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From: freedman@calgary.UUCP
Newsgroups: comp.sys.apollo
Subject: Re: Multiple links
Message-ID: <919@vaxb.calgary.UUCP>
Date: Tue, 19-May-87 12:41:28 EDT
Article-I.D.: vaxb.919
Posted: Tue May 19 12:41:28 1987
Date-Received: Thu, 21-May-87 00:47:50 EDT
References: <8705150741.AA00372@yale-eli.arpa>
Organization: U. of Calgary, Calgary, Ab.
Lines: 21
Summary: Open System Toolkit

In article <8705150741.AA00372@yale-eli.arpa>, sundar@case.CSNET (Sundar Iyengar) writes:
> For example, we would like a link called x to point to
> //x1/a, //x2/a, //x3/a....  Every time x is referenced, it should
> be resolved to //x1/a.  However, if the node x1 is down or not accessible,
> x should resolve to //x2/b, and so on.  Similarly for links to
> other objects.

Sounds like an ideal job for Apollo's Open System Toolkit to me.  With this 
package, you can create new kinds of filesystem objects which behave in
special ways.  What you do is create a set of type manager routines which take
care of accessing the object.  Once this is done, you can access the object
using standard language or system calls (open, close, etc), and your manager
routines will take care of the rest.

In your case, you would write the appropriate routines for opening the file
according to your filename resolution scheme.  You can inherit routines from
existing filesystem types, so  you won't have to write any of the routines for
reading, writing, (etc) the files.

	Dan Freedman
	The University of Calgary Computer Science Department.