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[DeleGate-En] Re: Are broken downloads stored in cache?
17 Mar 1999 03:09:01 GMT (Yutaka Sato)

On 03/11/99(23:07) you "=?ISO-8859-2?Q?S=F7ltormos_Csaba?=" <> wrote
in <_A335@delegate-en.ML_>
 |One of my clients started to download a big 67M .zip file from ibm,
 |(Visual Age for Java, I think), but the connection timed out at 57M.:((
 |Next day he started again the download, hoping that the 57M will
 |come from the cache. But it isn't! 
 |So, my question is: are broken downloads stored in the cache, or not?

DeleGate erases a cache file if it seems be broken, typically when
the size of received data is smaller than that shown in Content-Length
header field of HTTP protocol or the response message for RETR command
of FTP protocol.

 |If so, then what is the reason we don't have it in the cache....

In general, broken data is useless and can be harmful for clients.
In most protocols, clients cannot know if the data is broken or not,
they don't have a method to "reload" correct data even if they know
the data is broken (except in HTTP), and they don't have method to
download remaining part of data.  Thus if broken data is left in
cache, clients will reuse it without knowing it's broken, or without
method to reload correct data.

 |I looked at the http logfile. There something like "FTP/HTTP gateway opened"
 |and there is a line containing "XFERLOG:", which I see before this only in the 
 |ftp log files.

"XFERLOG" will be logged when FTP server is accessed.

Yutaka Sato <>   @ @ 
Computer Science Division, Electrotechnical Laboratory      ( - )
1-1-4 Umezono, Tsukuba, Ibaraki, 305-8568 Japan            _<   >_

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