Merge pull request #183 from dizzzz/feature/add_xquery_startup_trigger

Allow start of arbitrary XQuery during eXist-db startup.

src/org/exist/collections/triggers/XQueryStartupTrigger.java

@@ -0,0 +1,173 @@
+/*
+ *  eXist Open Source Native XML Database
+ *  Copyright (C) 2014 The eXist Project
+ *  http://exist-db.org
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public License
+ *  as published by the Free Software Foundation; either version 2
+ *  of the License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+package org.exist.collections.triggers;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.log4j.Logger;
+
+import org.exist.security.xacml.AccessContext;
+import org.exist.source.Source;
+import org.exist.source.SourceFactory;
+import org.exist.storage.DBBroker;
+import org.exist.storage.StartupTrigger;
+import org.exist.xmldb.XmldbURI;
+import org.exist.xquery.CompiledXQuery;
+import org.exist.xquery.XQuery;
+import org.exist.xquery.XQueryContext;
+import org.exist.xquery.value.Sequence;
+
+/**
+ * Startup Trigger to fire XQuery scripts during database startup. Usage:
+ *
+ * <pre>
+ * {@code
+ * <startup>
+ *   <triggers>
+ *     <trigger class="org.exist.collections.triggers.XQueryStartupTrigger">
+ *       <parameter name="xquery" value="/db/script1.xq"/>
+ *       <parameter name="xquery" value="/db/script2.xq"/>
+ *     </trigger>
+ *   </triggers>
+ * </startup>
+ * }
+ * </pre>
+ *
+ * @author Dannes Wessels
+ */
+public class XQueryStartupTrigger implements StartupTrigger {
+
+    protected final static Logger LOG = Logger.getLogger(XQueryStartupTrigger.class);
+
+    @Override
+    public void execute(DBBroker broker, Map<String, List<? extends Object>> params) {
+
+        LOG.info("Starting Startup Trigger for stored XQueries");
+
+        for (String path : getParameters(params)) {
+            executeQuery(broker, path);
+        }
+
+    }
+
+    /**
+     * Get all XQuery paths
+     */
+    private List<String> getParameters(Map<String, List<? extends Object>> params) {
+
+        // Return values
+        List<String> paths = new ArrayList<String>();
+
+        // The complete data map
+        Set<Map.Entry<String, List<? extends Object>>> data = params.entrySet();
+
+        // Iterate over all entries
+        for (Map.Entry<String, List<? extends Object>> entry : data) {
+
+            // only the 'xpath' parameter is used.
+            if ("xquery".equals(entry.getKey())) {
+
+                // Iterate over all values (object lists)
+                List<? extends Object> list = entry.getValue();
+                for (Object o : list) {
+
+                    if (o instanceof String) {
+                        String value = (String) o;
+
+                        if (value.startsWith("/")) {
+
+                            // Rewrite to URL in database
+                            value = XmldbURI.EMBEDDED_SERVER_URI_PREFIX + value;
+
+                            // Prevent double entries
+                            if (!paths.contains(value)) {
+                                paths.add(value);
+                            }
+
+                        } else {
+                            LOG.error(String.format("Path '%s' should start with a '/'", value));
+                        }
+                    }
+                }
+            }
+
+        }
+
+        LOG.debug(String.format("Found %s 'xquery' entries.", paths.size()));
+
+        return paths;
+    }
+
+    /**
+     * Execute xquery on path
+     *
+     * @param broker eXist database broker
+     * @param path path to query, formatted as xmldb:exist:///db/...
+     */
+    private void executeQuery(DBBroker broker, String path) {
+        XQueryContext context = null;
+        try {
+            // Get path to xquery
+            Source source = SourceFactory.getSource(broker, null, path, false);
+
+            if (source == null) {
+                LOG.info(String.format("No Xquery found at '%s'", path));
+
+            } else {
+                // Setup xquery service
+                XQuery service = broker.getXQueryService();
+                context = service.newContext(AccessContext.TRIGGER);
+
+                // Allow use of modules with relative paths
+                String moduleLoadPath = StringUtils.substringBeforeLast(path, "/");
+                context.setModuleLoadPath(moduleLoadPath);
+
+                // Compile query
+                CompiledXQuery compiledQuery = service.compile(context, source);
+
+                LOG.info(String.format("Starting Xquery at '%s'", path));
+
+                // Finish preparation
+                context.prepareForExecution();
+
+                // Execute
+                Sequence result = service.execute(compiledQuery, null);
+
+                // Log results
+                LOG.info(String.format("Result xquery: '%s'", result.getStringValue()));
+
+            }
+
+        } catch (Throwable t) {
+            // Dirty, catch it all
+            LOG.error(String.format("An error occured during preparation/execution of the xquery script %s: %s", path, t.getMessage()), t);
+
+        } finally {
+            if (context != null) {
+                context.runCleanupTasks();
+            }
+        }
+    }
+
+}