Sun Java System Reference Configuration Series: Portal Service on Application Server Cluster

Availability in the Deployment Architecture

The deployment architecture that is represented in Figure 2–2 uses several strategies to meet the availability requirements of the reference configuration. Availability requirements fall into the two categories that are discussed in the following sections:

Service Availability

Service availability means that a service is available, even when a service provider fails. Service availability is generally achieved using multiple identically configured service instances (redundancy). Redundancy eliminates single points of failure (assuming that simultaneous failure of all instances is extremely unlikely). If one instance providing a service fails, another instance is available to take over. This mechanism is known as service failover.

Service failover is supported in the reference configuration through two mechanisms:

Session State Availability

Session state availability means that data associated with a user session is not lost during a service failover. When a service failover occurs, the session state data that is stored by the failed instance is made available to the failover instance. This mechanism is known as session failover. The result is that the service failover is transparent to the user: the user will not be required to log in again or to restart a business operation.

Session failover is supported in the reference configuration through two mechanisms:

Note –

When a user is successfully authenticated with Access Manager, the browser is redirected to a Portal Server instance. A portal desktop session is created on this instance and is mapped to the user's Access Manager session. This portal desktop session is used to track Portal Server specific information such as the user's merged display profile and provider properties. If a Portal Server instance fails, the desktop session is automatically re-created by using the user's display profile and attributes that are stored in the Access Manager's user session. However, provider properties that are stored in local memory are lost.