Registering Server Processes for HTTP Load Balancing

When you scale your cluster by adding a new Java instance, you expect that at a certain point the new cluster elements are registered with the system to start processing client requests. Concerning HTTP load balancing, there are two options when new server processes are registered for load balancing:

?     after they complete their Starting startup state and go to Starting applications state (the startup state of the Web AS elements is visible in the SAP Management Console).

?     after they complete the Starting applications state and go to Runningstate.

In the first case (the default behavior), the new server process is registered when all of its Enterprise Runtime managers and service components are successfully started. However, by that time not all applications are synchronized and started by the Deploy Service (this concerns only applications that must be automatically started at server process startup!). Therefore, there is possibility that a user can request an application that is not started yet and get a 503 Application stopped error response.

In the second case, the possibility of getting the 503 Application stopped error response is eliminated as the server process is registered for load balancing only after applications are successfully started. Therefore, we recommend that you use this behavior. It is controlled by the DelayedServerNodeRegistration property of the HTTP Provider service on the Java dispatcher. For more information, see HTTP Provider Service.