NonStop SSH SFTP API Reference Manual

Introduction
The Problem
A predominant option for securing file transfers with NonStop servers is to implement the SSH/SFTP protocol suite. As
many sites used the FTP protocol for their file transfers before, this involves converting their transfer procedures from
FTP to SFTP. This is usually very straight forward for interactive and batch transfers which can invoke the SFTP instead
of FTP client program. However, some sites have built applications which programmatically invoke FTP file transfers
using the FTP API library, which is part of the HP NonStop™ TCP/IP applications and utilities. Although it would be
possible to use FTP tunneling over SSH with those applications, a complete migration to SFTP is preferred in many
cases.
The SFTP API Solution
The SFTP API allows applications that previously used the FTP API to convert to SFTP in an easy manner. In many
cases, the conversion can be accomplished with only a few program changes. In the ideal case, programs do not need to
be changed or even re-compiled at all.
The following picture describes how applications transfer files with the FTP API:
When initiating an FTP session via the FTP APILIB, the library will start an FTP client process to handle the actual file
transfers for the application. APILIB will then communicate via inter-process messages with the FTP client process,
mapping the library calls to FTP commands to be processed by the FTP client.
The SFTP API solution works exactly the same way, as the following picture illustrates:
HP NonStop SFTP API Reference Manual . Introduction • 6