[Mulgara-svn] r1260 - trunk/src/jar/querylang/java/org/mulgara/protocol/http
pag at mulgara.org
pag at mulgara.org
Tue Sep 16 04:52:10 UTC 2008
Author: pag
Date: 2008-09-15 21:52:09 -0700 (Mon, 15 Sep 2008)
New Revision: 1260
Added:
trunk/src/jar/querylang/java/org/mulgara/protocol/http/ProtocolServlet.java
trunk/src/jar/querylang/java/org/mulgara/protocol/http/TqlServlet.java
Modified:
trunk/src/jar/querylang/java/org/mulgara/protocol/http/SparqlServlet.java
Log:
Refactored the SPARQL servlet to an abstract class, and now SPARQL and TQL serlvets are simple extensions of this class. TQL is using SPARQL protocols for much of the return data, with the exception of XML query results, as this schema was already set.
Added: trunk/src/jar/querylang/java/org/mulgara/protocol/http/ProtocolServlet.java
===================================================================
--- trunk/src/jar/querylang/java/org/mulgara/protocol/http/ProtocolServlet.java (rev 0)
+++ trunk/src/jar/querylang/java/org/mulgara/protocol/http/ProtocolServlet.java 2008-09-16 04:52:09 UTC (rev 1260)
@@ -0,0 +1,362 @@
+/*
+ * The contents of this file are subject to the Open Software License
+ * Version 3.0 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.opensource.org/licenses/osl-3.0.txt
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ */
+
+package org.mulgara.protocol.http;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.HttpSession;
+
+import org.mulgara.connection.Connection;
+import org.mulgara.connection.SessionConnection;
+import org.mulgara.parser.Interpreter;
+import org.mulgara.protocol.StreamedAnswer;
+import org.mulgara.query.Answer;
+import org.mulgara.query.Query;
+import org.mulgara.query.QueryException;
+import org.mulgara.query.TuplesException;
+import org.mulgara.query.operation.Command;
+import org.mulgara.server.SessionFactory;
+import org.mulgara.server.SessionFactoryProvider;
+import org.mulgara.util.functional.Fn2;
+
+/**
+ * A query gateway for query languages.
+ *
+ * @created Sep 7, 2008
+ * @author Paul Gearon
+ * @copyright © 2008 <a href="http://www.topazproject.org/">The Topaz Project</a>
+ * @licence <a href="{@docRoot}/../../LICENCE.txt">Open Software License v3.0</a>
+ */
+public abstract class ProtocolServlet extends HttpServlet {
+
+ /**
+ * Internal type definition of a function that takes "something" and an output stream,
+ * and returns a {@link StreamedAnswer}
+ */
+ protected interface StreamConstructor<T> extends Fn2<T,OutputStream,StreamedAnswer> { }
+
+ /**
+ * Internal type definition of a function that takes an Answer and an output stream,
+ * and returns a {@link StreamedAnswer}
+ */
+ protected interface AnswerStreamConstructor extends StreamConstructor<Answer> { }
+
+ /**
+ * Internal type definition of a function that takes an Object and an output stream,
+ * and returns a {@link StreamedAnswer}
+ */
+ protected interface ObjectStreamConstructor extends StreamConstructor<Object> { }
+
+ /** The parameter identifying the query. */
+ private static final String QUERY_ARG = "query";
+
+ /** The parameter identifying the output type. */
+ protected static final String OUTPUT_ARG = "out";
+
+ /** The output parameter value for indicating JSON output. */
+ protected static final String OUTPUT_JSON = "json";
+
+ /** The output parameter value for indicating XML output. */
+ protected static final String OUTPUT_XML = "xml";
+
+ /** The default output type to use. */
+ protected static final String DEFAULT_OUTPUT_TYPE = OUTPUT_XML;
+
+ /** The content type of the results. */
+ protected static final String CONTENT_TYPE = "application/sparql-results+xml";
+
+ /** Session value for database connection. */
+ private static final String CONNECTION = "session.connection";
+
+ /** Session value for interpreter. */
+ protected static final String INTERPRETER = "session.interpreter";
+
+ /** The server for finding a session factory. */
+ private SessionFactoryProvider server;
+
+ /** Session factory for accessing the database. */
+ private SessionFactory cachedSessionFactory;
+
+ /** This object maps request types to the constructors for that output. */
+ protected final Map<String,AnswerStreamConstructor> streamBuilders = new HashMap<String,AnswerStreamConstructor>();
+
+ /** This object maps request types to the constructors for sending objects to that output. */
+ protected final Map<String,ObjectStreamConstructor> objectStreamBuilders = new HashMap<String,ObjectStreamConstructor>();
+
+ /**
+ * Creates the servlet for communicating with the given server.
+ * @param server The server that provides access to the database.
+ */
+ public ProtocolServlet(SessionFactoryProvider server) throws IOException {
+ this.cachedSessionFactory = null;
+ this.server = server;
+ initializeBuilders();
+ }
+
+
+ /**
+ * Initialize the functional mappings of output types to the objects that manage them.
+ */
+ abstract protected void initializeBuilders();
+
+ /**
+ * Respond to a request for the servlet.
+ * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
+ */
+ protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+ String queryStr = req.getParameter(QUERY_ARG);
+ try {
+ Query query = getQuery(queryStr, req);
+
+ Answer result = executeQuery(query, req);
+
+ String outputType = req.getParameter(OUTPUT_ARG);
+ sendAnswer(result, outputType, resp);
+
+ try {
+ result.close();
+ } catch (TuplesException e) {
+ throw new InternalErrorException("Error closing: " + e.getMessage());
+ }
+
+ } catch (ServletException e) {
+ e.sendResponseTo(resp);
+ }
+ }
+
+
+ /**
+ * Respond to a request for the servlet. This may handle update queries.
+ * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
+ */
+ protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+ String queryStr = req.getParameter(QUERY_ARG);
+ try {
+ Command cmd = getCommand(queryStr, req);
+
+ Object result = executeCommand(cmd, req);
+
+ String outputType = req.getParameter(OUTPUT_ARG);
+ if (result instanceof Answer) {
+ sendAnswer((Answer)result, outputType, resp);
+ } else {
+ sendStatus(result, outputType, resp);
+ }
+
+ } catch (ServletException e) {
+ e.sendResponseTo(resp);
+ }
+ }
+
+
+ /**
+ * Provide a description for the servlet.
+ * @see javax.servlet.GenericServlet#getServletInfo()
+ */
+ public abstract String getServletInfo();
+
+
+ /**
+ * Converts a SPARQL query string into a Query object. This uses extra parameters from the
+ * client where appropriate, such as the default graph.
+ * @param query The query string issued by the client.
+ * @param req The request from the client.
+ * @return A new Query object, built from the query string.
+ * @throws BadRequestException Due to an invalid command string.
+ */
+ Query getQuery(String query, HttpServletRequest req) throws BadRequestException {
+ if (query == null) throw new BadRequestException("Query must be supplied");
+ try {
+ Interpreter interpreter = getInterpreter(req);
+ return interpreter.parseQuery(query);
+ } catch (Exception e) {
+ throw new BadRequestException(e.getMessage());
+ }
+ }
+
+
+ /**
+ * Converts a SPARQL query to a Command. For normal SPARQL this will be a Query,
+ * but SPARQL Update may create other command types.
+ * @param cmd The command string.
+ * @param req The client request object.
+ * @return The Command object specified by the cmd string.
+ * @throws BadRequestException Due to an invalid command string.
+ */
+ Command getCommand(String cmd, HttpServletRequest req) throws BadRequestException {
+ if (cmd == null) throw new BadRequestException("Command must be supplied");
+ try {
+ Interpreter interpreter = getInterpreter(req);
+ return interpreter.parseCommand(cmd);
+ } catch (Exception e) {
+ throw new BadRequestException(e.getMessage());
+ }
+ }
+
+
+ /**
+ * Execute a query on the database, and return the {@link Answer}.
+ * @param query The query to run.
+ * @param req The client request object.
+ * @return An Answer containing the results of the query.
+ * @throws ServletException Due to an error executing the query.
+ * @throws IOException If there was an error establishing a connection.
+ */
+ Answer executeQuery(Query query, HttpServletRequest req) throws ServletException, IOException {
+ try {
+ return query.execute(getConnection(req));
+ } catch (IllegalStateException e) {
+ throw new ServiceUnavailableException(e.getMessage());
+ } catch (QueryException e) {
+ throw new InternalErrorException(e.getMessage());
+ } catch (TuplesException e) {
+ throw new InternalErrorException(e.getMessage());
+ }
+ }
+
+
+ /**
+ * Execute a command on the database, and return whatever the result is.
+ * @param cmd The command to run.
+ * @param req The client request object.
+ * @return An Object containing the results of the query.
+ * @throws ServletException Due to an error executing the query.
+ * @throws IOException If there was an error establishing a connection.
+ */
+ Object executeCommand(Command cmd, HttpServletRequest req) throws ServletException, IOException {
+ try {
+ return cmd.execute(getConnection(req));
+ } catch (IllegalStateException e) {
+ throw new ServiceUnavailableException(e.getMessage());
+ } catch (Exception e) {
+ throw new InternalErrorException(e.getMessage());
+ }
+ }
+
+
+ /**
+ * Sends an Answer back to a client, using the request protocol.
+ * @param answer The answer to send to the client.
+ * @param outputType The protocol requested by the client.
+ * @param resp The response object for communicating with the client.
+ * @throws IOException Due to a communications error with the client.
+ * @throws BadRequestException Due to a bad protocol type.
+ * @throws InternalErrorException Due to an error accessing the answer.
+ */
+ void sendAnswer(Answer answer, String outputType, HttpServletResponse resp) throws IOException, BadRequestException, InternalErrorException {
+ send(streamBuilders, answer, outputType, resp);
+ }
+
+
+ /**
+ * Writes information to the client stream. This is a general catch-all for non-answer
+ * information.
+ * @param result The data to return to the client.
+ * @param outputType The requested format for the response.
+ * @param resp The object for responding to a client.
+ * @throws IOException Due to an error communicating with the client.
+ * @throws BadRequestException Due to a bad protocol type.
+ * @throws InternalErrorException Due to an error accessing the result.
+ */
+ void sendStatus(Object result, String outputType, HttpServletResponse resp) throws IOException, BadRequestException, InternalErrorException {
+ send(objectStreamBuilders, result, outputType, resp);
+ }
+
+
+ /**
+ * Sends an result back to a client, using the requested protocol.
+ * @param <T> The type of the data that is to be streamed to the client.
+ * @param builders The map of protocol types to the objects that implement streaming for
+ * that protocol.
+ * @param data The result to send to the client.
+ * @param type The protocol type to use when talking to the client.
+ * @param resp The respons object for talking to the client.
+ * @throws IOException Due to a communications error with the client.
+ * @throws BadRequestException Due to a bad protocol type.
+ * @throws InternalErrorException Due to an error accessing the answer.
+ */
+ <T> void send(Map<String,? extends StreamConstructor<T>> builders, T data, String type, HttpServletResponse resp) throws IOException, BadRequestException, InternalErrorException {
+ resp.setContentType(CONTENT_TYPE);
+ resp.setHeader("pragma", "no-cache");
+
+ // establish the output type
+ if (type == null) type = DEFAULT_OUTPUT_TYPE;
+ else type = type.toLowerCase();
+
+ // get the constructor for the stream outputter
+ StreamConstructor<T> constructor = builders.get(type);
+ if (constructor == null) throw new BadRequestException("Unknown result type: " + type);
+
+ try {
+ OutputStream out = resp.getOutputStream();
+ constructor.fn(data, out).emit();
+ out.close();
+ } catch (IOException ioe) {
+ // There's no point in telling the client if we can't talk to the client
+ throw ioe;
+ } catch (Exception e) {
+ throw new InternalErrorException(e.getMessage());
+ }
+ }
+
+
+ /**
+ * Gets the SPARQL interpreter for the current session,
+ * creating it if it doesn't exist yet.
+ * @param req The current request environment.
+ * @return A connection that is tied to this HTTP session.
+ */
+ abstract protected Interpreter getInterpreter(HttpServletRequest req) throws BadRequestException;
+
+
+ /**
+ * Gets the connection for the current session, creating it if it doesn't exist yet.
+ * @param req The current request environment.
+ * @return A connection that is tied to this HTTP session.
+ * @throws IOException When an error occurs creating a new session.
+ */
+ private Connection getConnection(HttpServletRequest req) throws IOException, IllegalStateException {
+ HttpSession httpSession = req.getSession();
+ Connection connection = (Connection)httpSession.getAttribute(CONNECTION);
+ if (connection == null) {
+ try {
+ connection = new SessionConnection(getSessionFactory().newSession(), null, null);
+ } catch (QueryException qe) {
+ throw new IOException("Unable to create a connection to the database. " + qe.getMessage());
+ }
+ httpSession.setAttribute(CONNECTION, connection);
+ }
+ return connection;
+ }
+
+
+ /**
+ * This method allows us to put off getting a session factory until the server is
+ * ready to provide one.
+ * @return A new session factory.
+ */
+ private SessionFactory getSessionFactory() throws IllegalStateException {
+ if (cachedSessionFactory == null) {
+ cachedSessionFactory = server.getSessionFactory();
+ if (cachedSessionFactory == null) throw new IllegalStateException("Server not yet ready. Try again soon.");
+ }
+ return cachedSessionFactory;
+ }
+
+}
Modified: trunk/src/jar/querylang/java/org/mulgara/protocol/http/SparqlServlet.java
===================================================================
--- trunk/src/jar/querylang/java/org/mulgara/protocol/http/SparqlServlet.java 2008-09-09 09:45:25 UTC (rev 1259)
+++ trunk/src/jar/querylang/java/org/mulgara/protocol/http/SparqlServlet.java 2008-09-16 04:52:09 UTC (rev 1260)
@@ -16,33 +16,22 @@
import java.io.OutputStream;
import java.net.URI;
import java.net.URISyntaxException;
-import java.util.HashMap;
+import java.util.Collections;
import java.util.List;
-import java.util.Map;
-import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
-import org.mulgara.connection.Connection;
-import org.mulgara.connection.SessionConnection;
import org.mulgara.protocol.StreamedAnswer;
import org.mulgara.protocol.StreamedSparqlJSONAnswer;
import org.mulgara.protocol.StreamedSparqlJSONObject;
import org.mulgara.protocol.StreamedSparqlXMLAnswer;
import org.mulgara.protocol.StreamedSparqlXMLObject;
import org.mulgara.query.Answer;
-import org.mulgara.query.Query;
-import org.mulgara.query.QueryException;
-import org.mulgara.query.TuplesException;
-import org.mulgara.query.operation.Command;
-import org.mulgara.server.SessionFactory;
import org.mulgara.server.SessionFactoryProvider;
import org.mulgara.sparql.SparqlInterpreter;
import org.mulgara.util.functional.C;
import org.mulgara.util.functional.Fn1E;
-import org.mulgara.util.functional.Fn2;
/**
* A query gateway for SPARQL.
@@ -52,32 +41,11 @@
* @copyright © 2008 <a href="http://www.topazproject.org/">The Topaz Project</a>
* @licence <a href="{@docRoot}/../../LICENCE.txt">Open Software License v3.0</a>
*/
-public class SparqlServlet extends HttpServlet {
+public class SparqlServlet extends ProtocolServlet {
/** Serialization ID */
- private static final long serialVersionUID = -830221563286477537L;
+ private static final long serialVersionUID = 5047396536306099528L;
- /**
- * Internal type definition of a function that takes "something" and an output stream,
- * and returns a {@link StreamedAnswer}
- */
- private interface StreamConstructor<T> extends Fn2<T,OutputStream,StreamedAnswer> { }
-
- /**
- * Internal type definition of a function that takes an Answer and an output stream,
- * and returns a {@link StreamedAnswer}
- */
- private interface AnswerStreamConstructor extends StreamConstructor<Answer> { }
-
- /**
- * Internal type definition of a function that takes an Object and an output stream,
- * and returns a {@link StreamedAnswer}
- */
- private interface ObjectStreamConstructor extends StreamConstructor<Object> { }
-
- /** The parameter identifying the query. */
- private static final String QUERY_ARG = "query";
-
/** The parameter identifying the graph. */
private static final String DEFAULT_GRAPH_ARG = "default-graph-uri";
@@ -85,40 +53,24 @@
@SuppressWarnings("unused")
private static final String NAMED_GRAPH_ARG = "named-graph-uri";
- /** The parameter identifying the output type. */
- private static final String OUTPUT_ARG = "out";
+ /** An empty graph for those occasions when no graph is set. */
+ private static final List<URI> DEFAULT_NULL_GRAPH_LIST = Collections.singletonList(URI.create("sys:null"));
- /** The output parameter value for indicating JSON output. */
- private static final String OUTPUT_JSON = "json";
+ static {
+ }
- /** The output parameter value for indicating XML output. */
- private static final String OUTPUT_XML = "xml";
- /** The default output type to use. */
- private static final String DEFAULT_OUTPUT_TYPE = OUTPUT_XML;
+ /**
+ * Creates the servlet for communicating with the given server.
+ * @param server The server that provides access to the database.
+ */
+ public SparqlServlet(SessionFactoryProvider server) throws IOException {
+ super(server);
+ }
- /** The content type of the results. */
- private static final String CONTENT_TYPE = "application/sparql-results+xml";
- /** Session value for database connection. */
- private static final String CONNECTION = "session.connection";
-
- /** Session value for interpreter. */
- private static final String INTERPRETER = "session.interpreter";
-
- /** The server for finding a session factory. */
- private SessionFactoryProvider server;
-
- /** Session factory for accessing the database. */
- private SessionFactory cachedSessionFactory;
-
- /** This object maps request types to the constructors for that output. */
- private static final Map<String,AnswerStreamConstructor> streamBuilders = new HashMap<String,AnswerStreamConstructor>();
-
- /** This object maps request types to the constructors for sending objects to that output. */
- private static final Map<String,ObjectStreamConstructor> objectStreamBuilders = new HashMap<String,ObjectStreamConstructor>();
-
- static {
+ /** @see org.mulgara.protocol.http.ProtocolServlet#initializeBuilders() */
+ protected void initializeBuilders() {
AnswerStreamConstructor jsonBuilder = new AnswerStreamConstructor() {
public StreamedAnswer fn(Answer ans, OutputStream s) { return new StreamedSparqlJSONAnswer(ans, s); }
};
@@ -142,67 +94,6 @@
/**
- * Creates the servlet for communicating with the given server.
- * @param server The server that provides access to the database.
- */
- public SparqlServlet(SessionFactoryProvider server) throws IOException {
- this.cachedSessionFactory = null;
- this.server = server;
- }
-
-
- /**
- * Respond to a request for the servlet.
- * @see javax.servlet.http.HttpServlet#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
- */
- protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
- String queryStr = req.getParameter(QUERY_ARG);
- try {
- Query query = getQuery(queryStr, req);
-
- Answer result = executeQuery(query, req);
-
- String outputType = req.getParameter(OUTPUT_ARG);
- sendAnswer(result, outputType, resp);
-
- try {
- result.close();
- } catch (TuplesException e) {
- throw new InternalErrorException("Error closing: " + e.getMessage());
- }
-
- } catch (ServletException e) {
- e.sendResponseTo(resp);
- }
- }
-
-
- /**
- * Respond to a request for the servlet. This may handle update queries, though SPARQL
- * is not yet standardized to handle these yet.
- * @see javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
- */
- protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
- String queryStr = req.getParameter(QUERY_ARG);
- try {
- Command cmd = getCommand(queryStr, req);
-
- Object result = executeCommand(cmd, req);
-
- String outputType = req.getParameter(OUTPUT_ARG);
- if (result instanceof Answer) {
- sendAnswer((Answer)result, outputType, resp);
- } else {
- sendStatus(result, outputType, resp);
- }
-
- } catch (ServletException e) {
- e.sendResponseTo(resp);
- }
- }
-
-
- /**
* Provide a description for the servlet.
* @see javax.servlet.GenericServlet#getServletInfo()
*/
@@ -212,164 +103,19 @@
/**
- * Converts a SPARQL query string into a Query object. This uses extra parameters from the
- * client where appropriate, such as the default graph.
- * @param query The query string issued by the client.
- * @param req The request from the client.
- * @return A new Query object, built from the query string.
- * @throws BadRequestException Due to an invalid command string.
- */
- Query getQuery(String query, HttpServletRequest req) throws BadRequestException {
- if (query == null) throw new BadRequestException("Query must be supplied");
- try {
- SparqlInterpreter interpreter = getInterpreter(req);
- interpreter.setDefaultGraphUris(getRequestedDefaultGraphs(req));
- return interpreter.parseQuery(query);
- } catch (Exception e) {
- throw new BadRequestException(e.getMessage());
- }
- }
-
-
- /**
- * Converts a SPARQL query to a Command. For normal SPARQL this will be a Query,
- * but SPARQL Update may create other command types.
- * @param cmd The command string.
- * @param req The client request object.
- * @return The Command object specified by the cmd string.
- * @throws BadRequestException Due to an invalid command string.
- */
- Command getCommand(String cmd, HttpServletRequest req) throws BadRequestException {
- if (cmd == null) throw new BadRequestException("Command must be supplied");
- try {
- SparqlInterpreter interpreter = getInterpreter(req);
- interpreter.setDefaultGraphUris(getRequestedDefaultGraphs(req));
- return interpreter.parseCommand(cmd);
- } catch (Exception e) {
- throw new BadRequestException(e.getMessage());
- }
- }
-
-
- /**
- * Execute a query on the database, and return the {@link Answer}.
- * @param query The query to run.
- * @param req The client request object.
- * @return An Answer containing the results of the query.
- * @throws ServletException Due to an error executing the query.
- * @throws IOException If there was an error establishing a connection.
- */
- Answer executeQuery(Query query, HttpServletRequest req) throws ServletException, IOException {
- try {
- return query.execute(getConnection(req));
- } catch (IllegalStateException e) {
- throw new ServiceUnavailableException(e.getMessage());
- } catch (QueryException e) {
- throw new InternalErrorException(e.getMessage());
- } catch (TuplesException e) {
- throw new InternalErrorException(e.getMessage());
- }
- }
-
-
- /**
- * Execute a command on the database, and return whatever the result is.
- * @param cmd The command to run.
- * @param req The client request object.
- * @return An Object containing the results of the query.
- * @throws ServletException Due to an error executing the query.
- * @throws IOException If there was an error establishing a connection.
- */
- Object executeCommand(Command cmd, HttpServletRequest req) throws ServletException, IOException {
- try {
- return cmd.execute(getConnection(req));
- } catch (IllegalStateException e) {
- throw new ServiceUnavailableException(e.getMessage());
- } catch (Exception e) {
- throw new InternalErrorException(e.getMessage());
- }
- }
-
-
- /**
- * Sends an Answer back to a client, using the request protocol.
- * @param answer The answer to send to the client.
- * @param outputType The protocol requested by the client.
- * @param resp The response object for communicating with the client.
- * @throws IOException Due to a communications error with the client.
- * @throws BadRequestException Due to a bad protocol type.
- * @throws InternalErrorException Due to an error accessing the answer.
- */
- void sendAnswer(Answer answer, String outputType, HttpServletResponse resp) throws IOException, BadRequestException, InternalErrorException {
- send(streamBuilders, answer, outputType, resp);
- }
-
-
- /**
- * Writes information to the client stream. This is a general catch-all for non-answer
- * information.
- * @param result The data to return to the client.
- * @param outputType The requested format for the response.
- * @param resp The object for responding to a client.
- * @throws IOException Due to an error communicating with the client.
- * @throws BadRequestException Due to a bad protocol type.
- * @throws InternalErrorException Due to an error accessing the result.
- */
- void sendStatus(Object result, String outputType, HttpServletResponse resp) throws IOException, BadRequestException, InternalErrorException {
- send(objectStreamBuilders, result, outputType, resp);
- }
-
-
- /**
- * Sends an result back to a client, using the requested protocol.
- * @param <T> The type of the data that is to be streamed to the client.
- * @param builders The map of protocol types to the objects that implement streaming for
- * that protocol.
- * @param data The result to send to the client.
- * @param type The protocol type to use when talking to the client.
- * @param resp The respons object for talking to the client.
- * @throws IOException Due to a communications error with the client.
- * @throws BadRequestException Due to a bad protocol type.
- * @throws InternalErrorException Due to an error accessing the answer.
- */
- <T> void send(Map<String,? extends StreamConstructor<T>> builders, T data, String type, HttpServletResponse resp) throws IOException, BadRequestException, InternalErrorException {
- resp.setContentType(CONTENT_TYPE);
- resp.setHeader("pragma", "no-cache");
-
- // establish the output type
- if (type == null) type = DEFAULT_OUTPUT_TYPE;
- else type = type.toLowerCase();
-
- // get the constructor for the stream outputter
- StreamConstructor<T> constructor = builders.get(type);
- if (constructor == null) throw new BadRequestException("Unknown result type: " + type);
-
- try {
- OutputStream out = resp.getOutputStream();
- constructor.fn(data, out).emit();
- out.close();
- } catch (IOException ioe) {
- // There's no point in telling the client if we can't talk to the client
- throw ioe;
- } catch (Exception e) {
- throw new InternalErrorException(e.getMessage());
- }
- }
-
-
- /**
* Gets the SPARQL interpreter for the current session,
* creating it if it doesn't exist yet.
* @param req The current request environment.
* @return A connection that is tied to this HTTP session.
*/
- private SparqlInterpreter getInterpreter(HttpServletRequest req) {
+ protected SparqlInterpreter getInterpreter(HttpServletRequest req) throws BadRequestException {
HttpSession httpSession = req.getSession();
SparqlInterpreter interpreter = (SparqlInterpreter)httpSession.getAttribute(INTERPRETER);
if (interpreter == null) {
interpreter = new SparqlInterpreter();
httpSession.setAttribute(INTERPRETER, interpreter);
}
+ interpreter.setDefaultGraphUris(getRequestedDefaultGraphs(req));
return interpreter;
}
@@ -382,7 +128,7 @@
*/
private List<URI> getRequestedDefaultGraphs(HttpServletRequest req) throws BadRequestException {
String[] defaults = req.getParameterValues(DEFAULT_GRAPH_ARG);
- if (defaults == null) return null;
+ if (defaults == null) return DEFAULT_NULL_GRAPH_LIST;
try {
return C.map(defaults, new Fn1E<String,URI,URISyntaxException>(){public URI fn(String s)throws URISyntaxException{return new URI(s);}});
} catch (URISyntaxException e) {
@@ -390,39 +136,4 @@
}
}
-
- /**
- * Gets the connection for the current session, creating it if it doesn't exist yet.
- * @param req The current request environment.
- * @return A connection that is tied to this HTTP session.
- * @throws IOException When an error occurs creating a new session.
- */
- private Connection getConnection(HttpServletRequest req) throws IOException, IllegalStateException {
- HttpSession httpSession = req.getSession();
- Connection connection = (Connection)httpSession.getAttribute(CONNECTION);
- if (connection == null) {
- try {
- connection = new SessionConnection(getSessionFactory().newSession(), null, null);
- } catch (QueryException qe) {
- throw new IOException("Unable to create a connection to the database. " + qe.getMessage());
- }
- httpSession.setAttribute(CONNECTION, connection);
- }
- return connection;
- }
-
-
- /**
- * This method allows us to put off getting a session factory until the server is
- * ready to provide one.
- * @return A new session factory.
- */
- private SessionFactory getSessionFactory() throws IllegalStateException {
- if (cachedSessionFactory == null) {
- cachedSessionFactory = server.getSessionFactory();
- if (cachedSessionFactory == null) throw new IllegalStateException("Server not yet ready. Try again soon.");
- }
- return cachedSessionFactory;
- }
-
}
Added: trunk/src/jar/querylang/java/org/mulgara/protocol/http/TqlServlet.java
===================================================================
--- trunk/src/jar/querylang/java/org/mulgara/protocol/http/TqlServlet.java (rev 0)
+++ trunk/src/jar/querylang/java/org/mulgara/protocol/http/TqlServlet.java 2008-09-16 04:52:09 UTC (rev 1260)
@@ -0,0 +1,103 @@
+/*
+ * The contents of this file are subject to the Open Software License
+ * Version 3.0 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.opensource.org/licenses/osl-3.0.txt
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ */
+
+package org.mulgara.protocol.http;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpSession;
+
+import org.mulgara.itql.TqlInterpreter;
+import org.mulgara.protocol.StreamedAnswer;
+import org.mulgara.protocol.StreamedSparqlJSONAnswer;
+import org.mulgara.protocol.StreamedSparqlJSONObject;
+import org.mulgara.protocol.StreamedSparqlXMLObject;
+import org.mulgara.protocol.StreamedTqlXMLAnswer;
+import org.mulgara.query.Answer;
+import org.mulgara.server.SessionFactoryProvider;
+
+/**
+ * A query gateway for TQL.
+ *
+ * @created Sep 14, 2008
+ * @author Paul Gearon
+ * @copyright © 2008 <a href="http://www.topazproject.org/">The Topaz Project</a>
+ * @licence <a href="{@docRoot}/../../LICENCE.txt">Open Software License v3.0</a>
+ */
+public class TqlServlet extends ProtocolServlet {
+
+ /** Serialization ID */
+ private static final long serialVersionUID = -72714067636720775L;
+
+
+ /**
+ * Creates the servlet for communicating with the given server.
+ * @param server The server that provides access to the database.
+ */
+ public TqlServlet(SessionFactoryProvider server) throws IOException {
+ super(server);
+ }
+
+
+ /** @see org.mulgara.protocol.http.ProtocolServlet#initializeBuilders() */
+ protected void initializeBuilders() {
+ // TODO: create a JSON answer and a XML object for TQL.
+ AnswerStreamConstructor jsonBuilder = new AnswerStreamConstructor() {
+ public StreamedAnswer fn(Answer ans, OutputStream s) { return new StreamedSparqlJSONAnswer(ans, s); }
+ };
+ AnswerStreamConstructor xmlBuilder = new AnswerStreamConstructor() {
+ public StreamedAnswer fn(Answer ans, OutputStream s) { return new StreamedTqlXMLAnswer(ans, s); }
+ };
+ streamBuilders.put(OUTPUT_JSON, jsonBuilder);
+ streamBuilders.put(OUTPUT_XML, xmlBuilder);
+ streamBuilders.put(null, xmlBuilder);
+
+ ObjectStreamConstructor jsonObjBuilder = new ObjectStreamConstructor() {
+ public StreamedAnswer fn(Object o, OutputStream s) { return new StreamedSparqlJSONObject(o, s); }
+ };
+ ObjectStreamConstructor xmlObjBuilder = new ObjectStreamConstructor() {
+ public StreamedAnswer fn(Object o, OutputStream s) { return new StreamedSparqlXMLObject(o, s); }
+ };
+ objectStreamBuilders.put(OUTPUT_JSON, jsonObjBuilder);
+ objectStreamBuilders.put(OUTPUT_XML, xmlObjBuilder);
+ objectStreamBuilders.put(null, xmlObjBuilder);
+ }
+
+
+ /**
+ * Provide a description for the servlet.
+ * @see javax.servlet.GenericServlet#getServletInfo()
+ */
+ public String getServletInfo() {
+ return "Mulgara TQL Query Endpoint";
+ }
+
+
+ /**
+ * Gets the TQL interpreter for the current session,
+ * creating it if it doesn't exist yet.
+ * @param req The current request environment.
+ * @return A connection that is tied to this HTTP session.
+ */
+ protected TqlInterpreter getInterpreter(HttpServletRequest req) throws BadRequestException {
+ HttpSession httpSession = req.getSession();
+ TqlInterpreter interpreter = (TqlInterpreter)httpSession.getAttribute(INTERPRETER);
+ if (interpreter == null) {
+ interpreter = new TqlInterpreter();
+ httpSession.setAttribute(INTERPRETER, interpreter);
+ }
+ return interpreter;
+ }
+
+}
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