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  • December 16, 2015

Even Applications can be Updated with ZDT Patching

Zero Downtime Patching enables a convenient method of updating production applications on WebLogic Server without incurring any application downtime or loss of session data for your end-users.  This new feature may be especially useful for users who want to update multiple applications at the same time, or for those who cannot take advantage of the Production Redeployment feature due to various limitations or restrictions. Now there is a convenient alternative to complex application patching methods.

This rollout is based on the process and mechanism for automating rollouts across a domain while allowing applications to continue to service requests. In addition to the reliable automation, the Zero Downtime Patching feature also combines Oracle Traffic Director (OTD) load balancer and WebLogic Server to provide some advanced techniques for preserving active sessions and even handling incompatible session state during the patching process.

To rollout an application update, follow these 3 simple steps.

1. Produce a copy of the updated the application(s), test and verify. Note the administrator is responsible for making sure that the updated application sources are distributed to the appropriate nodes.  For stage mode, the updated application source needs to be available on the file system for the AdminServer to distribute the application source.  For no stage and external stage mode, the updated application source needs to be available on the file system for each node.

2. Create a JSON formatted file with the details of any applications that need to be updated during the rollout.


{"applications":[
{
"applicationName":"ScrabbleStage",
"patchedLocation":"/scratch/wlsconfg/Domains/Domain1221/applications/ScrabbleStagev2.war",
"backupLocation": "/scratch/wlsconfg/Domains/Domain1221/applications/ScrabbleStagev1.war"
},
{
"applicationName":"ScrabbleNoStage",
"patchedLocation":"/scratch/wlsconfg/Domains/Domain1221/applications/ScrabbleNoStagev2.war",
"backupLocation":"/scratch/wlsconfg/Domains/Domain1221/applications/ScrabbleNoStagev1.war"
},
{
"applicationName":"ScrabbleExternalStage",
"patchedLocation":"/scratch/wlsconfg/Domains/Domain1221/applications/ScrabbleExternalStagev2.war",
"backupLocation":"/scratch/wlsconfg/Domains/Domain1221/applications/ScrabbleExternalStagev1.war"
}
]}

3. Simply run the Application rollout using a WLST command like this one:

rolloutApplications(“Cluster1”, “/pathTo/applicationRolloutProperties”)

The Admin Server will start the rollout that coordinates the rolling restart of each node in the cluster named “Cluster1”. While the servers are shutdown, the original application source is moved to the specified backup location, and the new application source is copied into place.  Each server in turn is then started in admin mode.  While the server is in admin mode, the application redeploy command is called for that specific server, causing it to reload the new source.  Then the server is resumed to its original running state and is serving the updated application.

For more information about updating Applications with Zero Downtime Patching view the documentation.

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