The workflow involved in creating a tenant is illustrated in the diagram below:
The workflow involved in scaling up based on the in-flight request count is as follows:
- In the scale-up workflow based on the value of requests-in flight, Load Balancer (LB) sends the in-flight request count to Complex Event Processor (CEP) using the thrift protocol.
- The CEP will aggregate the in-flight request count continuously and will publish the summarized health statistics to the Message broker (MB).
- The Auto-scaler (AS), which will be subscribed to the Summarized Health Stats topic on MB will obtain the values and using the Drools engine, and it will check the auto-scaling and deployment policies for the functionality required based on the count and the threshold values defined.
- When it is required to scale up, AS will send the scale up and create instance information to the Cloud Controller (CC).
- The CC creates the additional new instances accordingly and sends the details about the created instances to the IaaS.