JAR, WAR, EAR

Different ways to package java files for deployment.
EAR (Application Server) > WAR (Web Server) > JAR (JRE)

Notes based on these articles

What are the differences among jar, war and ear files?

JAR vs WAR vs EAR

Java ARchive (JAR)

Application JAR can be executed in any JRE env without Server.

• compiled java classes .class
• resources (image, etc)
• other JARs (dependency libraries)
• META-INF/MANIFEST.MF etc
• Application JAR (has starting point main()) vs Library JAR

Web ARchive (WAR)

Deployed in Web Server/Web Container in Application Server

• JAR
• JSP, Servlets, HTML, CSS and any images needed to render the Web page
• WEB-INF/web.xml etc

Enterprise Application ARchive (EAR)

Deployed in Java EE application server for large enterprise applications.

• META-INF/application.xml
• WAR
• JAR

Create a JAR

$ vi Hello.java         // Put main method here
$ javac Hello.java      // Create .class
$ vi Hello.mf           // Create manifest specifying entry point
$ cat Hello.mf
Main-Class: Hello
$ jar -cvmf Hello.mf Hello.jar Hello.class    // Create jar
$ java -jar Hello.jar       // Execute
Hello!
$ java -cp Hello.jar Hello  // Execute w/o mf - specify entry point
Hello!

Reference: https://docs.oracle.com/javase/tutorial/deployment/jar/index.html

Creating a WAR

$ java -cvf HelloWeb.war *   // Top directory containing WEB-INF dir

How to deploy WAR on Docker. Notes from:

Deploy WAR in Docker tomcat container

# Create Dockerfile 
FROM tomcat:8.0
MAINTAINER your_name
# COPY path-to-your-application-war path-to-webapps-in-docker-tomcat
COPY some-app/target/some-app.war /usr/local/tomcat/webapps

Build Docker image and run in a container

docker image build -t your_name/some-app-image
docker run -it --publish 8081:8080 your_name/some-app-image

Create an EAR

$ java -cvf myApplication.ear Hello.jar
$ java -cvf myApplication.ear HelloWeb.war

TomEE: Getting Started in 5 min or Less

Step-by-Step High Availability with Docker and Java EE