I am trying to figure out how to achieve fail over using MDB and Joram as my
JMS.
I was wondering if someone could answer a few questions about how they all
work together. First let me explain my set-up, then ask my questions.
I have two machines solaris2 and solaris3.
On each machine I start: rmiregistry, joram, then jonas.
My joram a3servers.xml file looks like.
<?xml version="1.0"?>
<!DOCTYPE config SYSTEM "../xml/a3config.dtd">
<config>
<domain name="D1"/>
<server id="0" name="S0" hostname="solaris2">
<network domain="D1" port="11741"/>
<service class="fr.dyade.aaa.mom.ConnectionFactory" args="16020"/>
</server>
<server id="1" name="S1" hostname="solaris3">
<network domain="D1" port="11741"/>
<service class="fr.dyade.aaa.mom.ConnectionFactory" args="16020"/>
</server>
</config>
I start joram on solaris2 like: java -Dinstall.root=$JONAS_ROOT
-DTransaction=ATransaction
-Dfr.dyade.aaa.agent.A3CONF_DIR=$JONAS_ROOT/config "$@"
fr.dyade.aaa.agent.AgentServer 0 ./s0
on solaris3, like this: java -Dinstall.root=$JONAS_ROOT
-DTransaction=ATransaction
-Dfr.dyade.aaa.agent.A3CONF_DIR=$JONAS_ROOT/config "$@"
fr.dyade.aaa.agent.AgentServer 1 ./s1
Now I have tried just starting Jonas on each machine, letting each jonas
connect to its local joram and create its own topic. But the topic actually
seems to contain some routing information, i.e.
joram://solaris2:16020/#0.0.1027. So the MDB on each machine would each bind
to a different topic and I wouldn't see JMS messages broadcast to each MDB
as hoped.
So then I tried to start up everything on solaris2, then start the
rmiregistry and joram on solaris3. Now I run a program that gets the Remote
for the Topic from the rmigregistry on solaris2 and rebinds it to the
registry on solaris3. I do this because I need to use RMI and not jermie
and I want to cluster it so I don't have a single rmiregistry as a single
point of failure. Then I start up jonas on solaris3, which sees the topic
already in existence and thus binds its MDB to it.
Now when anyone publishes a message topic, it is broadcast to all MDB's. The
problem is that if any one part crashes, they all lose connection to the
JMS.
The next thing I tried was to create the topic in a separate program before
I start any Jonas servers. The program serializes the topic to a file. Then
I have another program rebind the unmarshalled object in the local
rmiregistry, and then make copies of its remote to the other registeries.
Now, I have been able to bring down a single machine, and restart them and
have them handle fail over.
There is still a problem. For example, if I create the original topic on
solaris2, then I have to be able to bring solaris2 up to its original state
to have everything recover. If solaris2 becomes inoperable, I will not be
able to recover without restarting the entire cluster.
So these are my questions:
When jonas creates a MDB, does it bind to connection to a Joram server
socket? If so, is there any way to get it to try to reconnect when it loses
a socket connection?
What does jonas/joram do with the URL in the Topic
(joram://solaris2:16020/#0.0.1027)? Does it use it like routing information?
The reason I ask is that if I create the topic on solaris2
(joram://solaris2:16020/#0.0.1027), and start up everything on solaris3 and
bind the local jonas to a local joram, using the topic created on solaris2,
and then take down joram on solaris2, but not the JVM that holds the topic
object, then JMS services on solaris3 go down too. I would have guessed that
since solaris3 jonas has a solaris3 joram and can still reach the original
topic, it would be fine--but I was wrong. If I bring up joram again on
solaris2, in a short period of time, then JMS on solaris3 starts working
again (but only if DTransaction=ATransaction ). It seems like all JMS for
that topic goes though the joram on solaris2. But if I take down the joram
on solaris3, JMS services on solaris3 go down. So it seems to need BOTH
jorams to be up to run--now I have 2 points of failure.
Is there any established methods (using RMI) for achieving fault tolerance
and fail over for joram?
What are the classes that Jonas uses for handling JMS connections? Is there
any thought or work being done for handling broken connections?
I have tried redeploying my MDB's and from all that I have been reading, and
my own experience, it appears that the Hot Deploy feature still doesn't
work. Is there a work around or any progress being made on this?
Thanks in advance for the time you have spent to read this long problem. If
there is any information I can offer to help, please contact me.
Thanks,
Lucas McGregor
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