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<!DOCTYPE document [
<!ENTITY project SYSTEM "project.xml">
<document url="fs-jdbc-realm.html">
<author email="">Craig McClanahan</author>
<section name="Table of Contents">
<section name="Overview">
<subsection name="Introduction">
<p>The purpose of the <strong>JDBCRealm</strong> implementation is to
provide a mechanism by which Tomcat can acquire information needed
to authenticate web application users, and define their security roles,
from a relational database accessed via JDBC APIs. For integration
with Catalina, the resulting class(es) must implement the
<code>org.apache.catalina.Realm</code> interface.</p>
<p>This specification reflects a combination of functionality that is
already present in the <code>org.apache.catalina.realm.JDBCRealm</code>
class, as well as requirements for enhancements that have been
discussed. Where appropriate, requirements statements are marked
<em>[Current]</em> and <em>[Requested]</em> to distinguish them.</p>
<p>The current status of this functional specification is
<strong>PROPOSED</strong>. It has not yet been discussed and
agreed to on the TOMCAT-DEV mailing list.</p>
<subsection name="External Specifications">
<p>The implementation of this functionality depends on the following
external specifications:</p>
<li><a href="">
Java Database Connectivity</a> (version 2.0 or later)</li>
<li><a href="">
Java Database Connectivity Optional Package</a> (version 2.0 or later)</li>
<subsection name="Implementation Requirements">
<p>The implementation of this functionality shall conform to the
following requirements:</p>
<li>Be realized in one or more implementation classes.</li>
<li>Implement the <code>org.apache.catalina.Realm</code> interface.
<li>Implement the <code>org.apache.catalina.Lifecycle</code>
interface. [Current]</li>
<li>Subclass the <code>org.apache.catalina.realm.RealmBase</code>
base class.</li>
<li>Live in the <code>org.apache.catalina.realm</code> package.
<li>Support a configurable debugging detail level. [Current]</li>
<li>Log debugging and operational messages (suitably internationalized)
via the <code>getContainer().log()</code> method. [Current]</li>
<section name="Dependencies">
<subsection name="Environmental Dependencies">
<p>The following environmental dependencies must be met in order for
JDBCRealm to operate correctly:</p>
<li>The desire to utilize JDBCRealm must be registered in
<code>$CATALINA_BASE/conf/server.xml</code>, in a
<code>&lt;Realm&gt;</code> element that is nested inside a
corresponding <code>&lt;Engine&gt;</code>, <code>&lt;Host&gt;</code>,
or <code>&lt;Context&gt;</code> element.</li>
<subsection name="Container Dependencies">
<p>Correct operation of JDBCRealm depends on the following
specific features of the surrounding container:</p>
<li>Interactions with <code>JDBCRealm</code> will be initiated by
the appropriate <code>Authenticator</code> implementation, based
on the login method that is selected.</li>
<li><code>JDBCRealm</code> must have the JDBC standard API classes
available to it. For a JDK 1.2 or later container, these APIs
are included in the standard platform.</li>
<li>When connection pooling is implemented, <code>JDBCRealm</code>
must have the JDBC Optional Package (version 2.0 or later) APIs
available to it. This library is available as a separate
download (and will be included in Tomcat binary distributions).</li>
<section name="Functionality">
<subsection name="Overview of Operation">
<p>The main purpose of <code>JDBCRealm</code> is to allow Catalina to
authenticate users, and look up the corresponding security roles, from
the information found in a relational database accessed via JDBC APIs.
For maximum flexibility, the details of how this is done (for example,
the names of the required tables and columns) should be configurable.</p>
<p>Each time that Catalina needs to authenticate a user, it will call
the <code>authenticate()</code> method of this Realm implementation,
passing the username and password that were specified by the user. If
we find the user in the database (and match on the password), we accumulate
all of the security roles that are defined for this user, and create a
new <code>GenericPrincipal</code> object to be returned. If the user
is not authenticated, we return <code>null</code> instead. The
<code>GenericUser</code> object caches the set of security roles that
were owned by this user at the time of authentication, so that calls to
<code>isUserInRole()</code> can be answered without going back to the
database every time.</p>
<subsection name="Detailed Functional Requirements">
<h3>Configurable Properties</h3>
<p>The implementation shall support the following properties
that can be configured with JavaBeans property setters:</p>
<li>Configuration parameters defining the JDBC driver to use, the
database connection URL to be accessed, and the username/password
to use for logging in. [Current]</li>
<li>Configuration parameters describing the connection pool to be
created to support simultaneous authentications. [Requested]</li>
<li>Name of the tables to be searched for users and roles. [Current]</li>
<li>Name of the columns to be used for usernames, passwords, and
role names. [Current]</li>
<h3>Lifecycle Functionality</h3>
<p>The following processing must be performed when the <code>start()</code>
method is called:</p>
<li>Establish a connection to the configured database, using the
configured username and password. [Current]</li>
<li>Configure and establish a connection pool of connections to the
database. [Requested]</li>
<p>The following processing must be performed when the <code>stop()</code>
method is called:</p>
<li>Close any opened connections to the database.</li>
<h3>Method authenticate() Functionality</h3>
<p>When <code>authenticate()</code> is called, the following processing
is required:</p>
<li>Acquire the one and only connection [Current] or acquire a connection
from the connection pool [Requested].</li>
<li>Select the one and only row from the user's table for this user,
and retrieve the corresponding password column. If zero rows (or
more than one row) are found, return <code>null</code>.</li>
<li>Authenticate the user by comparing the (possibly encrypted) password
value that was received against the password presented by the user.
If there is no match, return <code>null</code>.</li>
<li>Acquire a <code>List</code> of the security roles assigned to the
authenticated user by selecting from the roles table.</li>
<li>Construct a new instance of class
<code>org.apache.catalina.realm.GenericPrincipal</code>, passing as
constructor arguments: this realm instance, the authenticated
username, and a <code>List</code> of the security roles associated
with this user.</li>
<li><strong>WARNING</strong> - Do not attempt to cache and reuse previous
<code>GenericPrincipal</code> objects for a particular user, because
the information in the directory server might have changed since the
last time this user was authenticated.</li>
<li>Return the newly constructed <code>GenericPrincipal</code>.</li>
<h3>Method hasRole() Functionality</h3>
<p>When <code>hasRole()</code> is called, the following processing
is required:</p>
<li>The <code>principal</code> that is passed as an argument SHOULD
be one that we returned (instanceof class
<code>org.apache.catalina.realm.GenericPrincipal</code>, with a
<code>realm</code> property that is equal to our instance.</li>
<li>If the passed <code>principal</code> meets these criteria, check
the specified role against the list returned by
<code>getRoles()</code>, and return <code>true</code> if the
specified role is included; otherwise, return <code>false</code>.</li>
<li>If the passed <code>principal</code> does not meet these criteria,
return <code>false</code>.</li>
<section name="Testable Assertions">
<p>In addition to the assertions implied by the functionality requirements
listed above, the following additional assertions shall be tested to
validate the behavior of <code>JDBCRealm</code>:</p>