How to build & deploy a HelloWorld API function

using Java on OpenShiftin 8 steps

Jan Voseckytwitter: @jvosecky

In this tutorial

• For OpenShift beginners• IDE: Eclipse

– no command line used

• Language: Java• Goal: build and deploy a HelloWorld API function

Step 1: In Eclipse…

• Install Eclipse plugin for OpenShift– Menu Help > Eclipse Marketplace– In the search box, type: jboss tools– Choose the plugin depending on your version of

Eclipse

Step 2: OpenShift.com

• https://www.openshift.com/ – Register account– Login to your account, where you can:

• Create, manage, delete apps• Find Quickstarts and deploy them

• Documentation:– https://www.openshift.com/developers

Step 3: In Eclipse

• Create a new OpenShift application– New > Project… > OpenShift > OpenShift Application

• Login with your OpenShift account• Add your SSH keys

– If you don’t have SSH keys, the wizard can generate them for you

• Add 2 new windows in Eclipse:– Window > Show View > Other >

1. Git > Git staging

2. Jboss Tools > OpenShift Explorer

Structure of a Java web app

Your Java code (*.java)

Any other files needed by Java (config, txt, xml, etc)

Frontend (html, css, jsp, etc)

Step 4: HelloWord API function

package api;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.*;

import javax.servlet.http.*;

public class HelloWorld extends HttpServlet {

private static final long serialVersionUID = -3950937333898038206L;

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

String name = request.getParameter("name");

PrintWriter out = response.getWriter();

out.println("{\"status\":\"Hello " + name + "!\"");

out.flush();

out.close();

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doGet(request, response);

}

}

Under folder: src/main/java/api/

Step 5: Add a dependency

– Similar to “include a library” in a desktop Java application– Here we don’t include any JAR file, instead we point to a

central repository that contains *most* libraries– Open pom.xml:

• Tab: Dependencies• Seach for: javaee-web-api

– Wanna add other dependencies?• Search for them: e.g., “mysql”

Step 6: Update web.xml

<web-app version="3.0”

xmlns="http://java.sun.com/xml/ns/javaee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"

metadata-complete="false">

<servlet>

<servlet-name>HelloWorld</servlet-name>

<servlet-class>api.HelloWorld</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>HelloWorld</servlet-name>

<url-pattern>/api/HelloWorld</url-pattern>

</servlet-mapping>

</web-app>

Under folder: src/main/webapp/WEB-INF/

Step 7: Commit and Push your code

1 2

3

Step 8: See the result!

• Frontend:http://[APP NAME]-[YOUR DOMAIN].rhcloud.com

• API:http://[APP NAME]-[YOUR DOMAIN].rhcloud.com/api/HelloWorld?name=Joe

Useful Links

• Presentations:– http://www.slideshare.net/XavierCoulon/devoxx2013-fr-jbdsopenshift?qid=15557

a00-3f56-4899-9572-dc03301e7bd6&v=default&b=&from_search=14

– http://www.slideshare.net/anoochit/using-openshift-paas?qid=15557a00-3f56-4899-9572-dc03301e7bd6&v=default&b=&from_search=13

• Getting started:– https://www.openshift.com/get-started

• Tutorial for Java & Eclipse:– https://

www.openshift.com/blogs/day-28-openshift-eclipse-integration-for-java-developers

• Lots of tutorials:– https://www.openshift.com/author/shekhar-gulati