1 /**
2 * Copyright (c) 2011, University of Konstanz, Distributed Systems Group
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of the University of Konstanz nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 /**
29 *
30 */
31 package org.treetank.service.jaxrx.util;
32
33 import java.io.IOException;
34 import java.io.OutputStream;
35
36 import javax.ws.rs.WebApplicationException;
37 import javax.ws.rs.core.Response;
38
39 import org.treetank.access.NodeReadTrx;
40 import org.treetank.access.conf.SessionConfiguration;
41 import org.treetank.access.conf.StandardSettings;
42 import org.treetank.api.IStorage;
43 import org.treetank.api.INodeReadTrx;
44 import org.treetank.api.ISession;
45 import org.treetank.axis.AbsAxis;
46 import org.treetank.exception.TTException;
47 import org.treetank.service.xml.xpath.XPathAxis;
48
49 /**
50 * This class is responsible to offer XPath processing functions for REST.
51 *
52 * @author Patrick Lang, Lukas Lewandowski, University of Konstanz.
53 *
54 */
55 public class RestXPathProcessor {
56
57 /**
58 * This field the begin result element of a XQuery or XPath expression.
59 */
60 private static transient String beginResult = "<jaxrx:result xmlns:jaxrx=\"http://jaxrx.org/\">";
61
62 /**
63 * This field the end result element of a XQuery or XPath expression.
64 */
65 private static transient String endResult = "</jaxrx:result>";
66
67 /**
68 * Path to storage.
69 */
70 private final IStorage mDatabase;
71
72 /**
73 *
74 * Constructor.
75 *
76 * @param pDatabase
77 * path to the storage
78 */
79 public RestXPathProcessor(final IStorage pDatabase) {
80 mDatabase = pDatabase;
81 }
82
83 /**
84 * Getting part of the XML based on a XPath query
85 *
86 * @param resourceName
87 * where the content should be extracted
88 * @param xpath
89 * contains XPath query
90 * @param nodeid
91 * To response the resource with a restid for each node ( <code>true</code>) or without (
92 * <code>false</code>).
93 * @param revision
94 * The revision of the requested resource. If <code>null</code>,
95 * than response the latest revision.
96 * @param output
97 * The OutputStream reference which have to be modified and
98 * returned
99 * @return the queried XML fragment
100 * @throws IOException
101 * The exception occurred.
102 * @throws TTException
103 */
104 public OutputStream getXpathResource(final String resourceName, final String xpath, final boolean nodeid,
105 final Long revision, final OutputStream output, final boolean wrapResult) throws IOException,
106 TTException {
107
108 // work around because of query root char '/'
109 String qQuery = xpath;
110 if (xpath.charAt(0) == '/')
111 qQuery = ".".concat(xpath);
112 if (mDatabase.existsResource(resourceName)) {
113 if (wrapResult) {
114 output.write(beginResult.getBytes());
115 doXPathRes(resourceName, revision, output, nodeid, qQuery);
116 output.write(endResult.getBytes());
117 } else {
118 doXPathRes(resourceName, revision, output, nodeid, qQuery);
119 }
120
121 } else {
122 throw new WebApplicationException(Response.Status.NOT_FOUND);
123 }
124 return output;
125 }
126
127 /**
128 * Getting part of the XML based on a XPath query
129 *
130 * @param resourceName
131 * where the content should be extracted
132 *
133 * @param query
134 * contains XPath query
135 * @param rId
136 * To response the resource with a restid for each node ( <code>true</code>) or without (
137 * <code>false</code>).
138 * @param doRevision
139 * The revision of the requested resource. If <code>null</code>,
140 * than response the latest revision.
141 * @param output
142 * The OutputStream reference which have to be modified and
143 * returned
144 * @param doNodeId
145 * specifies whether node id should be shown
146 * @param doWrap
147 * output of result elements
148 * @throws TTException
149 */
150 public void getXpathResource(final String resourceName, final long rId, final String query,
151 final boolean doNodeId, final Long doRevision, final OutputStream output, final boolean doWrap)
152 throws TTException {
153
154 // work around because of query root char '/'
155 String qQuery = query;
156 if (query.charAt(0) == '/')
157 qQuery = ".".concat(query);
158
159 ISession session = null;
160 INodeReadTrx rtx = null;
161 try {
162 if (mDatabase.existsResource(resourceName)) {
163 session = mDatabase.getSession(new SessionConfiguration(resourceName, StandardSettings.KEY));
164 // Creating a transaction
165
166 if (doRevision == null) {
167 rtx = new NodeReadTrx(session.beginBucketRtx(session.getMostRecentVersion()));
168 } else {
169 rtx = new NodeReadTrx(session.beginBucketRtx(doRevision));
170 }
171
172 final boolean exist = rtx.moveTo(rId);
173 if (exist) {
174 final AbsAxis axis = new XPathAxis(rtx, qQuery);
175 if (doWrap) {
176 output.write(beginResult.getBytes());
177 for (final long key : axis) {
178 WorkerHelper.serializeXML(session, output, false, doNodeId, key, doRevision)
179 .call();
180 }
181
182 output.write(endResult.getBytes());
183 } else {
184 for (final long key : axis) {
185 WorkerHelper.serializeXML(session, output, false, doNodeId, key, doRevision)
186 .call();
187 }
188
189 }
190 } else {
191 throw new WebApplicationException(404);
192 }
193 }
194
195 } catch (final Exception globExcep) {
196 throw new WebApplicationException(globExcep, Response.Status.INTERNAL_SERVER_ERROR);
197 }
198 }
199
200 /**
201 * This method performs an XPath evaluation and writes it to a given output
202 * stream.
203 *
204 * @param resource
205 * The existing resource.
206 * @param revision
207 * The revision of the requested document.
208 * @param output
209 * The output stream where the results are written.
210 * @param nodeid
211 * <code>true</code> if node id's have to be delivered. <code>false</code> otherwise.
212 * @param xpath
213 * The XPath expression.
214 * @throws TTException
215 */
216 private void doXPathRes(final String resource, final Long revision, final OutputStream output,
217 final boolean nodeid, final String xpath) throws TTException {
218 // Storage connection to treetank
219 ISession session = null;
220 INodeReadTrx rtx = null;
221 try {
222 if (mDatabase.existsResource(resource)) {
223 session = mDatabase.getSession(new SessionConfiguration(resource, StandardSettings.KEY));
224 // Creating a transaction
225 if (revision == null) {
226 rtx = new NodeReadTrx(session.beginBucketRtx(session.getMostRecentVersion()));
227 } else {
228 rtx = new NodeReadTrx(session.beginBucketRtx(revision));
229 }
230
231 final AbsAxis axis = new XPathAxis(rtx, xpath);
232 for (final long key : axis) {
233 WorkerHelper.serializeXML(session, output, false, nodeid, key, revision).call();
234 }
235 }
236 } catch (final Exception globExcep) {
237 throw new WebApplicationException(globExcep, Response.Status.INTERNAL_SERVER_ERROR);
238 } finally {
239 WorkerHelper.closeRTX(rtx, session);
240
241 }
242 }
243 }