[javagroups-users] Using JGroups on EC2 autoscaling group

[<Mal...@co...>]

On an EC-2 autoscaled service environment all instances, potentially, come 
and go. There's no fixed abode for services such as message brokers or 
Gossip servers. 

I've been looking at JGroups for EclipseLink cache coordination in this 
environment. The RDS is the one fixed point so the JDBC_PING system seems 
ideal. The RDS will, in production. be HA, and none of our apps will work 
without it anyway. Of course there's no existing code in EclipseLink for 
using JGroups as it's transport, but I don't think it will be hard to 
write one. Of course I could use S3_PING, but there's an issue in testing 
this on our local system because of firewall/proxy settings.

I arrived at a configuration of JGroups 1.12.0 which works fine on a 
single machine, but when I run it on two instances on EC-2 the two 
instances seem oblivious to one another.

I'm not seeing any error messages which I'd expect to be generated by one 
instance trying to make contact with instances on the other machine if it 
were, say a firewall issue.

I'm testing this configuration using the Draw demo and running on Windows 
instances, because all the demos seem to be GUI and unix instances don't 
come with X-Windows.

I've tried this with both UDP and TCP, with and without DAISYCHAIN. With 
S3_PING and JDBC_PING. I've been going through the source code trying to 
understand the discovery behaviour. The database/S3 content is as I'd 
expect. 

Is there a lurking assumption that a central gossip server at a known 
location is required? If so it would be simpler for me to use a message 
broker. The possibility of a peer-to-peer discovery system is central to 
my interest in JGroups.

Or am I missing something obvious, like a security settings issue?

Here's my configuration (much of it copied from documentation).

<?xml version="1.0" encoding="UTF-8"?>

<config>
    <TCP id="101"
 
    bind_addr="SITE_LOCAL"
    bind_port="7200"
                       discard_incompatible_packets="true"
                       max_bundle_size="60000"
                       max_bundle_timeout="30"
                       enable_bundling="true"
                       thread_pool.enabled="true"
                       thread_pool.min_threads="1"
                       thread_pool.max_threads="25"
                       thread_pool.keep_alive_time="5000"
                       thread_pool.queue_enabled="false"
                       thread_pool.queue_max_size="100"
                       thread_pool.rejection_policy="Run"
                       oob_thread_pool.enabled="true"
                       oob_thread_pool.min_threads="1"
                       oob_thread_pool.max_threads="8"
                       oob_thread_pool.keep_alive_time="5000"
                       oob_thread_pool.queue_enabled="false"
                       oob_thread_pool.queue_max_size="100"
                       oob_thread_pool.rejection_policy="Run"/>


    <JDBC_PING
        id="102"
        connection_driver="com.mysql.jdbc.Driver"
    connection_username="sysaws" connection_password="sysaws"
 
connection_url="jdbc:mysql://ccaws.cfpw8y8ejgxf.us-west-1.rds.amazonaws.com:3306/aws"
    initialize_sql=""
    level="debug"
    />
    <TRACE name="98"/>

    <MERGE2 id="103" max_interval="30000"
                          min_interval="10000"/>
    <FD_SIMPLE id="104"/>
    <FD  id="105" timeout="10000" max_tries="5" />
    <VERIFY_SUSPECT timeout="1500"  />
    <BARRIER />
    <pbcast.NAKACK
                                 use_mcast_xmit="false" gc_lag="0"
 retransmit_timeout="300,600,1200,2400,4800"
                                 discard_delivered_msgs="true"/>
    <UNICAST timeout="300,600,1200,2400,3600"/>
    <pbcast.STABLE stability_delay="1000" desired_avg_gossip="50000"
                                 max_bytes="400000"/>
    <VIEW_SYNC avg_send_interval="60000"   />
    <pbcast.GMS print_local_addr="true" join_timeout="3000"
                 level="debug"             view_bundling="true"/>
    <FC max_credits="20000000"
                                  min_threshold="0.10"/>
    <FRAG2 frag_size="50000"  />
    <pbcast.STATE_TRANSFER  />
 
</config>





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