Java 10 Simple HTTP Server

• Main goal is to use Java 9/10 to create a microservice
• Second goaln is to update the code to replace System.out.println(HelloWorld) into a web server
• Third goal: Integrate with Travis-CI

Check java version

java --version

java 10.0.1 2018-04-17
Java(TM) SE Runtime Environment 18.3 (build 10.0.1+10)
Java HotSpot(TM) 64-Bit Server VM 18.3 (build 10.0.1+10, mixed mode)

javac --version

javac 10.0.1

Simplistic HelloWorld project using Classical mode

First step is to understand module, jlink...to be able to build an App suitable for microservices, IOT and Kubernetes

Get into the simplistic application directory

cd app1

Verify the presence of the source code

ls src/helloworld

HelloWorld.java

Compile the source java code

javac -d classes src/helloworld/*.java

Check javac call worked

ls classes/helloworld/

HelloWorld.class

Let's run the simplistic application using the classical way

java --class-path classes helloworld.HelloWorld

Hello World

Simplistic HelloWorld project using classical Jar files

Let's package the code as a jar file

mkdir jars
cd classes
jar cvf ../jars/helloworld.jar helloworld/
cd ..

java --class-path jars/helloworld.jar helloworld.HelloWorld

Simplistic HelloWorld project using Java 9 modules

Get into the simplistic application directory

cd app1

Compile the source java code

javac -d mods/helloworld/ src/module-info.java src/helloworld/HelloWorld.java

Let's run the simplistic application using the java-module way

java --module-path mods -m helloworld/helloworld.HelloWorld

Simplistic HelloWorld project using modules for microservices purpose (embeded JRE)

Build the microservice on the local machine

mkdir microservices
jlink --module-path mods --add-modules helloworld,java.base --output microservices/helloworld

Test the microservice on the local machine

Go to the microservice helloworld bin directory. Ensure you are using ./java not java

cd microservices/helloworld/bin/
./java -m helloworld/helloworld.HelloWorld
Hello World

Test the microservice on a remote machine with no java installed

Let's tar up the microservice folder

cd microservices
tar -czvf helloworld.tar.gz helloworld/

Transfer microservice to machine without Java. I happen have a coreos based VM:

scp helloworld.tar.gz coreos@192.168.122.10:/home/coreos
Password:
helloworld.tar.gz                                                                                                                               100%   16MB  16.0MB/s   00:00

ssh coreos@192.168.122.10
Password:
Last login: Sun Jul  1 18:34:37 UTC 2018 from 192.168.122.7 on ssh
Container Linux by CoreOS stable (1745.7.0)
Update Strategy: No Reboots

java
-bash: java: command not found

mkdir microservices
mv helloworld.tar.gz microservices/
cd microservices/
tar -xf helloworld.tar.gz
cd helloworld/bin/

ls

java  keytool

./java -m helloworld/helloworld.HelloWorld

Hello World

Simple HelloWorld Server

Compile the server

cd app2
javac -d mods/simpleserver/ src/module-info.java src/simpleserver/*.java

Start in background and test

java --module-path mods -m simpleserver/simpleserver.Main &
curl -i http://localhost:4250/helloworld

Stop the server

fg
CTRL C

Package as a microservice

jlink --module-path mods --add-modules simpleserver,java.base --output microservices/simpleserver
cd microservices
tar -czvf simpleserver.tar.gz simpleserver/

Simple AppServer

Compile the server

cd app3
javac -d mods/simplewebsrv/ src/module-info.java src/simplewebsrv/*.java

Start in background and test

java --module-path mods -m simplewebsrv/simplewebsrv.SimpleWebSrv &

curl -i http://localhost:9000/
curl -i http://localhost:9000/echoHeader
curl -i http://localhost:9000/echoGet
curl -i http://localhost:9000/echoGet?foo=bar

Stop the server

fg
CTRL C

Package as a microservice

jlink --module-path mods --add-modules simplewebsrv,java.base --output microservices/simplewebsrv
cd microservices
tar -czvf simplewebsrv.tar.gz simplewebsrv/

Links

• app1
• app2
• app3