| // Copyright 2006 The Apache Software Foundation |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package org.apache.tapestry5.services; |
| |
| /** |
| * Allows for deferred execution of logic, useful when trying to get multiple components to coordinate behavior. A |
| * component may add a command to be executed "{@link #end() at the end of the heartbeat}". The classic example of this |
| * is a Label and the field it labels; since we don't know which order the two will render, we can't tell if the field's |
| * id is correct until after both have rendered. |
| * <p/> |
| * The Heartbeat is injected into components via the {@link org.apache.tapestry5.annotations.Environmental} annotation. |
| */ |
| public interface Heartbeat |
| { |
| /** |
| * Begins a new Heartbeat. Heartbeats nest. Every call to begin() should be matched by a call to {@link #end()}. |
| */ |
| void begin(); |
| |
| /** |
| * Executes all commands since the most recent {@link #begin()}. |
| */ |
| void end(); |
| |
| /** |
| * Adds a new command to the current Heartbeat. The command will be executed by {@link #end()}. |
| * |
| * @param command command to be executed at the end of the heartbeat |
| */ |
| void defer(Runnable command); |
| } |