Hi,
Please see my comments inline.
Thanks,
Kshitiz
glassfish_at_javadesktop.org wrote:
> HI kshitiz
>
> When an application fails to respond it is not necessary that it is undeployed. There may be other internal reasons as well.
> Undeploying application is always planned but what about plan failures when the application is deployed and is unable to respond doe to any sub tier failure or any other reason.
> Q1:
> How does lb/HA in Sun app Server take care of unplanned breakdowns at application level.
> Is there a way one can configure Sun Apps' lb to react on the basis of response code it recieves from application level or an instance.
> For ex if an instance send 404 Bad gateway then lb should ideally send that request to the second instance.
>
Let me put your requirement in my words - "In case one instance does not
respond in a configurable amount of time, request should be retried on
another available instance, and response should be send back to client".
There a feature available in load-balancer to achieve it and it is
called idempotent urls. Please refer to document available @
http://docs.sun.com/app/docs/doc/819-3679/abdij?l=en&q=idempotent&a=view
Please note this should be used only in case request does not cause any
change or inconsistency in the application.
Also retry mechanism is not based on response code from the first tried
instance, it is only based on timeout.
> Q2
> In the current even if the lb judges a bad instance because of stopped node agent/instance or undeployed application it does not resend the failed requests to the second instance, the always get 404 Bad-Gateway, Ideally these requests should be resent to instance/application by lb. I personally feel that SunApps lb is not competitive enough to manage even these simple scenarios. Would like to kno w your stand on it. If yes, is development underway to enhance its functionality ?
>
As I mentioned earlier, all instances in a cluster should be
homogeneous. If it failed on one instance, it will fail with same error
on other instance.
Hopefully above suggestion will help you.
> Q3 How can I upgrade my lb to support the features of 9.1 by adding patch/code to existing 8.2 version ?
>
The load-balancer plugin library are available as separate bundle. You
can download the latest bundle from
http://download.java.net/javaee5/external/<OS>/aslb/jars and try with
latest one. In high probability it will work with 8.2 as well.
> Many Thanks
> Anzy
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