Re: NSURLConnection and resumes
Re: NSURLConnection and resumes
- Subject: Re: NSURLConnection and resumes
- From: Frederick Cheung <email@hidden>
- Date: Thu, 7 Oct 2004 08:32:57 +0100
On 7 Oct 2004, at 04:10, Rudi Sherry wrote:
If the server accepts byte-range requests you could add a Range header
to the request; here's a sample:
[ URLRequest setValue: @"bytes=100032-433566" forHTTPHeaderField:
@"Range" ];
.. assuming you know how large the file is. The first number is the
byte offset from the beginning of the file and the second number is
the last byte offset that you'll receive (remember that it's
inclusive, so the last byte index is one less than the length of the
file).
If the server allows byte-range requests, you'll probably get a
multi-part message with one part; if the server doesn't support them,
you'll get the entire file.
You can also specify the range "bytes=123123-" to indicate that you
wish that you want to start at the specified offset and continue to the
end of the file. The ability to resume may be indicated via an
Accept-Ranges: bytes header (or explicitly denied with Accept-Ranges:
none)
The rfc says that servers must not send multi-part message unless that
client has indicated that it can receive it. (a range request with
multiple parts implies this, eg bytes=123-567,789-1234), although I
have on rare occasions seen software that does.
One should check the Content-Range header to verify that the server has
complied with the request. I have also seen servers who refuse to use a
Range header when there is not an If-Range header
Fred
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