Mailing List Archive

On Tuesday 12 October 2004 10:31 am, Hareesh Nagarajan wrote:
> Hi,
>
> If a client asked an HTTP 1.0 server to send it a jpeg file, then does
> the server send it as it is, or does the server perform some encoding
> on the file and then send the encoded data? If so what kind of
> encoding is it? I continue to remain unsure despite having read the
> RFC.

a jpeg is a *binary* file, encodings are performed on text files, not binary.

regards,
Christian Parpart.

--
Netiquette: http://www.ietf.org/rfc/rfc1855.txt
11:05:28 up 48 days, 22:45, 1 user, load average: 0.01, 0.12, 0.12

>>If a client asked an HTTP 1.0 server to send it a jpeg file, then does
>>the server send it as it is, or does the server perform some encoding
>>on the file and then send the encoded data? If so what kind of
>>encoding is it? I continue to remain unsure despite having read the
>>RFC.
>
>
> a jpeg is a *binary* file, encodings are performed on text files, not binary.

True, jpegs are binary, but HTTP is a text protocol, so binaries are
encoded into MIME, which is text. Try telnetting to port 80 and issuing
"GET / HTTP/1.0" (then hit return twice). Or maybe "GET /someimage.jpg
HTTP/1.0" and see what pops out.

Rgs,
Adam


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gentoo-user@gentoo.org mailing list

> True, jpegs are binary, but HTTP is a text protocol, so binaries are
> encoded into MIME, which is text. Try telnetting to port 80 and issuing
> "GET / HTTP/1.0" (then hit return twice). Or maybe "GET /someimage.jpg
> HTTP/1.0" and see what pops out.

I tried to get that Yahoo! Logo which is in GIF. There appears to be
no encoding. When is base64 encoding used in HTTP/1.0?

IMAGE: http://us.i1.yimg.com/us.yimg.com/i/ww/m6v8c.gif

<telnet>
hareesh: 1/ $ telnet us.i1.yimg.com 80
Trying 69.225.175.73...
Connected to us.i1.yimg.com.
Escape character is '^]'.
GET /us.yimg.com/i/ww/m6v8c.gif HTTP/1.0

HTTP/1.0 200 OK
Content-Type: image/gif
Content-Length: 7875
Last-Modified: Fri, 15 Apr 1994 00:00:00 GMT
Date: Tue, 12 Oct 2004 14:47:12 GMT
Connection: close
Expires: Thu, 15 Apr 2010 20:00:00 GMT

GIF89....binary data.....
</telnet>

Thanks,
--
Hareesh Nagarajan
WEB: http://puggy.symonds.net/~hareesh

--
gentoo-user@gentoo.org mailing list

Adam Carter wrote:

> True, jpegs are binary, but HTTP is a text protocol, so binaries are
> encoded into MIME, which is text. Try telnetting to port 80 and issuing
> "GET / HTTP/1.0" (then hit return twice). Or maybe "GET /someimage.jpg
> HTTP/1.0" and see what pops out.

MIME is a way to send data across a data path which might not understand
binary data. However, that doesn't mean you *have* to encode the data.
encoding can be "none", and normally is under HTTP. The http server will
tag the data with a mime-type, so the receiving application has a clue
what to do with the data once it gets it... unless you use IE in which
case it ignores mime-type and just uses the extension.

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gentoo-user@gentoo.org mailing list

Billy wrote:
> The http server will
> tag the data with a mime-type, so the receiving application has a clue
> what to do with the data once it gets it... unless you use IE in which
> case it ignores mime-type and just uses the extension.

During my web-design days I had an account on one of those
free-hosting-but-insert-add web sites which modified your html. Do get
over that I renamed all the .html files to .jpg and uploaded onto the
server. IIRC IE could display just fine the web page. So it can't ignore
the mime-type.


--

Adi

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gentoo-user@gentoo.org mailing list

On Tue, 12 Oct 2004 18:16:56 +0300, Adrian CAPDEFIER
<adriancapdefier@digifin.ro> wrote:
> During my web-design days I had an account on one of those
> free-hosting-but-insert-add web sites which modified your html. Do get
> over that I renamed all the .html files to .jpg and uploaded onto the
> server. IIRC IE could display just fine the web page. So it can't ignore
> the mime-type.

IE used to use a rather complicated process to work out the content
type of a file was. The file extension and sniffing the data itself
were involved. I believe the XP SP2 disabled all that sniffing.

--
David Dorward <http://dorward.me.uk><http://blog.dorward.me.uk>

--
gentoo-user@gentoo.org mailing list

Adrian CAPDEFIER wrote:

> During my web-design days I had an account on one of those
> free-hosting-but-insert-add web sites which modified your html. Do get
> over that I renamed all the .html files to .jpg and uploaded onto the
> server. IIRC IE could display just fine the web page. So it can't ignore
> the mime-type.

I could have sworn I've seen IE ignore mime types, but you're right. I
made a web script to test it, and sure enough, IE will happily open a
jpeg file as an application/msword document, and it will try as hard as
it can to display a real word document as an image/jpeg.


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gentoo-user@gentoo.org mailing list

On 12 Oct 2004, at 03:29, Adam Carter wrote:
>>> If a client asked an HTTP 1.0 server to send it a jpeg file, then
>>> does
>>> the server send it as it is, or does the server perform some encoding
>>> on the file and then send the encoded data? If so what kind of
>>> encoding is it? I continue to remain unsure despite having read the
>>> RFC.
>> a jpeg is a *binary* file, encodings are performed on text files, not
>> binary.
>
> True, jpegs are binary, but HTTP is a text protocol, so binaries are
> encoded into MIME, which is text. Try telnetting to port 80 and
> issuing "GET / HTTP/1.0" (then hit return twice). Or maybe "GET
> /someimage.jpg HTTP/1.0" and see what pops out.

False. Binary data transferred over HTTP are not encoded in any fashion.