2. Auto-Scaling and Cloud Bursting : 2.6 Autoscaling and Bursting a vApp
   
2.6 Autoscaling and Bursting a vApp
Several ways to control autoscaling and bursting of a vApp are described in this section. All require the upscale and downscale workflows to be triggered from a monitoring system:
*PullvCenter Orchestrator checks an external monitoring system to determine whether upscaling or downscaling is required.
*PushThe monitoring system can provide enough information to Orchestrator or to an application that then talks to Orchestrator. vCenter Orchestrator can use any of the following mechanisms to start a workflow:
*The SOAP web serviceto start the workflows directly.
*The REST web serviceto start the workflows directly.
*The AMQP plug-into trigger a workflow when consuming a message that has been published on an AMQP message bus.
*The SNMP plug-into trigger a workflow when receiving an SNMP trap.