    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
    015    package org.apache.tapestry5;
    016
    017    import 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     */
    029    public 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    }