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| |
| <document> |
| <properties> |
| <title>Apache Synapse - Sample 57</title> |
| </properties> |
| <body> |
| <section name="Sample 57: Dynamic Load Balancing Between 3 Nodes"> |
| <div class="xmlConf"><definitions xmlns="http://ws.apache.org/ns/synapse"> |
| |
| <sequence name="main" onError="errorHandler"> |
| <in> |
| <send> |
| <endpoint name="dynamicLB"> |
| <dynamicLoadbalance failover="true" |
| algorithm="org.apache.synapse.endpoints.algorithms.RoundRobin"> |
| <membershipHandler |
| class="org.apache.synapse.core.axis2.Axis2LoadBalanceMembershipHandler"> |
| <property name="applicationDomain" value="apache.axis2.app.domain"/> |
| </membershipHandler> |
| </dynamicLoadbalance> |
| </endpoint> |
| </send> |
| <drop/> |
| </in> |
| |
| <out> |
| <!-- Send the messages where they have been sent (i.e. implicit To EPR) --> |
| <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></div> |
| <subsection name="Objective"> |
| <p> |
| Demonstrate the ability of Synapse to perform dynamic load balancing. In |
| dynamic load balancing, nodes can be added and removed from the pool dynamically. |
| </p> |
| </subsection> |
| <subsection name="Pre-requisites"> |
| <p> |
| <ul> |
| <li> |
| Deploy the LoadbalanceFailoverService by switching to samples/axis2Server/src/LoadbalanceFailoverService |
| directory and running 'ant'. |
| </li> |
| <li> |
| Enable clustering for the sample Axis2 server. Edit the axis2.xml file at |
| samples/axis2Server/repository/conf directory and set the 'enable' attribute |
| on the 'clustering' element to 'true'. Specify the IP address of the |
| machine as the values of 'mcastBindAddress' and 'localMemberHost' |
| parameters. |
| </li> |
| <li> |
| Enable clustering for Synapse by editing repository/conf/axis2.xml file. |
| This should be done by setting the 'enable' attribute of the 'clustering' |
| element to 'true'. Also provide the IP address of your machine as the |
| values of the 'mcastBindAddress' and 'localMemberHost' parameters. In |
| addition also set the 'enable' attribute on 'groupManagement' element |
| to 'true'. |
| </li> |
| <li> |
| Start Synapse using the configuration numbered 57 (repository/conf/sample/synapse_sample_57.xml) |
| <div class="command"> |
| Unix/Linux: sh synapse.sh -sample 57<br/> |
| Windows: synapse.bat -sample 57 |
| </div> |
| </li> |
| <li> |
| Start 3 instances of the sample Axis2 server as follows. |
| <div class="command">./axis2server.sh -http 9001 -https 9005 -name MyServer1<br/> |
| ./axis2server.sh -http 9002 -https 9006 -name MyServer2<br/> |
| ./axis2server.sh -http 9003 -https 9007 -name MyServer3</div> |
| </li> |
| </ul> |
| </p> |
| </subsection> |
| <subsection name="Executing the Client"> |
| <p> |
| Note that the Synapse configuration does not define any concrete addresses or |
| URLs as targets. They are discovered dynamically by the dynamic load balance |
| endpoint. To test this feature start the load balance and failover client using |
| the following command: |
| </p> |
| <div class="command">ant loadbalancefailover -Di=100</div> |
| <p> |
| This client sends 100 requests to the LoadbalanceFailoverService through Synapse. |
| Synapse will distribute the load among the three nodes we have started |
| in 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: |
| </p> |
| <div class="consoleOutput">[java] Request: 1 ==> Response from server: MyServer1 |
| [java] Request: 2 ==> Response from server: MyServer2 |
| [java] Request: 3 ==> Response from server: MyServer3 |
| [java] Request: 4 ==> Response from server: MyServer1 |
| [java] Request: 5 ==> Response from server: MyServer2 |
| [java] Request: 6 ==> Response from server: MyServer3 |
| [java] Request: 7 ==> Response from server: MyServer1 |
| ...</div> |
| <p> |
| Now run the client without the -Di=100 parameter, to send infinite requests. While |
| running the client shutdown the server named MyServer1. You can observe that |
| requests are only distributed among MyServer2 and MyServer3 after shutting down |
| MyServer1. Console output before and after shutting down MyServer1 is listed below |
| (MyServer1 was shutdown after request 63): |
| </p> |
| <div class="consoleOutput">... |
| [java] Request: 61 ==> Response from server: MyServer1 |
| [java] Request: 62 ==> Response from server: MyServer2 |
| [java] Request: 63 ==> Response from server: MyServer3 |
| [java] Request: 64 ==> Response from server: MyServer2 |
| [java] Request: 65 ==> Response from server: MyServer3 |
| [java] Request: 66 ==> Response from server: MyServer2 |
| [java] Request: 67 ==> Response from server: MyServer3 |
| ...</div> |
| <p> |
| Now restart MyServer1. You can observe that requests will be again sent to all |
| three servers. If you start a new Axis2 instance (say MyServer4) that will also |
| be added to the load balance pool dynamically. |
| </p> |
| </subsection> |
| </section> |
| <p><a href="../samples.html">Back to Catalog</a></p> |
| </body> |
| </document> |
