The workflow involved in scaling up Apache Stratos based on load average is illustrated in the diagram below:
The workflow involved in scaling up WSO2 Private PaaS based on load average is as follows:
- In the scale-up workflow based on the value of load average, the cartridge instance sends the load average count to Complex Event Processor (CEP) using the thrift protocol.
- CEP will aggregate the load average statistics 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.
Scale-up workflow based on the memory consumption values, will be the same as the above scale-up workflow based on the value of load average.