Re: Why have a multipart document address?

[Andrew Pam <xanni@xxxxxxxxxxxxxxxxx>]

On Tue, Feb 08, 2005 at 11:03:24PM -0600, Jack Seay wrote:
> Is it necessary to have the server number as part of a document 
> address?

Yes, for guaranteed unique IDs.

> What if the server is shut down or the document needs to be 
> moved? Maybe the author just wants to use a different server.

Doesn't matter.  The document addresses are globally unique identifiers,
not locators.  It was never intended to use the server numbers to locate
documents, only to ensure that each server can safely generate document
IDs that will not conflict with those generated by other servers.

> If a language that implements the Linda functions designed by David 
> Gelernter was used, it wouldnât matter where the document was stored. 
> Just make sure it is located in more than one place for safety. There 
> wouldnât be a server address at all.   A query about a document would 
> just request a document number and distributed agents would retrieve it 
> from wherever it is located on the network of servers and return it to 
> you.

That's exactly the Xanadu design.  There is no separate "server address".

> Also, why have a version number as part of the address? Why not just 
> give each new added document a new document number. If it is a new 
> version of another document, it will transclude much of the previous 
> document. The revisor could be the original author, a group of writers, 
> or a different writer. There could be major changes, or just a few. How 
> do you decide if itâs a new version or just transcludes a lot from 
> another document. If the version number is eliminated from the address, 
> it doesnât have to become a hardcoded item. A separate document could 
> tie the various versions together with links. And by looking at all the 
> documents that transclude the current one, newer versions will be 
> found.

The difference is in the author's intent.  All documents in the Xanadu
docuverse are just collections of content from potentially all over
the docuverse, but what makes it a "document" is the declaration of
an author that a certain arrangement of material comprises a work that
can be distinctly identified.  Versions allow authors to indicate that
they regard several iterations to be fundamentally the same document.

Of course other authors are welcome to transclude portions to make their
own revisions, but those then become new jointly authored documents
which can in turn have versions of their own.  In other words it is not
a technical necessity but an author convenience feature.  Documents need
not have titles at all, or they can have multiple titles, but it would
be inconvenient to have to create titles for each revision of a work
just to distinguish them.

> Also, why have the author part of the document address? What if there 
> are several authors? What if the author uses several names? What if it 
> is published by a group of people working for a business? What if that 
> business sells?

The author ID is just an ID, and can stand for a group of people, or
one of many aliases of an individual, or a corporate role.  The name
associated with the ID could be changed without affecting the ID itself.

> Could a series of relational tables (or xanalogical documents or zigzag 
> dimensions) store the information on authors, publishers, buyers, 
> links, formats, etc. and combine the data in whatever way is needed to 
> create the composited document?

Sure.

Hope that helps,
		Andrew
-- 
mailto:xanni@xxxxxxxxxx                         Andrew Pam
http://www.xanadu.com.au/                       Chief Scientist, Xanadu
http://www.glasswings.com.au/                   Partner, Glass Wings
http://www.sericyb.com.au/                      Manager, Serious Cybernetics