System.Net.WebClient.DownloadFile doesn't work with http attachments

[A.M-SG]

Hi,

I have an aspx page at the web server that provides PDF documents for smart
client applications.

Here is the code in aspx page that defines content type:

Response.ContentType = "application/octet-stream";
Response.AppendHeader("Content-Disposition",
"attachment;filename=test.pdf");

I tested the aspx page by using browser and it works just fine.

Now I need to receive that file by using the
System.Net.WebClient.DownloadFile. The problem is that DownloadFile method
returns the following exception:

"Unable to read data from the transport connection: The connection was
closed."

I tested the DownloadFile method to open a direct pdf file like the
following statement:

(new
System.Net.WebClient()).DownloadFile(http://localhost/test.pdf,"c:\\test.pdf");

It works just fine.

How can I use System.Net.WebClient. DownloadFile to download http
attachments?

Any help would be apprecited,
Alan

 

[Kevin Spencer]

The answer is in your question, but you may not recognize it.

An HTTP Request is for a single resource, identified by the URL of the
resource, or in the case of the WebClient, a URI plus a file descriptor. You
have an ASPX page that returns a file with a couple of special Response
Headers in it. Those Response Headers read:

Response.ContentType = "application/octet-stream";

Response.AppendHeader("Content-Disposition",

"attachment;filename=test.pdf");

This header indicates that the client should prompt the client to make a
second request for the file descriptor specified (text.pdf), and that the
Content-Type of that file is binary.

So, what you have to do is read the Response Headers, and make a second
request for that file specified.

IETF RFC 1806 has a detailed explanation of this Response Header:

http://www.ietf.org/rfc/rfc1806.txt

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
A watched clock never boils.