# Tomcat and Apache

This document describes the steps needed to install Apache Tomcat. It also optionally describes how to integrate Tomcat with the Apache Web Server, and how to configure MySQL to work with Tomcat Servlets and JSPs.

## Installation

Install and configure Apache as in the LAMP tutorial. You may install PHP and MySQL at this time if you want them.

Then install Tomcat:

    # pacman -S tomcat

## Configuring Tomcat

Edit `/etc/conf.d/tomcat`. Replace the line

    TOMCAT_JAVA_HOME=/usr/lib/jvm/java-1.6.0-openjdk \

with this one (assuming that `/opt/java` is your JAVA_HOME):

    TOMCAT_JAVA_HOME=/opt/java \

###### THE FOLLOWING SHOULD NO LONGER BE NEEDED

Edit `/etc/conf.d/tomcat`. Change CATALINA_USER to some user that suites your system (like "nobody")

    modprobe capability

Now add capabilities to modules in `/etc/rc.conf`.

Also you may have to edit `/etc/rc.d/tomcat` to change the java home for jsvc. In the "start" section you have change this line:

    -home /usr/lib/jvm/java-1.6.0-openjdk \

with this one (assuming that `/opt/java` is your JAVA_HOME):

    -home /opt/java \

## Test Tomcat

Run in terminal (as root):

    # /etc/rc.d/tomcat start

Notice that you can check the logs in `/opt/tomcat/logs/catalina.log`.

Tomcat should be running. Test by visiting http://localhost:8080/ in a web browser. You can browse the JSP and servlet examples if you like.

This is all that is needed to run Tomcat as a stand-alone server. You can add new webapp directories to the `/opt/tomcat/webapps` directory. Optionally, if you want to place webapps in a different directory, you can make `/opt/tomcat/webapps/` a symbolic link to another directory. For example, if you wanted to place your web applications in `/home/httpd/tomcat` run these commands (as root):

    # cd /opt/tomcat
    # mv webapps /home/httpd/tomcat
    # ln -s /home/httpd/tomcat/webapps webapps

You can also place symbolic links within the webapps directory.

If you wish tomcat to start on bootup:
Edit `/opt/tomcat/bin/catalina.sh` and add this line at the top:

    JAVA_HOME=/opt/java

This is needed because JAVA_HOME is not set when the daemons are started
Edit `/etc/rc.conf`:

    DAEMONS=(some daemons now add tomcat)

Or add this line to `rc.local`:

    /etc/rc.d/tomcat start

## Configure Apache

### Without mod_jk

If you have mod_proxy installed (default since Apache 2.0) you only need to include two directives in your `httpd.conf` file for each web application that you wish to forward to Tomcat 5. For example, to forward an application at context path /myapp:

    ProxyPass         /myapp  http://localhost:8080/myapp
    ProxyPassReverse  /myapp  http://localhost:8080/myapp

Note: starting from Apache 2.2 included mod_proxy supports the AJP protocol and so it's a viable alternative to mod_jk (this package). It's far easier to configure in `httpd.conf` or inside a <VirtualHost>:

    ProxyPass / ajp://127.0.0.1:8009/APPNAME
    ProxyPassReverse / ajp://127.0.0.1:8009/APPNAME

Instead of / you can map APPNAME to an arbitrary web path. mod_jk (described below) should be used only if its advanced features are needed.

### Using mod_jk

There are two ways to install mod_jk: from AUR or from upstream. In the latter case you should copy it to the directory `/usr/lib/httpd/modules/`. Then rename the file to `mod_jk.so` and set it executable with

    # chmod a+x mod_jk.so

Edit `/etc/httpd/conf/httpd.conf`
Add this line to the end of the LoadModule section:

    LoadModule jk_module               modules/mod_jk.so

Add these lines below the LoadModule section:

    <IfModule jk_module>
        JkWorkersFile   /etc/httpd/conf/workers.properties
        JkShmFile       /var/run/shm.file
        JkShmSize       1048576
    </IfModule>

Create the file `/etc/httpd/conf/workers.properties`. It should contain the following:

    # Define some properties
    workers.apache_log=/var/log/httpd/
    workers.tomcat_home=/opt/tomcat
    workers.java_home=/opt/java
    ps=/
    worker.list=worker2
    # Define worker's properties
    worker.worker2.type=ajp13
    worker.worker2.host=localhost
    worker.worker2.port=8009
    worker.worker2.mount=/jsp-examples /jsp-examples/*

Start Apache. Run in terminal (as root):

    # /etc/rc.d/httpd start

Only run httpd after tomcat is started (EDIT: I'm not sure if this is true, I can restart & start tomcat and apache separately from each other, I will just get a 'Service unavailable' in Apache if I request a .jsp while tomcat is restarting..)

Visit http://localhost/jsp-examples The Tomcat JSP examples should be visible.

If you want to have URLs other than examples map to tomcat, modify the .mount attribute like

    worker.worker2.mount=/jsp-examples /jsp-examples/* /someapp /someapp/*

to your `workers.properties` file. The `someapp` will map http://localhost/someapp/ to `/opt/tomcat/webapps/someapp/` as interpreted by tomcat. There are more complex workers.properties configurations; search the website for more info. http://tomcat.apache.org/connectors-doc/reference/workers.html

## Configure MySQL

Do this section only if you want to connect to MySQL from within Tomcat or the Java environment in general.

Review the MySQL documentation and download the driver. 3.0 is a good choice: http://www.mysql.com/products/connector-j/

Untar the driver and copy `=mysql-connector-java-3.0.11-stable-bin.jar` into `/opt/java/jre/lib/ext`

    tar xfvz mysql-connector-java-3.0.11-stable.tar.gz
    cp mysql-connector-java-3.0.11-stable/mysql-connector-java-3.0.11-stable-bin.jar /opt/java/jre/lib/ext

Start MySQL if it isn't already running (as root):

    # /etc/rc.d/mysqld start

Test that the driver can be loaded:
Save this as `~TestMysql.java`

        public class TestMysql {
            public static void main(String[] args) {
                try {
                    Class.forName("com.mysql.jdbc.Driver").newInstance();
                } catch (Exception e) {
                    System.out.println("The driver couldn't be loaded");
                    return;
                }
                System.out.println("The driver was loaded");
            }
        }

Compile the file:

    $ javac TestMysql.java

Run the file

    $ java -classpath :/opt/java/jre/lib/ext TestMysql

It will output "The driver was loaded" if the driver is available, otherwise "The driver couldn't be loaded"

You should be able to use the driver using DriverManager.getConnection() in Java programs now. It should also automatically be available to Tomcat servlets and JSPs. See The Mysql Connector/J documentation for more information.

Category:

- Web Server