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1. Re: JBoss Loadbalancer
Hello!
> what do you mean? Discovery of other nodes having the load-balancer is
> easy
> to do thanks to the clustering framework.
I meant discovery of webservers running on a cluster. This means that the
servlet-containers must export their deployed webapps. Failover between two
loadbalancers is another thing. I think it is nearly impossible in Java without
generating a single point of failure - and there was my henn and egg problem.
In EJB-clustering the client KNOWS the other servers. But a Web-client is
dumb....
>
> > > - virtual host support
> > > - failover
>
> you mean sticky sessions?
>
No. Failover means that if the client is sticky on node1 and node1 dies the
client must be redirected to node2. Virtual host support means that the LB
schedules requests to the servers depending on the "Host"-line in the
HTTP-header.
CU
Thomas
> > I meant discovery of webservers running on a cluster. This means that
> the
> > servlet-containers must export their deployed webapps. Failover
> > between two
> > loadbalancers is another thing. I think it is nearly impossible
>
>
> For this, use the ReplicantManager service. We have to do exactly the same
> for proxy generation for EJBs.
You mean for discovery of other LBs running?
>
> > in Java without
> > generating a single point of failure - and there was my henn and
> > egg problem.
> > In EJB-clustering the client KNOWS the other servers. But a Web-client
> is
> > dumb....
>
> Sure. The same with hardware loadbalancer if you have only one ;)
But HW-LBs with failover capability can modify their NIC-parameters (change
IP-address etc.) if they detect a problem on their buddy. This is impossible
with Java. You can achieve this through LB-software on Linux for example.
But a Java-only solution is impossible.
CU
Thomas
> we need to know which EJB is deployed on which node of the cluster to
> generate a proxy. You need to do the same: you need to know which
> application is running on which node and then your LB and take this list
> >from any node and define its routing table.
sure. I know which webapp is deployed where - BUT i do not know to which
virtual host the webapp is connected. For example we have 2 webapps deployed
each of them listening on different ports... This is servlet-container specific.
> sure, not Java-only solution. But the java-only solution is a cheap
> solution
> otherwise you buy a router. You may have two machines, with the exact same
> configuration, one in standby. When one dies, a script toggle the IP
> address
> so that the other java nodes can take over. Simply but efficient.
Do you read my mind? ;-)))
CU
Thomas
> I meant discovery of webservers running on a cluster. This means that the
> servlet-containers must export their deployed webapps. Failover
> between two
> loadbalancers is another thing. I think it is nearly impossible
For this, use the ReplicantManager service. We have to do exactly the same
for proxy generation for EJBs.
> in Java without
> generating a single point of failure - and there was my henn and
> egg problem.
> In EJB-clustering the client KNOWS the other servers. But a Web-client is
> dumb....
Sure. The same with hardware loadbalancer if you have only one ;)
> > For this, use the ReplicantManager service. We have to do
> exactly the same
> > for proxy generation for EJBs.
>
> You mean for discovery of other LBs running?
we need to know which EJB is deployed on which node of the cluster to
generate a proxy. You need to do the same: you need to know which
application is running on which node and then your LB and take this list
from any node and define its routing table.
> > > in Java without
> > > generating a single point of failure - and there was my henn and
> > > egg problem.
> > > In EJB-clustering the client KNOWS the other servers. But a Web-client
> > is
> > > dumb....
> >
> > Sure. The same with hardware loadbalancer if you have only one ;)
>
> But HW-LBs with failover capability can modify their
> NIC-parameters (change
> IP-address etc.) if they detect a problem on their buddy. This is
> impossible
> with Java. You can achieve this through LB-software on Linux for example.
> But a Java-only solution is impossible.
sure, not Java-only solution. But the java-only solution is a cheap solution
otherwise you buy a router. You may have two machines, with the exact same
configuration, one in standby. When one dies, a script toggle the IP address
so that the other java nodes can take over. Simply but efficient.
> sure. I know which webapp is deployed where - BUT i do not know to which
> virtual host the webapp is connected. For example we have 2
> webapps deployed
> each of them listening on different ports... This is
> servlet-container specific.
yes, but keep it simple at first: assume we have homogeneous deployments
i.e. all web apps are deployed under the same context and running on the
same port. -
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3. Re: JBoss Loadbalancer
I will hopefully commit the code at the end of the week. The code is NOT in CVS at the moment.
CU
Thomas -
4. Re: JBoss Loadbalancer
Hello!
A first version of the JBoss HTTP loadbalancer is in CVS now. Feel free to test...
CU
Thomas
