user manual

Chapter 7: Clustering web components 73

Setting up your web container with JSS

Modifying a Borland web container for failover

In the Borland web container configuration file, server.xml, you need to add an

entry similar to the following code sample for each web application. For more

information about the server.xml file, go to Chapter 5, “Web server to web

container connectivity”.

<Store className="org.apache.catalina.session.BorlandStore"

storeName="jss_factory"/>

</Manager>

The preceding code specifies the use of a PersistentManager with a storage

class BorlandStore. It also specifies the connection to a BorlandStore factory

named jss_factory. There must be a JSS with that factory name running in the

local network.

For a description of jss.factoryName, go to Chapter 6, “Java Session Service

(JSS) configuration”.

Session storage implementation

There are two methods of implementing session storage for your clustered

web components:

■

“Programmatic implementation” on page 73

■

“Automatic implementation” on page 73

Programmatic implementation

The Programmatic implementation assumes that each time you change the

session attributes, you call session.SetAttribute() to notify the Borland web

container that you have changed the session attributes.

This is a common operation in servlet development and when executed, there

is no need to modify the server.xml file. Each time you change the session

data, it is immediately written to the database through the JSS. Then if your

web container instance unexpectedly goes down, the next web container

instance designated to pick up the session accesses the session data. In

essence, the Programmatic implementation guarantees to save changes

immediately.

Automatic implementation

The Automatic implementation lets you store the session data periodically to

JSS, regardless of whether the data has changed. By using this

implementation, you do not need to notify the web container that the session

attribute has changed.

For example, you can change state without calling setAttribute () as depicted

in the following code example: