001 // Copyright 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
015 package org.apache.tapestry.web;
016
017 import java.io.IOException;
018 import java.io.OutputStream;
019 import java.io.PrintWriter;
020
021 import org.apache.tapestry.util.ContentType;
022
023 /**
024 * Controls the response to the client, and specifically allows for creating the output stream (or
025 * print writer) to which content is sent. This is essentially a generic version of
026 * {@link javax.servlet.http.HttpServletResponse}. Some operations may be unsupported in some
027 * implementations (for example, the portlet implementation can't handle any of the setHeader
028 * methods).
029 *
030 * @author Howard M. Lewis Ship
031 * @since 4.0
032 */
033 public interface WebResponse
034 {
035 /**
036 * Returns a output stream to which output should be sent. This method should only be invoked
037 * once on a response.
038 *
039 * @return the output stream, configured for the given type.
040 */
041
042 public OutputStream getOutputStream(ContentType contentType) throws IOException;
043
044 /**
045 * Returns a {@link PrintWriter} to which output should be sent. This method should be invoked
046 * once on a response. A second call is expected to be so that an exception page can be
047 * rendered, and the underlying request data is reset.
048 */
049
050 public PrintWriter getPrintWriter(ContentType contentType) throws IOException;
051
052 /**
053 * Encodes a URL, which adds information to the URL needed to ensure that the request triggered
054 * by the URL will be associated with the current session (if any). In most cases, the string is
055 * returned unchanged.
056 */
057
058 public String encodeURL(String url);
059
060 /**
061 * Resets any buffered content. This may be used after an error to radically change what the
062 * output will be.
063 */
064
065 public void reset();
066
067 public void setContentLength(int contentLength);
068
069 /**
070 * Returns a value to be prefixed or suffixed with any client-side JavaScript elements
071 * (variables and function names) to ensure that they are unique with the context of the entire
072 * page. For servlets, this is the empty string.
073 */
074
075 public String getNamespace();
076
077 /**
078 * Sets a response header as a date.
079 *
080 * @param name
081 * the name of the header to set
082 * @param date
083 * the date value to set, in milliseconds since the epoch
084 */
085 public void setDateHeader(String name, long date);
086
087 /**
088 * Sets a response header as a string.
089 *
090 * @param name
091 * the name of the header to set
092 * @param value
093 * the value for the named header
094 */
095
096 public void setHeader(String name, String value);
097
098 /**
099 * Sets a response header with the given name and integer value.
100 *
101 * @param name
102 * the name of the header to set
103 * @param value
104 * the value for the named header
105 */
106 public void setIntHeader(String name, int value);
107
108 /**
109 * Sets the status code for this response.
110 */
111 public void setStatus(int status);
112
113 /**
114 * Sends an error response.
115 */
116
117 public void sendError(int statusCode, String message) throws IOException;
118 }