diff --git a/CHANGELOG.md b/CHANGELOG.md index 629338a..d680ec7 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -10,7 +10,8 @@ This project adheres to [Semantic Versioning](http://semver.org/) and ### Added - `RDF.IRI` as a more suitable URI/IRI representation for RDF, bringing enormous - performance and memory-consumption benefits + performance and memory consumption benefits (see [here](https://github.com/marcelotto/rdf-ex/issues/1) + for the details about the improvements) ### Changed diff --git a/README.md b/README.md index 05e07c1..334dd15 100644 --- a/README.md +++ b/README.md @@ -3,7 +3,6 @@ [![Travis](https://img.shields.io/travis/marcelotto/rdf-ex.svg?style=flat-square)](https://travis-ci.org/marcelotto/rdf-ex) [![Hex.pm](https://img.shields.io/hexpm/v/rdf.svg?style=flat-square)](https://hex.pm/packages/rdf) [![Inline docs](http://inch-ci.org/github/marcelotto/rdf-ex.svg)](http://inch-ci.org/github/marcelotto/rdf-ex) -[![Coverage Status](https://coveralls.io/repos/github/marcelotto/rdf-ex/badge.svg?branch=master)](https://coveralls.io/github/marcelotto/rdf-ex?branch=master) An implementation of the [RDF](https://www.w3.org/TR/rdf11-primer/) data model in Elixir. @@ -13,9 +12,9 @@ An implementation of the [RDF](https://www.w3.org/TR/rdf11-primer/) data model i - fully compatible with the RDF 1.1 specification - no dependencies - in-memory data structures for RDF descriptions, RDF graphs and RDF datasets -- support for RDF vocabularies via Elixir modules for safe, i.e. compile-time checked and concise usage of URIs +- support for RDF vocabularies via Elixir modules for safe, i.e. compile-time checked and concise usage of IRIs - XML schema datatypes for RDF literals (not yet all supported) -- sigils for the most common types of nodes, i.e. URIs, literals, blank nodes and lists +- sigils for the most common types of nodes, i.e. IRIs, literals, blank nodes and lists - a description DSL resembling Turtle in Elixir - implementations for the [N-Triples], [N-Quads] and [Turtle] serialization formats - [JSON-LD] is implemented in the separate [JSON-LD.ex] package (as every format requiring additional dependencies will be published in separate packages) @@ -36,31 +35,37 @@ end The [RDF standard](http://www.w3.org/TR/rdf11-concepts/) defines a graph data model for distributed information on the web. A RDF graph is a set of statements aka RDF triples consisting of three nodes: -1. a subject node with an URI or a blank node, -2. a predicate node with the URI of a RDF property, -3. an object node with an URI, a blank node or a RDF literal value. +1. a subject node with an IRI or a blank node, +2. a predicate node with the IRI of a RDF property, +3. an object node with an IRI, a blank node or a RDF literal value. Let's see how the different types of nodes are represented with RDF.ex in Elixir. -### URIs +### IRIs -Although the RDF standards speaks of IRIs, an internationalized generalization of URIs, RDF.ex currently supports only URIs. They are represented with Elixirs builtin [`URI`](http://elixir-lang.org/docs/stable/elixir/URI.html) struct. It's a pragmatic, temporary decision, which will likely be subject to changes, in favour of a more dedicated representation of IRIs specialised for its usage within RDF data. See this [issue](https://github.com/marcelotto/rdf-ex/issues/1) for progress on this matter. - -The `RDF` module defines a handy constructor function `RDF.uri/1`: +RDF.ex follows the RDF specs and supports [IRIs](https://en.wikipedia.org/wiki/Internationalized_Resource_Identifier), an internationalized generalization of URIs, permitting a wider range of Unicode characters. They are represented with the `RDF.IRI` structure and can be constructed either with `RDF.IRI.new/1` or `RDF.IRI.new!/1`, the latter of which additionally validates, that the given IRI is actually a valid absolute IRI or raises an exception otherwise. ```elixir -RDF.uri("http://www.example.com/foo") +RDF.IRI.new("http://www.example.com/foo") +RDF.IRI.new!("http://www.example.com/foo") ``` -Besides being a little shorter than `URI.parse` and better `import`able, it will provide a gentlier migration to the mentioned, more optimized URI-representation in RDF.ex. +The `RDF` module defines the alias functions `RDF.iri/1` and `RDF.iri!/1` delegating the resp. `new` function: -An URI can also be created with the `~I` sigil: +```elixir +RDF.iri("http://www.example.com/foo") +RDF.iri!("http://www.example.com/foo") +``` + +Besides being a little shorter than `RDF.IRI.new` and better `import`able, their usage will automatically benefit from any future IRI creation optimizations and is therefore recommended over the original functions. + +A literal IRI can also be written with the `~I` sigil: ```elixir ~I ``` -But there's an even shorter notation for URI literals. +But there's an even shorter notation for IRI literals. ### Vocabularies @@ -69,52 +74,42 @@ RDF.ex supports modules which represent RDF vocabularies as `RDF.Vocabulary.Name Furthermore, the [rdf_vocab] package contains predefined `RDF.Vocabulary.Namespace`s for the most popular vocabularies. -These `RDF.Vocabulary.Namespace`s (a special case of a `RDF.Namespace`) allow for something similar to QNames in XML: an atom or function qualified with a `RDF.Vocabulary.Namespace` can be resolved to an URI. +These `RDF.Vocabulary.Namespace`s (a special case of a `RDF.Namespace`) allow for something similar to QNames in XML: an atom or function qualified with a `RDF.Vocabulary.Namespace` can be resolved to an IRI. There are two types of terms in a `RDF.Vocabulary.Namespace` which are resolved differently: 1. Capitalized terms are by standard Elixir semantics module names, i.e. - atoms. At all places in RDF.ex where an URI is expected, you can use atoms + atoms. At all places in RDF.ex where an IRI is expected, you can use atoms qualified with a `RDF.Namespace` instead. If you want to resolve them - manually, you can pass a `RDF.Namespace` qualified atom to `RDF.uri`. + manually, you can pass a `RDF.Namespace` qualified atom to `RDF.iri`. 2. Lowercased terms for RDF properties are represented as functions on a - `RDF.Vocabulary.Namespace` module and return the URI directly, but since `RDF.uri` can also handle URIs directly, you can safely and consistently use it with lowercased terms too. + `RDF.Vocabulary.Namespace` module and return the IRI directly, but since `RDF.iri` can also handle IRIs directly, you can safely and consistently use it with lowercased terms too. ```elixir -iex> import RDF, only: [uri: 1] +iex> import RDF, only: [iri: 1] iex> alias RDF.NS.{RDFS} iex> RDFS.Class RDF.NS.RDFS.Class -iex> uri(RDFS.Class) -%URI{authority: "www.w3.org", fragment: "Class", host: "www.w3.org", - path: "/2000/01/rdf-schema", port: 80, query: nil, scheme: "http", - userinfo: nil} +iex> iri(RDFS.Class) +~I iex> RDFS.subClassOf -%URI{authority: "www.w3.org", fragment: "subClassOf", host: "www.w3.org", - path: "/2000/01/rdf-schema", port: 80, query: nil, scheme: "http", - userinfo: nil} -iex> uri(RDFS.subClassOf) -%URI{authority: "www.w3.org", fragment: "subClassOf", host: "www.w3.org", - path: "/2000/01/rdf-schema", port: 80, query: nil, scheme: "http", - userinfo: nil} +~I +iex> iri(RDFS.subClassOf) +~I ``` As this example shows, the namespace modules can be easily `alias`ed. When required, they can be also aliased to a completely different name. Since the `RDF` vocabulary namespace in `RDF.NS.RDF` can't be aliased (it would clash with the top-level `RDF` module), all of its elements can be accessed directly from the `RDF` module (without an alias). ```elixir -iex> import RDF, only: [uri: 1] +iex> import RDF, only: [iri: 1] iex> RDF.type -%URI{authority: "www.w3.org", fragment: "type", host: "www.w3.org", - path: "/1999/02/22-rdf-syntax-ns", port: 80, query: nil, scheme: "http", - userinfo: nil} -iex> uri(RDF.Property) -%URI{authority: "www.w3.org", fragment: "Property", host: "www.w3.org", - path: "/1999/02/22-rdf-syntax-ns", port: 80, query: nil, scheme: "http", - userinfo: nil} +~I +iex> iri(RDF.Property) +~I ``` -This way of expressing URIs has the additional benefit, that the existence of the referenced URI is checked at compile time, i.e. whenever a term is used that is not part of the resp. vocabulary an error is raised by the Elixir compiler (unless the vocabulary namespace is non-strict; see below). +This way of expressing IRIs has the additional benefit, that the existence of the referenced IRI is checked at compile time, i.e. whenever a term is used that is not part of the resp. vocabulary an error is raised by the Elixir compiler (unless the vocabulary namespace is non-strict; see below). For terms not adhering to the capitalization rules (lowercase properties, capitalized non-properties) or containing characters not allowed within atoms, the predefined namespaces in `RDF.NS` and `RDF.Vocab` define aliases accordingly. If unsure, have a look at the documentation or their definitions. @@ -150,7 +145,7 @@ The produced statements are returned by this function as a `RDF.Description` str There are two basic ways to define a namespace for a vocabulary: 1. You can define all terms manually. -2. You can extract the terms from existing RDF data for URIs of resources under the specified base URI. +2. You can extract the terms from existing RDF data for IRIs of resources under the specified base IRI. It's recommended to introduce a dedicated module for the defined namespaces. In this module you'll `use RDF.Vocabulary.Namespace` and define your vocabulary namespaces with the `defvocab` macro. @@ -161,14 +156,14 @@ defmodule YourApp.NS do use RDF.Vocabulary.Namespace defvocab EX, - base_uri: "http://www.example.com/ns/", + base_iri: "http://www.example.com/ns/", terms: ~w[Foo bar] end ``` -The `base_uri` argument with the URI prefix of all the terms in the defined -vocabulary is required and expects a valid URI ending with either a `"/"` or +The `base_iri` argument with the IRI prefix of all the terms in the defined +vocabulary is required and expects a valid IRI ending with either a `"/"` or a `"#"`. Terms will be checked for invalid characters at compile-time and will raise a compiler error. This handling of invalid characters can be modified with the `invalid_characters` options, which is set to `:fail` by default. By setting it to `:warn` only warnings will be raised or it can be turned off completely with `:ignore`. A vocabulary namespace with extracted terms can be by defined either providing RDF data directly with the `data` option or from serialized RDF data file in the `priv/vocabs` directory: @@ -178,7 +173,7 @@ defmodule YourApp.NS do use RDF.Vocabulary.Namespace defvocab EX, - base_uri: "http://www.example.com/ns/", + base_iri: "http://www.example.com/ns/", file: "your_vocabulary.nt" end @@ -196,7 +191,7 @@ defmodule YourApp.NS do use RDF.Vocabulary.Namespace defvocab EX, - base_uri: "http://www.example.com/ns/", + base_iri: "http://www.example.com/ns/", file: "your_vocabulary.nt" alias: [example_term: "example-term"] @@ -210,33 +205,31 @@ defmodule YourApp.NS do use RDF.Vocabulary.Namespace defvocab EX, - base_uri: "http://www.example.com/ns/", + base_iri: "http://www.example.com/ns/", file: "your_vocabulary.nt", ignore: ~w[Foo bar] end ``` -Though strictly discouraged, a vocabulary namespace can be defined as non-strict with the `strict` option set to `false`. A non-strict vocabulary doesn't require any terms to be defined (although they can). A term is resolved dynamically at runtime by concatenation of the term and the base URI of the resp. namespace module: +Though strictly discouraged, a vocabulary namespace can be defined as non-strict with the `strict` option set to `false`. A non-strict vocabulary doesn't require any terms to be defined (although they can). A term is resolved dynamically at runtime by concatenation of the term and the base IRI of the resp. namespace module: ```elixir defmodule YourApp.NS do use RDF.Vocabulary.Namespace defvocab EX, - base_uri: "http://www.example.com/ns/", + base_iri: "http://www.example.com/ns/", terms: [], strict: false end -iex> import RDF, only: [uri: 1] +iex> import RDF, only: [iri: 1] iex> alias YourApp.NS.{EX} -iex> uri(EX.Foo) -%URI{authority: "www.example.com", fragment: nil, host: "www.example.com", - path: "/ns/Foo", port: 80, query: nil, scheme: "http", userinfo: nil} +iex> iri(EX.Foo) +~I iex> EX.bar -%URI{authority: "www.example.com", fragment: nil, host: "www.example.com", - path: "/ns/bar", port: 80, query: nil, scheme: "http", userinfo: nil} +~I iex> EX.Foo |> EX.bar(EX.Baz) #RDF.Description{subject: ~I ~I @@ -246,7 +239,7 @@ iex> EX.Foo |> EX.bar(EX.Baz) ### Blank nodes -Blank nodes are nodes of an RDF graph without an URI. They are always local to that graph and mostly used as helper nodes. +Blank nodes are nodes of an RDF graph without an IRI. They are always local to that graph and mostly used as helper nodes. They can be created with `RDF.BlankNode.new` or its alias function `RDF.bnode`. You can either pass an atom, string, integer or Erlang reference with a custom local identifier or call it without any arguments, which will create a local identifier automatically. @@ -297,7 +290,7 @@ import RDF.Sigils Note: Only languages without subtags are supported as modifiers of the `~L` sigil, i.e. if you want to use `en-US` as a language tag, you would have to use `RDF.literal` or `RDF.Literal.new`. -A typed literal can be created by providing the `datatype` option with an URI of a datatype. Most of the time this will be an [XML schema datatype]: +A typed literal can be created by providing the `datatype` option with an IRI of a datatype. Most of the time this will be an [XML schema datatype]: ```elixir RDF.literal("42", datatype: XSD.integer) @@ -374,7 +367,7 @@ iex> RDF.Literal.canonical(RDF.Integer.new("0042")) == true ``` -Note: Although you can create any XSD datatype by using the resp. URI with the `datatype` option of `RDF.Literal.new`, not all of them support the validation and conversion behaviour of `RDF.Literal`s and the `value` field simply contains the initially given value unvalidated and unconverted. +Note: Although you can create any XSD datatype by using the resp. IRI with the `datatype` option of `RDF.Literal.new`, not all of them support the validation and conversion behaviour of `RDF.Literal`s and the `value` field simply contains the initially given value unvalidated and unconverted. @@ -416,7 +409,7 @@ RDF.ex provides various data structures for collections of statements: All of these structures have similar sets of functions and implement Elixirs `Enumerable` protocol, Elixirs `Access` behaviour and the `RDF.Data` protocol of RDF.ex. -The `new` function of these data structures create new instances of the struct and optionally initialize them with initial statements. `RDF.Description.new` requires at least an URI or blank node for the subject, while `RDF.Graph.new` and `RDF.Dataset.new` take an optional URI for the name of the graph or dataset. +The `new` function of these data structures create new instances of the struct and optionally initialize them with initial statements. `RDF.Description.new` requires at least an IRI or blank node for the subject, while `RDF.Graph.new` and `RDF.Dataset.new` take an optional IRI for the name of the graph or dataset. ```elixir empty_description = RDF.Description.new(EX.Subject) @@ -428,7 +421,7 @@ empty_unnamed_dataset = RDF.Dataset.new empty_named_dataset = RDF.Dataset.new(EX.Dataset) ``` -As you can see, qualified terms from a vocabulary namespace can be given instead of an URI and will be resolved automatically. This applies to all of the functions discussed below. +As you can see, qualified terms from a vocabulary namespace can be given instead of an IRI and will be resolved automatically. This applies to all of the functions discussed below. The `new` functions can be called more shortly with the resp. delegator functions `RDF.description`, `RDF.graph` and `RDF.dataset`. @@ -657,9 +650,10 @@ The `head` option also allows to specify a custom node for the head of the list. The function `RDF.List.values/1` allows to get the values of a RDF list (including nested lists) as a native Elixir list. ```elixir -RDF.list(["foo", EX.Bar, ~B, [1, 2]]) -|> RDF.List.values -# [~L"foo", RDF.uri(EX.bar), ~B, [RDF.Integer.new(1), RDF.Integer.new(2)]] +iex> RDF.list(["foo", EX.Bar, ~B, [1, 2]]) |> RDF.List.values +[~L"foo", ~I, ~B, + [%RDF.Literal{value: 1, datatype: ~I}, + %RDF.Literal{value: 2, datatype: ~I}]] ```