[Go-essp-tech] verification of datanode status

[stephen.pascoe at stfc.ac.uk]

Hi all,

I have now retracted this dataset.  However, we should really be able to delete it without access to the datanode.  There must be a hessian API to delete datasets from a Gateway because esgpublish does I don't know of a way without having a esgpublisher installation.

Estani, is there anything in your toolset that could do this, or be a starting point for an implementation?

Cheers,
Stephen.

---
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] On Behalf Of Eric Nienhouse
Sent: 19 December 2011 22:03
To: Estanislao Gonzalez
Cc: go-essp-tech at ucar.edu
Subject: Re: [Go-essp-tech] verification of datanode status

Hi All,

A long standing Gateway requirement is to provide search and discovery 
of datasets (and other metadata) regardless of the state of remote 
services.  In the event that a data node service is unavailable, users 
should still be able to identify datasets, determine what has been 
published and generate download scripts.

This guiding requirement was discussed at great length by the ESG-CET 
project group and was accepted as a key element in support of the 
community's best interest for data discovery.  Identifying "what has 
been published" was a key use case driving this need.  This advantage of 
this approach is that it allows users to find out "what exists" during 
periods of unexpected downtime or other service unavailability.

Henrik noted that the DMI data node is no longer serving datasets 
publishing into ESG.  In this case these datasets can be discovered at 
the Gateway, however, they are inaccessible and out of sync.  If these 
data are no longer meant to be accessed, I'd suggest they be "retracted" 
from the gateway and they will no longer appear in the search results.

Thanks,

-Eric

Estanislao Gonzalez wrote:
> T(sorry the message got cut)
> ...it's up to the publisher to define when data shouldn't be accessible 
> anymore.
>
> There are some improvements that can be doen, but most I can think of 
> will make the understanding of the system more complex to the end user.
>
> Datanode admin should rely on tools that help them get their nodes up 
> for as long as possible (nagios & Co).
>
> My 2c,
> Estani
> On 19.12.2011 08:04, Estanislao Gonzalez wrote:
>   
>> Hi Luca,
>>
>> That's not what Henrik meant. Neither the architecture retains a 
>> living
>> link to a data nose (not an index one, as you've pointed out)
>>
>> This is a feature IMO as the search engine is detached from the
>> dataone. The index might indeed "prune" the data nodes down, but 
>> unless
>> this is done synchroneusly it would difficult the federation
>> interaction.
>> Or to say it differently: Is up to the data node to assure data is
>> available, and if that's not desired anymore, On 19.12.2011 07:15,
>> Cinquini, Luca (3880) wrote:
>>     
>>> Hi Henirik,
>>> 	not sure about the gateway, but this is a feature the P2P system
>>> does have: has soon as a datanode is inaccessible, the search
>>> automatically prunes that node away, so the search results never
>>> contain dead links.
>>> thanks, Luca
>>>
>>> On Dec 19, 2011, at 3:58 AM, Henrik Wiberg wrote:
>>>
>>>       
>>>> Does the gateway somehow 'ping' its registered datanodes to verify
>>>> that
>>>> they are accessible? The datanode at dmi has not been running for 5
>>>> mounts still the datanodes published datasets are searchable and
>>>> displayed at the gateway cmip-gw-badc. Should not inaccessible
>>>> datasets
>>>> be removed from the search result?
>>>>
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>
>   

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