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Fuseki is a SPARQL 1.1 Server
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jena.fuseki.servlets;
import static java.lang.String.format ;
import static org.apache.jena.fuseki.server.CounterName.Requests ;
import static org.apache.jena.fuseki.server.CounterName.RequestsBad ;
import static org.apache.jena.fuseki.server.CounterName.RequestsGood ;
import java.io.IOException ;
import java.util.Enumeration ;
import java.util.Map ;
import java.util.concurrent.atomic.AtomicLong ;
import javax.servlet.ServletException ;
import javax.servlet.http.HttpServletRequest ;
import javax.servlet.http.HttpServletResponse ;
import org.apache.jena.atlas.RuntimeIOException ;
import org.apache.jena.fuseki.Fuseki ;
import org.apache.jena.fuseki.HttpNames ;
import org.apache.jena.fuseki.server.* ;
import org.apache.jena.query.ARQ ;
import org.apache.jena.query.QueryCancelledException ;
import org.apache.jena.sparql.util.Context ;
import org.apache.jena.web.HttpSC ;
/**
* Base servlet for SPARQL requests.
*/
public abstract class SPARQL_ServletBase extends ServletBase
{
/**
* Creates a new SPARQL base Servlet.
*/
protected SPARQL_ServletBase() { super() ; }
// Common framework for handling HTTP requests
/**
* Handles GET and POST requests.
* @param request HTTP request
* @param response HTTP response
*/
protected void doCommon(HttpServletRequest request, HttpServletResponse response)
//throws ServletException, IOException
{
try {
long id = allocRequestId(request, response);
// Lifecycle
HttpAction action = allocHttpAction(id, request, response) ;
// then add to doCommonWorker
// work with HttpServletResponseTracker
printRequest(action) ;
action.setStartTime() ;
response = action.response ;
initResponse(request, response) ;
Context cxt = ARQ.getContext() ;
try {
execCommonWorker(action) ;
} catch (QueryCancelledException ex) {
// Also need the per query info ...
String message = String.format("The query timed out (restricted to %s ms)", cxt.get(ARQ.queryTimeout));
// Possibility :: response.setHeader("Retry-after", "600") ; // 5 minutes
responseSendError(response, HttpSC.SERVICE_UNAVAILABLE_503, message);
} catch (ActionErrorException ex) {
if ( ex.exception != null )
ex.exception.printStackTrace(System.err) ;
// Log message done by printResponse in a moment.
if ( ex.message != null )
responseSendError(response, ex.rc, ex.message) ;
else
responseSendError(response, ex.rc) ;
} catch (RuntimeIOException ex) {
log.warn(format("[%d] Runtime IO Exception (client left?) RC = %d", id, HttpSC.INTERNAL_SERVER_ERROR_500)) ;
responseSendError(response, HttpSC.INTERNAL_SERVER_ERROR_500, ex.getMessage()) ;
} catch (Throwable ex) {
// This should not happen.
//ex.printStackTrace(System.err) ;
log.warn(format("[%d] RC = %d : %s", id, HttpSC.INTERNAL_SERVER_ERROR_500, ex.getMessage()), ex) ;
responseSendError(response, HttpSC.INTERNAL_SERVER_ERROR_500, ex.getMessage()) ;
}
action.setFinishTime() ;
printResponse(action) ;
archiveHttpAction(action) ;
} catch (Throwable th) {
log.error("Internal error", th) ;
}
}
// ---- Operation lifecycle
/**
* Returns a fresh HTTP Action for this request.
* @param id the Request ID
* @param request HTTP request
* @param response HTTP response
* @return a new HTTP Action
*/
protected HttpAction allocHttpAction(long id, HttpServletRequest request, HttpServletResponse response) {
// Need a way to set verbose logging on a per servlet and per request basis.
return new HttpAction(id, request, response, verboseLogging) ;
}
/**
* Validates a HTTP Action.
* @param action HTTP Action
*/
protected abstract void validate(HttpAction action) ;
/**
* Performs the HTTP Action.
* @param action HTTP Action
*/
protected abstract void perform(HttpAction action) ;
/**
* Default start step.
* @param action HTTP Action
*/
protected void startRequest(HttpAction action) {
}
/**
* Default finish step.
* @param action HTTP Action
*/
protected void finishRequest(HttpAction action) { }
/**
* Archives the HTTP Action.
* @param action HTTP Action
* @see HttpAction#minimize()
*/
private void archiveHttpAction(HttpAction action)
{
action.minimize() ;
}
/**
* Executes common tasks, including mapping the request to the right dataset, setting the dataset into the HTTP
* action, and retrieving the service for the dataset requested. Finally, it calls the
* {@link #executeAction(HttpAction)} method, which executes the HTTP Action life cycle.
* @param action HTTP Action
*/
private void execCommonWorker(HttpAction action)
{
DatasetRef dsRef = null ;
String uri = action.request.getRequestURI() ;
String datasetUri = mapRequestToDataset(uri) ;
if ( datasetUri != null ) {
dsRef = DatasetRegistry.get().get(datasetUri) ;
if ( dsRef == null ) {
errorNotFound("No dataset for URI: "+datasetUri) ;
return ;
}
} else
dsRef = FusekiConfig.serviceOnlyDatasetRef() ;
action.setDataset(dsRef) ;
String serviceName = mapRequestToService(dsRef, uri, datasetUri) ;
ServiceRef srvRef = dsRef.getServiceRef(serviceName) ;
action.setService(srvRef) ;
executeAction(action) ;
}
/**
* Utility method, that increments and returns the AtomicLong value.
* @param x AtomicLong
*/
protected void inc(AtomicLong x)
{
x.incrementAndGet() ;
}
/**
* Executes the HTTP Action. Serves as intercept point for the UberServlet.
* @param action HTTP Action
*/
protected void executeAction(HttpAction action)
{
executeLifecycle(action) ;
}
/**
* Handles the service request lifecycle. Called directly by the UberServlet,
* which has not done any stats by this point.
* @param action {@link HttpAction}
* @see HttpAction
*/
protected void executeLifecycle(HttpAction action)
{
incCounter(action.dsRef, Requests) ;
incCounter(action.srvRef, Requests) ;
startRequest(action) ;
try {
validate(action) ;
} catch (ActionErrorException ex) {
incCounter(action.dsRef,RequestsBad) ;
throw ex ;
}
try {
perform(action) ;
// Success
incCounter(action.srvRef, RequestsGood) ;
incCounter(action.dsRef, RequestsGood) ;
} catch (ActionErrorException ex) {
incCounter(action.srvRef, RequestsBad) ;
incCounter(action.dsRef, RequestsBad) ;
throw ex ;
} catch (QueryCancelledException ex) {
incCounter(action.srvRef, RequestsBad) ;
incCounter(action.dsRef, RequestsBad) ;
throw ex ;
} finally {
finishRequest(action) ;
}
}
/**
* Increments a counter.
* @param counters a {@link Counter}
* @param name a {@link CounterName}
*/
protected static void incCounter(Counters counters, CounterName name) {
try {
if ( counters.getCounters().contains(name) )
counters.getCounters().inc(name) ;
} catch (Exception ex) {
Fuseki.serverLog.warn("Exception on counter inc", ex) ;
}
}
/**
* Decrements a counter.
* @param counters a {@link Counter}
* @param name a {@link CounterName}
*/
protected static void decCounter(Counters counters, CounterName name) {
try {
if ( counters.getCounters().contains(name) )
counters.getCounters().dec(name) ;
} catch (Exception ex) {
Fuseki.serverLog.warn("Exception on counter dec", ex) ;
}
}
/**
* Sends an error when the PATCH method is called.
* Throws ServletException or IOException as per overloaded method signature.
* @param request HTTP request
* @param response HTTP response
* @throws ServletException from overloaded method signature
* @throws IOException from overloaded method signature
*/
protected void doPatch(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "HTTP PATCH not supported");
}
/**
* Prints the HTTP Action request to the program log, using the INFO level.
* @param action {@link HttpAction}
*/
private void printRequest(HttpAction action)
{
String url = wholeRequestURL(action.request) ;
String method = action.request.getMethod() ;
log.info(format("[%d] %s %s", action.id, method, url)) ;
if ( action.verbose ) {
Enumeration en = action.request.getHeaderNames() ;
for (; en.hasMoreElements();) {
String h = en.nextElement() ;
Enumeration vals = action.request.getHeaders(h) ;
if (!vals.hasMoreElements())
log.info(format("[%d] %s", action.id, h)) ;
else {
for (; vals.hasMoreElements();)
log.info(format("[%d] %-20s %s", action.id, h, vals.nextElement())) ;
}
}
}
}
/**
* Initiates the response, by setting common headers such as Access-Control-Allow-Origin and Server, and
* the Vary header if the request method used was a GET.
* @param request HTTP request
* @param response HTTP response
*/
private void initResponse(HttpServletRequest request, HttpServletResponse response)
{
setCommonHeaders(response) ;
String method = request.getMethod() ;
// All GET and HEAD operations are sensitive to conneg so ...
if ( HttpNames.METHOD_GET.equalsIgnoreCase(method) || HttpNames.METHOD_HEAD.equalsIgnoreCase(method) )
setVaryHeader(response) ;
}
/**
* Prints the HTTP Action response to the program log, using the INFO level.
* @param action {@link HttpAction}
*/
private void printResponse(HttpAction action)
{
long time = action.getTime() ;
HttpServletResponseTracker response = action.response ;
if ( action.verbose )
{
if ( action.contentType != null )
log.info(format("[%d] %-20s %s", action.id, HttpNames.hContentType, action.contentType)) ;
if ( action.contentLength != -1 )
log.info(format("[%d] %-20s %d", action.id, HttpNames.hContentLengh, action.contentLength)) ;
for ( Map.Entry e: action.headers.entrySet() )
log.info(format("[%d] %-20s %s", action.id, e.getKey(), e.getValue())) ;
}
String timeStr = fmtMillis(time) ;
if ( action.message == null )
log.info(String.format("[%d] %d %s (%s) ", action.id, action.statusCode, HttpSC.getMessage(action.statusCode), timeStr)) ;
else
log.info(String.format("[%d] %d %s (%s) ", action.id, action.statusCode, action.message, timeStr)) ;
}
/**
* Given a time epoch, it will return the time in milli seconds if it is less than 1000,
* otherwise it will normalize it to display as second.
* It appends a 'ms' suffix when using milli seconds, and ditto s for seconds.
* For instance:
*
* - 10 emits 10 ms
* - 999 emits 999 ms
* - 1000 emits 1.000000 s
* - 10000 emits 10.000000 s
*
* @param time the time epoch
* @return the time in milli seconds or in seconds
*/
private static String fmtMillis(long time)
{
// Millis only? seconds only?
if ( time < 1000 )
return String.format("%,d ms", time) ;
return String.format("%,.3f s", time/1000.0) ;
}
/**
* Map request to uri in the registry. null means no mapping done (passthrough).
* @param uri the URI
* @return the dataset
*/
protected String mapRequestToDataset(String uri)
{
return mapRequestToDataset$(uri) ;
}
/**
* A possible implementation for mapRequestToDataset(String) that assumes the form /dataset/service.
* @param uri the URI
* @return the dataset
*/
protected static String mapRequestToDataset$(String uri)
{
// Chop off trailing part - the service selector
// e.g. /dataset/sparql => /dataset
int i = uri.lastIndexOf('/') ;
if ( i == -1 )
return null ;
if ( i == 0 )
{
// started with '/' - leave.
return uri ;
}
return uri.substring(0, i) ;
}
/**
* Maps a request to a service (e.g. Query, Update).
* @param dsRef a {@link DatasetRef}
* @param uri the URI
* @param datasetURI the dataset URI
* @return an empty String (i.e. "") if the DatasetRef is null, or if its name is longer than the URI's name.
* Otherwise will return the service name.
*/
protected String mapRequestToService(DatasetRef dsRef, String uri, String datasetURI)
{
if ( dsRef == null )
return "" ;
if ( dsRef.name.length() >= uri.length() )
return "" ;
return uri.substring(dsRef.name.length()+1) ; // Skip the separating "/"
}
/**
* Implementation of mapRequestToDataset(String) that looks for the longest match in the registry.
* This includes use in direct naming GSP.
* @param uri the URI
* @return null if the URI is null, otherwise will return the longest match in the registry.
*/
protected static String mapRequestToDatasetLongest$(String uri)
{
if ( uri == null )
return null ;
// This covers local, using the URI as a direct name for
// a graph, not just using the indirect ?graph= or ?default
// forms.
String ds = null ;
for ( String ds2 : DatasetRegistry.get().keys() ) {
if ( ! uri.startsWith(ds2) )
continue ;
if ( ds == null )
{
ds = ds2 ;
continue ;
}
if ( ds.length() < ds2.length() )
{
ds = ds2 ;
continue ;
}
}
return ds ;
}
}
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