Setting up MB instances in different machines
- Download the latest version of MB and extract it into a folder.
- Make an exact copy of that folder in three separate machines. Let's assume MB1 is in the machine with IP1, MB2 in the machine with IP2 and MB3 in the machine with IP3.
- Start all the above instances by running one of the following commands:
Setting up a WSO2 ESB instance
Start ESB in the default port (port offset 0). This is possible if you used the single machine setup above, as those servers were started with different port offsets. If you are using different machines, use another machine to start WSO2 ESB. Instructions can be found in Configure with WSO2 Message Broker.
It is not possible to start multiple WSO2 products with their default configurations simultaneously in the same environment. Since all WSO2 products use the same port in their default configuration, there will be port conflicts.
There is only a single difference to enable failover across the three brokers we have setup. That is when specifying the following:
connectionfactory.ConnectionFactory connectionfactory.QueueConnectionFactory connectionfactory.TopicConnectionFactory
For example, if you hope to use a single machine MB setup as described above,
connectionfactory.QueueConnectionFactory = amqp://admin:[email protected]/carbon?failover='roundrobin'&cyclecount='2'&brokerlist='tcp://localhost:5673? retries='5'&connectdelay='30000';tcp://localhost:5674?retries='5'&connectdelay='30000';tcp://localhost:5675?retries='5'&connectdelay='30000''
If you hope to use the broker setup made across several machines as described above,
connectionfactory.QueueConnectionFactory = amqp://admin:[email protected]/carbon?failover='roundrobin'&cyclecount='2'&brokerlist='tcp://IP1:5672? retries='5'&connectdelay='30000';tcp://IP2:5672?retries='5'&connectdelay='30000';tcp://IP3:5672?retries='5'&connectdelay='30000''
The parameters used above are described in detail below:
brokerlist='<broker url>[;<broker url>]'
The broker list defines the various brokers that can be used for this connection. A minimum of one broker URL is required. Additional URLs are semi-colon(';') delimited.
Broker URL format
Option Default Description retries 1 The number of times to retry connection to this Broker ssl false Use ssl on the connection connecttimeout 30000 How long in (milliseconds) to wait for the connection to succeed connectdelay 30000none How long in (milliseconds) to wait before attempting to reconnect
Brokerlist failover option
Method Description singlebroker This will only use the first broker in the list. roundrobin This method tries each broker in turn. nofailover [New in 0.5] This method disables all retry and failover logic.
The current default is to use the singlebroker method when only one broker is present, and the roundrobin method with multiple brokers. The method value in the URL may also be any valid class on the classpath that implements the FailoverMethod interface.
Option Default Description cyclecount 1 The number of times to loop through the list of available brokers before failure.
Testing the setup
When sending messages to a queue (you can configure SOAP UI to send messages continuously one after the other) using the setup described above, kill MB1. You will notice that failover happens at ESB to the second broker i.e MB2. The logs at the ESB side will indicate that failover occurred.
If there were any previous messages at MB1, they will not be delivered.