spring-security/docs/manual/src/docbook/appendix-namespace.xml

<?xml version="1.0" encoding="UTF-8"?>
<appendix version="5.0" xml:id="appendix-namespace" xmlns="http://docbook.org/ns/docbook"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xi="http://www.w3.org/2001/XInclude">

  <info>
    <title>The Security Namespace</title>
  </info>

  <para>
    This appendix provides a reference to the elements available in the security namespace and information on
    the underlying beans they create (a knowledge of the individual classes and how they work together is assumed -
    you can find more information in the project Javadoc and elsewhere in this document).
    If you haven't used the namespace before, please read the
    <link xlink:href="#ns-config">introductory chapter</link> on namespace configuration, 
    as this is intended as a supplement to the information there. Using a good quality XML editor while editing a 
    configuration based on the schema is recommended as this will provide contextual information on which elements 
    and attributes are available as well as comments explaining their purpose.
  </para>

  <section xml:id="nsa-http">
    <title>Web Application Security - the <literal>&lt;http&gt;</literal> Element</title>
    <para>
      The <literal>&lt;http&gt;</literal> element encapsulates the security configuration for the web layer of your application. 
      It creates a <classname>FilterChainProxy</classname> bean named "springSecurityFilterChain" which maintains the stack of
      security filters which make up the web security configuration <footnote><para>See the
      <link xlink:href="#ns-web-xml"> introductory chapter</link> for how to set up the mapping from
        your <literal>web.xml</literal></para></footnote>. Some core filters are always created and others will
       be added to the stack depending on the attributes child elements which are present. The positions of the standard
      filters are fixed (see <link xlink:href="#filter-stack">the filter order table</link> in the namespace introduction),
      removing a common source of errors with previous versions of the framework when users had to configure the
      filter chain explicitly in the<classname>FilterChainProxy</classname> bean. You can, of course, still do this
      if you need full control of the configuration.
    </para>
    <para>
      All filters which require a reference to the <interfacename>AuthenticationManager</interfacename> will be automatically
      injected with the internal instance created by the namespace configuration (see the
      <link xlink:href="#ns-auth-manager"> introductory chapter</link> for more on the <interfacename>AuthenticationManager</interfacename>).
    </para>
    <para>
        The <literal>&lt;http&gt;</literal> namespace block always creates an <classname>HttpSessionContextIntegrationFilter</classname>,
        an <classname>ExceptionTranslationFilter</classname> and a <classname>FilterSecurityInterceptor</classname>. These are fixed
        and cannot be replaced with alternatives.
    </para>

    <section xml:id="nsa-http-attributes">
      <title><literal>&lt;http&gt;</literal> Attributes</title>
      <para>
        The attributes on the <literal>&lt;http&gt;</literal> element control some of the properties on the
        core filters.
      </para>
      <section xml:id="nsa-servlet-api-provision">
        <title><literal>servlet-api-provision</literal></title>
        <para>
          Provides versions of <literal>HttpServletRequest</literal> security methods such as
          <literal>isUserInRole()</literal> and <literal>getPrincipal()</literal> which are implemented by
          adding a <classname>SecurityContextHolderAwareRequestFilter</classname> bean to the stack. Defaults to "true".
        </para>
      </section>

      <section xml:id="nsa-path-type">
        <title><literal>path-type</literal></title>
        <para>
          Controls whether URL patterns are interpreted as ant paths (the default) or regular expressions. In practice
          this sets a particular <interfacename>UrlMatcher</interfacename> instance on the <classname>FilterChainProxy</classname>.
        </para>
      </section>

      <section xml:id="nsa-lowercase-comparisons">
        <title><literal>lowercase-comparisons</literal></title>
        <para>
          Whether test URLs should be converted to lower case prior to comparing with defined path patterns. If unspecified,
          defaults to "true"
        </para>
      </section>

      <section xml:id="session-fixation-protection">
        <title><literal>session-fixation-protection</literal></title>
        <para>
          Indicates whether an existing session should be invalidated when a user authenticates and a new session started.
          If set to "none" no change will be made. "newSession" will create a new empty session.
          "migrateSession" will create a new session and copy the session attributes to the new session. Defaults to "migrateSession".
        </para>
        <para>
          If enabled this will add a <classname>SessionFixationProtectionFilter</classname> to the stack. The session fixation protection
          options on namespace-created instances of <classname>AbstractAuthenticationProcessingFilter</classname> will also be set appropriately.
        </para>
      </section>

      <section xml:id="nsa-realm">
        <title><literal>realm</literal></title>
        <para>
          Sets the realm name used for basic authentication (if enabled). Corresponds to the <literal>realmName</literal> proerty on
          <classname>BasicProcessingFilterEntryPoint</classname>.
        </para>
      </section>

      <section xml:id="nsa-entry-point-ref">
        <title><literal>entry-point-ref</literal></title>
        <para>
          Normally the <interfacename>AuthenticationEntryPoint</interfacename> used will be set depending on which
          authentication mechanisms have been configured. This attribute allows this behaviour to be overridden
          by defining a customized <interfacename>AuthenticationEntryPoint</interfacename> bean which will start the authentication
          process.
        </para>
      </section>

      <section xml:id="nsa-access-decision-manager-ref">
        <title><literal>access-decision-manager-ref</literal></title>
        <para>
          Optional attribute specifying the ID of the <interfacename>AccessDecisionManager</interfacename> implementation which should be
          used for authorizing HTTP requests. By default an <classname>AffirmativeBased</classname> implementation is used for with
          a <classname>RoleVoter</classname> and an <classname>AuthenticatedVoter</classname>.
        </para>
      </section>

      <section xml:id="nsa-access-denied-page">
        <title><literal>access-denied-page</literal></title>
        <para>
          Allows the access denied page to be set (the user will be redirected here if an
          <exceptionname>AccessDeniedException</exceptionname> is raised). Corresponds to the
          <literal>errorPage</literal> property set on the <classname>AccessDeniedHandlerImpl</classname> which is
          used by the <classname>ExceptionTranslationFilter</classname>.
        </para>
      </section>

      <section xml:id="nsa-once-per-request">
        <title><literal>once-per-request</literal></title>
        <para>
          Corresponds to the <literal>observeOncePerRequest</literal> property of
          <classname>FilterSecurityInterceptor</classname>. Defaults to "true".
        </para>
      </section>
      
      <section xml:id="create-session">
        <title><literal>create-session</literal></title>
        <para>
          Controls the eagerness with which an HTTP session is created. If not set, defaults to "ifRequired". Other options are "always" and "never".
          The setting of this attribute affect the <literal>allowSessionCreation</literal> and <literal>forceEagerSessionCreation</literal>
          properties of <classname>HttpSessionContextIntegrationFilter</classname>. <literal>allowSessionCreation</literal> will always be true unless
          this attribute is set to "never". <literal>forceEagerSessionCreation</literal> is "false" unless it is set to "always".
          So the default configuration allows session creation but does not force it. The exception is if concurrent session control is enabled,
          when <literal>forceEagerSessionCreation</literal> will be set to true, regardless of what the setting is here. Using "never" would
          then cause an exception during the initialization of <classname>HttpSessionContextIntegrationFilter</classname>.
        </para>
      </section>
    </section>

    <section>
      <title>The <literal>&lt;intercept-url&gt;</literal> Element</title>
      <para>
        This element is used to define the set of URL patterns that the application is interested in
        and to configure how they should be handled. It is used to construct the
        <interfacename>FilterInvocationDefinitionSource</interfacename> used by the <classname>FilterSecurityInterceptor</classname> and
        to exclude particular patterns from the filter chain entirely (by setting the attribute <literal>filters="none"</literal>). 
        It is also responsible for configuring a <classname>ChannelProcessingFilter</classname> if particular URLs need to be accessed
        by HTTPS, for example.
      </para>

      <section xml:id="nsa-pattern">
        <title><literal>pattern</literal></title>
        <para>
          The pattern which defines the URL path. The content will depend on the <literal>path-type</literal> attribute from the 
          containing http element, so will default to ant path syntax.
        </para>
      </section>
      <section xml:id="nsa-method">
        <title><literal>method</literal></title>
        <para>
          The HTTP Method which will be used in combination with the pattern to match an incoming request. If omitted, any method will match.
        </para>
      </section>
      <section xml:id="nsa-access">
        <title><literal>access</literal></title>
        <para>
          Lists the access attributes which will be stored in the <interfacename>FilterInvocationDefinitionSource</interfacename> for the defined 
          URL pattern/method combination. This should be a comma-separated list of the attributes (such as role names). 
        </para>
      </section>
      <section xml:id="nsa-requires-channel">
        <title><literal>requires-channel</literal></title>
        <para>
          Can be "http" or "https" depending on whether a particular URL pattern should be accessed over HTTP or HTTPS respectively. Alternatively
          the value "any" can be used when there is no preference. If this attribute is present on any <literal>&lt;intercept-url&gt;</literal>
          element, then a <classname>ChannelProcessingFilter</classname> will be added to the filter stack and its additional dependencies added
          to the application context. See the chapter on <link xlink:href="#channel-security-config">channel security</link> for an
          example configuration using traditional beans.
        </para>
        <para>
          If a <literal>&lt;port-mappings&gt;</literal> configuration is added, this will be used to by the <classname>SecureChannelProcessor</classname>
          and <classname>InsecureChannelProcessor</classname> beans to determine the ports used for redirecting to HTTP/HTTPS. 
        </para>
      </section>      
    </section>
    
    <section>
      <title>The <literal>&lt;port-mappings&gt;</literal> Element</title>
      <para>
        By default, an instance of <classname>PortMapperImpl</classname> will be added to the configuration for use in redirecting
        to secure and insecure URLs. This element can optionally be used to override the default mappings which that class defines. Each
        child <literal>&lt;port-mapping&gt;</literal> element defines a pair of HTTP:HTTPS ports. The default mappings are 80:443
        and 8080:8443. An example of overriding these can be found in the <link xlink:href="#ns-requires-channel">namespace introduction</link>.
      </para>
    </section>

    <section xml:id="nsa-form-login">
      <title>The <literal>&lt;form-login&gt;</literal> Element</title>
      <para>
        Used to add an <classname>UsernamePasswordAuthenticationProcessingFilter</classname> to the filter stack and an 
        <classname>LoginUrlAuthenticationEntryPoint</classname> to the application context to provide authentication
        on demand. This will always take precedence over other namespace-created entry points.
        If no attributes are supplied, a login page will be generated automatically at the URL "/spring-security-login"
        <footnote><para>This feature is really just provided for convenience and is not intended for production (where a 
        view technology will have been chosen and can be used to render a customized login page). The class 
        <classname>DefaultLoginPageGeneratingFilter</classname> is responsible for rendering the login
        page and will provide login forms for both normal form login and/or OpenID if required.</para></footnote>
        The behaviour can be customized using the following attributes.
      </para>

      <section>
        <title><literal>login-page</literal></title>
        <para>
          The URL that should be used to render the login page. Maps to the <literal>loginFormUrl</literal>
          property of the <classname>LoginUrlAuthenticationEntryPoint</classname>. Defaults to
          "/spring-security-login".
        </para>
      </section>

      <section>
        <title><literal>login-processing-url</literal></title>
        <para>
          Maps to the <literal>filterProcessesUrl</literal> property of <classname>UsernamePasswordAuthenticationProcessingFilter</classname>.
          The default value is "/j_spring_security_check".
        </para>
      </section>
      
      <section>
        <title><literal>default-target-url</literal></title>
        <para>Maps to the <literal>defaultTargetUrl</literal> property of <classname>UsernamePasswordAuthenticationProcessingFilter</classname>. If
        not set, the default value is "/" (the application root). A user will be taken to this URL after logging in, provided they
        were not asked to login while attempting to access a secured resource, when they will be taken to the originally requested URL.
        </para>
      </section>
      
      <section>
        <title><literal>always-use-default-target</literal></title>
        <para>
          If set to "true", the user will always start at the value given by <literal>default-target-url</literal>, regardless of how 
          they arrived at the login page. Maps to the <literal>alwaysUseDefaultTargetUrl</literal> property of
          <classname>UsernamePasswordAuthenticationProcessingFilter</classname>. Default value is "false".
        </para>
      </section>

      <section>
        <title><literal>authentication-failure-url</literal></title>
        <para>
          Maps to the <literal>authenticationFailureUrl</literal> property of <classname>UsernamePasswordAuthenticationProcessingFilter</classname>.
          Defines the URL the browser will be redirected to on login failure. Defaults to "/spring_security_login?login_error", which will
          be automatically handled by the automatic login page generator, re-rendering the login page with an error message.
        </para>
      </section>
    </section>
    
    <section xml:id="nsa-http-basic">
      <title>The <literal>&lt;http-basic&gt;</literal> Element</title>
      <para>
        Adds a <classname>BasicProcessingFilter</classname> and <classname>BasicProcessingFilterEntryPoint</classname> to the
        configuration. The latter will only be used as the configuration entry point if form-based login is not enabled.
      </para>
    </section>

    <section xml:id="nsa-remember-me">
      <title>The <literal>&lt;remember-me&gt;</literal> Element</title>
      <para>
        Adds the <classname>RememberMeProcessingFilter</classname> to the stack. This in turn will
        be configured with either a <classname>TokenBasedRememberMeServices</classname>, a <classname>PersistentTokenBasedRememberMeServices</classname>
        or a user-specified bean implementing <interfacename>RememberMeServices</interfacename> depending on the attribute settings.
      </para>
      <section>
        <title><literal>data-source-ref</literal></title>
        <para>
          If this is set, <classname>PersistentTokenBasedRememberMeServices</classname> will be used and configured with 
          a <classname>JdbcTokenRepositoryImpl</classname> instance.
        </para>
      </section>
      
      <section>
        <title><literal>token-repository-ref</literal></title>
        <para>
          Configures a <classname>PersistentTokenBasedRememberMeServices</classname> but allows the use of a custom
          <interfacename>PersistentTokenRepository</interfacename> bean.
        </para>
      </section>      
      
      <section>
        <title><literal>services-ref</literal></title>
        <para>
          Allows complete control of the <interfacename>RememberMeServices</interfacename> implementation that will be used
          by the filter. The value should be the Id of a bean in the application context which implements this interface.
        </para>
      </section> 
      
      <section>
        <title><literal>token-repository-ref</literal></title>
        <para>
          Configures a <classname>PersistentTokenBasedRememberMeServices</classname> but allows the use of a custom
          <interfacename>PersistentTokenRepository</interfacename> bean.
        </para>
      </section>       
      
      <section>
        <title>The <literal>key</literal> Attribute</title>
        <para>Maps to the "key" property of <classname>AbstractRememberMeServices</classname>. Should be set to a unique
        value to ensure that remember-me cookies are only valid within the one application <footnote><para>This doesn't affect
          the use of <classname>PersistentTokenBasedRememberMeServices</classname>, where the tokens are stored on the server side.</para></footnote>.
        </para>
      </section>

      <section>
        <title><literal>token-validity-seconds</literal></title>
        <para>
          Maps to the <literal>tokenValiditySeconds</literal> property of <classname>AbstractRememberMeServices</classname>. Specifies the period
          in seconds for which the remember-me cookie should be valid. By default it will be valid for 14 days.
        </para>
      </section>

      <section>
        <title><literal>user-service-ref</literal></title>
        <para>
          The remember-me services implementations require access to a <interfacename>UserDetailsService</interfacename>, so there has to be 
          one defined in the application context. If there is only one, it will be selected and used automatically by the namespace configuration.
          If there are multiple instances, you can specify a bean Id explicitly using this attribute.
        </para>
      </section>
    </section>

    <section xml:id="nsa-concurrent-session-control">
      <title>The <literal>&lt;concurrent-session-control&gt;</literal> Element</title>
      <para>
        Adds support for concurrent session control, allowing limits to be placed on the number of active sessions a user can have.
        A <classname>ConcurrentSessionFilter</classname> will be created, along with a <classname>ConcurrentSessionControllerImpl</classname>
        and an instance of <interfacename>SessionRegistry</interfacename> (a <classname>SessionRegistryImpl</classname> instance unless the user
        wishes to use a custom bean). The controller is registered with the namespace's <interfacename>AuthenticationManager</interfacename> 
        (<classname>ProviderManager</classname>). Other namespace-created beans which require a reference to the <interfacename>SessionRegistry</interfacename>
        will automatically have it injected. 
      </para>
      <para>
        Note that the <literal>forceEagerSessionCreation</literal> of <classname>HttpSessionContextIntegrationFilter</classname> will
        be set to <literal>true</literal> if concurrent session control is in use.
      </para>
      
      <section>
        <title>The <literal>max-sessions</literal> attribute</title>
        <para>Maps to the <literal>maximumSessions</literal> property of <classname>ConcurrentSessionControllerImpl</classname>.</para>
      </section>

      <section>
        <title>The <literal>expired-url</literal> attribute</title>
        <para>
          The URL a user will be redirected to if they attempt to use a session which has been "expired" by 
          the concurrent session controller because the user has exceeded the number of allowed sessions and has logged 
          in again elsewhere. Should be set unless <literal>exception-if-maximum-exceeded</literal> is set.
          If no value is supplied, an expiry message will just be written directly back to the response.
        </para>
      </section>
      
      <section>
        <title>The <literal>exception-if-maximum-exceeded</literal> attribute</title>
        <para>If set to "true" a <exceptionname>ConcurrentLoginException</exceptionname> should be raised when a user 
          attempts to exceed the maximum allowed number of sessions. The default behaviour is to expire the original session.
        </para>
      </section>
      
      <section>
        <title>The <literal>session-registry-alias</literal> and <literal>session-registry-ref</literal> attributes</title>
        <para>
          The user can supply their own <interfacename>SessionRegistry</interfacename> implementation using the
          <literal>session-registry-ref</literal> attribute. The other concurrent session control beans will be wired
          up to use it. 
        </para>
        <para>
          It can also be useful to have a reference to the internal session registry for use in your own
          beans or an admin interface. You can expose the interal bean using the <literal>session-registry-alias</literal>
          attribute, giving it a name that you can use elsewhere in your configuration.
        </para>
      </section>

    </section>
    
    <section xml:id="nsa-anonymous">
      <title>The <literal>&lt;anonymous&gt;</literal> Element</title>
      <para>
        Adds an <classname>AnonymousProcessingFilter</classname> to the stack and an <classname>AnonymousAuthenticationProvider</classname>. 
        Required if you are using the <literal>IS_AUTHENTICATED_ANONYMOUSLY</literal> attribute.
      </para>
    </section>
    
    <section xml:id="nsa-x509">
      <title>The <literal>&lt;x509&gt;</literal> Element</title>
      <para>
        Adds support for X.509 authentication. An <classname>X509PreAuthenticatedProcessingFilter</classname> will be 
        added to the stack and a <classname>PreAuthenticatedProcessingFilterEntryPoint</classname> bean will be created. The
        latter will only be used if no other authentication mechanisms are in use (it's only functionality is to return an HTTP
        403 error code). A <classname>PreAuthenticatedAuthenticationProvider</classname> will also be created which delegates the
        loading of user authorities to a <interfacename>UserDetailsService</interfacename>.
      </para>
      <section>
        <title>The <literal>subject-principal-regex</literal> attribute</title>
        <para>
          Defines a regular expression which will be used to extract the username from the certificate (for use with the
          <interfacename>UserDetailsService</interfacename>). 
        </para>
      </section>
      <section>
        <title>The <literal>user-service-ref</literal> attribute</title>
        <para>
          Allows a specific <interfacename>UserDetailsService</interfacename> to be used with X.509 in the case where
          multiple instances are configured. If not set, an attempt will be made to locate a suitable instance automatically and
          use that.
        </para>
      </section>
    </section>

    <section xml:id="nsa-openid-login">
      <title>The <literal>&lt;openid-login&gt;</literal> Element</title>
      <para>
        Similar to <literal>&lt;form-login&gt;</literal> and has the same attributes. The default value for <literal>login-processing-url</literal> 
        is "/j_spring_openid_security_check". An <classname>OpenIDUsernamePasswordAuthenticationProcessingFilter</classname> and <classname>OpenIDAuthenticationProvider</classname>
        will be registered. The latter requires a reference to a <interfacename>UserDetailsService</interfacename>. Again, this can be
        specified by Id, using the <literal>user-service-ref</literal> attribute, or will be located automatically in the application context.
      </para>
    </section>

    <section xml:id="nsa-logout">
      <title>The <literal>&lt;logout&gt;</literal> Element</title>
      <para>
        Adds a <classname>LogoutFilter</classname> to the filter stack. This is configured 
        with a <classname>SecurityContextLogoutHandler</classname>.
      </para>
      <section>
        <title>The <literal>logout-url</literal> attribute</title>
        <para>
          The URL which will cause a logout (i.e. which will be processed by the filter). Defaults to "/j_spring_security_logout".
        </para>
      </section>
      <section>
        <title>The <literal>logout-success-url</literal> attribute</title>
        <para>
          The destination URL which the user will be taken to after logging out. Defaults to "/".
        </para>
      </section>
      <section>
        <title>The <literal>invalidate-session</literal> attribute</title>
        <para>
          Maps to the <literal>invalidateHttpSession</literal> of the <classname>SecurityContextLogoutHandler</classname>.
          Defaults to "true", so the session will be invalidated on logout.
        </para>
      </section>
    </section>
  </section>
  
  <section>
    <title>Authentication Services</title>
    <para>
      If you are using the namespace, an <interfacename>AuthenticationManager</interfacename> is
      automatically registered and will be used by all the namespace-created beans which need to reference it.
      The bean is an instance of Spring Security's <classname>ProviderManager</classname> class, which needs to be
      configured with a list of one or more <interfacename>AuthenticationProvider</interfacename> instances.
      These can either be created using syntax elements provided by the namespace, or they can be
      standard bean definitions, marked for addition to the list using the 
      <literal>custom-authentication-provider</literal> element.
    </para>
    
    <section>
      <title>The &lt;authentication-provider&gt; Element</title>
      <para>
        This element is basically a shorthand syntax for configuring a <link xlink:href="#dao-provider"><classname>DaoAuthenticationProvider</classname></link>.
        <classname>DaoAuthenticationProvider</classname> loads user information from a <interfacename>UserDetailsService</interfacename> and 
        compares the username/password combination with the values supplied at login. The <interfacename>UserDetailsService</interfacename> instance
        can be defined either by using an available namespace element (<literal>jdbc-user-service</literal> or by using the <literal>user-service-ref</literal> 
        attribute to point to a bean defined elsewhere in the application context). You can find examples of these variations in the
        <link xlink:href="#ns-auth-providers">namespace introduction</link>.
      </para>
    </section>
    <section>
      <title>Using <literal>&lt;custom-authentication-provider&gt;</literal> to register an AuthenticationProvider</title>
      <para>
        If you have written your own <interfacename>AuthenticationProvider</interfacename> implementation (or want
        to configure one of Spring Security's own implementations as a traditional bean for some reason, then
        you can use the following syntax to add it to the internal <classname>ProviderManager</classname>'s list:
        <programlisting><![CDATA[
  <bean id="myAuthenticationProvider" class="com.something.MyAuthenticationProvider">
    <security:custom-authentication-provider />
  </bean>
  ]]></programlisting>
      </para>
    </section>
    
    <section>
      <title>The <literal>&lt;authentication-manager&gt;</literal> Element</title>
      <para>
        Since the <interfacename>AuthenticationManager</interfacename> will be automatically registered in the application
        context, this element is entirely optional. It allows you to define an alias name for the internal instance for use
        in your own configuration and also to supply a link to a <interfacename>ConcurrentSessionController</interfacename>
        if you are configuring concurrent session control yourself rather than through the namespace (a rare requirement).
        Its use is described in the <link xlink:href="#ns-auth-manager">namespace introduction</link>.
      </para>
    </section>
    
  </section>
  
  <section>
    <title>Method Security</title>
    
    <section>
      <title>The <literal>&lt;global-method-security&gt;</literal> Element</title>
      <para>
        This element is the primary means of adding support for securing methods on Spring Security beans. Methods can
        be secured by the use of annotations (defined at the interface or class level) or by defining a set of 
        pointcuts as child elements, using AspectJ syntax.
      </para>
      <para>
        Method security uses the same <interfacename>AccessDecisionManager</interfacename> configuration as web security,
        but this can be overridden as explained above <xref xlink:href="#nsa-access-decision-manager-ref"/>, using the same
        attribute.
      </para>
      <section>
        <title>The <literal>&lt;secured-annotations&gt;</literal> and <literal>&lt;jsr250-annotations&gt;</literal> Attributes</title>
        <para>
          Setting these to "true" will enable support for Spring Security's own <literal>@Secured</literal> annotations and
          JSR-250 annotations, respectively. They are both disabled by default. Use of JSR-250 annotations also adds a
          <classname>Jsr250Voter</classname> to the <interfacename>AccessDecisionManager</interfacename>, so you need to 
          make sure you do this if you are using a custom implementation and want to use these annotations.
        </para>
      </section>
      <section>
        <title>Securing Methods using <literal>&lt;protect-pointcut&gt;</literal></title>
        <para>
          Rather than defining security attributes on an individual method or class basis using the 
          <literal>@Secured</literal> annotation, you can define cross-cutting security constraints across whole 
          sets of methods and interfaces in your service layer using the <literal>&lt;protect-pointcut&gt;</literal> 
          element. This has two attributes:
          <itemizedlist>
            <listitem><para><literal>expression</literal> - the pointcut expression</para></listitem>
            <listitem><para><literal>access</literal> - the security attributes which apply</para></listitem>
          </itemizedlist>
          You can find an example in the <link xlink:href="#ns-protect-pointcut">namespace introduction</link>.
        </para>
      </section>
      <section xml:id="nsa-custom-after-invocation">
        <title>The <literal>&lt;custom-after-invocation-provider&gt;</literal> Element</title>
        <para>
          This element can be used to decorate an <interfacename>AfterInvocationProvider</interfacename>
          for use by the security interceptor maintained by the <literal>&lt;global-method-security&gt;</literal>
          namespace.
        </para>
        <para>
          The syntax is the same as for <literal>&lt;custom-authentication-provider&gt;</literal>.
        </para>
      </section>
    </section>
    <section>
      <title>LDAP Namespace Options</title>
      <para>
        LDAP is covered in some details in <link xlink:href="#ldap">its own chapter</link>. We will expand on that
        here with some explanation of how the namespace options map to Spring beans. The LDAP implementation uses
        Spring LDAP extensively, so some familiarity with that project's API may be useful. 
      </para>
      <section>
        <title>Defining the LDAP Server using the <literal>&lt;ldap-server&gt;</literal> Element</title>
        <para>
          This element sets up a Spring LDAP <interfacename>ContextSource</interfacename> for use by the 
          other LDAP beans, defining the location of the LDAP server and other information (such as a username
          and password, if it doesn't allow anonymous access) for connecting to it. It can also be used to 
          create an embedded server for testing. 
          Details of the syntax for both options are covered in the <link xlink:href="#ldap-server">LDAP chapter</link>.
          The actual <interfacename>ContextSource</interfacename> implementation is 
          <classname>DefaultSpringSecurityContextSource</classname> which extends Spring LDAP's 
          <classname>LdapContextSource</classname> class. The <literal>manager-dn</literal> and <literal>manager-password</literal>
          attributes map to the latter's <literal>userDn</literal> and <literal>password</literal> properties respectively.
        </para>
        <para>
          If you only have one server defined in your application context, the other LDAP namespace-defined beans
          will use it automatically. Otherwise, you can give the element an "id" attribute and refer to it from other
          namespace beans using the <literal>server-ref</literal> attribute. This is actually the bean Id of the 
          <literal>ContextSource</literal> instance, if you want to use it in other traditional Spring beans.
        </para>
      </section>
      <section>
        <title>The <literal>&lt;ldap-provider&gt;</literal> Element</title>
        <para>
          This element is shorthand for the creation of an <classname>LdapAuthenticationProvider</classname> instance.
          By default this will be configured with a <classname>BindAuthenticator</classname> instance and a 
          <classname>DefaultAuthoritiesPopulator</classname>. 
        </para>
        <section>
          <title>The <literal>user-dn-pattern</literal> Attribute</title>
          <para>
            If your users are at a fixed location in the directory (i.e. you can work out the DN
            directly from the username without doing a directory search), you can use this attribute
            to map directly to the DN. It maps directly to the <literal>userDnPatterns</literal>
            property of <classname>AbstractLdapAuthenticator</classname>.
          </para>
        </section>

        <section>
          <title>The <literal>user-search-base</literal> and <literal>user-search-filter</literal> Attributes</title>
          <para>
            If you need to perform a search to locate the user in the directory, then you
            can set these attributes to control the search. The <classname>BindAuthenticator</classname> will be configured
            with a <classname>FilterBasedLdapUserSearch</classname> and the attribute values map directly to the first two
            arguments of that bean's constructor. If these attributes aren't set and no <literal>user-dn-pattern</literal>
            has been supplied as an alternative, then the default search values of <literal>user-search-filter="(uid={0})"</literal>
            and <literal>user-search-base=""</literal> will be used.
          </para>
        </section>
        <section>
          <title><literal>group-search-filter</literal>, <literal>group-search-base</literal>, <literal>group-role-attribute</literal> and <literal>role-prefix</literal> Attributes</title>
          <para>
            The value of <literal>group-search-base</literal> is mapped to the <literal>groupSearchBase</literal> constructor argument
            of <classname>DefaultAuthoritiesPopulator</classname> and defaults to "ou=groups". The default filter value is
            "(uniqueMember={0})", which assumes that the entry is of type "groupOfUniqueNames". <literal>group-role-attribute</literal>
            maps to the <literal>groupRoleAttribute</literal> attribute and defaults to "cn". Similarly <literal>role-prefix</literal>
            maps to <literal>rolePrefix</literal> and defaults to "ROLE_".
          </para>
        </section>
        <section>
          <title>The <literal>&lt;password-compare&gt;</literal> Element</title>
          <para>
            This is used as child element to <literal>&lt;ldap-provider&gt;</literal>  and switches
            the authentication strategy from <classname>BindAuthenticator</classname> to
            <classname>PasswordComparisonAuthenticator</classname>. This can optionally be supplied with a 
            <literal>hash</literal> attribute or with a child <literal>&lt;password-encoder&gt;</literal>
            element to hash the password before submitting it to the directory for comparison.
          </para>
        </section>
      </section>
      <section>
        <title>The <literal>&lt;ldap-user-service&gt;</literal> Element</title>
        <para>
          This element configures an LDAP <interfacename>UserDetailsService</interfacename>. The class used
          is <classname>LdapUserDetailsService</classname> which is a combination of a  <classname>FilterBasedLdapUserSearch</classname>
          and a <classname>DefaultAuthoritiesPopulator</classname>. The attributes it supports have the same usage as in
          <literal>&lt;ldap-provider&gt;</literal>.
        </para>
      </section>
    </section>
  </section>

</appendix>