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 * Contains the information needed to encode a request for a service; the servlet path plus and
019 * query parameters. The service encoding is passed to each
020 * {@link org.apache.tapestry.engine.ServiceEncoder} , which is allowed to modify the encoding
021 * (typically, by changing the servlet path and settting query parameters to null). From this
022 * modified encoding, an {@link org.apache.tapestry.engine.ILink}can be constructed.
023 * <p>
024 * Additionally, when a request is dispatched by Tapestry, an SRE is also created and passed to each
025 * {@link org.apache.tapestry.engine.ServiceEncoder}&nbsp;for decoding. Here, the query parameters
026 * that may have been nulled out by the encoding are restored.
027 * 
028 * @author Howard M. Lewis Ship
029 * @since 4.0
030 * @see org.apache.tapestry.services.ServiceConstants
031 */
032public interface ServiceEncoding
033{
034
035    /**
036     * Returns the value for the named parameter. If multiple values are stored for the query
037     * parameter, only the first is returned.
038     * 
039     * @parameter name the name of the query parameter to access
040     * @return the value, or null if no such query parameter exists
041     */
042
043    public String getParameterValue(String name);
044
045    /**
046     * Returns the value for the named parameter.
047     * 
048     * @parameter name the name of the query parameter to access
049     * @return the values, or null if no such query parameter exists
050     */
051    public String[] getParameterValues(String name);
052
053    /**
054     * Updates the servlet path for the encoding. In some cases, this is a combination of the
055     * servlet and additional path info.
056     */
057
058    public void setServletPath(String servletPath);
059
060    /**
061     * Sets the value for the named query parameter to the provided string.
062     * 
063     * @param name
064     *            the name of the parameter to set.
065     * @param value
066     *            the new value, which may be null.
067     */
068    public void setParameterValue(String name, String value);
069
070    /**
071     * Sets the values for a named query parameter.
072     */
073
074    public void setParameterValues(String name, String[] values);
075
076    /**
077     * Returns the servlet path for the request. This is the portion of the URL recognized as the
078     * servlet. When the URL pattern (in web.xml) ends in a "*" (such as "/book/*"), this method
079     * will return the matched servlet portion ("/book/") and {#link #getPathInfo} will return the
080     * rest of the URL.
081     */
082
083    public String getServletPath();
084
085    /**
086     * Returns the portion of the URL after the servlet itself.
087     * 
088     * @return pathInfo if path info was supplied in the request, or null otherwise.
089     */
090    public String getPathInfo();
091
092    /**
093     * Returns an array of parameter names. The names are returned in alphabetically sorted order.
094     * This list includes all parameter names, even those for which the stored value is null.
095     */
096
097    public String[] getParameterNames();
098}