C# - Download files from FTP which have higher last-modified date -

i have ftp server files. have same files in in local directory (in c:\).

when i'll run program, i'd searches files in ftp server have last-modified timestamp later same file (equal name) in local directory , download files founded.

can give me or tip, please? i'll appreciate answers!

unfortunately, there's no reliable , efficient way retrieve timestamps using features offered .net framework not support ftp mlsd command. mlsd command provides listing of remote directory in standardized machine-readable format. command , format standardized rfc 3659.

alternatives can use supported .net framework:

• the listdirectorydetails method (the ftp list command) retrieve details of files in directory , deal ftp server specific format of details (*nix format similar ls *nix command common, drawback format may change on time, newer files "may 8 17:48" format used , older files "oct 18 2009" format used).

  examples:
  dos/windows format: c# class parse webrequestmethods.ftp.listdirectorydetails ftp response
  *nix format: parsing ftpwebrequest listdirectorydetails line

• the getdatetimestamp method (an ftp mdtm command) individually retrieve timestamps each file. advantage response standardized rfc 3659 yyyymmddhhmmss[.sss]. disadvantage have send separate request each file, can quite inefficient.

  const string uri = "ftp://example.com/remote/path/file.txt"; ftpwebrequest request = (ftpwebrequest)webrequest.create(uri); request.method = webrequestmethods.ftp.getdatetimestamp; ftpwebresponse response = (ftpwebresponse)request.getresponse(); console.writeline("{0} {1}", uri, response.lastmodified); 

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alternatively can use 3rd party ftp client implementation supports modern mlsd command.

for example winscp .net assembly supports that.

you can use session.listdirectory or session.enumerateremotefiles methods , read remotefileinfo.lastwritetime of files in returned collection.

or easier, can use session.synchronizedirectories have library automatically download (synchronize) modified files:

// setup session options sessionoptions sessionoptions = new sessionoptions {     protocol = protocol.ftp,     hostname = "ftp.example.com",     username = "user",     password = "mypassword", };  using (session session = new session()) {     // connect     session.open(sessionoptions);      // synchronize files     session.synchronizedirectories(         synchronizationmode.local, @"d:\www", "/home/martin/public_html", false).check(); } 

(i'm author of winscp)