[REBOL] FTP large files (Answering my own question)
From: doug::vos::eds::com at: 5-Apr-2002 15:28
About FTP of large files.
Here is a quote from the rebol documetation...
(sorry I did not read...)
Transferring Large Files
Transferring large files requires special considerations. You may want to
transfer the file in chunks to reduce the memory required by your computer
and to provide user feedback while the transfer is happening.
Here is an example that downloads a very large binary file in chunks.
inp: open/binary/direct ftp://ftp.site.com/big-file.bmp
out: open/binary/new/direct %big-file.bmp
buf-size: 200000
buffer: make binary! buf-size + 2
while [not zero? size: read-io inp buffer buf-size][
write-io out buffer size
total: total + size
print ["transferred:" total]
]
Be sure to use the /direct refinement, otherwise the entire file will be
buffered internally by REBOL. The read-io and write-io functions allow reuse
of the buffer memory that has already allocated. Other functions such as
copy would allocate additional memory.
If the transfer fails, you can restart FTP from where it left off. To do so,
examine the output file or the size variable to determine where to restart
the transfer. Open the file again with a custom refinement that specifies
restart and the location from which to start the read. Here is an example of
the open function to use when the total variable indicates the length
already read:
inp: open/binary/direct/custom
ftp://ftp.site.com/big-file.bmp
reduce ['restart total]
You should note that restart only works for binary transfers. It cannot be
used with text transfers because the line terminator conversion that takes
place will cause incorrect offsets.
