Question

I’m understand that
<security-role><role-name>Admin</role-name></security-role>
is for container map it with tomcat-users.xml (realm)

but I confuse about if I didn’t use realm but I use database how container know which field in my database is for role-name or it have naming convention in database field name like “role_name” and container will know it

Thank you for every advices

Answer 1

Just use a database realm and configure the table and column names in a <Realm> element in server configuration file. For Tomcat, this is described in the Realm HOWTO. Here’s an extract of relevance, from the JDBCRealm chapter:

Quick Start

To set up Tomcat to use JDBCRealm, you will need to follow these steps:

1. If you have not yet done so, create tables and columns in your
   database that conform to the
   requirements described above.
2. Configure a database username and password for use by Tomcat, that
   has at least read only access to the
   tables described above. (Tomcat will
   never attempt to write to these
   tables.)
3. Place a copy of the JDBC driver you will be using inside the
   $CATALINA_HOME/lib directory. Note
   that only JAR files are recognized!
4. Set up a <Realm> element, as described below, in your
   $CATALINA_BASE/conf/server.xml file.
5. Restart Tomcat 6 if it is already running.

Realm Element Attributes

To configure JDBCRealm, you will
create a <Realm> element and nest it
in your $CATALINA_BASE/conf/server.xml
file, as described above. The
attributes for the JDBCRealm are
defined in the Realm configuration
documentation.

Example

An example SQL script to create the
needed tables might look something
like this (adapt the syntax as
required for your particular
database):

create table users (
  user_name         varchar(15) not null primary key,  
  user_pass         varchar(15) not null
);

create table user_roles (
  user_name         varchar(15) not null,
  role_name         varchar(15) not null,
  primary key(user_name, role_name)
);

Example Realm elements are included
(commented out) in the default
$CATALINA_BASE/conf/server.xml file.
Here’s an example for using a MySQL
database called “authority”,
configured with the tables described
above, and accessed with username
“dbuser” and password “dbpass”:

<Realm className="org.apache.catalina.realm.JDBCRealm"
      driverName="org.gjt.mm.mysql.Driver"  
   connectionURL="jdbc:mysql://localhost/authority?user=dbuser&amp;password=dbpass"
       userTable="users" userNameCol="user_name" userCredCol="user_pass"   
   userRoleTable="user_roles" roleNameCol="role_name"/>

Pretty clear, isn’t it? If you already have a JDBC datasource configured in Tomcat (for connection pooling and on), then you can also use DataSourceRealm instead.

The tomcat-users.xml which you’re talking about is by the way called UserDatabaseRealm.