Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Administration Reference

web-container-availability

Enables availability in the web container, including HTTP session persistence to the high-availability database (HADB).

If availability is disabled, there is no high availability for HTTP session persistence. In other words, persistence-type=memory.

If availability is enabled but no other web-container-availability attributes are specified, the default session persistence configuration is as follows:

persistence-type=ha
persistence-frequency=time-based
persistence-scope=session

The default configuration for all applications can be changed by setting the various web-container-availability attributes and properties.

You can override the various web-container-availability attributes and properties for a specific application in sun-web.xml. For details, see the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Developer’s Guide.

Superelements

availability-service

Subelements

The following table describes subelements for the web-container-availability element.

Table 1–161 web-container-availability Subelements

Element 

Required 

Description 

property

zero or more 

Specifies a property or a variable. 

Attributes

The following table describes attributes for the web-container-availability element.

Table 1–162 web-container-availability Attributes

Attribute 

Default 

Description 

availability-enabled

true

(optional) If set to true, and if availability is enabled for the server instance (see availability-service), high-availability features apply to all web applications deployed to the server instance that do not have availability disabled. All instances in a cluster should have the same availability value to ensure consistent behavior.

persistence-type

memory

(optional) Specifies the session persistence mechanism for web applications that have availability enabled. Allowed values are memory (no persistence) file (the file system) and ha (the HADB). For production environments that require session persistence, use ha.

If set to memory, the manager-properties element’s sessionFilename property specifies the file system location where the HTTP session state is stored if the server instance is gracefully shut down. This is useful for internal testing but is not supported for production environments.

If set to file, the store-properties element’s directory property specifies the file system location where the HTTP session state is stored. Persisting to the file system is useful for internal testing but is not supported for production environments.

persistence-frequency

web-method

(optional) Specifies how often the session state is stored. Applicable only if the persistence-type is ha. Allowed values are as follows:

  • web-method - The session state is stored at the end of each web request prior to sending a response back to the client. This mode provides the best guarantee that the session state is fully updated in case of failure.

  • time-based - The session state is stored in the background at the frequency set by the reapIntervalSeconds property. This mode provides less of a guarantee that the session state is fully updated. However, it can provide a significant performance improvement because the state is not stored after each request.

persistence-scope

session

(optional) Specifies how much of the session state is stored. Applicable only if the persistence-type is ha. Allowed values are as follows:

  • session - The entire session state is stored every time. This mode provides the best guarantee that your session data is correctly stored for any distributable web application.

  • modified-session - The entire session state is stored if it has been modified. A session is considered to have been modified if HttpSession.setAttribute() or HttpSession.removeAttribute() was called. You must guarantee that setAttribute() is called every time an attribute is changed. This is not a J2EE specification requirement, but it is required for this mode to work properly.

  • modified-attribute - Only modified session attributes are stored. For this mode to work properly, you must follow some guidelines, which are explained immediately following this table.

sso-failover-enabled

false

(optional) If true, the single sign-on state is highly available. To enable single sign-on, use the sso-enabled property of the virtual-server element.

http-session-store-pool-name

availability-service store-pool-name attribute value

(optional) Specifies the jndi-name of the jdbc-resource used for connections to the HADB for session persistence.

For more information about setting up a connection pool and JDBC resource for the HADB, see the description of the configure-ha-cluster command in the Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Reference Manual.

If the persistence-scope attribute is set to modified-attribute , your web application must follow these guidelines: