[ogsa-dmi-wg] Proposals

[Allen Luniewski]

I have looked at Ravi's proposals and would like to offer some comments.

The second proposal, on retries, basically seems okay to me.  I suspect
that there is an issue to be addressed regarding what is done with data
that is partially transferred when a transfer is retried.  But, perhaps,
that is covered if the operation eventually succeeds (presumably no orphan
data) or fails (covered by the DMI spec regarding cleanup after failure).

I have serious concerns about the first proposal, for multiple objects to
be transferred.  I see two major problems:
      1. The proposal makes no restrictions on what the source/sink DEPRs
refer to.  Ravi's clear goal is that they refer to different objects on the
same server.
            However, the proposal makes no such restriction.  Thus the
proposal admits to the N sources being on N different servers, perhaps
widely separated
            both geographically and organizationally.  The complications
that this creates for the DTF and DTI are almost unimaginable and, I feel,
uncaccpetable.
            I see no way to make a simple change to this proposal to
address this problem.
      2. There is nothing in the proposal that ties a particular source
DEPR to a particular sink DEPR.  Since the source/sink sequences are
ordered, perhaps the
            desire is to make the connection via that ordering.  Thus this
can probably be handled fairly simply.
As a mater of principle, I think that this whole issue is not one that the
DMI spec either should or needs to address.  Rather, the multiplicity of
entities to be transferred should solely be an issue to be addressed by the
client when getting the DEPR from the source (sink).  The source (sink)
should mint the DEPR in a way that encodes the multiplicity of entities to
be transferred.  Then, when the DTF and DTI pass that DEPR back to the
source (sink) it can take the DEPR apart and properly handle the
multiplicity of objects.  I can see backing away from this rigid approach
to allow ***implementations*** of a DTI to be aware of the way that certain
DEPRs are minted (e.g., if we are transferring multiple files, the
source/sink file systems and the FTP DTI could agree on the way multiple
files are denoted in the DEPRs).  In either case, it should not be the
responsibility of the DMI spec to specify this behavior.

Allen Luniewski
IBM WebSphere Cross Brand Services
IBM Silicon Valley Laboratory
555 Bailey Ave.
San Jose, CA 95141

408-463-2255
408-930-1844 (mobile)



                                                                           
             Ravi Madduri                                                  
             <madduri at mcs.anl.                                             
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             es at ogf.org                                                    
                                                                   Subject 
                                       [ogsa-dmi-wg] Proposals             
             12/04/2007 02:24                                              
             PM                                                            
                                                                           
                                                                           
                                                                           
                                                                           




Hi
Please find attached my proposals to include more than one source/sink
pairs in the RequestDataTransferInstance and another proposal to
include the retry information in the transfer request. I can talk
about the proposal more in tomorrow's call

Thanks
[attachment "DMI_Proposal_Retries" deleted by Allen Luniewski/Almaden/IBM]
--
Ravi K Madduri
The Globus Alliance | Argonne National Laboratory | University of
Chicago
http://www-unix.mcs.anl.gov/~madduri

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