NIHVIVO-1363 Create a separate controller to handle AJAX sparql queries. The calling sequence changes slightly.

webapp/config/web.xml

@@ -1255,6 +1255,15 @@
     <url-pattern>/edit/primitiveDelete</url-pattern>    
   </servlet-mapping>
    
+  <servlet>
+    <servlet-name>ajaxSparqlQuery</servlet-name>
+    <servlet-class>edu.cornell.mannlib.vitro.webapp.controller.ajax.SparqlQueryAjaxController</servlet-class>    
+  </servlet>
+  <servlet-mapping>
+    <servlet-name>ajaxSparqlQuery</servlet-name>
+    <url-pattern>/ajax/sparqlQuery</url-pattern>    
+  </servlet-mapping>
+   
   <!-- ============================== servlet-mappings ======================== -->
   <servlet-mapping>
     <servlet-name>fetch</servlet-name>

webapp/src/edu/cornell/mannlib/vitro/webapp/controller/ajax/SparqlQueryAjaxController.java

@@ -0,0 +1,110 @@
+/* $This file is distributed under the terms of the license in /doc/license.txt$ */
+
+package edu.cornell.mannlib.vitro.webapp.controller.ajax;
+
+import static javax.servlet.http.HttpServletResponse.SC_INTERNAL_SERVER_ERROR;
+import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import com.hp.hpl.jena.query.DataSource;
+import com.hp.hpl.jena.query.Dataset;
+import com.hp.hpl.jena.query.DatasetFactory;
+import com.hp.hpl.jena.query.Query;
+import com.hp.hpl.jena.query.QueryExecution;
+import com.hp.hpl.jena.query.QueryExecutionFactory;
+import com.hp.hpl.jena.query.QueryFactory;
+import com.hp.hpl.jena.query.ResultSet;
+import com.hp.hpl.jena.query.ResultSetFormatter;
+import com.hp.hpl.jena.query.Syntax;
+import com.hp.hpl.jena.rdf.model.Model;
+
+import edu.cornell.mannlib.vedit.beans.LoginStatusBean;
+import edu.cornell.mannlib.vitro.webapp.controller.VitroRequest;
+
+/**
+ * Handle an AJAX request for a SPARQL query. On entry, the "query" parameter
+ * contains the query string.
+ * 
+ * The result is delivered in JSON format.
+ */
+public class SparqlQueryAjaxController extends VitroAjaxController {
+	private static final Log log = LogFactory
+			.getLog(SparqlQueryAjaxController.class);
+
+	private static final String PARAMETER_QUERY = "query";
+	private static final String RESPONSE_MIME_TYPE = "application/javascript";
+
+	/**
+	 * If you are logged in, you can use this servlet.
+	 */
+	@Override
+	protected boolean testIsAuthorized(HttpServletRequest request) {
+		return LoginStatusBean.getBean(request).isLoggedIn();
+	}
+
+	@Override
+	protected void doRequest(VitroRequest vreq, HttpServletResponse response)
+			throws ServletException, IOException {
+
+		Model model = vreq.getJenaOntModel();
+		if (model == null) {
+			log.error("JenaOntModel not found.");
+			response.sendError(SC_INTERNAL_SERVER_ERROR,
+					"JenaOntModel not found");
+			return;
+		}
+
+		String queryParam = vreq.getParameter(PARAMETER_QUERY);
+		log.debug("queryParam was : " + queryParam);
+		if ((queryParam == null) || queryParam.isEmpty()) {
+			response.sendError(SC_NOT_FOUND, "'" + PARAMETER_QUERY
+					+ "' parameter is required");
+		}
+
+		Query query = QueryFactory.create(queryParam, Syntax.syntaxARQ);
+		if (!query.isSelectType()) {
+			log.debug("Not a 'select' query.");
+			response.sendError(SC_NOT_FOUND,
+					"Only 'select' queries are allowed.");
+		}
+
+		Dataset dataset = chooseDatasetToQueryAgainst(vreq);
+
+		executeQuery(response, query, dataset);
+		return;
+	}
+
+	private Dataset chooseDatasetToQueryAgainst(VitroRequest vreq) {
+		Dataset dataset = vreq.getDataset();
+		if (dataset != null) {
+			return dataset;
+		}
+
+		DataSource dataSource = DatasetFactory.create();
+		dataSource.setDefaultModel(vreq.getJenaOntModel());
+		return dataSource;
+	}
+
+	private void executeQuery(HttpServletResponse response, Query query,
+			Dataset dataset) throws IOException {
+		QueryExecution qe = QueryExecutionFactory.create(query, dataset);
+		try {
+			ResultSet results = qe.execSelect();
+			response.setContentType(RESPONSE_MIME_TYPE);
+			OutputStream out = response.getOutputStream();
+			ResultSetFormatter.outputAsJSON(out, results);
+		} finally {
+			qe.close();
+		}
+	}
+
+}

webapp/src/edu/cornell/mannlib/vitro/webapp/controller/ajax/VitroAjaxController.java

@@ -0,0 +1,54 @@
+/* $This file is distributed under the terms of the license in /doc/license.txt$ */
+
+package edu.cornell.mannlib.vitro.webapp.controller.ajax;
+
+import java.io.IOException;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import edu.cornell.mannlib.vitro.webapp.controller.VitroRequest;
+
+/**
+ * A base class for servlets that handle AJAX requests.
+ */
+public abstract class VitroAjaxController extends HttpServlet {
+	/**
+	 * Sub-classes must implement this method to verify that the user is
+	 * authorized to execute this request.
+	 */
+	protected abstract boolean testIsAuthorized(HttpServletRequest request);
+
+	/**
+	 * Sub-classes must implement this method to handle both GET and POST
+	 * requests.
+	 */
+	protected abstract void doRequest(VitroRequest vreq,
+			HttpServletResponse resp) throws ServletException, IOException;
+
+	/**
+	 * Sub-classes should not override this. Instead, implement doRequest().
+	 */
+	@Override
+	protected final void doGet(HttpServletRequest req, HttpServletResponse resp)
+			throws ServletException, IOException {
+		VitroRequest vreq = new VitroRequest(req);
+		if (testIsAuthorized(vreq)) {
+			doRequest(vreq, resp);
+		} else {
+			resp.sendError(HttpServletResponse.SC_FORBIDDEN, "Not authorized");
+		}
+	}
+
+	/**
+	 * Sub-classes should not override this. Instead, implement doRequest().
+	 */
+	@Override
+	protected final void doPost(HttpServletRequest req, HttpServletResponse resp)
+			throws ServletException, IOException {
+		doGet(req, resp);
+	}
+
+}