1. Concepts
  2. Developing Applications for Converged Application Server
  3. Developing "Zero Downtime" Upgradable Applications

Developing "Zero Downtime" Upgradable Applications

With Converged Application Server, you can upgrade a deployed SIP application to a newer version without losing existing calls being processed by the application. This type of application upgrade is accomplished by deploying the newer application version alongside the older version. Converged Application Server automatically manages the SIP Servlet mapping so that new requests are directed to the new version. Subsequent messages for older, established dialogs are directed to the older application version until the calls complete. After all of the older dialogs have completed and the earlier version of the application is no longer processing calls, you can safely un-deploy it.

Converged Application Server's upgrade feature ensures that no calls are dropped while during the upgrade of a production application. The upgrade process also enables you to revert or rollback the process of upgrading an application. If, for example, you determine that there is a problem with the newer version of the deployed application, you can simply un-deploy the newer version. Converged Application Server then automatically directs all new requests to the older application version.

Requirements and Restrictions for Upgrading Deployed Applications

To use the application upgrade functionality of Converged Application Server:

  • You must assign version information to your updated application in order to distinguish it from the older application version. Note that only the newer version of a deployed application requires version information; if the currently-deployed application contains no version designation, Converged Application Server automatically treats this application as the “older" version.

  • Both the deployed application and the updated application must provide only SIP protocol functionality. You cannot upgrade converged HTTP/SIP applications using these procedures.

  • A maximum of two different versions of the same application can be deployed at one time.

  • If your application hard-codes the use of an application name (for example, in composed applications where multiple SIP Servlets process a given call), you must replace the application name with calls to a helper method that obtains the base application name. Converged Application Server provides SipApplicationRuntimeMBean methods for obtaining the base application name and version identifier, as well as determining whether the current application version is active or retiring.

  • When applications take part in a composed application (using application composition techniques), Converged Application Server always uses the latest version of an application when only the base name is supplied.