[NET-652] Ftp Connection Resuming

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 3.6
• Component/s: FTP
• Assignee: Unassigned
• Reporter: chenzero
• Created: 20/Jan/18 14:00
• Updated: 22/Jan/18 15:08
• Resolved: 22/Jan/18 15:08

Description

In a unstable networking, it can not download a relative big file from FTP server.

For most FTP servers, the "REST" command is supported, and can be used to specify the transfer starting offset.

in additional, a progress data is saved at the end of the local fie.

The format is: signature(32 bytes) + remoteFile timestamp(long) + transferred offset(long)

so, the whole progress data is 48 bytes.

if connection broken, the FtpClient will first read progress data from the local file

and transfer resumed from the offset.