001// Copyright 2007, 2010 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5;
016
017import org.apache.tapestry5.services.javascript.JavaScriptSupport;
018
019/**
020 * Interface for any kind of object (typically, a component) that can provide a {@linkplain #getClientId() client-side
021 * id}, typically used in the generation of client-side (JavaScript) logic. For components, the client id will be null
022 * or inaccurate until after the component has rendered itself. Inside of any kind of loop, the clientId property is
023 * only accurate just after the component has rendered, and before it renders again.
024 * <p/>
025 * Some components must be configured to provide a client id. In many cases, the client id matches the component's
026 * {@linkplain ComponentResourcesCommon#getId() component id}, typically passed through
027 * {@link JavaScriptSupport#allocateClientId(String)} to ensure uniqueness.
028 */
029public interface ClientElement
030{
031    /**
032     * Returns a unique id for the element. This value will be unique for any given rendering of a page. This value is
033     * intended for use as the id attribute of the client-side element, and will be used with any DHTML/Ajax related
034     * JavaScript.
035     */
036    String getClientId();
037}