User guide

name="ServerPeer">jboss.m essaging:service=ServerPeer</depends>

<depends>jboss.messaging:service=PostOffice</depends>

<attribute name="JNDINam e">Sam pleTopic</attribute>

</m bean>

</server>

EODS

## this will workaround the problem that in a VPC, instance hostname is not

resolvable

grep -q 10.0.1.15 /etc/hosts || \

for (( i=1 ; i<255 ; i++ )); do

echo -e "10.0.1.$i\tip-10-0-1-$i" ;

done >> /etc/hosts

EOF

Running JBoss Enterprise Application Platform cluster in a subnet with network mask smaller than 24

bits or spanning multiple subnets complicates acquiring a unique server peer ID for each cluster

member.

Please refer to the CLUSTER_ID variable in Appendix A, User Script Parameters for information on how to

make such a configuration work reliably.

The auto-scaling Amazon EC2 feature can be used with JBoss Enterprise Application Platform cluster

nodes. However make sure you test before deployment. You should ensure that your particular

workloads scale to the desired number of nodes and that the performance meets your needs with the

the instance type you are planning to use (different instance types receive a different share of the EC2

cloud resources).

Furthermore instance locality and current network/storage/host machine/RDS utilization can affect

performance of a cluster. T est with your expected real-life loads and try to account for unexpected

conditions.

Down-scaling a cluster

The Amazon EC2 scale-down action terminates the nodes without any chance to gracefully shut

down, and, as some transactions might be interrupted, other cluster nodes (and load balancers)

will need time to fail over. This is likely to impact your application users' experience.

It is recommended that you scale down your application cluster manually by disabling the server

from the mod_cluster management interface until processed sessions are completed or shutting

down the JBoss Enterprise Application Platform instance gracefully (SSH access to the instance

or JON can be used).

Test that your chosen procedure for scaling-down does not lead to adverse effects on your

users' experience. Additional measures might be required for particular workloads, load balancers

and setups.

6.6. Verifying everything is connected and running

1. Open http://<elastic IP of EWS> in browser.

2. Open http://<elastic IP of EWS>/jm ssender in browser.

Check that all cluster nodes are logging a message per every jmssender request (no matter

which node jmssender is opened from).

Chapter 6. Launching clustered JBoss Enterprise Application Platform instances