Spring BOOT & microservices

@ladislavGazo

gazo@seges.sk

huge application servers

monolithic architecture

long restarts

no save-reload cycle

wired to a set of dependencies

Microservices

PROS

Each microservice is relatively small

Easier for a developer to understand

The IDE is faster making developers more productive
The web container starts faster

Easier to scale development.

Each team can develop, deploy and scale their service independently of all of the other teams.

PROS 2

Improved fault isolation

In comparison, one misbehaving component of a monolithic architecture can bring down the entire system.

Each service can be developed and deployed independently

Eliminates any long-term commitment to a technology stack

BUT...

(there is always at least one...)

Developers must deal with the additional complexity of creating a distributed system

testing
transactions
use-cases span multiple microservices

Deployment complexity In production

Increased memory consumption

... TACKLE WITH

when to split to multiple microservices

what should be inside one microservice

single responsibility principle

...

it is the art

Spring BOOT

http://projects.spring.io/spring-boot/

opinionated way how to do modern applications

Very easy to start

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.1.8.RELEASE</version>
</parent>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

ta-daaaa .... web app built :)

APP CODE

package hello;

import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;
import org.springframework.stereotype.*;
import org.springframework.web.bind.annotation.*;

@Controller
@EnableAutoConfiguration
public class SampleController {

    @RequestMapping("/")
    @ResponseBody
    String home() {
        return "Hello World!";
    }

    public static void main(String[] args) throws Exception {
        SpringApplication.run(SampleController.class, args);
    }
}

... the beauty of autoconfiguration

3 options

JRebel

jHipster Reloader

Spring Loaded

jHipster reloader

-javaagent:/home/user/.m2/repository/io/github/jhipster/loaded/agent/0.12/agent-0.12.jar


<profiles>
  <profile>
    <id>reloaded</id>
      <dependencies>
        <dependency>
          <groupId>io.github.jhipster.loaded</groupId>
          <artifactId>agent</artifactId>
          <version>0.12</version>
          <exclusions>
            <exclusion>
              <groupId>org.springframework</groupId>
              <artifactId>springloaded</artifactId>
            </exclusion>
          </exclusions>
        </dependency>

        <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>springloaded</artifactId>
        </dependency>
      </dependencies>
  </profile>
</profiles>

Interesting dependencies

benefit of Spring Boot

MVC
data access
templating
security
...

... anything from the Spring stack

REST

@RestController

based on Spring MVC

TEMPLATING

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

using Thymeleaf

Spring Security

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-security</artifactId>
</dependency>

@EnableWebMvcSecurity

@EnableGlobalMethodSecurity

http.authorizeRequests().antMatchers("/identity/login", "/page/**", "/client/**", "/user/**").permitAll().anyRequest().authenticated();
		
http.csrf().disable();
		
		http.sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS);
http.addFilterBefore(new AuthenticationTokenFilter(identityService), AnonymousAuthenticationFilter.class);
http.exceptionHandling().authenticationEntryPoint(new UnauthorizedEntryPoint());

MIGRATIONS

<dependency>
			<groupId>org.flywaydb</groupId>
			<artifactId>flyway-core</artifactId>
</dependency>

migration files

V1.1__init.sql

V1.2__data.sql

...

DATA ACCESS

<dependency>   			<groupId>com.h2database</groupId>
			<artifactId>h2</artifactId>
</dependency>

<dependency>    	<groupId>org.postgresql</groupId>
	<artifactId>postgresql</artifactId>
</dependency>

autodetection of the driver

DATA ACCESS II.

spring.datasource.url: jdbc:postgresql://localhost/mydb
spring.datasource.username: myuser
spring.datasource.password: mypass
spring.datasource.driverClassName: org.postgresql.Driver

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

CONFIGURATION

driven mainly by:

Spring Java Configuration

Spring Annotations

Spring Profiles

simple YAML / properties file

Cherry

@Component
@ConfigurationProperties(prefix="connection")
public class ConnectionSettings {

    private String username;

    private InetAddress remoteAddress;

    // ... getters and setters

}

# application.yml

connection:
    username: admin
    remoteAddress: 192.168.1.1

Kontanjere

SKALA

giter8 template

https://github.com/lgazo/scala-boot.g8

curl https://raw.githubusercontent.com/n8han/conscript/master/setup.sh | sh# add to your path ~/bin
cs n8han/giter8

g8 lgazo/scala-boot

Questions?

@ladislavGazo

gazo@seges.sk