VMware VCLOUD SDK FOR JAVA 1.0 - DEVELOPER S GUIDE Manuale Utente Scaricare il pdf (Pagina 43)

ReadyToBurst() function

The ReadyToBurst section of our orchestration process polls the BIG-IP

LTM controllers for data about current application response time, and for

connection counts. When the identified thresholds are met this method will

return TRUE to the caller, indicating that it's time to burst to the cloud.

Note

Two main thresholds used when monitoring the LTM in Private Cloud are:

Statistics Profile for reading response times,



Connection Threshold to make sure enough connections are made in the

private cloud to sample the response time data. '



RespPercentageThreshold to determine the percentage of slow response

times recorded out of total response times samples to determine overall

slowness of the system.

1. Initialize the BIG-IP Interface and get access to User statistics

Binding Stubs (LocalLBProfileUserStatisticBindingStub).

2. Get statistics for the User Defined Statistics ('responseHistogram').

3. Read the value for the user statistics mapping to all the counters

(that represents total number of requests with various response time

ranges such as <5ms, 5-7 ms, 7-12 ms, 12-15 ms, >15 ms).

4. Read the value of the counter representing the slowest response

times.

for(All the user stats entries) {

// Every User stats entry corresponds to the counter

// Get total number of requests by adding all the counter values.

totalRequests += userStat.getValue();

if(Stat Name corresponds to counter for >15 ms response) {

slowRequests = usrStats.getValue();

}

5. Check if Total number of requests are more than the 'Connection

Threshold'.

6. Check if the percentage of slowRequests counter out of total

requests in greater then the threshold ('RespPercentageThreshold')

definition.

7. If both the above conditions are satisfied then we are ready to burst.

if(totalRequests > 'Connection Threshold) &&

slowRequests > (totalRequests * 'RespPercentageThreshold' / 100) {

// We are ready to perform cloud bursting action (provisioning in public cloud)

return TRUE

}

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VMware VCLOUD SDK FOR JAVA 1.0 - DEVELOPER S GUIDE Manuale Utente Pagina 43