How to monitor the created tcp connections for a particular proxy service in WSO2 ESB

As an example if we want to monitor the number of tcp connections created during a proxy invocation, the following steps can be performed.

1. Assume you need to monitor the number of tcp connections created for the following proxy service :

 <?xml version="1.0" encoding="UTF-8"?>  
 <proxy xmlns="http://ws.apache.org/ns/synapse"  
     name="Proxy1"  
     transports="https,http"  
     statistics="disable"  
     trace="disable"  
     startOnLoad="true">  
   <target>  
    <inSequence>  
      <property name="NO_KEEPALIVE" value="true" scope="axis2"/>  
      <clone>  
       <target>  
         <sequence>  
          <send>  
            <endpoint>  
             <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>  
            </endpoint>  
          </send>  
         </sequence>  
       </target>  
        <target>  
         <sequence>  
          <send>  
            <endpoint>  
             <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>  
            </endpoint>  
          </send>  
         </sequence>  
       </target>  
       <target>  
         <sequence>  
          <send>  
            <endpoint>  
             <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>  
            </endpoint>  
          </send>  
         </sequence>  
       </target>  
      </clone>  
    </inSequence>  
    <outSequence>  
      <aggregate>  
       <completeCondition>  
         <messageCount/>  
       </completeCondition>  
       <onComplete xmlns:m0="http://services.samples" expression="//m0:getQuoteResponse">  
         <send/>  
       </onComplete>  
      </aggregate>  
    </outSequence>  
   </target>  
   <description/>  
 </proxy>  

You will see there are 5 clones. Therefore it should create only 5 tcp connections.

2. We have used SimpleStockQuoteService service as the backend.

3. Since you need to monitor the connections created, we should delay the response coming from the backend. Therefore we need to change the code slightly in the SimpleStockQuoteService.

We have include a Thread.sleep() for 10 seconds until we monitor the number of connections.

Therefore go to <ESB_HOME>/samples/axis2Server/src/SimpleStockQuoteService/src/samples/services/SimpleStockQuoteService.java

and add the Thread.sleep(10000); as below to hold the response for sometime.

 public GetQuoteResponse getQuote(GetQuote request) throws Exception {  
 Thread.sleep(10000);  
 if ("ERR".equals(request.getSymbol())) {  
 throw new Exception("Invalid stock symbol : ERR");  
 }  
 System.out.println(new Date() + " " + this.getClass().getName() +  
 " :: Generating quote for : " + request.getSymbol());  
 return new GetQuoteResponse(request.getSymbol());  
 }   

4. Build the SimpleStockQuoteService once again by “ant” in here, <ESB_HOME>/samples/axis2Server/src/SimpleStockQuoteService

5. Now start the axis2server

6. Now you have to open a terminal and provide the following netstat command to get the process id.

sudo netstat --tcp --listening --programs

You will see the relevant SimpleStockQuoteService which is up in port 9000 like below.

tcp6 0 0 [::]:9000 [::]:* LISTEN 20664/java

So your process ID will be 20664.

7. Then open a terminal and provide the below command to view the tcp connections for the particular process id.

watch -n1 -d "netstat -n -tap | grep 20664"

8. Now open your soapui and send the following request to Proxy1

 <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ser="http://services.samples" xmlns:xsd="http://services.samples/xsd">  
   <soapenv:Header/>  
   <soapenv:Body>  
    <ser:getQuote>  
      <!--Optional:-->  
      <ser:request>  
       <!--Optional:-->  
       <xsd:symbol>IBM</xsd:symbol>  
      </ser:request>  
    </ser:getQuote>  
   </soapenv:Body>  
 </soapenv:Envelope>  

9. View the tcp connections created in the terminal which you have been monitoring as soon as you send the request. You should be able to view only 3 connections since we have configured like that in proxy using clone mediator.

tcp6 0 0 127.0.0.1:9000 127.0.0.1:44218 ESTABLISHED 20664/java

tcp6 0 0 127.0.0.1:9000 127.0.0.1:44219 ESTABLISHED 20664/java

tcp6 0 0 127.0.0.1:9000 127.0.0.1:44217 ESTABLISHED 20664/java