[Go-essp-tech] resolution on securing opendap aggregations via ESGF

Tue May 24 04:01:32 MDT 2011

IMHO CIM is a red herring.  Why would we want to put a CIM simulation record (a substantial chunk of XML) into every single THREDDS catalog?  That would be extreme database denormalisation.

QC data could be more feasible.  However, what if data from datanode A is replicated to DKRZ, they do QC L2 and find it doesn't pass.  How is this communicated?  Do we ask datanode A to republish saying their data is bad?  Will they do it?  Even without this human problem keeping QC information consistent across replicas will become a headache.

S.

---
Stephen Pascoe  +44 (0)1235 445980
Centre of Environmental Data Archival
STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, UK

From: Estanislao Gonzalez [mailto:gonzalez at dkrz.de]
Sent: 24 May 2011 08:59
To: Gavin M. Bell
Cc: Pascoe, Stephen (STFC,RAL,RALSP); Luca.Cinquini at jpl.nasa.gov; go-essp-tech at ucar.edu
Subject: Re: [Go-essp-tech] resolution on securing opendap aggregations via ESGF

Hi,

just to be more precise: indeed I think security and CIM data (meta-data from experiments and so on) should be kept away from the catalogs.

Still, Luca's idea of merging QC level info with the files itself might be a valid idea. The difference is that QC is pretty much like a "semantic" checksum for a file. AFAIK you cannot "downgrade"  the QC without altering the file, i.e. if the file is QC L2 and while performing QC L3 checks an error is found, the file will either be QC L3 approved (the modeler defines the "oddity" as "expected") or it doesn't, which implies a "QC L2 passed; QC L3 failed" flag or the retraction (and maybe re-publication) of it altogether.

Well, that's at least why I think the QC flag is a little different and it's *closely* related to the file. The only difference with the checksum is IMHO that it takes more time to be determined (as well as require other files for it's computation) and thus it's performed in an out-of-band fashion.

We need that QC flag somewhere... and it's far more important than the rest of the CIM meta-data (getting back to Gavin's point about CIM issues and differentiating it to this QC flag: yes, you can still get to the file and download it without CIM data... but without the QC flag you'll have no clue if you *really* want to rely on this data).

To be honest I can't understand why people download this data if they *know* it might get corrected. Would you start writing a paper on something that might be altogether wrong?... I suspect they don't realize this.

Anyway, my 2c...

Thanks,
Estani

Am 24.05.2011 03:06, schrieb Gavin M. Bell:
Hi Luca,

I think that the separation of concerns trumps the apparent "simplicity".  Though it is apparently easy to republish (I am not sure I fully agree with that, at least not from the anecdotal information I hear from folks)... it is unnecessary to publish if we keep concerns separated.

As Estani said, the publisher publishes and does basic mechanical sanity checks on data.  That should be the full extent of its operation.  As far as what is easy... one could 'easily' set up an index over the CIM info and "join" on datasetid.  This also provides loose coupling.  If the CIM system has issues, that just means that when you look at your search results you won't see CIM info, but you will still see the dataset and be able to fetch and manipulate it and everything else.  Also if the CIM changes it doesn't affect the pubblisher or publishing in any way.  Catalogs should be viewed as "files" in the system... they essentially are logical files (containing pointers to physical files).

I am still not convinced by your arguments that fusing and coupling these two semantically different aspects of the system so tightly is the right long term architectural solution.  It may be good now, but it not as flexible later. We should leave open the avenue for other meta-metadata to be imbued onto our system ex-post-facto without much ado.

my $0.02

On 5/23/11 2:08 AM, stephen.pascoe at stfc.ac.uk<mailto:stephen.pascoe at stfc.ac.uk> wrote:

I'm with Estani on this.  Authorisation decisions are best decoupled from the application where possible.  Phil is on leave today but I'm sure he'd say the same thing and give much more detailed reasoning.

I think the catalogue already mixes slightly too much information together: location-independent file metadata and location-specific service information.  If we add access control it becomes too tightly coupled.

Stephen.

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Stephen Pascoe  +44 (0)1235 445980

Centre of Environmental Data Archival

STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, UK

-----Original Message-----

From: go-essp-tech-bounces at ucar.edu<mailto:go-essp-tech-bounces at ucar.edu> [mailto:go-essp-tech-bounces at ucar.edu] On Behalf Of Estanislao Gonzalez

Sent: 21 May 2011 09:30

To: Cinquini, Luca (3880)

Cc: go-essp-tech at ucar.edu<mailto:go-essp-tech at ucar.edu>

Subject: Re: [Go-essp-tech] resolution on securing opendap aggregations via ESGF

Hi,

In my opinion we shouldn't encode the access restriction in the catalog

for these reasons:

1) Changing the access would involved re-publishing the files. (this

will be done for instance when QC L2 is reached CMIP5 Research -> CMIP5

Commercial). And think about what would happen if we want to change the

access restriction in a couple of years... we should publish everything

again, and that would involve quite some effort to understand the

procedure again...

2) I'm not sure of this, but I fear TDS security cannot handle multiple

roles. Right now you can publish to as many roles as required, and read

and write access is kept separately. This would involve extending the

TDS capabilities.

3) There could be potential inconsistencies if the authorization service

is detached from datanode (like with the gateway right now) and the

publisher alters the role but forgets to cascade the changes to the

authorizing service (which would proceed according to the last harvested

info)

4) And last but not least, I'm not sure we want to mix administration

with publication. The publisher should only care about making data

available, the administrator should organize this and be responsible for

the security.

So basically I don't agree :-) Although I do think, if required, we

could change "esg-user" for "esgf-controlled" if it's more intuitive.

My 2c anyways,

Estani

Am 20.05.2011 19:17, schrieb Cinquini, Luca (3880):

Hi,

  a few points again on the issue of securing opendap aggregations served by the TDS with ESGF filters:

o There's a new release of the ESGF security filters (esg-orp 1.1.2) that maps the TDS request URI to the dataset ID, and should solve this problem. You can experiment with the JPL test TDS server:

http://test-datanode.jpl.nasa.gov/thredds/catalog.html

where the AIRS dataset (and aggregations) is secured, the MLS is not.

o Now the data node authorization filter will correctly identify the aggregation as secured, and call the configured authorization service. Currently, the p2p Node authorization service can be configured to allow authorization based on URL matching, so it will work. The gateway authorization service will have to implement its own logic to establish authorization.

o Finally, I am wondering if we shouldn't change the way we encode authorization in thredds catalogs. Right now, we use restrictAccess="esg-user" for ALL collections, but should we consider about encoding the proper required access control attribute instead, for example restrictAccess="CMIP5 Research" ? Something to think about - there are prons and cons about this - it's all a question on wether the access control belongs in the catalog (and can be harvested for searching...) or not.

thanks, Luca

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--

Gavin M. Bell

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 "Never mistake a clear view for a short distance."

               -Paul Saffo

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Estanislao Gonzalez

Max-Planck-Institut für Meteorologie (MPI-M)

Deutsches Klimarechenzentrum (DKRZ) - German Climate Computing Centre

Room 108 - Bundesstrasse 45a, D-20146 Hamburg, Germany

Phone:   +49 (40) 46 00 94-126

E-Mail:  gonzalez at dkrz.de<mailto:gonzalez at dkrz.de>

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