finj - Terminology
[ L A S T U P D A T E : 2022-03-03 ]
What is this good for ?
A minimum of terminology is necessary to make sure that
we are all talking of the same things in the same way. This
page lists some of those terms with their definitions.
Part of this terminology comes from section 2.2 of
RFC959;
the rest is a collection of definitions found here and there.
-- javier
> ASCII
The ASCII character set is as defined in the ARPA-Internet
Protocol Handbook. In FTP, ASCII characters are defined to be
the lower half of an eight-bit code set (i.e., the most
significant bit is zero).
> access controls
Access controls define
users'
access privileges to the use of a system, and to the
files
in that system. Access controls are
necessary to prevent unauthorized or accidental use of
files.
It is the prerogative of a
server-FTP process
to invoke access controls.
> byte size
There are two byte sizes of interest in FTP: the logical byte
size of the
file,
and the transfer byte size used for the transmission
of the data. The transfer byte size is always 8 bits. The transfer
byte size is not necessarily the byte size in which the data is to be
stored in a system, nor the logical byte size for interpretation of the
structure of the data.
> control connection
The communication path between the
user-PI and server-PI
for the exchange of commands and replies. This connection follows
the Telnet Protocol.
> data connection
A full duplex connection over which data is transferred, in a
specified mode and type
The data transferred may be a part of a
file,
an entire
file
or a number of
files.
The path may be between a
server-DTP and a user-DTP
or between two server-DTPs.
> data port
The passive data transfer process "listens" on the data port
for a connection from the active transfer process in order to open
the data connection.
> DTP
The data transfer process establishes and manages the
data connection.
The DTP can be passive or active.
> End-of-Line
The end-of-line sequence defines the separation of printing
lines. The sequence is Carriage Return, followed
by Line Feed.
> EOF
The end-of-file condition that defines the end of a
file
being transferred.
> EOR
The end-of-record condition that defines the end of a
record
being transferred.
> error recovery
A procedure that allows a
user
to recover from certain errors such as failure of either host system
or transfer process. In FTP, error recovery may involve restarting
a file transfer as a given checkpoint.
> FTP command
A set of commands that comprise the control information flowing from the
user-FTP to the server-FTP
process.
> FTP reply
[NOT YET WRITTEN]
> file
An ordered set of computer data (including programs), of
arbitrary length, uniquely identified by a
pathname.
> file system
[NOT YET WRITTEN]
> java application
[NOT YET WRITTEN]
> mode
The mode in which data is to be transferred via a
data connection.
The mode defines the data format during transfer including
EOR and EOF.
The transfer modes defined in FTP are described in the
Section on Transmission Modes (§3.4) of
RFC959.
> NVT
The Network Virtual Terminal as defined in the Telnet Protocol.
> NVFS
The Network Virtual
File System.
A concept which defines a standard network
file system
with standard commands and
pathname
conventions.
> page
A
file
may be structured as a set of independent parts called
pages. FTP supports the transmission of discontinuous
files as independent indexed pages.
> pathname
Pathname is defined to be the character string which must be
input to a
file system
by a
user
in order to identify a
file.
Pathname normally contains device and/or directory names,
and file name specification. FTP does not yet specify a standard
pathname convention. Each
user
must follow the
file
naming conventions of the
file systems
involved in the transfer.
> PI
The protocol interpreter. The user and server sides of the
protocol have distinct roles implemented in a
user-PI and a server-PI.
> record
A sequential file may be structured as a number
of contiguous parts called records. Record structures are supported by
FTP but a file need not have record structure.
> server-DTP
The data transfer process, in its normal "active" state,
establishes the
data connection
with the "listening"
data port. It sets up parameters
for transfer
> server-FTP process
A process or set of processes which perform the function of
file transfer in cooperation with a
user-FTP process
and, possibly, another server. The functions consist of a
protocol interpreter
(PI)
and a data transfer protocol
(DTP).
> server-PI
The server protocol interpreter "listens" on Port L for
a connection from a
user-PI
and establishes a
control communication connection.
It receives standard
FTP commands
from the
user-PI,
sends replies, and governs the
server-DTP.
> type
The data representation type used for data transfer and storage.
Type implies certain transformations between the time of data
storage and data transfer. The representation types defined in FTP
are described in the Section on Establishing Data Connections (§3.2) of
RFC959.
> user
A person or a process on behalf of a person wishing to obtain a
file transfer service. The human user may interact
directly with a server-FTP process,
but use of a user-FTP process
is preferred since the protocol design is weighted towards automata.
> user-DTP
The data transfer process "listens" on the
data port
for a connection from a
server-FTP process.
If two servers are transferring data between them, the
user-DTP
is inactive.
> user-FTP process
A set of functions including a protocol interpreter, a data transfer
process and a user interface which together perform the function of
file transfer in cooperation with one or more
server-FTP processes.
The user interface allows a local language to be used in the
command-reply dialogue with the
user.
> user-PI
The user protocol interpreter initiates the
control connection
from its port U to the
server-FTP process,
initiates
FTP commands,
and governs the
user-DTP
if that process is part of the file transfer.
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