michael@0: package org.mozilla.gecko.util;
michael@0: 
michael@0: /**
michael@0:  * Callback interface for Gecko requests.
michael@0:  *
michael@0:  * For each instance of EventCallback, exactly one of sendResponse, sendError, or sendCancel
michael@0:  * must be called to prevent observer leaks. If more than one send* method is called, or if a
michael@0:  * single send method is called multiple times, an {@link IllegalStateException} will be thrown.
michael@0:  */
michael@0: public interface EventCallback {
michael@0:     /**
michael@0:      * Sends a success response with the given data.
michael@0:      *
michael@0:      * @param response The response data to send to Gecko. Can be any of the types accepted by
michael@0:      *                 JSONObject#put(String, Object).
michael@0:      */
michael@0:     public void sendSuccess(Object response);
michael@0: 
michael@0:     /**
michael@0:      * Sends an error response with the given data.
michael@0:      *
michael@0:      * @param response The response data to send to Gecko. Can be any of the types accepted by
michael@0:      *                 JSONObject#put(String, Object).
michael@0:      */
michael@0:     public void sendError(Object response);
michael@0: 
michael@0:     /**
michael@0:      * Cancels the request, preventing any Gecko-side callbacks from being executed.
michael@0:      */
michael@0:     public void sendCancel();
michael@0: }