Performing a rollout on an edition

When you perform a rollout on an edition, you replace an active edition with a new edition. The new edition might be a simple modification to the application, or contain a more substantial change. If the new edition is compatible with earlier versions, then you can perform a rollout to replace the active edition without impacting existing clients. To perform a rollout on a new edition, you must first install the application edition with the new edition information.

1. Install the new edition.
   Use the same steps that are described in installing an application edition, but specify your new edition information. For example, type 2.0 in the Application edition field and Second edition in the Application description field. Select the same deployment targets that are used for the current edition.
2. Save and synchronize your nodes.
3. Specify the rollout settings.
   Click Applications > Edition control center > application_name. Select your new edition, for example, 2.0, and click Roll out.

   Specify the following settings for enterprise or other middleware applications:

   1. Select Atomic or Grouped rollout type.

      Use group rollout to replace editions on members of the target cluster in a group of one. Group rollout is the most typical choice, and is useful when the cluster contains four or more members. Alternatively, you can perform group rollout with a specified group size through scripting. For more information about group rollout, read about application edition management administrative tasks. When the new edition becomes available during group rollout, all requests are directed to the new edition.

      Use atomic rollout to replace one edition with another on half of the cluster at a time. This rollout type serves all user requests with a consistent edition of the application. Because all user requests are served a consistent edition, your cluster runs at half capacity as the first half of the cluster is updated. As the second half of the cluster is updated, all requests are queued or delayed until the update is complete. If your cluster has four or more members, consider dividing up the cluster into smaller groups and perform a group rollout. Atomic mode is also used with a single-server deployment target. In a single-server deployment target, the actions that are carried out against the second half of the cluster are omitted and requests are queued or delayed while the server is updated. If you stop your deployment targets before you start atomic rollout, the deployment targets are started when the new edition replaces the active edition regardless of the reset strategy you choose. This procedure provides better availability to the requests that are serviced during the rollout period.

      Avoid trouble: Before you begin an atomic rollout, determine the load capability of the target server cluster. An atomic rollout activates the new edition on half of the cluster first, but requests are not routed to this half until the full update is complete. While the first half of the cluster is taken offline and updated, application requests are routed to the second half of the cluster, which is running the old edition. The first half of the cluster remains offline while the second half is taken offline and updated. During this step, the entire cluster is offline and requests that arrive are queued or delayed until the rollout is complete. Conduct application rollouts during periods of low demand for the application to reduce the impact to requests during rollout.
   2. Select the reset strategy.
      The reset strategy instructs the application edition manager how each deployment target loads the new edition into the server runtime.

      Use a soft reset strategy to reset the application by stopping or restarting the application in each server of the cluster as the next edition replaces the old edition in that server. Soft reset is the most typical choice and the most optimal performing application reset because it results in loading the new edition by recycling the application in the running application server. The server stays up during this process. With soft reset, native libraries are not unloaded from memory. Soft reset is generally safe for applications that use no native libraries. When soft reset is used in a production environment, monitor the application server process to ensure that sufficient virtual memory exits.

      A hard reset strategy recycles the entire application server of the cluster as the next edition replaces the former edition in the server, refreshing both process memory and any native libraries used by the application. This strategy prevents virtual storage exhaustion and allows new versions of native libraries to be loaded. Select hard reset as your reset strategy when you perform a rollout on an edition that depends on new versions of native libraries or other dependencies that are refreshed only by recycling the entire application server, or if you have large applications that consume a lot of memory for just-in-time compilation (JIT).

   3. Set the drainage interval in seconds.
      The drainage interval gives the HTTP sessions time to complete before the application or server is reset. The drainage interval specifies the amount of time that the application edition manager waits before the reset strategy starts.

      Affinities, such as transaction, activity, and compensation-scope, and activities unknown to Intelligent Management, lengthen the effective drainage interval because the server does not stop until these units of work complete. Applications with activities unknown to Intelligent Management can use the AppEditionManager MBean quiesce initiated notification as a trigger to begin shutdown processing and use the drainage interval as a time period during which to complete the shutdown. This process is unnecessary for persistent sessions, for example, those backed in database or replicated through VMware Distributed Resource Scheduler (DRS), but is important for transient (in memory) sessions.

      The goal of the drainage interval is to allow requests with affinities and inflight requests to complete. To prevent the loss of transient sessions, set the drainage interval to exceed the application session timeout interval. After the rollout starts, as each server updates, the server is marked as ineligible to begin any new sessions. Set this value to 0 to wait for sessions to complete for all inflight requests. To wait until the drainage interval or sessions complete for all inflight requests, set the drainage interval to a value greater than 0.

      The application edition quiesce manager might not wait the full length of the drainage interval. Performance Monitoring Infrastructure (PMI) statistics are available for the quiesce manager to determine if all active requests on a server have been quiesced. If all requests are quiesced before the drainage interval, the application edition quiesce manager does not need to wait for the full drainage interval. To force a soft reset to wait the entire drainage interval, you can set the appedition.rollout.softreset.fulldrainageinterval system property to true on the deployment manager.

      The drainage interval allows existing sessions to complete. However, at the end of the drainage interval, a period exists during which inflight requests can still arrive. In such cases, the on-demand router (ODR) provides a timeout value of 60 seconds within which to complete the quiesce operation. If the requests end within 60 seconds or the 60 seconds expire, the application, or the server in the case of a hard reset strategy, is stopped. Next, if inflight requests have still not ended, WebSphere® Application Server Network Deployment provides a quiesce time of 60 seconds before stopping the application or the server instance. For hard reset strategies, WebSphere Application Server Network Deployment provides a quiesce time of 180 seconds before stopping the server instance. You can use the com.ibm.ws.webcontainer.ServletDestroyWaitTime custom property to define the amount of time that the Web container waits for the requests to complete. For more information, read about web container custom properties.

      You can use the com.ibm.ejs.sm.server.quiesceTimeout custom property to define the amount of the time that the server instance waits for the requests to complete before initiating shutdown. For more information about the timeout property, read about Java virtual machine custom properties. You must set both the com.ibm.ws.webcontainer.ServletDestroyWaitTime custom property and the com.ibm.ejs.sm.server.quiesceTimeout custom property on each of the server instances on which the application editions are deployed.

   Specify the following settings for Session Initiation Protocol (SIP) applications:
   1. Choose a quiesce strategy.
      The quiesce strategy specifies how old servers or cluster members that host the current edition are removed. This setting does not affect the new edition that is being rolled out.

      Quiesce server or cluster members after all active sessions or dialogs are completed:

      Removes the server or cluster member when all of the active sessions and dialogs for the server or cluster member complete.

      Quiesce servers or cluster member after the specified interval:

      Removes the server or cluster member after a specified time period. Specify an amount of time, in seconds, minutes, or hours.

      Attention: Performing a rollout is not supported for SIP applications that are deployed on a dynamic cluster that has been converted from a static cluster.
4. Start the rollout.
   Click OK. This action launches an interruption-free replacement of the previous edition with your new edition.