BESStreamResponseHandler.cc

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00001 // BESStreamResponseHandler.cc
00002 
00003 // This file is part of bes, A C++ back-end server implementation framework
00004 // for the OPeNDAP Data Access Protocol.
00005 
00006 // Copyright (c) 2004,2005 University Corporation for Atmospheric Research
00007 // Author: Patrick West <pwest@ucar.edu> and Jose Garcia <jgarcia@ucar.edu>
00008 //
00009 // This library is free software; you can redistribute it and/or
00010 // modify it under the terms of the GNU Lesser General Public
00011 // License as published by the Free Software Foundation; either
00012 // version 2.1 of the License, or (at your option) any later version.
00013 // 
00014 // This library is distributed in the hope that it will be useful,
00015 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00016 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017 // Lesser General Public License for more details.
00018 // 
00019 // You should have received a copy of the GNU Lesser General Public
00020 // License along with this library; if not, write to the Free Software
00021 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00022 //
00023 // You can contact University Corporation for Atmospheric Research at
00024 // 3080 Center Green Drive, Boulder, CO 80301
00025  
00026 // (c) COPYRIGHT University Corporation for Atmostpheric Research 2004-2005
00027 // Please read the full copyright statement in the file COPYRIGHT_UCAR.
00028 //
00029 // Authors:
00030 //      pwest       Patrick West <pwest@ucar.edu>
00031 //      jgarcia     Jose Garcia <jgarcia@ucar.edu>
00032 
00033 #include <iostream>
00034 #include <fstream>
00035 #include <string>
00036 #include <unistd.h>
00037 #include <stdio.h>
00038 
00039 using std::ifstream ;
00040 using std::ios ;
00041 using std::cerr ;
00042 using std::endl ;
00043 using std::string ;
00044 
00045 #include "BESStreamResponseHandler.h"
00046 #include "BESRequestHandlerList.h"
00047 #include "BESHandlerException.h"
00048 #include "BESDataNames.h"
00049 #include "BESContainer.h"
00050 
00051 #define BES_STREAM_BUFFER_SIZE 4096
00052 
00053 BESStreamResponseHandler::BESStreamResponseHandler( string name )
00054     : BESResponseHandler( name )
00055 {
00056 }
00057 
00058 BESStreamResponseHandler::~BESStreamResponseHandler( )
00059 {
00060 }
00061 
00074 void
00075 BESStreamResponseHandler::execute( BESDataHandlerInterface &dhi )
00076 {
00077     _response = 0 ;
00078 
00079     // What if there is a special way to stream back a data file?
00080     // Should we pass this off to the request handlers and put
00081     // this code into a different class for reuse? For now
00082     // just keep it here. pcw 10/11/06
00083 
00084     // I thought about putting this in the transmit method below
00085     // but decided that this is like executing a non-buffered
00086     // request, so kept it here. Plus the idea expressed above
00087     // led me to leave the code in the execute method.
00088     // pcw 10/11/06
00089     if( dhi.containers.size() != 1 )
00090     {
00091         string err = (string)"Unable to stream file: "
00092                      + "no container specified" ;
00093         throw BESHandlerException( err, __FILE__, __LINE__ ) ;
00094     }
00095 
00096     dhi.first_container() ;
00097     BESContainer *container = dhi.container ;
00098     string filename = container->access() ;
00099     if( filename.empty() )
00100     {
00101         string err = (string)"Unable to stream file: "
00102                      + "filename not specified" ;
00103         throw BESHandlerException( err, __FILE__, __LINE__ ) ;
00104     }
00105 
00106     int bytes = 0 ;
00107     ifstream os ;
00108     os.open( filename.c_str(), ios::in ) ;
00109     if( !os )
00110     {
00111         string err = (string)"Unable to stream file: "
00112                      + "can not open file "
00113                      + filename ;
00114         throw BESHandlerException( err, __FILE__, __LINE__ ) ;
00115     }
00116 
00117     int nbytes ;
00118     int fd = fileno( stdout ) ;
00119     char block[BES_STREAM_BUFFER_SIZE] ;
00120     os.read( block, sizeof block ) ;
00121     nbytes = os.gcount() ;
00122     while( nbytes )
00123     {
00124         bytes += nbytes ;
00125         int written = write( fd, (void*)block, nbytes ) ;
00126         os.read( block, sizeof block ) ;
00127         nbytes = os.gcount() ;
00128     }
00129     os.close() ;
00130 }
00131 
00140 void
00141 BESStreamResponseHandler::transmit( BESTransmitter *transmitter,
00142                                  BESDataHandlerInterface & )
00143 {
00144     // The Data is transmitted when it is read, dumped to stdout
00145 }
00146 
00153 void
00154 BESStreamResponseHandler::dump( ostream &strm ) const
00155 {
00156     strm << BESIndent::LMarg << "BESStreamResponseHandler::dump - ("
00157                              << (void *)this << ")" << endl ;
00158     BESIndent::Indent() ;
00159     BESResponseHandler::dump( strm ) ;
00160     BESIndent::UnIndent() ;
00161 }
00162 
00163 BESResponseHandler *
00164 BESStreamResponseHandler::BESStreamResponseBuilder( string handler_name )
00165 {
00166     return new BESStreamResponseHandler( handler_name ) ;
00167 }
00168 

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