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 
00037 using std::ifstream ;
00038 using std::ios ;
00039 using std::endl ;
00040 using std::string ;
00041 
00042 #include "BESStreamResponseHandler.h"
00043 #include "BESRequestHandlerList.h"
00044 #include "BESNotFoundError.h"
00045 #include "BESInternalError.h"
00046 #include "BESDataNames.h"
00047 #include "BESContainer.h"
00048 
00049 #define BES_STREAM_BUFFER_SIZE 4096
00050 
00051 BESStreamResponseHandler::BESStreamResponseHandler( const string &name )
00052     : BESResponseHandler( name )
00053 {
00054 }
00055 
00056 BESStreamResponseHandler::~BESStreamResponseHandler( )
00057 {
00058 }
00059 
00070 void
00071 BESStreamResponseHandler::execute( BESDataHandlerInterface &dhi )
00072 {
00073     _response = 0 ;
00074 
00075     // What if there is a special way to stream back a data file?
00076     // Should we pass this off to the request handlers and put
00077     // this code into a different class for reuse? For now
00078     // just keep it here. pcw 10/11/06
00079 
00080     // I thought about putting this in the transmit method below
00081     // but decided that this is like executing a non-buffered
00082     // request, so kept it here. Plus the idea expressed above
00083     // led me to leave the code in the execute method.
00084     // pcw 10/11/06
00085     if( dhi.containers.size() != 1 )
00086     {
00087         string err = (string)"Unable to stream file: "
00088                      + "no container specified" ;
00089         throw BESInternalError( err, __FILE__, __LINE__ ) ;
00090     }
00091 
00092     dhi.first_container() ;
00093     BESContainer *container = dhi.container ;
00094     string filename = container->access() ;
00095     if( filename.empty() )
00096     {
00097         string err = (string)"Unable to stream file: "
00098                      + "filename not specified" ;
00099         throw BESInternalError( err, __FILE__, __LINE__ ) ;
00100     }
00101 
00102     int bytes = 0 ;
00103     ifstream os ;
00104     os.open( filename.c_str(), ios::in ) ;
00105     if( !os )
00106     {
00107         string err = (string)"Unable to stream file: "
00108                      + "can not open file "
00109                      + filename ;
00110         throw BESNotFoundError( err, __FILE__, __LINE__ ) ;
00111     }
00112 
00113     int nbytes ;
00114     char block[BES_STREAM_BUFFER_SIZE] ;
00115     os.read( block, sizeof block ) ;
00116     nbytes = os.gcount() ;
00117     while( nbytes )
00118     {
00119         bytes += nbytes ;
00120         dhi.get_output_stream().write( (char*)block, nbytes ) ;
00121         os.read( block, sizeof block ) ;
00122         nbytes = os.gcount() ;
00123     }
00124     os.close() ;
00125 }
00126 
00134 void
00135 BESStreamResponseHandler::transmit( BESTransmitter *transmitter,
00136                                     BESDataHandlerInterface &dhi )
00137 {
00138     // The Data is transmitted when it is read, dumped to stdout, so there is nothing
00139     // to transmot here.
00140 }
00141 
00148 void
00149 BESStreamResponseHandler::dump( ostream &strm ) const
00150 {
00151     strm << BESIndent::LMarg << "BESStreamResponseHandler::dump - ("
00152                              << (void *)this << ")" << endl ;
00153     BESIndent::Indent() ;
00154     BESResponseHandler::dump( strm ) ;
00155     BESIndent::UnIndent() ;
00156 }
00157 
00158 BESResponseHandler *
00159 BESStreamResponseHandler::BESStreamResponseBuilder( const string &name )
00160 {
00161     return new BESStreamResponseHandler( name ) ;
00162 }
00163 

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