next up previous contents
Next: Objects Up: The Prospero Protocol Previous: WARNING

 

Directory, Link, and Object Attributes

This appendix describes the object and directory information maintained by the Prospero file system.

Please note that this appendix is in very rough form. Many of the attribute definitions have not yet been properly written. A lot of the attribute documentation can be found in section gif of this document.

Attributes have three namespaces associated with them: APPLICATION attributes, INTRINSIC attributes, and FIELDs. Attributes in the FIELD namespace have a registered meaning, and are understood by all clients and servers that use them. APPICATION attributes are defined by users and application programs. Application attributes should be registered (with info-prospero@ISI.EDU) or start with a prefix registered for the application or start with the two-character sequence X-.

and are unrestricted. Intrinsic attributes have special registered meanings, providing prossibly transient or derived information. The server has flexibility about whether it allows you to change them. Modifying them may have special implications -- for instance, setting the SIZE of a file to ``0 bytes'' will truncate the file. INTRINSIC attributes are either not modifiable, or else the server uses special mechanisms to modify them.

In addition, there is a fourth namespace used internally by routines running on the Prospero server. INTERNAL attributes are never sent across the network; they cannot be read with GET-OBJECT-INFO or LIST and cannot be modified with EDIT-OBJECT-INFO. However, they do appear in the server's data files.

Attributes may have the + or - suffix attached to their names.gif Attribute with the + suffix should always be returned by the server. Attributes with the - suffix should be returned only if explicitly asked for. Note that it is always acceptable for a server to return attributes not asked for. The - indicates programmer preference.gif





Padma Indraganti
Thu Jun 20 13:02:20 PDT 1996