Mini REST web application with Angular frontend

This application comes as a war package. It contains a minimal REST service and a minimal Angular frontend. The REST service is implemented using Jersey REST.

The WAR file can be deployed in a Tomcat.

Dependencies

The dependencies include some modules removed from JDK 9 onwards. I assume the application runs on JDK 1.8 to JDK 11.

Tested on Tomcat 9.0.13, JDK 1.8, JDK 10, JDK 11.

Call example

Start page

http://localhost:8080/mini-ng

REST service call

Echo endpoint

http://localhost:8080/mini-ng/rest/echo/199

How to compile and package

Compile including Node.js frontend build

This build includes the build of the frontend into the dist directory and fixes the web context. For details, see maven-exec-plugin and maven-replacer-plugin sections in pom.xml. The result of the build is added to the WAR file. For details, see maven-war-plugin section in pom.xml.

The build is activated by the profile ng, which itself is activated by default.

mvn clean install

Compile without build of frontend

This build is faster and simply uses an earlier build result in src/frontend/dist. This does not work if there has been no build of the frontend before.

mvn clean install -P \!ng

(depending on the shell used, an escaping '\' is required. E.g. bash needs it.)

How to run

Copy war file from target directory into webapp of a tomcat installation.

How to run in OpenShift container

Set up build config

Define a project and an application in OpenShift. Use the URL of this Github Repo as source repository. Examine the Dockerfile regarding $SWREPO. This URL should point to a web server with several required software archives. See ADD directive lines in Dockerfile for what is needed. You must provide the web site yourself.

An OpenShift build then creates the builder image containing the tools required for a build. These include JDK 11, Maven, Node 10 and Tomcat 9. For no apparent reason I also added a JDK 8.

Set up deployment config

The project's build is started by deploying the image. Check the files run and assemble for some ENV variables that need to be added to the deployment config. After successful build, the application is deployed and started in Tomcat.

Prerequisites

Download & Install Node.js

Install Angular CLI

npm install -g @angular/cli

CORS issues

As this application runs both frontend and backend in a single war, there is no CORS issue.

If you run the frontent externally using ng serve and access it via localhost:4200, you will have the CORS issue, because the backend runs on e.g. localhost:8080. This case may happen during development.

There are several ways to tackle this issue:

• Simplest approach: For Firefox, use "cors-plugin" from Rahudevan to switch off the browsers CORS feature.

• Other approach is to use a proxy configuration for Node.js.

• Other approach is to solve it on server side. The application contains code for that (CORSFilter) and the filter is activated in web.xml. This should work, but it does not. Other problem with this approach is, that every REST implementation solves the problem totally different. Even Jersey 1 and 2 are different.