AT+i Programmer's Manual - SE Spezial-Electronic AG

File Transfer Protocol (FTP) Theory of Operation
29 File Transfer Protocol (FTP) Theory of Operation
29.1 Introduction
The FTP client component in iChip extends iChip‘s general-purpose sockets to
incorporate an additional, dedicated socket for FTP activities. From the host‘s
perspective, the FTP capabilities are a logical extension of the capabilities of e-mail and
direct socket manipulation.
As in all other iChip protocol implementations, host involvement in the specifics of FTP
is minimal. iChip needs to deal with non-standard FTP issues, such as possible
differences between FTP server responses, on its own. Multi-stage FTP protocol
sequences are atomized under iChip control to minimize complexity and need for host
processor intervention.
The FTP protocol is described in RFC 959.
29.2 iChip Family FTP Client Command Set
Open FTP link to FTP Server
Retrieve File List from Server
Change Directory on Server
Retrieve File Contents from Server
Open a New File on Server
Open an existing File on Server for Append
Send Binary Data to an open File on Server
Close a File on Server After Binary Data Send
Delete File on Server
Close FTP Session
29.3 iChip FTP Client Operation Mode
FTP specifies several operational modes. The RFC calls for a minimum implementation,
which should be observed by all FTP servers. iChip restricts its operation mode to the
minimum implementation to assure best intersystem compatibility.
Character Types: ASCII Non-print
Structure: File
Mode: Stream
29.4 FTP Command Socket
The FTP command socket is normally on port 21 (decimal) of an FTP server. However,
other ports can be specified to support special cases.