Subject: 1) Approved Pages review for use of distributed directory

From: "Mel Jones (Tie: 444-4363)" <[email-masked]>
Date: Tue, 1 Jun 93 17:28:38 EDT

Ref:  Your note of 1 Jun 1993 11:02:03 -0800

Steve:

Thanks for the comment about possible need of a new return code on
Allocate when the distributed directory isn't available.  That was an
option, but we chose to put it under the CM_PARAMETER_ERROR return code
(it's in the text at the front of the section detailing changes to
chapter 4) for a number of reasons:

  ** Migration
     Program that are using a side-info entry won't know about a new
     return code.  Thinking of it as an error in your parameters (i.e.,
     you set up a destination_info characterstic that doesn't work)
     maps to an existing return code and should let existing code run
     as is.

  ** Secondary Return Codes, etc.
     As we've done new architecture, there were a couple of choices
     for how to fix the old problem of not enough detail on return
     codes.  Either plan for new methods, commonly referred to as
     "secondary-return codes" or start mapping every new condition
     to a new number and text string.  This is a classic example of
     the problem, because the error condition correctly maps to
     the general meaning of CM_PARAMETER_ERROR, but the return code
     doesn't specifically say that the directory was the problem (it says
     that in the text blurb underneath reasons for CM_PARAMETER_ERROR).
     So, we could put in a new return code CM_DN_NOT_RECOGNIZED_BY_DIR,
     or we could continue to use the old method and assume that when
     we get the secondary return code problem fixed.  We chose the latter,
     assuming that one of the things the implementation will be able to
     hand back is a more definite explanation of the secondary meaning.

     There should be a presentation on sec-return codes at the June CIW, by
     the way, on the direction of this piece of architecture.

Thanks again for the comments, and I hope the above makes sense.  If you'll
be at the June CIW, we can discuss further.

Regards,
Mel