Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Developer's Guide

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# User Authentication for Single Sign-on

The single sign-on feature of the Application Server allows multiple web applications deployed to the same virtual server to share the user authentication state. With single sign-on enabled, users who log in to one web application become implicitly logged into other web applications on the same virtual server that require the same authentication information. Otherwise, users would have to log in separately to each web application whose protected resources they tried to access.

An example application using the single sign-on scenario could be a consolidated airline booking service that searches all airlines and provides links to different airline web sites. Once the user signs on to the consolidated booking service, the user information can be used by each individual airline site without requiring another sign-on.

Single sign-on operates according to the following rules:

- Single sign-on applies to web applications configured for the same realm and virtual server. The realm is defined by the `realm-name` element in the `web.xml` file. For information about virtual servers, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Guide.

- As long as users access only unprotected resources in any of the web applications on a virtual server, they are not challenged to authenticate themselves.

- As soon as a user accesses a protected resource in any web application associated with a virtual server, the user is challenged to authenticate himself or herself, using the login method defined for the web application currently being accessed.

- Once authenticated, the roles associated with this user are used for access control decisions across all associated web applications, without challenging the user to authenticate to each application individually.

- When the user logs out of one web application (for example, by invalidating the corresponding session), the user’s sessions in all web applications are invalidated. Any subsequent attempt to access a protected resource in any application requires the user to authenticate again.

The single sign-on feature utilizes HTTP cookies to transmit a token that associates each request with the saved user identity, so it can only be used in client environments that support cookies.

To configure single sign-on, set the following properties in the `virtual-server` element of the `domain.xml` file:

- `sso-enabled` - If `false`, single sign-on is disabled for this virtual server, and users must authenticate separately to every application on the virtual server. The default is `true`.

- `sso-max-inactive-seconds` - Specifies the time after which a user’s single sign-on record becomes eligible for purging if no client activity is received. Since single sign-on applies across several applications on the same virtual server, access to any of the applications keeps the single sign-on record active. The default value is 5 minutes (`300` seconds). Higher values provide longer single sign-on persistence for the users at the expense of more memory use on the server.

- `sso-reap-interval-seconds` - Specifies the interval between purges of expired single sign-on records. The default value is `60`.

Here is an example configuration with all default values:

    <virtual-server id="server" ... >
         ...
        <property name="sso-enabled" value="true"/>
         <property name="sso-max-inactive-seconds" value="450"/>
         <property name="sso-reap-interval-seconds" value="80"/>
     </virtual-server>

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