IScalable (Heron Spi Documentation)

```
@LimitedPrivate
@Unstable
public interface IScalable
```
Schedulers that implement IScalable support scaling topologies up or down by adding or removing containers.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Set<PackingPlan.ContainerPlan>`	`addContainers(Set<PackingPlan.ContainerPlan> containersToAdd)`	Requests new containers for scaling a topology
`void`	`removeContainers(Set<PackingPlan.ContainerPlan> containersToRemove)`	Requests containers to be released for down-scaling a topology.

- Method Detail
  - addContainers
```
Set<PackingPlan.ContainerPlan> addContainers(Set<PackingPlan.ContainerPlan> containersToAdd)
```
    Requests new containers for scaling a topology
    
    Parameters:
    
    containersToAdd - Set of containers to be added by the scheduler
    
    Returns:
    
    Set of added containers with real ids and resources from the scheduler
  - removeContainers
```
void removeContainers(Set<PackingPlan.ContainerPlan> containersToRemove)
```
    Requests containers to be released for down-scaling a topology.
    
    Parameters:
    
    containersToRemove - Set of containers to be removed by the scheduler