Semantic Web and knowledge map entry (a)
RDF / XML
Body: For shared concepts clear and detailed description of a formal system. It refers to an abstract model can be used to describe the world object types, attributes, and relationships of the type of constitution.
RDF / XML is mainly about is how to use XML way to represent RDF Fig.
Ovals represent nodes, while rectangles represent text, arcs predicate.
Node Description
<rdf:Description rdf:about="A"></rdf:Description>A node itself needs to be rdf: Description defined by rdf: about resources described uri.
Rdf space in front of the name, the default is the natural space rdf space.
Attribute Description
A description of how the value of the property d D it?
属性描述
<rdf:Description rdf:about="A">
<d>D</d>
</rdf:Description>
简写
<rdf:Description rdf:about="A" d="D"></rdf:Description>Path Description
How to describe a path from A to B it?
Can be defined rdf: nodeId manner specified unique nodeId, can also rdf: parseType specified node is empty Resouce.
属性描述,注意这里的B也是个节点，所以也需要Description
<rdf:Description rdf:about="A">
<a rdf:nodeId="abc"></a>
</rdf:Description>
<rdf:Description rdf:nodeId="abc">
<b>
<rdf:Description rdf:about="B" ></rdf:Description>
</b>
</rdf:Description>
不单独写空节点，即用resource
<rdf:Description rdf:about="A">
<a rdf:parseType="Resource">
<b>
<rdf:Description rdf:about="B" ></rdf:Description>
</b>
</a>
</rdf:Description>Text representation
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:ex="http://purl.org/dc/elements/1.1/">
<rdf:Description rdf:about="http://example.com">
<ex:prop rdf:parseType="Literal" xmlns:a="http://example.org/a#">
123
</ex:prop>
</rdf:Description>
</rdf:RDF>xmlns i.e. xml namespace, the definition of a command space.
Using the syntax: xmlns: namespace-prefix = "namespaceURI".
Here the definition of a name as a command space
The results can be seen after resolved to:
| Number | Subject | Predicate | Object |
|---|---|---|---|
| 1 | http://example.com](http://example.com/) | http://purl.org/dc/elements/1.1/prop) | "123"^^http://www.w3.org/1999/02/22-rdf-syntax-ns#XMLLiteral |
Parse URL: https: //www.w3.org/RDF/Validator/rdfval
Can be seen by analyzing the contents of the resolution became a prop point text types, namely by specifying rdf: parseType = "Literal" to achieve. Predicate RDF: parseType = "the Literal" , the contents of the node is specified plain text, the interpreter does not need to be explained.
type of data
May be used rdf: datatype specified text data type
<rdf:RDF>
<rdf:Description rdf:about="http://example.com">
<a rdf:datatype="http://www.w3.org/2001/XMLSchema#int">
123
</a>
</rdf:Description>
</rdf:RDF>Similarly, there string, date, decimal data type and the like may be specified in the above datatype.
RDF Schema (RDFS)
Full name RDFS RDF Schema, RDF Schema class in object-oriented programming language is very similar to a class. This is so that the resources can be defined as a subclass of the class and instances of classes.
<rdf:RDF
xmlns:rdf= "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xml:base= "http://www.animals.fake/animals#">
<rdf:Description rdf:ID="animal">
<rdf:type
rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
</rdf:Description>
<rdf:Description rdf:ID="horse">
<rdf:type
rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
<rdfs:subClassOf rdf:resource="#animal"/>
</rdf:Description>
</rdf:RDF>rdf: type
is used to represent the subject is an example of the predicate, the subject is a resource, the predicate is a class, the above described example is an example of class animal, Horse is class instance.
rdfs:subClassOf
Is used to indicate the subject is a subclass of the predicate, the subject and predicate is a class. The above example shows that the horse is a subclass of the animal.
rdfs:subPropertyOf
Is used to indicate the subject sub-attribute of the predicate, the subject and predicate properties are
rdfs:domain
It is used to indicate the attribute domain
rdfs:range
It used to represent the range
In addition, all are all the resources (resource): all classes (class) are the resources, all the attributes (property) all resources, all resources are literal.
container
Open Lists
open lists to add new elements to the container issue.
rdf: Seq expressed as a predetermined ordered list of values (such as sorting in alphabetical order of a), may contain duplicate values.
rdf: Bag as represented by a predetermined value unordered list may contain duplicate values.
rdf: Alt represents a list of alternative values (the user can select only one of these values).
<rdf:RDF>
<rdf:Description rdf:about="http://a.com">
<a>
<rdf:Alt>
<rdf:li>CD</rdf:li>
<rdf:li>Record</rdf:li>
<rdf:li>Tape</rdf:li>
</rdf:Alt>
</a>
</rdf:Description>
</rdf:RDF>RDF: Li , interpreter interpreting automatically generated number.
Closed Lists
closed lists can not be added to container element, it becomes collections. By rdf: parseType = "collections" object can be regarded as closed lists.
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:cd="http://recshop.fake/cd#">
<rdf:Description
rdf:about="http://recshop.fake/cd/Beatles">
<cd:artist rdf:parseType="Collection">
<rdf:Description rdf:about="http://recshop.fake/cd/Beatles/George"/>
<rdf:Description rdf:about="http://recshop.fake/cd/Beatles/John"/>
<rdf:Description rdf:about="http://recshop.fake/cd/Beatles/Paul"/>
<rdf:Description rdf:about="http://recshop.fake/cd/Beatles/Ringo"/>
</cd:artist>
</rdf:Description>
</rdf:RDF>Turtle syntax
turtle represented by triples, each behind a sentence. indicates the end of a sentence.
Prefix
@prefix book: <http://aa.com> .
@prefix ex: <http://axx.com> .@Prefix specified by the prefix, the prefix can be used so that in the back.
book:uri ex:a "aaa".