# Controller

If your Visualforce page contains a canvas app, you can use methods in the Controller object to publish an event that the canvas app subscribes to. It contains these methods:

| Method        | Signature                                                  | Description                                                                                                                                                              |
| ------------- | ---------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `publish`     | `publish(String name, Object payload [, String[] target])` | Used to publish an event that the canvas app subscribes to. The `target` parameter is optional. It can contain a single canvas app name or an array of canvas app names. |
| `resize`      | `resize(String height, String width, String target)`       | Used by a Visualforce page to resize a canvas app iFrame.                                                                                                                |
| `subscribe`   | `subscribe(Subscriber event)`                              | Used by a Visualforce page to subscribe to events that the canvas app might publish.                                                                                     |
| `unsubscribe` | `unsubscribe(Unsubscriber event)`                          | Used by a Visualforce page to unsubscribe to parent events that the canvas app might publish.                                                                            |

**See Also**

- [Using Events between a Visualforce Page and a Canvas App](/docs/platform/canvas-framework/guide/canvas-vf-app-resizing.md)
- [SignedRequest](/docs/platform/canvas-framework/guide/signed-request-object.md)