semantic

Semantic Web ToolKit for Erlang applications

Inspiration

Linked-Data are used widely by Semantic Web to publish structured data so that it can be interlinked by application. The library provides toolkit for Erlang application, defines data models and abstract syntax to interpret and manipulate Linked-Data as a collection of ground facts / knowledge statement / triples. You can use it to build inter-operable Web services, data interfaces or persist Linked Data. The library solve a following aspects:

define Erlang native formats for knowledge statement and its serialization formats
provide common rules for data type mapping between Semantic Web and Erlang application
resolve complexity of IRI identity and provides build in database of semantic name-spaces
implements Semantic codecs for N-Triple, JSON-LD and pure JSON formats.

Getting started

The latest version of the library is available at its master branch. All development, including new features and bug fixes, take place on the master branch using forking and pull requests as described in contribution guidelines.

Installation

If you use rebar you can include semantic library in your project with

{semantic, ".*",
   {git, "https://github.com/fogfish/semantic", {branch, master}}
}

Usage

The library exposes public interface through exports of semantic.erl module. Just call required function with required arguments, check out Supported features and More Information chapter for details.

Build library and run the development console

make
make run

Let's take a short tour to the library

%% start library and configure built-in prefixes for compact IRI/URI 
semantic:start().

%% decode stream of N-triples 
A = semantic:nt(<<"<http://example.org/a> <http://xmlns.com/foaf/0.1/name> \"text\"@en .\n">>).

%% compile generic triple to native type-safe representation
B = semantic:typed(A).

%% intake knowledge fact from JSON-LD data source
JsonLD = #{
   <<"@context">> => #{<<"price">> => <<"http://schema.org/price">>},
   <<"@id">> => <<"http://example.org/a">>,
   <<"price">> => 20
}.
C = semantic:jsonld(JsonLD).
D = semantic:typed(C).

Supported features

Native format

The library expresses knowledge fact(s) using map as 'type-safe' container type (the statement type is expressed using Erlang native data types mapping). This statement is compiled using semantic:typed/1 function, that takes an abstract triple format and produces a native one.

-type spo()  :: #{s => s(), p => p(), o => o(), type => lang() | type()}.

%% deduct semantic type from Erlang native term
{iri, <<"xsd">>, <<"integer">>} = semantic:typeof(1).

%% deduct Erlang native type from knowledge statement
iri = semantic:native({{iri, <<"a">>}, {iri, <<"b">>}, {iri, <<"c">>}}).

Compact identifiers

Compact identifiers is an approach to reduce IRI / URI overhead using <prefix> : <suffix> notation. The library implements compaction automatically using built-in dictionary of prefixes. For example the library applies following reduction to uri:

http://xmlns.com/foaf/0.1/name  ->  foaf:name

{iri, <<"foaf">>, <<"name">>} = semantic:compact({iri, <<"http://xmlns.com/foaf/0.1/name">>}).
{iri, <<"http://xmlns.com/foaf/0.1/name">>} = semantic:absolute({iri, <<"foaf">>, <<"name">>}).

Knowledge intake

The library supports multiple external formats for knowledge intake:

N-triples
JSON-LD

More Information

RDF 1.1 -- Concepts and Abstract Syntax
JSON-LD 1.0 -- A JSON-based Serialization for Linked Data
study native interface
supported data type

How to Contribute

semantic is Apache 2.0 licensed and accepts contributions via GitHub pull requests.

getting started

Fork the repository on GitHub
Read the README.md for build instructions
Make pull request

commit message

The commit message helps us to write a good release note, speed-up review process. The message should address two question what changed and why. The project follows the template defined by chapter Contributing to a Project of Git book.

Short (50 chars or less) summary of changes

More detailed explanatory text, if necessary. Wrap it to about 72 characters or so. In some contexts, the first line is treated as the subject of an email and the rest of the text as the body. The blank line separating the summary from the body is critical (unless you omit the body entirely); tools like rebase can get confused if you run the two together.

Further paragraphs come after blank lines.

Bullet points are okay, too

Typically a hyphen or asterisk is used for the bullet, preceded by a single space, with blank lines in between, but conventions vary here

Bugs

If you detect a bug, please bring it to our attention via GitHub issues. Please make your report detailed and accurate so that we can identify and replicate the issues you experience:

specify the configuration of your environment, including which operating system you're using and the versions of your runtime environments
attach logs, screen shots and/or exceptions if possible
briefly summarize the steps you took to resolve or reproduce the problem

References

http://www.w3.org/TR/2014/PR-rdf11-concepts-20140109/

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

fogfish / semantic

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