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 Foundatiion; 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 Atmospheric 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::endl ;
00042 using std::string ;
00043 
00044 #include "BESStreamResponseHandler.h"
00045 #include "BESRequestHandlerList.h"
00046 #include "BESHandlerException.h"
00047 #include "BESDataNames.h"
00048 #include "BESContainer.h"
00049 
00050 #define BES_STREAM_BUFFER_SIZE 4096
00051 
00052 BESStreamResponseHandler::BESStreamResponseHandler( const string &name )
00053     : BESResponseHandler( name )
00054 {
00055 }
00056 
00057 BESStreamResponseHandler::~BESStreamResponseHandler( )
00058 {
00059 }
00060 
00073 void
00074 BESStreamResponseHandler::execute( BESDataHandlerInterface &dhi )
00075 {
00076     _response = 0 ;
00077 
00078     // What if there is a special way to stream back a data file?
00079     // Should we pass this off to the request handlers and put
00080     // this code into a different class for reuse? For now
00081     // just keep it here. pcw 10/11/06
00082 
00083     // I thought about putting this in the transmit method below
00084     // but decided that this is like executing a non-buffered
00085     // request, so kept it here. Plus the idea expressed above
00086     // led me to leave the code in the execute method.
00087     // pcw 10/11/06
00088     if( dhi.containers.size() != 1 )
00089     {
00090         string err = (string)"Unable to stream file: "
00091                      + "no container specified" ;
00092         throw BESHandlerException( err, __FILE__, __LINE__ ) ;
00093     }
00094 
00095     dhi.first_container() ;
00096     BESContainer *container = dhi.container ;
00097     string filename = container->access() ;
00098     if( filename.empty() )
00099     {
00100         string err = (string)"Unable to stream file: "
00101                      + "filename not specified" ;
00102         throw BESHandlerException( err, __FILE__, __LINE__ ) ;
00103     }
00104 
00105     int bytes = 0 ;
00106     ifstream os ;
00107     os.open( filename.c_str(), ios::in ) ;
00108     if( !os )
00109     {
00110         string err = (string)"Unable to stream file: "
00111                      + "can not open file "
00112                      + filename ;
00113         throw BESHandlerException( err, __FILE__, __LINE__ ) ;
00114     }
00115 
00116     int nbytes ;
00117     char block[BES_STREAM_BUFFER_SIZE] ;
00118     os.read( block, sizeof block ) ;
00119     nbytes = os.gcount() ;
00120     while( nbytes )
00121     {
00122         bytes += nbytes ;
00123         dhi.get_output_stream().write( (char*)block, nbytes ) ;
00124         os.read( block, sizeof block ) ;
00125         nbytes = os.gcount() ;
00126     }
00127     os.close() ;
00128 }
00129 
00138 void
00139 BESStreamResponseHandler::transmit( BESTransmitter *transmitter,
00140                                  BESDataHandlerInterface & )
00141 {
00142     // The Data is transmitted when it is read, dumped to stdout
00143 }
00144 
00151 void
00152 BESStreamResponseHandler::dump( ostream &strm ) const
00153 {
00154     strm << BESIndent::LMarg << "BESStreamResponseHandler::dump - ("
00155                              << (void *)this << ")" << endl ;
00156     BESIndent::Indent() ;
00157     BESResponseHandler::dump( strm ) ;
00158     BESIndent::UnIndent() ;
00159 }
00160 
00161 BESResponseHandler *
00162 BESStreamResponseHandler::BESStreamResponseBuilder( const string &name )
00163 {
00164     return new BESStreamResponseHandler( name ) ;
00165 }
00166 

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