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Objective: Demonstrate the weighted load balancing among a set of endpoints

Code Block
languagehtml/xml
linenumberstrue
<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://ws.apache.org/ns/synapse">
    <sequence name="main" onError="errorHandler">
        <in>
            <send>
                <endpoint>
                    <loadbalance
                            algorithm="org.apache.synapse.endpoints.algorithms.WeightedRoundRobin">
                        <endpoint>
                            <address uri="http://localhost:9001/services/LBService1">
                                <enableAddressing/>
                                <suspendOnFailure>
                                    <initialDuration>20000</initialDuration>
                                    <progressionFactor>1.0</progressionFactor>
                                </suspendOnFailure>
                            </address>
                            <property name="loadbalance.weight" value="1"/>
                        </endpoint>
                        <endpoint>
                            <address uri="http://localhost:9002/services/LBService1">
                                <enableAddressing/>
                                <suspendOnFailure>
                                    <initialDuration>20000</initialDuration>
                                    <progressionFactor>1.0</progressionFactor>
                                </suspendOnFailure>
                            </address>
                            <property name="loadbalance.weight" value="2"/>
                        </endpoint>
                        <endpoint>
                            <address uri="http://localhost:9003/services/LBService1">
                                <enableAddressing/>
                                <suspendOnFailure>
                                    <initialDuration>20000</initialDuration>
                                    <progressionFactor>1.0</progressionFactor>
                                </suspendOnFailure>
                            </address>
                            <property name="loadbalance.weight" value="3"/>
                        </endpoint>
                    </loadbalance>
                </endpoint>
            </send>
            <drop/>
        </in>
        <out>
            <send/>
        </out>
    </sequence>
    <sequence name="errorHandler">
        <makefault response="true">
            <code xmlns:tns="http://www.w3.org/2003/05/soap-envelope" value="tns:Receiver"/>
            <reason value="COULDN'T SEND THE MESSAGE TO THE SERVER."/>
        </makefault>
        <send/>
    </sequence>
</definitions>

Prerequisites:

  • Start ESB with sample configuration 59: i.e. wso2esb-samples.sh -sn 59
  • Deploy the LoadbalanceFailoverService and start three instances of sample Axis2 server as mentioned in sample 52.

Above configuration sends messages with the weighted loadbalance behaviour. Weight of each leaf address endpoint is defined by integer value of "loadbalance.weight" property associated with each endpoint. If weight of a endpoint is x, x number of requests will send to that endpoint before switch to next active endpoint. 
To test this, run the loadbalancefailover client to send 100 requests as follows:

Code Block
languagebash
ant loadbalancefailover -Di=100

This client sends 100 requests to the LoadbalanceFailoverService through ESB. ESB will distribute the load among the three endpoints mentioned in the configuration in weighted round-robin manner. LoadbalanceFailoverService appends the name of the server to the response, so that client can determine which server has processed the message. If you examine the console output of the client, you can see that requests are processed by three servers as follows:

Code Block
[java] Request: 1 ==> Response from server: MyServer1
[java] Request: 2 ==> Response from server: MyServer2
[java] Request: 3 ==> Response from server: MyServer2
[java] Request: 4 ==> Response from server: MyServer3
[java] Request: 5 ==> Response from server: MyServer3
[java] Request: 6 ==> Response from server: MyServer3
[java] Request: 7 ==> Response from server: MyServer1
[java] Request: 8 ==> Response from server: MyServer2
[java] Request: 9 ==> Response from server: MyServer2
[java] Request: 10 ==> Response from server: MyServer3
[java] Request: 11 ==> Response from server: MyServer3
[java] Request: 12 ==> Response from server: MyServer3
...

As logs, endpoint with weight 1 received a 1 request and endpoint with weight 2 received 2 requests and etc... in a cycle

 

 

 

Excerpt
hiddentrue

Sample on Weighted load balancing between 3 endpoints