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| |
| <document> |
| <properties> |
| <title>Apache Synapse - Sample 52</title> |
| </properties> |
| <body> |
| <section name="Sample 52: Session-less Load Balancing Between 3 Endpoints"> |
| <div class="xmlConf"><definitions xmlns="http://ws.apache.org/ns/synapse"> |
| |
| <sequence name="main" onError="errorHandler"> |
| <in> |
| <send> |
| <endpoint> |
| <loadbalance> |
| <endpoint> |
| <address uri="http://localhost:9001/services/LBService1"> |
| <enableAddressing/> |
| <suspendDurationOnFailure>60</suspendDurationOnFailure> |
| </address> |
| </endpoint> |
| <endpoint> |
| <address uri="http://localhost:9002/services/LBService1"> |
| <enableAddressing/> |
| <suspendDurationOnFailure>60</suspendDurationOnFailure> |
| </address> |
| </endpoint> |
| <endpoint> |
| <address uri="http://localhost:9003/services/LBService1"> |
| <enableAddressing/> |
| <suspendDurationOnFailure>60</suspendDurationOnFailure> |
| </address> |
| </endpoint> |
| </loadbalance> |
| </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 act as a load balancer for a set of |
| servers hosting stateless services |
| </p> |
| </subsection> |
| <subsection name="Pre-requisites"> |
| <p> |
| <ul> |
| <li> |
| Deploy the LoadbalanceFailoverService in the sample Axis2 server (go to |
| samples/axis2Server/src/LoadbalanceFailoverService and run 'ant') |
| </li> |
| <li> |
| Start 3 instances of the Axis2 server on different ports 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> |
| <li> |
| Start Synapse using the configuration numbered 52 (repository/conf/sample/synapse_sample_52.xml) |
| <div class="command"> |
| Unix/Linux: sh synapse.sh -sample 52<br/> |
| Windows: synapse.bat -sample 52 |
| </div> |
| </li> |
| </ul> |
| </p> |
| </subsection> |
| <subsection name="Executing the Client"> |
| <p> |
| Invoke the sample client as follows |
| </p> |
| <div class="command">ant loadbalancefailover -Di=100</div> |
| <p> |
| This will send 100 requests to the LoadbalanceFailoverService through Synapse. |
| Synapse will distribute the load among the three endpoints mentioned in the |
| configuration 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 requests indefinitely. |
| While running the client shutdown the server named MyServer1. Then you can observe |
| that requests are only distributed among MyServer2 and MyServer3. 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 within 60 seconds. This is because we have specified |
| <suspendDurationOnFailure> as 60 seconds in the configuration. Therefore, |
| load balance endpoint will suspend any failed child endpoint only for 60 seconds |
| after detecting the failure. |
| </p> |
| </subsection> |
| </section> |
| <p><a href="../samples.html">Back to Catalog</a></p> |
| </body> |
| </document> |
