This document discusses designing a REST microservice using Apache Camel technology. It covers integrating systems using Camel, implementing enterprise integration patterns with Camel, using different Camel DSLs like Java, XML, and REST. It demonstrates running the Camel application as a microservice in a Docker container and deploying it on Kubernetes and OpenShift using Fabric8 tools.

1.
Design a REST Microservice
using Apache Camel
technology
Charles Moulliard (@cmoulliard)
22 Jan 2016

2. Who
Committer, Coder, Architect
Work on Apache Camel, Karaf, Fabric8, Hawtio, Apiman, DeltaSpike
Mountain Biker, Belgian Beer Fan
Blog:
Twitter:
Email:
http://cmoulliard.github.io
@cmoulliard
cmoulliard@redhat.com

3. Agenda
Integration …
Apache Camel
Micro Container
Kubernetes Service

4.
Integration

5. Point to Point vision
Integrate many systems. Play with formats & protocols

6. Hub Approach
In 2003, it was reported that 70% of all EAI projects fail !

7. Bus
Communication done through a Bus with Normalized messages

8. MicroService
It is an architectural style where
an application
composed of individual
standalone services
communicating using
lightweight protocols
in event based manner




9.
Apache Camel

10. Apache Camel
Java Integration Framework
Implements Domain Specific Language
Supports Enterprise Integration Patterns


11. Enterprise Patterns
implemented
and more : Loadbalancer, Throttler, Delayer, …
> 50 patterns

12. Route, processor
Camel project Collection of routes
Route = Processor(s) + Interceptor(s)
Producing or consuming Message


13. Java DSL
Fluent API, extend RouteBuilder class
importorg.apache.camel.builder.RouterBuilder;
publicclassFilterRouteextendsRouteBuilder{
publicvoidconfigure()throwsException{
from("activemq:queue:all")
.filter(xpath("/quote/product='widget'"))
.to("activemq:widget");
}
}

14. XML DSL
Spring, Blueprint
<?xmlversion="1.0"encoding="UTF-8"?>
<beansxmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-
http://camel.apache.org/schema/springhttp://camel.apache.org/schema/spring/camel-spring.xsd
">
<beanid="quotesService"class="my.cool.demo.camel.QuotesService"/>"
<camelContext xmlns="http://camel.apache.org/schema/spring">
<route>
<fromuri="activemq:queue:all"/>
<filter>
<xpath>"/quote/product/='widget"</xpath>
<beanid="quotesService"method="widget"/>
</filter>
</route>
</camelContext>

15. REST DSL
One of the components available : servlet, jetty, netty, spark, restlet,
undertow
Hostname
Port
Root of the REST Application endpoint
@Overridepublicvoidconfigure()throwsException{
restConfiguration()
.component("servlet")
.host(HOST)
.setPort(PORT);
//usetherestDSLtodefinetherestservices
rest("/users/")
.get("{id}/hello")
.route()
.process(newProcessor(){
publicvoidprocess(Exchangeexchange)throwsException{
Stringid=exchange.getIn().getHeader("id",String.class);
exchange.getOut().setBody("Hello"+id+"!Welcomefrompod:"
}
});
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16. Container agnostic
Endpoints registered
CamelContext
Policy
Security
Lifecycle
Tracing
JMX
Threads can be configured


17.
Demo

18.
Docker Container

19. Process

20. Docker
Union FS mounted with immutable images
Benefits: portability, reusability, versioning, application-centric

21. Docker config

22. Docker
Container runtime, Process launcher

23. Maven Docker Plugin
docker:build Build image of app
docker:push Push image


<docker.from>fabric8/s2i-java:1.2</docker.from>
<docker.image>${docker.registryPrefix}fabric8/${project.artifactId}:${project.version}
<docker.port.container.jolokia>8778</docker.port.container.jolokia>
<docker.registryPrefix>${env.DOCKER_REGISTRY}/</docker.registryPrefix>
<plugin>
<groupId>org.jolokia</groupId>
<artifactId>docker-maven-plugin</artifactId>
<version>${docker.maven.plugin.version}</version>
<configuration>
<images>
<image>
<name>${docker.image}</name>
<build>
<from>${docker.from}</from>
<assembly>
<basedir>/deployments</basedir>
<descriptorRef>hawt-app</descriptorRef>
</assembly>
<env>
<JAVA_LIB_DIR>/deployments/lib</JAVA_LIB_DIR>
<JAVA_MAIN_CLASS>org.apache.camel.cdi.Main</JAVA_MAIN_CLASS>
</env>

24.
With Docker

26.
Kubernetes & Openshift

27. Kubernetes
Runtime & Operational management of containers
ApiServer (event, status)
Scheduler, Controller & State Storage
Agent - Kubelet - manage containers on host
Containers pods (= shared docker containers)

28. Kubernetes

29. Pod & docker
Communicate to each other using skyDNS to resolve hostname

30. Pod & port
Ports can be exposed

31. Pod & volume
Share data using mounted volume between host & container

32. Kubernetes Service
Kube Service loadbalanced through the pods using HA-Proxy Routes map
private with public IP address

33. Kube Application JSon

34.
Fabric8

35. Fabric8 Maven Plugin
fabric8:json generates Kube MetaData
fabric8:apply deploy on Openshift


<fabric8.service.name>hellorest</fabric8.service.name>
<fabric8.service.port>9090</fabric8.service.port>
<fabric8.service.containerPort>8080</fabric8.service.containerPort>
<fabric8.label.component>${project.artifactId}</fabric8.label.component>
<fabric8.label.container>tomcat</fabric8.label.container>
<fabric8.label.group>demo</fabric8.label.group>
<fabric8.service.type>LoadBalancer</fabric8.service.type>
<fabric8.iconRef>camel</fabric8.iconRef>
<plugin>
<groupId>io.fabric8</groupId>
<artifactId>fabric8-maven-plugin</artifactId>
<version>${fabric8.version}</version>
<executions>
<execution>
<id>json</id>
<goals>
<goal>json</goal>
</goals>

36.
With OpenShift & Kubernetes

38. Questions
Twitter :
Camel Rest MicroService in Action
@cmoulliard

https://github.com/FuseByExample/microservice-camel-in-action
http://fabric8.io/