/*
Copyright (C) 2005-2012, by the President and Fellows of Harvard College.
Licensed 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.
Dataverse Network - A web application to share, preserve and analyze research data.
Developed at the Institute for Quantitative Social Science, Harvard University.
Version 3.0.
*/
/*
* CensusRepositoryServlet.java
*
* Created on November 17, 2007, 2:23 PM
*
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
*/
package edu.harvard.iq.dvn.core.web.servlet;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.WritableByteChannel;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import javax.annotation.Resource;
import javax.ejb.EJB;
import javax.ejb.EJBException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;
/**
*
* @author leonid
* @version
*/
public class CensusRepositoryServlet extends HttpServlet{
/** Creates a new instance of CensusRepositoryServlet */
public CensusRepositoryServlet() {
}
@Resource(name="jdbc/VDCNetDS") DataSource dvnDatasource;
public void service(HttpServletRequest req, HttpServletResponse res) {
// no parameters supported,
// for now
Connection sqlConn = null;
PreparedStatement sth = null;
boolean[] categoryMap = null;
ResultSet dbIds = null;
// attempt to get a list of all local, publicly-available,
// subsettable datafiles from the database.
//
// on SQL failures, print a clear error page and send a
// standard "Service Temporarily Unavailable" status code.
try {
// Here's what I'm doing with the SQL searches:
//
// A datafile can be restricted in more ways than one;
// it can have its own "restricted" flag set, OR it can
// be part of a restricted study, which in turn can be part
// of a restricted Dataverse.
// So, if we need to do this on a single datafile, we first
// retreive the file's studyfile entry and check the restricted
// flag; then we retreive the filecategory to which the file
// then the study to which the filecategory belongs -- and now
// we can check the study's own restriction flag. Then we find
// the owner Dataverse for the study, and check if that is
// restricted. However, now that we need to retreive ALL the
// unrestricted datafiles, we cannot possibly do it this way
// -- it would take forever to run 4 SQL queries for every
// matching datafile we find in the studyfile table!
// So this is how I'm doing it: I first find all unrestricted
// dataverses; then I find all unrestricted studies, with the
// corresponding dataverse ids and filter the list against the list
// of unrestricted dataversese from step 1; now I have a list (map)
// of studies that are unrestricted AND are not part of a
// restricted dataverse; then I generate a list of all
// filecategories in these studies (file categories cannot be
// restricted!). And now I can run the final search for all
// unrestricted subsettable datafiles and filter the list against
// the unrestricted filecategoris from the previous step.
// There's only 4 SQL queries total; the drawback of this approach
// is that I have to carry around these bit maps of higher-level
// objects that are not restricted. However, these are only
// arrays of boolean values, so they should be manageable even if
// our archive grows significantly.
String sqlCmd= "SELECT id,filecategory_id from studyfile WHERE restricted = false AND subsettable = true AND NOT (filesystemlocation LIKE 'http%')";
sqlConn = dvnDatasource.getConnection();
sth = sqlConn.prepareStatement(sqlCmd);
dbIds = sth.executeQuery();
categoryMap = generateCategoryMap();
} catch(SQLException e) {
createErrorResponseGeneric(res, res.SC_SERVICE_UNAVAILABLE,
"Database services temporarily unavailable: " +
"Could not execute SQL statement" );
e.printStackTrace();
return;
}
//
// iterate through the list we received in response to the database
// query and print a list of FileDownload URLs.
// catch possible exceptions.
String fileId = null;
String hostHttpPrefix = null;
String lineOut = null;
PrintWriter out = null;
if ( req.getServerPort() != 80 ) {
hostHttpPrefix = req.getScheme() +"://" + req.getServerName() + ":" + req.getServerPort() + req.getContextPath();
} else {
hostHttpPrefix = req.getScheme() +"://" + req.getServerName() + req.getContextPath();
}
int categoryId = 0;
try {
res.setHeader ( "Content-Type", "text/plain;charset=ISO-8859-1" );
//OutputStream out = res.getOutputStream();
out = res.getWriter();
out.println ("available unrestricted subsettable datafiles:\n");
try {
while (dbIds.next()) {
categoryId = dbIds.getInt(2);
if ( categoryMap[categoryId] ) {
fileId = dbIds.getString(1);
lineOut = hostHttpPrefix + "/FileDownload/?fileId=" + fileId;
out.println (lineOut);
}
}
sqlConn.close();
} catch (SQLException e) {
createErrorResponseGeneric(res, res.SC_SERVICE_UNAVAILABLE,
"Database services temporarily unavailable: " +
"Could not retreive data from SQL Database" );
e.printStackTrace();
}
out.close();
} catch (IOException ex) {
if ( out != null ) {
out.close();
}
ex.printStackTrace();
}
// the end.
}
private void createErrorResponseGeneric(HttpServletResponse res, int status, String statusLine) {
res.setContentType("text/html");
res.setStatus ( status );
try {
PrintWriter out = res.getWriter();
out.println("<HTML>");
out.println("<HEAD><TITLE>Census Servlet</TITLE></HEAD>");
out.println("<BODY>");
out.println("<BIG>" + statusLine + "</BIG>");
if (status == res.SC_NOT_FOUND) {
for (int i = 0; i < 10; i++) {
out.println("<!-- This line is filler to handle IE case for 404 errors -->");
}
}
out.println("</BODY></HTML>");
} catch (IOException ex) {
ex.printStackTrace();
}
}
private boolean[] generateCategoryMap () throws SQLException {
boolean[] categoryMap = new boolean[128*1024];
boolean[] studyMap = generateStudyMap();
int catId = 0;
int studyId = 0;
int i = 0;
String sqlCmd= "SELECT id,study_id from filecategory ORDER BY id";
Connection sqlConn = dvnDatasource.getConnection();
PreparedStatement sth = sqlConn.prepareStatement(sqlCmd);
ResultSet rs = sth.executeQuery();
while (rs.next()) {
catId = rs.getInt(1);
studyId = rs.getInt(2);
while ( i < catId ) {
categoryMap[i++] = false;
}
if ( studyMap[studyId] ) {
categoryMap[catId] = true;
} else {
categoryMap[catId] = false;
}
i++;
}
sqlConn.close();
return categoryMap;
}
private boolean[] generateStudyMap () throws SQLException {
boolean[] studyMap = new boolean[32*1024];
boolean[] dvMap = generateDataverseMap();
int studyId = 0;
int dvId = 0;
int i = 0;
String sqlCmd= "SELECT id,owner_id from study WHERE restricted = false ORDER BY id";
Connection sqlConn = dvnDatasource.getConnection();
PreparedStatement sth = sqlConn.prepareStatement(sqlCmd);
ResultSet rs = sth.executeQuery();
while (rs.next()) {
studyId = rs.getInt(1);
dvId = rs.getInt(2);
while ( i < studyId ) {
studyMap[i++] = false;
}
if ( dvMap[dvId] ) {
studyMap[studyId] = true;
} else {
studyMap[studyId] = false;
}
i++;
}
sqlConn.close();
return studyMap;
}
private boolean[] generateDataverseMap () throws SQLException {
boolean[] dvMap = new boolean[256];
int dvId = 0;
int i = 0;
String sqlCmd= "SELECT id from vdc WHERE restricted = false ORDER BY id";
Connection sqlConn = dvnDatasource.getConnection();
PreparedStatement sth = sqlConn.prepareStatement(sqlCmd);
ResultSet rs = sth.executeQuery();
while (rs.next()) {
dvId = rs.getInt(1);
while ( i < dvId ) {
dvMap[i++] = false;
}
dvMap[dvId] = true;
i++;
}
sqlConn.close();
return dvMap;
}
}