[tdwg-tapir] Fwd: Tapir protocol - Harvest methods?[SEC=UNCLASSIFIED]
Roger Hyam (TDWG)
rogerhyam at mac.com
Wed May 14 12:58:18 CEST 2008
Hi Tim,
The thing about the sitemaps is that they describe resources with URIs
they are not just a dump of an excel file.
I will buy you a beer in Oz if any proposal that is put forward
mandates the use of GUIDs for primary keys in the CSV files (other
than perhaps the additional files Markus was proposing of one to many
relationships). I'd buy you several beers if you manage to get it
accepted :)
All the best,
Roger
BTW: Another way to represent a graph of data (other than a series of
linked csv files) would be to do it in RDF as Turtle then zipped. This
does way with the need of a separate dictionary to describe what the
columns mean, has to be UTF-8, can include data types etc
... A script to explode this back to tables probably wouldn't be too
slow but this is probably just fantasy on my part.
On 14 May 2008, at 11:21, Tim Robertson wrote:
> Roegr writes "I worry that we are working out how to move data about
> quickly"
>
> That is exactly what this is for, but why is it a worry (other than
> the
> likes of GBIF who really are worrying about moving data around
> quickly since
> everyone is shouting about latency problems)?
>
> It is a 166 times (3meg versus 500meg) more efficient transfer of a
> data
> source for those wishing to transfer the whole thing. It is still
> standards
> compliant for the document passed across (DwC + flat extension
> schemas), and
> by incorporating it's generation into tools like a TAPIR wrapper,
> would
> ensure this. The reality is, many of the very large datasets have
> to come
> to GBIF like this - the transfer protocols existing just do not
> perform.
>
> Furthermore, think how much easier it would be for someone like
> Catalogue of
> Life or ITIS to put up a service that says "hey, you give me the URL
> to your
> Locally generated DwC Index File and I'll give you back a report
> containing
> YOUR occurrence GUID, and MY LSID for your identification". Isn't
> that a
> good thing?
>
> In my view these files are additional to any existing interfaces,
> only meet
> certain data type requirements and by no means detract from any of the
> important work (both technical and social aspects) on GUID assigning,
> document schemas etc. Therefore, like sitemaps became a requirement
> for
> large web sites, I think a more efficient standards based (than just
> dump
> your data and we'll handle it) approach is required for our community.
>
>
>
>
>
> -----Original Message-----
> From: tdwg-tapir-bounces at lists.tdwg.org
> [mailto:tdwg-tapir-bounces at lists.tdwg.org] On Behalf Of Roger Hyam
> (TDWG)
> Sent: Wednesday, May 14, 2008 11:57 AM
> To: Markus Döring
> Cc: Hiscom-L Mailing List ((E-mail)); tdwg-tapir at lists.tdwg.org
> Subject: Re: [tdwg-tapir] Fwd: Tapir protocol - Harvest
> methods?[SEC=UNCLASSIFIED]
>
>
> Generally if we are going to have csv files for data transfer we
> don't need
> to have software implementations just some documentation on what the
> csv
> files should contain. Something along the lines of:
>
> 1) Make a report from your database as a csv file(s) with the
> following
> columns...
> 2) Zip it up.
> 3) Either put it on a webserver and send us the URL or upload it
> using this
> webform.
>
> We don't need to bother with TAPIR etc. You could even only produce
> a CSV
> file of the records that have changed so big data sets needn't be a
> problem.
>
> I worry that we are working out how to move data about quickly and
> forgetting that the real goal is to integrate data and that will
> only come
> if people have GUIDs on the stuff they own and use other peoples
> GUIDs in
> their data. Solutions based around CSV files do nothing to move
> people in
> that direction and I would suspect lead to making matters worse.
>
> Finding ourselves in hole digging quicker may not be the best option.
>
> Roger
>
> -------------------------------------------------------------
> Roger Hyam
> Roger at BiodiversityCollectionsIndex.org
> http://www.BiodiversityCollectionsIndex.org
> -------------------------------------------------------------
> Royal Botanic Garden Edinburgh
> 20A Inverleith Row, Edinburgh, EH3 5LR, UK
> Tel: +44 131 552 7171 ext 3015
> Fax: +44 131 248 2901
> http://www.rbge.org.uk/
> -------------------------------------------------------------
>
>
>
>
> On 14 May 2008, at 10:21, Markus Döring wrote:
>
>> Interesting that we all come to the same conclusions...
>> The trouble I had with just a simple flat csv file is repeating
>> properties like multiple image urls. ABCD clients dont use ABCD just
>> because its complex, but because they want to transport this
>> relational data. We were considering 2 solutions to extending this
>> csv
>> approach. The first would be to have a single large denormalised csv
>> file with many rows for the same record. It would require knowledge
>> about the related entities though and could grow in size rapidly. The
>> second idea which we think to adopt is allowing a single level of 1-
>> many related entities. It is basically a "star" design with the core
>> dwc table in the center and any number of extension tables around it.
>> Each "table" aka csv file will have the record id as the first
>> column,
>> so the files can be related easily and it only needs a single
>> identifier per record and not for the extension entities. This would
>> give a lot of flexibility while keeping things pretty simple to deal
>> with. It would even satisfy the ABCD needs as I havent yet seen
>> anyone
>> requiring 2 levels of related tables (other than lookup tables).
>> Those
>> extensions could even be a simple 1-1 relation, but would keep things
>> semantically together just like a xml namespace. The darwin core
>> extensions would be good for example.
>>
>> So we could have a gzipped set of files, maybe with a simple metafile
>> indicating the semantics of the columns for each file.
>> An example could look like this:
>>
>>
>> # darwincore.csv
>> 102 Aster alpinus subsp. parviceps ...
>> 103 Polygala vulgaris ...
>>
>> # curatorial.csv
>> 102 Kew Herbarium
>> 103 Reading Herbarium
>>
>> # identification.csv
>> 102 2003-05-04 Karl Marx Aster alpinus L.
>> 102 2007-01-11 Mark Twain Aster korshinskyi Tamamsch.
>> 102 2007-09-13 Roger Hyam Aster alpinus subsp. parviceps
>> Novopokr.
>> 103 2001-02-21 Steve Bekow Polygala vulgaris L.
>>
>>
>>
>> I know this looks old fashioned, but it is just so simple and gives
>> us
>> so much flexibility.
>> Markus
>>
>>
>> On 14 May, 2008, at 24:39, Greg Whitbread wrote:
>>
>>> We have used a very similar protocol to assemble the latest AVH
>>> cache.
>>> It should be noted that this is an as-well-as protocol that only
>>> works because we have an established semantic standard (hispid/
>>> abcd).
>>>
>>> greg
>>>
>>> trobertson at gbif.org wrote:
>>>> Hi All,
>>>>
>>>> This is very interesting too me, as I came up with the same
>>>> conclusion while harvesting for GBIF.
>>>>
>>>> As a "harvester of all records" it is best described with an
>>>> example:
>>>>
>>>> - Complete Inventory of ScientificNames: 7 minutes @ the limited
>>>> 200
>>>> records per page
>>>> - Complete Harvesting of records:
>>>> - 260,000 records
>>>> - 9 hours harvesting duration
>>>> - 500MB TAPIR+DwC XML returned (DwC 1.4 with geospatial and
>>>> curatorial
>>>> extensions)
>>>> - Extraction of DwC records from harvested XML: <2 minutes
>>>> - Resulting file size 32MB, Gzipped to <3MB
>>>>
>>>> I spun hard drives for 9 hours, and took up bandwidth that is paid
>>>> for, to retrieve something that could have been generated provider
>>>> side in minutes and transferred in seconds (3MB).
>>>>
>>>> I sent a proposal to TDWG last year termed "datamaps" which was
>>>> effectively what you are describing, and I based it on the Sitemaps
>>>> protocol, but I got nowhere with it. With Markus, we are making
>>>> more progress and I have spoken with several GBIF data providers
>>>> about a proposed new standard for full dataset harvesting and it
>>>> has
>>>> been received well. So Markus and I have started a new proposal
>>>> and
>>>> have a working name of 'Localised DwC Index' file generation (it is
>>>> an index if you have more than DwC data, and DwC is still standards
>>>> compliant) which is really a
>>>> GZipped Tab file dump of the data, which is slightly extensible.
>>>> The
>>>> document is not ready to circulate yet but the benefits section
>>>> reads
>>>> currently:
>>>>
>>>> - Provider database load reduced, allowing it to serve real
>>>> distributed queries rather than "full datasource" harvesters
>>>> - Providers can choose to publish their index as it suits them,
>>>> giving control back to the provider
>>>> - Localised index generation can be built into tools not yet
>>>> capable
>>>> of integrating with TDWG protocol networks such as GBIF
>>>> - Harvesters receive a full dataset view in one request, making it
>>>> very easy to determine what records are eligible for deletion
>>>> - It becomes very simple to write clients that consume entire
>>>> datasets.
>>>> E.g. data cleansing tools that the provider can run:
>>>> - Give me ISO Country Codes for my dataset
>>>> - The application pulls down the providers index file, generates
>>>> ISO country code, returns a simple table using the providers own
>>>> identifier
>>>> - Check my names for spelling mistakes
>>>> - Application skims over the records and provides a list that are
>>>> not known to the application
>>>> - Providers such as UK NBN cannot serve 20 million records to the
>>>> GBIF index using the existing protocols efficiently.
>>>> - They have the ability to generate a localised index however
>>>> - Harvesters can very quickly build up searchable indexes and it is
>>>> easy to create large indices.
>>>> - Node Portal can easily aggregate index data files
>>>> - true index to data, not an illusion of a cache. More like Google
>>>> sitemaps
>>>>
>>>> It is the ease at which one can offer tools to data providers that
>>>> really interests me. The technical threshold required to produce
>>>> services that offer reporting tools on peoples data is really very
>>>> low with this mechanism. This and the fact that large datasets
>>>> will
>>>> be harvestable - we have even considered the likes of bit-torrent
>>>> for the large ones although I think this is overkill.
>>>>
>>>> As a consumer therefore I fully support this move as a valuable
>>>> addition to the wrapper tools.
>>>>
>>>> Cheers
>>>>
>>>> Tim
>>>> (wrote the GBIF harvesting, and new to this list)
>>>>
>>>>
>>>>>
>>>>> Begin forwarded message:
>>>>>
>>>>>> From: "Aaron D. Steele" <eightysteele at gmail.com>
>>>>>> Date: 13 de mayo de 2008 22:40:09 GMT+02:00
>>>>>> To: tdwg-tapir at lists.tdwg.org
>>>>>> Cc: Aaron Steele <asteele at berkeley.edu>
>>>>>> Subject: Re: [tdwg-tapir] Tapir protocol - Harvest methods?
>>>>>>
>>>>>> at berkeley we've recently prototyped a simple php program that
>>>>>> uses an existing tapirlink installation to periodically dump
>>>>>> tapir
>>>>>> resources into a csv file. the solution is totally generic and
>>>>>> can
>>>>>> dump darwin core (and technically abcd schema, although it's
>>>>>> currently untested). the resulting csv files are zip archived and
>>>>>> made accessible using a web service. it's a simple approach that
>>>>>> has proven to be, at least internally, quite reliable and useful.
>>>>>>
>>>>>> for example, several of our caching applications use the web
>>>>>> service to harvest csv data from tapirlink resources using the
>>>>>> following
>>>>>> process:
>>>>>> 1) download latest csv dump for a resource using the web service.
>>>>>> 2) flush all locally cached records for the resource.
>>>>>> 3) bulk load the latest csv data into the cache.
>>>>>>
>>>>>> in this way, cached data are always synchronized with the
>>>>>> resource
>>>>>> and there's no need to track new, deleted, or changed records. as
>>>>>> an aside, each time these cached data are queried by the caching
>>>>>> application or selected in the user interface, log-only search
>>>>>> requests are sent back to the resource.
>>>>>>
>>>>>> after discussion with renato giovanni and john wieczorek, we've
>>>>>> decided that merging this functionality into the tapirlink
>>>>>> codebase would benefit the broader community. csv generation
>>>>>> support would be declared through capabilities. although
>>>>>> incremental harvesting wouldn't be immediately implemented, we
>>>>>> could certainly extend the service to include it later.
>>>>>>
>>>>>> i'd like to pause here to gauge the consensus, thoughts,
>>>>>> concerns,
>>>>>> and ideas of others. anyone?
>>>>>>
>>>>>> thanks,
>>>>>> aaron
>>>>>>
>>>>>> 2008/5/5 Kevin Richards <RichardsK at landcareresearch.co.nz>:
>>>>>>>
>>>>>>> I think I agree here.
>>>>>>>
>>>>>>> The harvesting "procedure" is really defined outside the Tapir
>>>>>>> protocol, is it not? So it is really an agreement between the
>>>>>>> harvester and the harvestees.
>>>>>>>
>>>>>>> So what is really needed here is the standard procedure for
>>>>>>> maintaining a "harvestable" dataset and the standard procedure
>>>>>>> for harvesting that dataset.
>>>>>>> We have a general rule at Landcare, that we never delete records
>>>>>>> in our datasets - they are either deprecated in favour of
>>>>>>> another
>>>>>>> record, and so the resolution of that record would point to the
>>>>>>> new record, or the are set to a state of "deleted", but are
>>>>>>> still
>>>>>>> kept in the dataset, and can be resolved (which would indicate a
>>>>>>> state of deleted).
>>>>>>>
>>>>>>> Kevin
>>>>>>>
>>>>>>>
>>>>>>>>>> "Renato De Giovanni" <renato at cria.org.br> 6/05/2008 7:33 a.m.
>>>>>>>>>>>>>
>>>>>>>
>>>>>>> Hi Markus,
>>>>>>>
>>>>>>> I would suggest creating new concepts for incremental
>>>>>>> harvesting,
>>>>>>> either in the data standards themselves or in some new
>>>>>>> extension.
>>>>>>> In the case of TAPIR, GBIF could easily check the mapped
>>>>>>> concepts
>>>>>>> before deciding between incremental or full harvesting.
>>>>>>>
>>>>>>> Actually it could be just one new concept such as "recordStatus"
>>>>>>> or
>>>>>>> "deletionFlag". Or perhaps you could also want to create your
>>>>>>> own
>>>>>>> definition for dateLastModified indicating which set of concepts
>>>>>>> should be considered to see if something has changed or not, but
>>>>>>> I guess this level of granularity would be difficult to be
>>>>>>> supported.
>>>>>>>
>>>>>>> Regards,
>>>>>>> --
>>>>>>> Renato
>>>>>>>
>>>>>>> On 5 May 2008 at 11:24, Markus Döring wrote:
>>>>>>>
>>>>>>>> Phil,
>>>>>>>> incremental harvesting is not implemented on the GBIF side as
>>>>>>>> far as I am aware. And I dont think that will be a simple thing
>>>>>>>> to implement on the current system. Also, even if we can detect
>>>>>>>> only the changed records since the last harevesting via
>>>>>>>> dateLastModified we still have no information about deletions.
>>>>>>>> We could have an arrangement saying that you keep deleted
>>>>>>>> records as empty records with just the ID and nothing else (I
>>>>>>>> vaguely remember LSIDs were supposed to work like this too).
>>>>>>>> But
>>>>>>>> that also needs to be supported on your side then, never
>>>>>>>> entirely removing any record. I will have a discussion with the
>>>>>>>> others at GBIF about that.
>>>>>>>>
>>>>>>>> Markus
>>>>>>> _______________________________________________
>>>>>>> tdwg-tapir mailing list
>>>>>>> tdwg-tapir at lists.tdwg.org
>>>>>>> http://lists.tdwg.org/mailman/listinfo/tdwg-tapir
>>>>>>>
>>>>>>>
>>>>>>>
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