Re: Easy and simple Linux triple-store

Done: https://github.com/ruby-rdf/rdf-do/issues/4

My explanation is a bit terse, sorry.

I'm also getting this:

[DEPRECATION] RDF::Statement#to_hash is deprecated, use RDF::Statement#to_h
instead.
This is due to the introduction of keyword arugments that attempt to turn
the last argument into a hash using #to_hash.
This can be avoided by explicitly passing an options hash as the last
argument.
Called from
/home/groobiest/huh/vendor/cache/ruby/2.3.0/gems/rdf-do-2.0.0/lib/rdf/do.rb:312

but it's just a warning.

Apart from that, I'm good to go. rdf-do and sqlite3 is the way to go for
quick 'n dirty I reckon. I'll be giving it a good workout.

On 1 November 2017 at 19:00, Tom Johnson <johnson.tom@gmail.com> wrote:

> Would you mind opening a ticket on the `rdf-do` GitHub?
>
> Many of the persistent Repository implementations are under-maintained, in
> large part
> because we don't have a good sense that there's a strong user base for
> most of them.
> Opening a ticket will serve in part to register your interest in seeing
> the DataObjects impl
> maintained.
>
> - Tom
>
> On Wed, Nov 1, 2017 at 10:58 AM, Anthony Durity <a.durity@umail.ucc.ie>
> wrote:
>
>> Righty-ho Tom,
>>
>> Super! Trying it out now.
>>
>> Though imho this info could feature more prominently in the initial
>> README at https://github.com/ruby-rdf/rdf in the tutorial section in
>> between
>> "Using RDF.rb and Spira to process RDF data from the British Ordnance
>> Survey"
>> and
>> "Getting started with RDF and SPARQL using 4store and RDF.rb"
>> ?
>>
>> Specifically the Using code from https://github.com/ruby-rdf/rdf-do:
>>
>> require 'rdf'
>> require 'rdf/ntriples'
>> require 'data_objects'
>> require 'do_sqlite3'
>> require 'rdf/do'
>>
>> repo = RDF::DataObjects::Repository.new uri: 'sqlite3:test.db'
>> # repo = RDF::DataObjects::Repository.new uri: 'postgres://postgres@server/database'
>> # heroku_repo = RDF::DataObjects::Repository.new uri: ENV['DATABASE_URL']
>> repo.load('http://datagraph.org/jhacker/foaf.nt')
>>
>> # How many statements did we have?
>> repo.count
>> #=> 10
>>
>> # Get the URI of the first subject
>> jhacker = repo.first.subject
>> #=> #<RDF::URI(http://datagraph.org/jhacker/foaf)>
>>
>> # Delete everything to do with it
>> jhacker_statements = repo.query(subject: jhacker)
>> repo.delete *jhacker_statements
>> repo.count
>> #=> 7
>>
>> # with Postgres, we could have done this, but SQLite gives us a locking error:
>> # repo.delete(*repo.query(subject: jhacker))
>>
>> # Changed our mind--bring it back
>> repo.insert *jhacker_statements
>> repo.count
>> #=> 10
>>
>> Having said that I'm getting an error on repo.first.subject
>>
>> …/vendor/cache/ruby/2.3.0/gems/rdf-2.2.11/lib/rdf/model/dataset.rb:67:in
>> `each_statement': undefined method `each' for nil:NilClass (NoMethodError)
>>     from …/vendor/cache/ruby/2.3.0/gems/rdf-2.2.11/lib/rdf/mixin/queryable.rb:172:in
>> `first'
>>     from test-store.rb:24:in `<main>'
>>
>> On 1 November 2017 at 17:19, Tom Johnson <johnson.tom@gmail.com> wrote:
>>
>>> > I can't find a single simple tutorial about using ruby-rdf to write
>>> to, modify, and query my own local triple-store.
>>>
>>> Ruby RDF has a `Repository`[0] abstraction that allows more-or-less
>>> transparent read/write over a number of backend implementations.
>>>
>>> The default implementation is an in-memory store, but many others exist,
>>> including for 4store[1], virtuoso[2], blazegraph[3], etc...
>>>
>>> Arguably the best maintained of these is `rdf-do`[4], which stores
>>> graphs to SQL through the DataObjects ORM.
>>> This gives you the option to just use Sqlite, if you please. This
>>> approach is not the most performant or scalable, but it's
>>> probably suitable for a web application, and work to swap to something
>>> more robust later should be fairly minimal (provided
>>> you can implement the `RDF::Repository` interface on your chosen
>>> backend. If you're using Ruby RDF, this is probably the
>>> solution you are looking for.
>>>
>>> [0] http://www.rubydoc.info/github/ruby-rdf/rdf/RDF/Repository
>>> [1] https://github.com/fumi/rdf-4store
>>> [2] https://github.com/ruby-rdf/rdf-virtuoso
>>> [3] https://github.com/ruby-rdf/rdf-blazegraph
>>> [4] https://github.com/ruby-rdf/rdf-do
>>>
>>> On Wed, Nov 1, 2017 at 9:53 AM, Leif Warner <abimelech@gmail.com> wrote:
>>>
>>>> I think Redland would be the equivalent of SQLite. I think it's backed
>>>> by BerkeleyDB or something. The whole suite comes with lots of useful
>>>> command-line tools.
>>>>
>>>> You could also just maintain an in-memory graph, and re-write it to
>>>> disk on program exit. Can write modifications to disk as they happen for
>>>> more durability, as a write-ahead log.
>>>>
>>>> On Nov 1, 2017 4:32 AM, "Anthony Durity" <a.durity@umail.ucc.ie> wrote:
>>>>
>>>>> Hullo all,
>>>>>
>>>>> Apologies if this is a stupid question.
>>>>>
>>>>> I would like to know if there is any tech that would be the
>>>>> triple-store equivalent to Sqlite? What I want is to create my only local
>>>>> graph based on nodes in Wikidata and data I generate myself.
>>>>>
>>>>> What technology do people use? Is there a recommended stack? I don't
>>>>> necessarily mean something like Ruby on Rails which is convention over
>>>>> configuration and "batteries included" by I don't mean Opengraph Virtuoso
>>>>> either, that's way too heavyweight.
>>>>>
>>>>> I'm running Ubuntu 17.10, a fairly popular distro. I can't seem to
>>>>> compile Redstone and anyway it appears unmaintained. Cayley looks cool but
>>>>> doesn't have its own on-disk back-end? (I don't understand that). Franz
>>>>> Allegrograph seems too commercial and lispy (maybe I'm wrong about this.).
>>>>> I don't want to use Jena because, um, Java.
>>>>>
>>>>> I can't find a single simple tutorial about using ruby-rdf to write
>>>>> to, modify, and query my own local triple-store.
>>>>>
>>>>> Most of the time I think it would be easier to define a relational
>>>>> model and map to triples on the fly and then I'd use tech that I'm familiar.
>>>>>
>>>>> For small projects what do people use? I don't want to spend a week
>>>>> setting up a local triple-store. I want something that is robust, I can set
>>>>> up nearly as easily as Rails, is actively maintained, and supports most of
>>>>> the current Semantic Web tech.
>>>>>
>>>>> Is there something obvious I'm not getting or that I'm overlooking?
>>>>>
>>>>> Thanks!
>>>>>     Anthony
>>>>>
>>>>
>>>
>>>
>>> --
>>> -Tom Johnson
>>>
>>
>>
>
>
> --
> -Tom Johnson
>