Re: Easy and simple Linux triple-store

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