c# - Downloading a dynamic file -

i creating file dynamically in web application. want send file user, many sites when download file.

i first tried approach @ download/stream file url - asp.net. didn't work because i'm in class that's layer removed aspx web page; result file overwrote itself, alternating unable create proper request/response objects.

then tried approach:

try {      webclient myclient = new webclient();     string basefile = path.getfilename( file_name );     myclient.downloadfile( file_name, basefile ); }     catch (webexception we) {         string message = we.message; } 

this raised exception: access path 'c:\program files (x86)\iis express\file-being-sent.ext' denied.

so, how stream file?

eta previous attempt:

    //create webrequest file     httpwebrequest filereq = (httpwebrequest)httpwebrequest.create( url ); //send request url      //create response request     httpwebresponse fileresp = (httpwebresponse)filereq.getresponse();      //if (filereq.contentlength > 0)     //    fileresp.contentlength = filereq.contentlength;      //get stream returned response     //stream = new stream();     writer = new streamwriter( file_name );     //stream = writer.basestream.length       // prepare response client. resp client response     var resp = httpcontext.current.response;      //indicate type of data being sent     //resp.contenttype = "application/octet-stream";     resp.contenttype = "application/zip";      //name file      resp.addheader( "content-disposition", "attachment; filename=\"" + path.getfilename( file_name ) + "\"" );     resp.addheader( "content-length", writer.basestream.length.tostring() );     // verify client connected.      if (resp.isclientconnected)     {         resp.write( writer );         resp.flush();     } 

i haven't figured out pass call httpcreaterequest().

eta2: here's i'm presently using. various sof posts should prompt user open or save dialog, still not me.

streamreader reader = new streamreader( file_name ); var resp = httpcontext.current.response;  //indicate type of data being sent resp.contenttype = "application/zip"; resp.appendheader( "content-disposition", "attachment; filename=\"" + path.getfilename( file_name ) + "\"" ); resp.appendheader( "content-length", reader.basestream.length.tostring() ); // verify client connected.  if (resp.isclientconnected) {     resp.clear();     resp.transmitfile( file_name ); //does not buffer memory, therefore scales better large files , heavy usage     resp.flush(); } 

eta3: iis trace log reports exception, system.web.httpexception: server cannot set content type after http headers have been sent. not make sense me, i'm setting content type before appending headers.

stack trace is:

[httpexception (0x80004005): server cannot set content type after http headers have been sent.] system.web.httpresponse.set_contenttype(string value) +9681570 system.web.httpresponseinternalwrapper.set_contenttype(string value) +41 system.web.ui.pagerequestmanager.renderpagecallback(htmltextwriter writer, control pagecontrol) +139 system.web.ui.control.renderchildreninternal(htmltextwriter writer, icollection children) +268 system.web.ui.control.renderchildren(htmltextwriter writer) +8 system.web.ui.page.render(htmltextwriter writer) +29 system.web.ui.control.rendercontrolinternal(htmltextwriter writer, controladapter adapter) +57 system.web.ui.control.rendercontrol(htmltextwriter writer, controladapter adapter) +100 system.web.ui.control.rendercontrol(htmltextwriter writer) +25 system.web.ui.page.processrequestmain(boolean includestagesbeforeasyncpoint, boolean includestagesafterasyncpoint) +1386 

eta4: moved streaming aspx page's code-behind file, has direct access response object. i'm still getting same exception. i'm @ loss explain why accepted approach complaining me response has been sent, or otherwise why code won't prompt user download file.

just move content type , header code after resp.clear()

using (streamreader reader = new streamreader( file_name )) {   var resp = httpcontext.current.response;   resp.bufferoutput = true; //this article   //resp.buffer = true;       //this msdn comments    // verify client connected.    if (resp.isclientconnected)   {     resp.clear();     resp.clearheaders();     //indicate type of data being sent     resp.contenttype = "application/zip";     resp.appendheader( "content-disposition", "attachment; filename=\"" + path.getfilename( file_name ) + "\"" );     resp.appendheader( "content-length", reader.basestream.length.tostring() );     resp.transmitfile( file_name ); //does not buffer memory, therefore scales better large files , heavy usage     resp.end();   } }