Failover

[Jiri Gabrys]

Hello,
would it be possible to notify interceptors about routing failure? I
would like to modify list of endpoints after failure to avoid crash of
whole infrastructure. Additional load from first failed server could
crash second server etc. ..
I would like to have one or more reserved servers which could take
incoming traffic if one of main servers die. Is there simple way of
doing this?

Thanks in advance,
Jiri Gabrys

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[Malkhaz Gaprindashvili]

Hello Jiri,
the components are loosely coupled at the moment. So the HTTP client can
not inform the interceptor because the HTTP client does not know there
is such an interceptor. But I like your idea to modify the list of
endpoints after a failure.
In case of failure you want to replace the URL of the crashed service
with the a URL of a standby endpoint.So the first step would be to
notify the interceptor. But I want to keep the loosely coupling. Perheps
we can build a notification service the interceptor could subscribe to.
This should be simple. The Loadbalancer is even simpler. Have a look at


https://predic8.com/svn/membrane/monitor/trunk/com.predic8.membrane.core/src/com/predic8/membrane/core/interceptor/balancer/LoadBalancingInterceptor.java

https://predic8.com/svn/membrane/monitor/trunk/com.predic8.membrane.core/src/com/predic8/membrane/core/interceptor/balancer/RoundRobinStrategy.java

It should be easy to write one that has a desired behaviour.

Malkhaz.

[Jiri Gabrys]

Hello Malkhaz,
thanks for a reply. I've already written my custom Interceptor
implementation and only thing I'm missing now is pubsub service for
notifications. Should I hold my breath and wait for next membrane
release? Or could you point me to class from which I should send
notification about failure? I can write some simple pubsub service on
my own then.

J.G.

[Thomas]

Hi Jiri,

we will need some time for the event service. If you want to you can
write the event service and send me a patch or the code. Maybe we can
integrate it into the code trunk.
I think the event service should be a simple implementation of the
observer pattern. You can place it in its own package.
You can send the events from the HTTPClient class. if you have any
questions don't hesitate to ask.

Thomas