001// Copyright 2004, 2005 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.tapestry.engine;
016
017/**
018 * Define a link that may be generated as part of a page render. The vast majority of links are tied
019 * to {@link IEngineService services}and are, in fact, callbacks. A small number, such as those
020 * generated by {@link org.apache.tapestry.link.GenericLink} component, are to arbitrary locations.
021 * In addition, ILink differentiates between the path portion of the link, and any query parameters
022 * encoded into a link, primarily to benefit {@link org.apache.tapestry.form.Form}, which needs to
023 * encode the query parameters as hidden form fields.
024 * <p>
025 * In addition, an ILink is responsible for passing constructed URLs through
026 * {@link org.apache.tapestry.IRequestCycle#encodeURL(String)} as needed.
027 * 
028 * @author Howard Lewis Ship
029 * @since 3.0
030 */
031
032public interface ILink
033{
034    /**
035     * Returns the relative URL as a String. A relative URL may include a leading slash, but omits
036     * the scheme, host and port portions of a full URL.
037     * 
038     * @return the relative URL, with no anchor, but including query parameters.
039     */
040
041    public String getURL();
042
043    /**
044     * Returns the relative URL as a String. This is used for most links.
045     * 
046     * @param anchor
047     *            if not null, appended to the URL
048     * @param includeParameters
049     *            if true, parameters are included
050     */
051
052    public String getURL(String anchor, boolean includeParameters);
053
054    /**
055     * Returns the absolute URL as a String, using default scheme, server and port, including
056     * parameters, and no anchor.
057     */
058
059    public String getAbsoluteURL();
060
061    /**
062     * Returns the absolute URL as a String.
063     * 
064     * @param scheme
065     *            if not null, overrides the default scheme.
066     * @param server
067     *            if not null, overrides the default server
068     * @param port
069     *            if non-zero, overrides the default port
070     * @param anchor
071     *            if not null, appended to the URL
072     * @param includeParameters
073     *            if true, parameters are included
074     */
075
076    public String getAbsoluteURL(String scheme, String server, int port, String anchor,
077            boolean includeParameters);
078
079    /**
080     * Returns the URL as either a local or absoluate URL, depending on whether any of the
081     * parameters are both non-null and mismatched against the incoming request.
082     * 
083     * @param scheme
084     *            if not null, overrides the default scheme.
085     * @param server
086     *            if not null, overrides the default server
087     * @param port
088     *            if non-zero, overrides the default port
089     * @param anchor
090     *            if not null, appended to the URL
091     * @param includeParameters
092     *            if true, parameters are included
093     * @see #getURL(String, boolean)
094     * @see #getAbsoluteURL(String, String, int, String, boolean)
095     * @since 4.0
096     */
097
098    public String getURL(String scheme, String server, int port, String anchor,
099            boolean includeParameters);
100
101    /**
102     * Returns an array of parameters names (in no alphabetical order).
103     * 
104     * @see #getParameterValues(String)
105     */
106
107    public String[] getParameterNames();
108
109    /**
110     * Returns the values for the named parameter. Will return null if the no value is defined for
111     * the parameter.
112     */
113
114    public String[] getParameterValues(String name);
115}