Comparing HTTP and FTP for transferring files

Question

What are the advantages  or limitations  of one over the other for transferring files over the Internet    I am aware of secure forms of both protocols  I d like to hear comparisons through personal experiences in terms of performance  reliability  file size limitations etc

User · Answer

Here s a performance comparison of the two   HTTP is more responsive for request-response of small files  but FTP may be better for large files if tuned properly   FTP used to be generally considered faster   FTP requires a control channel and state be maintained besides the TCP state but HTTP does not   There are 6 packet transfers before data starts transferring in FTP but only 4 in HTTP   I think a properly tuned TCP layer would have more effect on speed than the difference between application layer protocols  The Sun Blueprint Understanding Tuning TCP has details   Heres another good comparison of individual characteristics of each protocol

User · Answer

One consideration is that FTP can use non-standard ports  which can make getting though firewalls difficult  especially if you re using SSL   HTTP is typically on a known port  so this is rarely a problem   If you do decide to use FTP  make sure you read about Active and Passive FTP   In terms of performance  at the end of the day they re both spewing files directly down TCP connections so should be about the same

User · Answer

I just benchmarked a file transfer over both FTP and HTTP     over two very good server connections using the same 1GB  zip file under the same network conditions  tested one after the other    The result    using FTP  6 minutes using HTTP  4 minutes using a concurrent http downloader software  fdm   1 minute   So  basically under a  real life  situation   1  HTTP is faster than FTP when downloading one big file   2  HTTP can use parallel chunk download which makes it 6x times faster than FTP depending on the network conditions

User · Answer

One advantage of FTP is that there is a standard way to list files using dir or ls   Because of this  ftp plays nice with tools such as rsync   Granted  rsync is usually done over ssh  but the option is there

User · Answer

Many firewalls drop outbound connections which are not to ports 80 or 443  http  amp  https   some even drop connections to those ports that are not HTTP S   FTP may or may not be allowed  not to speak of the active PASV modes   Also  HTTP 1 1 allows for much better partial requests   only send from byte 123456 to the end of file    conditional requests and caching   only send if content changed if last-modified-date changed   and content compression  gzip    HTTP is much easier to use through a proxy   From my anecdotal evidence  HTTP is easier to make work with dropped slow flaky connections  e g  it is not needed to  re establish a login session before  re initiating transfer    OTOH  HTTP is stateless  so you d have to do authentication and building a trail of  who did what when  yourself   The only difference in speed I ve noticed is transferring lots of small files  HTTP with pipelining is faster  reduces round-trips  esp  noticeable on high-latency networks    Note that HTTP 2 offers even more optimizations  whereas the FTP protocol has not seen any updates for decades  and even extensions to FTP have insignificant uptake by users   So  unless you are transferring files through a time machine  HTTP seems to have won    Tangentially  there are protocols that are better suited for file transfer  such as rsync or BitTorrent  but those don t have as much mindshare  whereas HTTP is Everywhere

User · Answer

Both of them uses TCP as a transport protocol  but HTTP uses a persistent connection  which makes the performance of the TCP better

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