1. Scaling Policy Concepts Metrics – Periodically gather usage information about a component e.g. queue length, response time, memory usage Alerts (Conditions) – Analyze numbers collected by one or more metrics to reach a boolean conclusion Triggers (Action) – Invoked by alerts to scale up/down or take some other action

2. Scaling Policy Concepts Application Components have one or more Metrics (we may need a management resource to house the metrics) Assembly has one or more Alerts (conditions) and one or more Triggers (actions) Each Alert uses values from one or more metrics Each Alert can initiate one or more triggers Triggers may act in several ways. They may scale a component up or down by POSTing to a scaling URL on the component. Or they may send an email or a SMS message, etc.

3. Scaling Policy Relationships Assembly Application Component Metric Alert (Condition) Contains 1 * Trigger (Action) Platform Component 1 1 1 1 * * Initiates Has * * Uses 1 * Has 1 1 ** Acts on - Send email - Send SMS - Scale by posting to URL

4. What Goes in the Spec? Provide hooks/skeletons for enable metrics, actions and triggers to be added No normative scaling resources Perhaps add examples of scaling resources