Simplistic examples of various patterns with Java based frameworks.

Table of Contents

• Configuration Overview
• Database Initialization
  • Create Database and Role in Postgres
• Configure Web App Container
  • Prepare TomEE Plus
  • Download and Extract TomEE Plus
  • Configure DataSource

Configuration Overview

Many of the apps in this repository require some basic configuration of an application server, and sometimes a database or other system service. This base readme describes some of the common configuration requirements.

    TODO: separate various configuration concerns, such as 
    J2EE examples have different needs than the HDP examples.

Database Initialization

The database role and data store must be created outside the context of the webapp using features specific to the database being used.

Create Database and Role in Postgres

How to create database and role with PostgreSQL.

1. Create the database

    createdb -w -Upostgres -hlocalhost jpabasics;
   

2. Create the role

    psql -w -Upostgres -hlocalhost -djpabasics -c "\
            create role jpabasics;\
            alter role jpabasics with nosuperuser inherit nocreaterole nocreatedb login noreplication;\
            alter role jpabasics with unencrypted password 'jpabasics';\
    "
   

Configure Web App Container

The application container must be configured to expose the database connection as a datasource for Web Applications that need it. This section describes how to perform this configuration on a few popular application containers.

Preparing TomEE Plus

We assum TomEE Plus 1.7.1 for these instructions.

Download and Extract TomEE Plus

1. Download TomEE Plus 1.7.1

    http://archive.apache.org/dist/tomee/tomee-1.7.1/apache-tomee-1.7.1-plus.tar.gz
   

2. Extract inside your preferred installation directory.

    tar xvzf ~/Downloads/apache-tomee-1.7.1-plus.tar.gz
   

3. We will refer to the full path to the new apache-tomee-1.7.1 installation as $CATALINA_HOME in the rest of this document.

Add PostgreSQL Driver

1. Download the PostgreSQL JDBC 4.1 driver for the version of PostgreSQL you have installed. The example below assumes PostgreSQL 9.3.

    https://jdbc.postgresql.org/download/postgresql-9.3-1103.jdbc41.jar
   

2. Copy the driver to the tomcat lib directory

    cp ~/Downloads/postgresql-9.3-1103.jdbc41.jar $CATALINA_HOME/lib
   

Configure DataSource

We tell tomcat what database to use. The applications will lookup this information by the DataSource name.

1. Edit $CATALINA_HOME/conf/tomee.xml with the following contents:

    <?xml version="1.0" encoding="UTF-8"?>
    <tomee>
            <Resource  id="DocumentDS" type="DataSource">
              JdbcDriver org.postgresql.Driver
              JdbcUrl jdbc:postgresql://127.0.0.1:5432/jpabasics
              UserName jpabasics
              Password jpabasics
              JtaManaged true
              TestWhileIdle true
              InitialSize 5
            </Resource>
    </tomee>
   

Configuring Logging in TomEE 1.7.1

TomEE will use the native Java Logging implementation by default. We prefer using the slf4j APIs with an underlying logback implementation. Due to the variety of logging APIs, we'll also add a few other libraries to support logging by some of the dependent libraries.

1. Download the following libraries and add them to the tomcat classpath by editing /cloud/tomcat/bin/setenv.sh

    CLASSPATH=$CATALINA_HOME/bin/jul-to-slf4j-1.7.12.jar:\
    $CATALINA_HOME/bin/slf4j-api-1.7.12.jar:\
    $CATALINA_HOME/bin/logback-classic-1.1.3.jar:\
    $CATALINA_HOME/bin/logback-core-1.1.3.jar:\
    $CATALINA_HOME/bin/jcl-over-slf4j-1.7.12.jar:\
    $CATALINA_HOME/bin/slf4j-jcl-1.7.12.jar:\
    $CATALINA_HOME/bin/log4j-over-slf4j-1.7.12.jar
   

2. Restart tomcat