When can I delete a file after using it in Response.WriteFile()?

Question

Is the WriteFile call properly synchronous, and can I delete the file written immediately after the call?

Answer 1

If memory serves it is synchronous, as are the rest of the RESPONSE commands.

Answer 2

If you're writing a file to the client with Response.WriteFile(), a call to Response.Flush() will make sure it's been fully output to the client. Once that's done you can delete it off of the webserver.

You may want to come up with a more robust system if the file is mission-critical. Say, a client-side script to validate that the file was received OK and then alerts the webserver that the file can be deleted.

Answer 3

TransmitFile

You can also call TransmitFile to let IIS take care of it. It actually gets sent by IIS outside of your worker processs.

Memory Stream

If you are REALLY paranoid, don't send the file. Load it into a memory stream (if the size is reasonable) and transmit that. Then you can delete the file whenever you like. The file on disk will never be touched by IIS.

Answer 4

That is the solution, after use the syntax Response.WriteFile(fileName);, type the following code lines:

Response.Flush();
System.IO.File.Delete(fullPathFileName);
Response.End();

Answer 5

It is fully synchronous, as you can see by looking at the implementation of HttpResponse.WriteFile with Lutz Reflector. You can delete the file immediately after the call to Response.WriteFile.

You don't have the guarantee that the response stream has been completely transmitted to the client, but calling Response.Flush doesn't give you that guarantee either. So I don't see a need to call Response.Flush before deleting the file.

Avoid loading the file into a MemoryStream, it brings you no benefit, and has a cost in memory usage, especially for large files.