The code below is taken from 

ingoingFilter

 in 

HTTPQoS

Line 1 detects if the request has in input stream to measure. Line 3 creates an instance of 

PipedOutputStream named 

pout

. Line 4 creates an instance of 

PipedInputStream

, 

pin

 to 

which 

pout

 is passed as a parameter. This effectively means that whatever is fed to 

pout

 will 

automatically be passed to 

pin

.  

HTTPQoS.java 

1. if(request.hasOutputStream()){ 

2.    try { 

3.       PipedOutputStream pout = new PipedOutputStream(); 

4.       PipedInputStream  pin  = new PipedInputStream(pout); 

5.       new RequestDataMover(request.getOutputStream(),pout,myQOSParameters); 

6.       request.setOutputStream(pin); 

7.    } 

8.    catch (Exception ex) {} 

9.    } 

10. 

}

In line 5 a new instance of 

RequestDataMover 

in instantiated, the constructor of which is 

passed the current requests input stream, the instance of PipedOutputStream 

pout

 and an 

instance of 

QoSParameters

. Finally in line 6, the requests output stream is passed 

pin

. What 

this effectively allows is to monitor the request's output stream without interrupting it as it is 

passed to the target server. The implication of this are that the time data flows can be 

measured as can the amount of data transferred to the server. Additionally since the 

RequestDataMover

 is threaded it does not cause the filter to block. 

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