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Clustering support plugin bundle for GlassFish Admin Console
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To Upgrade Components Without Loss of Service

In a clustered environment, a rolling upgrade redeploys an application with a minimal loss of service and sessions. A session is any artifact, that can be replicated, for example:


HttpSession


SingleSignOn


ServletTimer


DialogFragment


Stateful session bean


You can use the load balancer and multiple clusters to upgrade components in GlassFish Server without any loss of service. A component can be, for example, a JVM machine, the GlassFish Server software, or a web application.
A rolling upgrade can take place under light to moderate loads. The procedure requires about 10-15 minutes for each GlassFish Server instance.
Applications must be compatible across the upgrade. They must work correctly during the transition when some instances are running the old version and other instances are running the new version. The old version and the new version must have the same shape of serializable classes that form object graphs that are stored in sessions (for example, nontransient instance variables). If the shape of these classes must change, the application developer must ensure that correct serialization behavior occurs. If the application is not compatible across the upgrade, the cluster must be stopped for a full redeployment.
This approach is not possible if the application upgrade involves a change to the application database schema.


Caution:
To prevent the risk of version mismatch when a session fails over, upgrade all instances in a cluster at the same time. Otherwise a session might fail over to an instance where different versions of components are running.



Perform this task on each cluster separately. A cluster acts as a safe boundary for session failover for instances in the cluster. Sessions in one cluster can never fail over to sessions in another cluster. Therefore, the risk of version mismatch is avoided.


Stop the cluster.
See To Stop a Cluster.


Upgrade the component in that cluster.


Start the cluster.
See To Start a Cluster.



See Also


To Create a Cluster


To Delete a Cluster


To Configure Availability Settings for a Cluster


To Start a Cluster


To Stop a Cluster


To Modify the Configuration of a Cluster


To Deploy an Application to a Cluster


To List Applications That Are Deployed to a Cluster


To Undeploy Applications From a Cluster


To Remove Applications From a Cluster


To Edit an Application That Is Deployed to a Cluster


To Enable or Disable an Application That Is Deployed to a Cluster


To Enable or Disable Load Balancing for an Application That Is Deployed to a Cluster


To Create a Resource for a Cluster


To List Resources for a Cluster


To Enable or Disable a Resource Globally


To Edit a Resource for a Cluster





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