservices can be tested in an effective and efficient way using contract testing, mainly because this testing approach focuses on contracts; in other words, it focuses on how components or microservices communicate with each other.
Syntax and semantics construct how components communicate with each other. By defining syntax and semantics in a standardized way and testing microservices based on their ability to generate the right message formats and meet behavioral expectations, you can rest assured knowing that the microservices will behave as intended when deployed.
#testing #software testing #test automation #microservice architecture #microservice #test #software test automation #microservice best practices #microservice deployment #microservice components
1597438200
What Is a Microservice Architecture? Why Is It Important Now?
We have been building software applications for many years using various tools, technologies, architectural patterns and best practices. It is evident that many software applications become large complex monolith over a period for various reasons. A monolith software application is like a large ball of spaghetti with criss-cross dependencies among its constituent modules. It becomes more complex to develop, deploy and maintain monoliths, constraining the agility and competitive advantages of development teams. Also, let us not undermine the challenge of clearing any sort of technical debt monoliths accumulate, as changing part of monolith code may have cascading impact of destabilizing a working software in production.
Over the years, architectural patterns such as Service Oriented Architecture (SOA) and Microservices have emerged as alternatives to Monoliths.
SOA was arguably the first architectural pattern aimed at solving the typical monolith issues by breaking down a large complex software application to sub-systems or “services”. All these services communicate over a common enterprise service bus (ESB). However, these sub-systems or services are actually mid-sized monoliths, as they share the same database. Also, more and more service-aware logic gets added to ESB and it becomes the single point of failure.
Microservice as an architectural pattern has gathered steam due to large scale adoption by companies like Amazon, Netflix, SoundCloud, Spotify etc. It breaks downs a large software application to a number of loosely coupled microservices. Each microservice is responsible for doing specific discrete tasks, can have its own database and can communicate with other microservices through Application Programming Interfaces (APIs) to solve a large complex business problem. Each microservice can be developed, deployed and maintained independently as long as it operates without breaching a well-defined set of APIs called contract to communicate with other microservices.
#microservice architecture #microservice #scaling #thought leadership #microservices build #microservice
1595338835
Microservices and Data Management - DZone Microservices
Introduction
For pure frontend developers who doesn’t have much exposure to backend or middleware technology, microservices are a vague thing. They might have high-level introduction. So, let us have some deep understanding of what microservices are, and how it is different from monolithic application data management.
Monolithic and Microservice
In a monolithic application, all the stakeholders like all the business logic, routing features, middle-wares and Database access code get used to implement all the functionalities of the application. It is basically a single unit application. It has a lot of challenges in terms of scalability and agility. On the other side, in a microservice, all the business logic, routing features, middle-wares, and database access code get used to implement a single functionality of the application. We break down the functionalities to the core level and then connect to related services. So, the functionalities are actually dependent on related services only and does not get affected if there is an issue with other services. This helps to make the application agile, flexible, and highly scalable.
Why Microservices
Independent DB for the Services
The very first important thing associated with microservices is that each functionality requires its own database and never connects to the database of other services. In a monolithic service, since you have a single database. if something goes wrong with it then the whole application gets crashed. But in microservice, since we have an independent database for each service, in case of any problem with any particular database, it certainly does not affect other services and your application does not crash as a whole.
No Dependency on Schema
We have many services in our application and each service requires its own database. Hence, each database has its own schema or structure. But, if any service is connected to other service and shares the data and during development, the source database changes its schema and does not update the dependent services, then the service will not function correctly and may crash. So, there should be no dependency on databases.
Performance
Depending on the nature of service, we choose the appropriate type of DB. Some services are more efficient in specific database. So, creating a single database for all the services in the application might affect performance. In Microservice, since we have individual DB for each of the service, it is quite flexible, independent, and functions efficiently.
Data Management
Unlike the monolithic approach, in microservice, each functionality or service connects to its own database and never gets connected to other database. So, the big question arises of how we communicate between two services. It is quite generic in an application that we require to get some information based on the combination of many service outputs. But as a thumb rule, services dont communicate. Then what is the solution to this issue? Let us see, how data communicates between the services.
#data management #monolith vs microservice #microservices benefits #microservices communication #microservices archiecture
1595335187
Microservices and Data Management - DZone Microservices
Introduction
For pure frontend developers who doesn’t have much exposure to backend or middleware technology, microservices are a vague thing. They might have high-level introduction. So, let us have some deep understanding of what microservices are, and how it is different from monolithic application data management.
Monolithic and Microservice
In a monolithic application, all the stakeholders like all the business logic, routing features, middle-wares and Database access code get used to implement all the functionalities of the application. It is basically a single unit application. It has a lot of challenges in terms of scalability and agility. On the other side, in a microservice, all the business logic, routing features, middle-wares, and database access code get used to implement a single functionality of the application. We break down the functionalities to the core level and then connect to related services. So, the functionalities are actually dependent on related services only and does not get affected if there is an issue with other services. This helps to make the application agile, flexible, and highly scalable.
Why Microservices
Independent DB for the Services
The very first important thing associated with microservices is that each functionality requires its own database and never connects to the database of other services. In a monolithic service, since you have a single database. if something goes wrong with it then the whole application gets crashed. But in microservice, since we have an independent database for each service, in case of any problem with any particular database, it certainly does not affect other services and your application does not crash as a whole.
No Dependency on Schema
We have many services in our application and each service requires its own database. Hence, each database has its own schema or structure. But, if any service is connected to other service and shares the data and during development, the source database changes its schema and does not update the dependent services, then the service will not function correctly and may crash. So, there should be no dependency on databases.
Performance
Depending on the nature of service, we choose the appropriate type of DB. Some services are more efficient in specific database. So, creating a single database for all the services in the application might affect performance. In Microservice, since we have individual DB for each of the service, it is quite flexible, independent, and functions efficiently.
Data Management
Unlike the monolithic approach, in microservice, each functionality or service connects to its own database and never gets connected to other database. So, the big question arises of how we communicate between two services. It is quite generic in an application that we require to get some information based on the combination of many service outputs. But as a thumb rule, services dont communicate. Then what is the solution to this issue? Let us see, how data communicates between the services.
#data management #monolith vs microservice #microservices benefits #microservices communication #microservices archiecture
1595342460
Microservices and Data Management - DZone Microservices
Introduction
For pure frontend developers who doesn’t have much exposure to backend or middleware technology, microservices are a vague thing. They might have high-level introduction. So, let us have some deep understanding of what microservices are, and how it is different from monolithic application data management.
Monolithic and Microservice
In a monolithic application, all the stakeholders like all the business logic, routing features, middle-wares and Database access code get used to implement all the functionalities of the application. It is basically a single unit application. It has a lot of challenges in terms of scalability and agility. On the other side, in a microservice, all the business logic, routing features, middle-wares, and database access code get used to implement a single functionality of the application. We break down the functionalities to the core level and then connect to related services. So, the functionalities are actually dependent on related services only and does not get affected if there is an issue with other services. This helps to make the application agile, flexible, and highly scalable.
Why Microservices
Independent DB for the Services
The very first important thing associated with microservices is that each functionality requires its own database and never connects to the database of other services. In a monolithic service, since you have a single database. if something goes wrong with it then the whole application gets crashed. But in microservice, since we have an independent database for each service, in case of any problem with any particular database, it certainly does not affect other services and your application does not crash as a whole.
No Dependency on Schema
We have many services in our application and each service requires its own database. Hence, each database has its own schema or structure. But, if any service is connected to other service and shares the data and during development, the source database changes its schema and does not update the dependent services, then the service will not function correctly and may crash. So, there should be no dependency on databases.
Performance
Depending on the nature of service, we choose the appropriate type of DB. Some services are more efficient in specific database. So, creating a single database for all the services in the application might affect performance. In Microservice, since we have individual DB for each of the service, it is quite flexible, independent, and functions efficiently.
Data Management
Unlike the monolithic approach, in microservice, each functionality or service connects to its own database and never gets connected to other database. So, the big question arises of how we communicate between two services. It is quite generic in an application that we require to get some information based on the combination of many service outputs. But as a thumb rule, services dont communicate. Then what is the solution to this issue? Let us see, how data communicates between the services.
#data management #monolith vs microservice #microservices benefits #microservices communication #microservices archiecture