VLBManager Clause Samples

VLBManager. VLBManager is used to monitor the logs of the load balancer and detects violations of the response time requirements. It reads the real time logs of the load balancer and calculates the average response time after every 60 seconds for each virtual machine in a Web farm. Whenever it detects that the average response time of any virtual machine is exceeding the required response time, it invokes the instantiateVirtualMachine method of VLBCoordinator with the required parameters and obtainer a new instance id. After obtaining the instance id, VLBManager waits for few seconds and tries to obtain instance id by using XML-RPC call to VLBCoordinator. After receiving the IP address of the newly instantiated virtual machine, it updates the configuration file of Ngnix and sends a signal to ▇▇▇▇▇ requesting it to reload the configuration file. Figure 3.5 shows a sequence diagram of the main use case, in which the system reads the Ngnix logs and analyzes them to obtain the average response time of each virtual machine. Figure 3.6 shows a sequence diagram of the use case in which the system detects that the average response time is greater than the maximum allowed response time and adds another virtual machine to the Web farm to distribute the load.