Spring Boot and Microservices

SPRING BOOT &
MICROSERVICES
@ladislavGazo
gazo@seges.sk

huge application servers
monolithic architecture
long restarts
no save-reload cycle
wired to a set of dependencies

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>
<artifactId>spring-boot-starter-security</artifactId>
</dependency>
@EnableWebMvcSecurity
@EnableGlobalMethodSecurity
http.authorizeRequests().antMatchers("/identity/login", "/page/**", "/client/**", "/user/**"
http.csrf().disable();
http.sessionManagement().sessionCreationPolicy(SessionCreationPolicy.STATELESS);
http.addFilterBefore(new AuthenticationTokenFilter(identityService), AnonymousAuthenticationFilter
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>
<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

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

THANK YOU... FOR...
ATTENTION

Spring Boot and Microservices

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