Network Working Group Alex McKenzie
Request for Comments #180 BBN
NIC #7123 25 June 1971
Categories: D.7, G.3
Updates: none
Obsoletes: none
File System Questionnaire
As noted in RFC #164 (page 35), a subcommittee of the NWG, under the
chairmanship of Abhay Bhushan, is currently generating proposals for a
"data transfer protocol" and a "file transfer protocol".
The subcommittee has decided that the file transfer protocol should
provide standard methods for requesting the transfer of a file but
should not, at this time, attempt to standardize file naming
conventions, access control conventions, and the like. Thus a user
who is, for example, trying to store a file on a remote Host will be
required to use the file naming conventions appropriate to the remote
Host.
Given the above point of view, it becomes imperative for users to have
some source of information about Host file conventions. Such
information, once compiled, will also serve as input to possible
standardization efforts of the file transfer subcommittee. For this
reason Abhay has asked me to solicit information on file conventions
from the Host organizations. What follows is a description of the
kinds of information of interest. I am well aware of the fact that
many of you are tired of writing system descriptions; Xerox copies of
short sections of your local documentation are fine if the result is
complete and comprehensible. (In the case that your Host will never
permit network use of your file system, a note to that effect would be
sufficient.)
Information Requested
1. File naming conventions - We (loosely) define a pathname to be
the data string which must be input to the file system by a user
(a network user if your system makes a distinction between local
and network users) in order to identify a file. We are interested
in syntax, semantics, and defaults. Typical components of pathnames
are:
- "device" fields
- user names
- version numbers
- index names
- punctuation marks
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Common types of defaults are:
- device is disk
- version number is largest in system
For hierarchical file structures, descriptions may be fairly
complex, but with lots of defaults; in such cases an illustration
of a "normal" pathname might be helpful.
2. Access control mechanisms - Access control mechanisms range from
simply knowledge of a file's pathname to elaborate hierarchies
of group-project-task-username membership with passwords and
separate controls for reading and writing. There are two
aspects of the access control mechanism which are of interest:
a. A description of what inputs the user should give the file
system, both at the time of file creation and at the time of
retrieval, in order to define the permitted modes of access
and to gain access. What are the syntax and semantics of
these inputs?
b. A description of the ways in which the access control
mechanism is designed to help (or hinder) the sharing of
files. For example, may two users "simultaniously" update a
given file? May the creator of the file define a set of
authorized users to the file system (and how)? Is it possible
to define different access controls for various subunits of a
given file?
3. Directories - Many systems maintain file directories which are
designed to be helpful to the user. A directory might, for
example, provide a list of all files created by a particular
individual, along with some information regarding file size,
file structure, access controls, etc. In general, such systems
allow the user to input a pathname and retrieve the directory to
which that pathname refers. Aspects of the directory structure of
interest are:
a. What are the syntax and semantics of a directory pathname?
b. What use is a directory, i.e., what type of information
does the directory contain?
c. What access controls are used for access to the directories?
For example, must a user supply a password in order to
retrieve a directory, and is this password typically the same
as the password he would use to retrieve a file listed in that
directory.
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4. Commands and functions of the file system - A general description
of what the file system is designed to do would be useful. For
example, the system might simply accept an entire file and store
it sequentially on a tape; with the only mode of retrieval being
to retrieve the entire file. On the other hand, the system might
provide the ability to access any "subfield" with a unique
pathname. Perhaps there is the ability to restructure a file,
change the access control, delete all the fields associated with a
directory, etc. We realize that this aspect of the file system
begins to overlap the area of "data management", which is the
responsibility of another subcommittee; therefore, use your
judgement as to what functions are an intrinsic aspect of the
file-handling system and which are aspects of "data-management".
5. Internal representation and I/O modes - The remote user of a file
system will normally be interested in internal representation of
data only insofar as that representation of data is reflected in
the I/O interface between the file system and the network. For
example, if all of the file system's I/O is in 8-bit ASCII
characters, then the user is unlikely to care if they are stored
in ASCII, EBCDIC, or some other form. However, if an alternate
transmission mode is available it may be useful; for example,
two PDP-10's, both of which store 5 characters and one "filler"
bit per word, might find it advantageous to transfer information
in this mode rather than converting between internal representation
and 8-bit ASCII for each character. Other information on internal
representation which would be of interest to the user might
include (if applicable):
- range of numeric data permitted
- maximum text string lengths
- whether the user must indicate "record" boundaries on input
- what "logical structure" information the user may specify
for a new file, and what he must specify
- whether the user must specify the file size before beginning
input, and how he does it
6. Undoubtedly, there will be aspects of each file system which don't
fit neatly into the categories above, but which users will find
important or essantial in using the system. These should be
identified and described if possible.
Please address responses to this questionnaire to:
Alex McKenzie
Bolt Beranek and Newman Inc.
50 Moulton Street
Cambridge, Massachusetts 02138
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If the questions above are confusing, don't hesitate to call me for
clarification at (617) 491-1850 ext. 441. I will issue another RFC
summarizing the responses after I have received a significant number
of them.
[ This RFC was put into machine readable form for entry ]
[ into the online RFC archives by Stefan Hinker 6/97 ]
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