    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}