<?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. The namespace is written in <link
        xlink:href="http://www.relaxng.org/">RELAX NG</link> Compact format and later converted into
        an XSD schema. If you are familiar with this format, you may wish to examine the <link
        xlink:href="https://fisheye.springsource.org/browse/spring-security/config/src/main/resources/org/springframework/security/config/spring-security-3.1.rnc"
        >schema file</link> directly.</para>
    <section xml:id="nsa-http">
        <title>Web Application Security - the <literal>&lt;http&gt;</literal> Element</title>
        <para> If you use an <literal>&lt;http&gt;</literal> element within your application, a
            <classname>FilterChainProxy</classname> bean named "springSecurityFilterChain" is
            created and the configuration within the element is used to build a filter chain within
            <classname>FilterChainProxy</classname>. As of Spring Security 3.1, additional
            <literal>http</literal> elements can be used to add extra filter chains <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 in a filter chain and others will be
            added to the stack depending on the attributes and 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> Each <literal>&lt;http&gt;</literal> namespace block always creates an
            <classname>SecurityContextPersistenceFilter</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-http-pattern">
                <title><literal>pattern</literal></title>
                <para>Defining a pattern for the <literal>http</literal> element controls the
                    requests which will be filtered through the list of filters which it defines.
                    The interpretation is dependent on the configured <link
                    xlink:href="#nsa-path-type">request-matcher</link>. If no pattern is defined,
                    all requests will be matched, so the most specific patterns should be declared
                    first. </para>
            </section>
            <section xml:id="nsa-http-secured">
                <title><literal>security</literal></title>
                <para>A request pattern can be mapped to an empty filter chain, by setting this
                    attribute to <literal>none</literal>. No security will be applied and none of
                    Spring Security's features will be available. </para>
            </section>
            <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-jaas-api-provision">
                <title><literal>jaas-api-provision</literal></title>
                <para>If available, runs the request as the <literal>Subject</literal> acquired from 
                    the <classname>JaasAuthenticationToken</classname> which is implemented by 
                    adding a <classname>JaasApiIntegrationFilter</classname> bean to the stack. 
                    Defaults to "false".</para>
            </section>
            <section xml:id="nsa-path-type">
                <title><literal>request-matcher</literal></title>
                <para> Defines the <interfacename>RequestMatcher</interfacename> strategy used in
                    the <classname>FilterChainProxy</classname> and the beans created by the
                    <literal>intercept-url</literal> to match incoming requests. Options are
                    currently <literal>ant</literal>, <literal>regex</literal> and
                    <literal>ciRegex</literal>, for ant, regular-expression and case-insensitive
                    regular-expression repsectively. A separate instance is created for each
                    <literal>intercept-url</literal> element using its <literal>pattern</literal>
                    and <literal>method</literal> attributes (see below). Ant paths are matched
                    using an <classname>AntPathRequestMatcher</classname> and regular expressions
                    are matched using a <classname>RegexRequestMatcher</classname>. See the Javadoc
                    for these classes for more details on exactly how the matching is preformed. Ant
                    paths are the default strategy.</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> property on
                    <classname>BasicAuthenticationEntryPoint</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-security-context-repo-ref">
                <title><literal>security-context-repository-ref</literal></title>
                <para> Allows injection of a custom
                    <interfacename>SecurityContextRepository</interfacename> into the
                    <classname>SecurityContextPersistenceFilter</classname>. </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> Deprecated in favour of the <literal>access-denied-handler</literal> child
                    element. </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="nsa-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 xml:id="nsa-use-expressions">
                <title><literal>use-expressions</literal></title>
                <para>Enables EL-expressions in the <literal>access</literal> attribute, as
                    described in the chapter on <link xlink:href="#el-access-web">expression-based
                    access-control</link>. </para>
            </section>
            <section xml:id="nsa-disable-url-rewriting">
                <title><literal>disable-url-rewriting</literal></title>
                <para>Prevents session IDs from being appended to URLs in the application. Clients
                    must use cookies if this attribute is set to <literal>true</literal>. </para>
            </section>
        </section>
        <section xml:id="nsa-access-denied-handler">
            <title><literal>&lt;access-denied-handler></literal></title>
            <para> This element allows you to set the <literal>errorPage</literal> property for the
                default <interfacename>AccessDeniedHandler</interfacename> used by the
                <classname>ExceptionTranslationFilter</classname>, (using the
                <literal>error-page</literal> attribute, or to supply your own implementation using
                the <literal>ref</literal> attribute. This is discussed in more detail in the
                section on <link xlink:href="#access-denied-handler">the
                <classname>ExceptionTranslationFilter</classname></link>.</para>
        </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>FilterInvocationSecurityMetadataSource</interfacename> used by
                the <classname>FilterSecurityInterceptor</classname>. It is also responsible for
                configuring a <classname>ChannelAuthenticationFilter</classname> if particular URLs
                need to be accessed by HTTPS, for example. When matching the specified patterns
                against an incoming request, the matching is done in the order in which the elements
                are declared. So the most specific matches patterns should come first and the most
                general should come last.</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>request-matcher</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. If an identical pattern
                    is specified with and without a method, the method-specific match will take
                    precedence.</para>
            </section>
            <section xml:id="nsa-access">
                <title><literal>access</literal></title>
                <para> Lists the access attributes which will be stored in the
                    <interfacename>FilterInvocationSecurityMetadataSource</interfacename> for the
                    defined URL pattern/method combination. This should be a comma-separated list of
                    the security configuration attributes (such as role names). </para>
            </section>
            <section xml:id="nsa-requires-channel">
                <title><literal>requires-channel</literal></title>
                <para> Can be <quote>http</quote> or <quote>https</quote> depending on whether a
                    particular URL pattern should be accessed over HTTP or HTTPS respectively.
                    Alternatively the value <quote>any</quote> 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>ChannelAuthenticationFilter</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>
                <title><literal>filters</literal></title>
                <para>Can only take the value <quote>none</quote>. This will cause any matching
                    request to bypass the Spring Security filter chain entirely. None of the rest of
                    the <literal>&lt;http></literal> configuration will have any effect on the
                    request and there will be no security context available for its duration. Access
                    to secured methods during the request will fail.</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>UsernamePasswordAuthenticationFilter</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>UsernamePasswordAuthenticationFilter</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>UsernamePasswordAuthenticationFilter</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>UsernamePasswordAuthenticationFilter</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>UsernamePasswordAuthenticationFilter</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>
                <title><literal>authentication-success-handler-ref</literal></title>
                <para>This can be used as an alternative to <literal>default-target-url</literal>
                    and <literal>always-use-default-target</literal>, giving you full control over
                    the navigation flow after a successful authentication. The value should be the
                    name of an <interfacename>AuthenticationSuccessHandler</interfacename> bean in
                    the application context. By default, an imlementation of
                    <classname>SavedRequestAwareAuthenticationSuccessHandler</classname> is used and
                    injected with the <literal>default-target-url</literal>.</para>
            </section>
            <section>
                <title><literal>authentication-failure-handler-ref</literal></title>
                <para>Can be used as an alternative to
                    <literal>authentication-failure-url</literal>, giving you full control over the
                    navigation flow after an authentication failure. The value should be he name of
                    an <interfacename>AuthenticationFailureHandler</interfacename> bean in the
                    application context. </para>
            </section>
        </section>
        <section xml:id="nsa-http-basic">
            <title>The <literal>&lt;http-basic&gt;</literal> Element</title>
            <para> Adds a <classname>BasicAuthenticationFilter</classname> and
                <classname>BasicAuthenticationEntryPoint</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>RememberMeAuthenticationFilter</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>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 <literal>id</literal> of a bean in the application
                    context which implements this interface. Should also implement 
                    <interfacename>LogoutHandler</interfacename> if a logout filter is in use.</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 <literal>id</literal> explicitly using this attribute. </para>
            </section>
            <section>
                <title><literal>authentication-success-handler-ref</literal></title>
                <para>Sets the <code>authenticationSuccessHandler</code> property on the
                    <classname>RememberMeAuthenticationFilter</classname> if custom navigation is required.
                    The value should be the name of a <interfacename>AuthenticationSuccessHandler</interfacename>
                    bean in the application context. </para>
            </section>
        </section>
        <section xml:id="nsa-session-mgmt">
            <title>The <literal>&lt;session-management&gt;</literal> Element</title>
            <para>Session-management related functionality is implemented by the addition of a
                <classname>SessionManagementFilter</classname> to the filter stack.</para>
            <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 session fixation protection is enabled, the
                    <classname>SessionManagementFilter</classname> is inected with a appropriately
                    configured <classname>DefaultSessionAuthenticationStrategy</classname>. See the
                    Javadoc for this class for more details. </para>
            </section>
        </section>
        <section xml:id="nsa-concurrent-session-control">
            <title>The <literal>&lt;concurrency-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, and a
                <classname>ConcurrentSessionControlStrategy</classname> will be used with the
                <classname>SessionManagementFilter</classname>. If a <literal>form-login</literal>
                element has been declared, the strategy object will also be injected into the
                created authentication filter. An instance of
                <interfacename>SessionRegistry</interfacename> (a
                <classname>SessionRegistryImpl</classname> instance unless the user wishes to use a
                custom bean) will be created for use by the strategy.</para>
            <section>
                <title>The <literal>max-sessions</literal> attribute</title>
                <para>Maps to the <literal>maximumSessions</literal> property of
                    <classname>ConcurrentSessionControlStrategy</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>error-if-maximum-exceeded</literal> attribute</title>
                <para>If set to "true" a
                    <exceptionname>SessionAuthenticationException</exceptionname> will 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>AnonymousAuthenticationFilter</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>X509AuthenticationFilter</classname> will be added to the stack and an
                <classname>Http403ForbiddenEntryPoint</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>OpenIDAuthenticationFilter</classname> and
                <classname>OpenIDAuthenticationProvider</classname> will be registered. The latter
                requires a reference to a <interfacename>UserDetailsService</interfacename>. Again,
                this can be specified by <literal>id</literal>, using the <literal>user-service-ref</literal>
                attribute, or will be located automatically in the application context. </para>
            <section>
                <title>The <literal>&lt;attribute-exchange></literal> Element</title>
                <para>The <literal>attribute-exchange</literal> element defines the list of
                    attributes which should be requested from the identity provider. More than one
                    can be used, in which case each must have an <literal>identifier-match</literal>
                    attribute, containing a regular expression which is matched against the supplied
                    OpenID identifer. This allows different attribute lists to be fetched from
                    different providers (Google, Yahoo etc).</para>
            </section>
        </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>success-handler-ref</literal> attribute</title>
                <para>May be used to supply an instance of <interfacename>LogoutSuccessHandler</interfacename>
                    which will be invoked to control the navigation after logging out.
                </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>
                <title>The <literal>delete-cookies</literal> attribute</title>
                <para>A comma-separated list of the names of cookies which should be deleted when the user logs out.
                </para>
            </section>
        </section>
        <section>
            <title>The <literal>&lt;custom-filter></literal> Element</title>
            <para>This element is used to add a filter to the filter chain. It doesn't create any
                additional beans but is used to select a bean of type
                <interfacename>javax.servlet.Filter</interfacename> which is already defined in the
                appllication context and add that at a particular position in the filter chain
                maintained by Spring Security. Full details can be found in the namespace
                chapter.</para>
        </section>
        <section xml:id="nsa-request-cache">
            <title>The <literal>&lt;request-cache></literal> Element</title>
            <para>Sets the <interfacename>RequestCache</interfacename> instance which will be used
                by the <classname>ExceptionTranslationFilter</classname> to store request
                information before invoking an
                <interfacename>AuthenticationEntryPoint</interfacename>. </para>
        </section>
        <section>
            <title>The <literal>&lt;http-firewall></literal> Element</title>
            <para>This is a top-level element which can be used to inject a custom implementation of
                <interfacename>HttpFirewall</interfacename> into the
                <classname>FilterChainProxy</classname> created by the namespace. The default
                implementation should be suitable for most applications.</para>
        </section>
    </section>
    <section xml:id="nsa-authentication">
        <title>Authentication Services</title>
        <para> Before Spring Security 3.0, an <interfacename>AuthenticationManager</interfacename>
            was automatically registered internally. Now you must register one explicitly using the
            <literal>&lt;authentication-manager&gt;</literal> element. This creates 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>authentication-provider</literal> element. </para>
        <section xml:id="nsa-authentication-manager">
            <title>The <literal>&lt;authentication-manager&gt;</literal> Element</title>
            <para> Every Spring Security application which uses the namespace must have include this
                element somewhere. It is responsible for registering the
                <interfacename>AuthenticationManager</interfacename> which provides authentication
                services to the application. It also allows you to define an alias name for the
                internal instance for use in your own configuration. Its use is described in the
                <link xlink:href="#ns-auth-manager">namespace introduction</link>. All elements
                which create <interfacename>AuthenticationProvider</interfacename> instances should
                be children of this element.</para>
            <para> The element also exposes an <literal>erase-credentials</literal> attribute which
                maps to the <literal>eraseCredentialsAfterAuthentication</literal> property of the
                <classname>ProviderManager</classname>. This is discussed in the <link
                xlink:href="#core-services-erasing-credentials">Core Services</link> chapter.</para>
            <section xml:id="nsa-authentication-provider">
                <title>The <literal>&lt;authentication-provider&gt;</literal> Element</title>
                <para> Unless used with a <literal>ref</literal> attribute, this element is
                    shorthand for configuring a <link xlink:href="#core-services-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>
                    <title>The <literal>&lt;password-encoder&gt;</literal> Element</title>
                    <para>Authentication providers can optionally be configured to use a password
                        encoder as described in the <link xlink:href="#ns-password-encoder"
                        >namespace introduction</link>. This will result in the bean being injected
                        with the appropriate <interfacename>PasswordEncoder</interfacename>
                        instance, potentially with an accompanying
                        <interfacename>SaltSource</interfacename> bean to provide salt values for
                        hashing. </para>
                </section>
            </section>
            <section>
                <title>Using <literal>&lt;authentication-provider&gt;</literal> to refer to an
                    <interfacename>AuthenticationProvider</interfacename> Bean</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 language="xml"><![CDATA[
  <security:authentication-manager>
    <security:authentication-provider ref="myAuthenticationProvider" />
  </security:authentication-manager>
  <bean id="myAuthenticationProvider" class="com.something.MyAuthenticationProvider"/>
  ]]></programlisting></para>
            </section>
        </section>
    </section>
    <section xml:id="nsa-method-security">
        <title>Method Security</title>
        <section xml:id="nsa-gms">
            <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>secured-annotations</literal> and
                    <literal>jsr250-annotations</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 xml:id="nsa-custom-metadata-source">
                <title>The <literal>&lt;metadata-source-ref&gt;</literal> Attribute</title>
                <para> An external <interfacename>MethodSecurityMetadataSource</interfacename>
                    instance can be supplied which will take priority over other sources
                    (such as the default annotations).
                </para>
            </section>
            <section xml:id="nsa-gms-mode">
                <title>The <literal>mode</literal> Attribute</title>
                <para>This attribute can be set to <quote>aspectj</quote> to specify that AspectJ
                    should be used instead of the default Spring AOP. Secured methods must be woven
                    with the <classname>AnnotationSecurityAspect</classname> from the
                    <literal>spring-security-aspects</literal> module. </para>
            </section>
            <section xml:id="nsa-protect-pointcut">
                <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;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. You can define zero or more of these within the
                    <literal>global-method-security</literal> element, each with a
                    <literal>ref</literal> attribute pointing to an
                    <interfacename>AfterInvocationProvider</interfacename> bean instance within your
                    application context. </para>
            </section>
        </section>
        <section xml:id="nsa-ldap">
            <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 <literal>id</literal> of the
                    <literal>ContextSource</literal> instance, if you want to use it in other
                    traditional Spring beans. </para>
            </section>
            <section xml:id="nsa-ldap-authentication-provider">
                <title>The <literal>&lt;ldap-authentication-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>. As with all namespace
                    authentication providers, it must be included as a child of the
                    <literal>authentication-provider</literal> element.</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>
