Ftp zlib compression

Ftp.dll FTP component supports zlib compression for all data transfers.

What is zlib

zlib is a compression method which can greatly decrease the size of data, similar to popular compression format – Zip.

How to use zlib

zlib can be used with Ftp.dll FTP/FTPS component thanks to the newly implemented MODE Z command. This command and format have been already adopted by popular FTP servers.

Ftp.dll automatically turns compression on, if it is supported by FTP server. zlib compression is transparent to users. It is activeted using MODE Z command. Once sent, client sends and receives compressed data, so all directory listings and file exchanges between server and client will be compressed.

What is the benefit?

Faster data transfers! Directory listing, which is text, can be highly compressed with zlib thus boosting the server and client network speed and reactivity.

Transfers of html, scripts or large logfiles (which are text) no longer needs to be zipped before being sent via ftp and should generally experience a 3-4 times gain in data transfers.

For example, a 60MB log file can turn into a 5MB data exchange when transferred with MODE Z enabled.

Depending on the file content, you will see different results:

  • Text files : ~15-20% of original size.
  • Html files : ~25-30% of original size.
  • Media, video, sound : ~90-95% of original size.
  • Already compressed documents with Zip, Rar, Ace etc. will see almost no gain at all.

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