开发基于Triplestore数据库的Web应用程序

Question

I've recently developed a "classic" 3-tier web applications using Java EE.
I've used GlassFish as application server, MS SQL Server as DBMS and xhtml pages with primefaces components for the front end.

Now, for educational purposes, I want to substitute the relational db with a pure triplestore database but I'm not sure about the procedure to follow.

I've searched a lot on google and on this site but I didn't find what I was looking for, because every answer I found was more theoretical than practical.
If possible, I need a sort of tutorial or some practical tips. I've read the documentation about Apache Jena but I'm not able to find a solid starting point.
In particoular:
- In order to use MS SQL Server with GlassFish I've used a JDBC Driver, created a datasource and a connection pool. Does it exist an equivalent procedure to set up a triple store database?
- To handle users authentication, I've used a Realm. What should I do now?

For the moment I've created "by hand" a RDF schema and using Jena Schemagen I've translated it into a Java Class. What should I do now?

Answer 1

After several attempts and other research on the net I finally achieved my goal.
I decided to develop a hybrid solution in which I manage users login and their navigation permits via MS SQL Server and JDBCRealm, while I use Jena TDB to save all the other data.

Starting with an RDF schema, I created a Java class that contains resources and properties to easily create my statements via code. Here's an example:

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
    xmlns="http://www.stackoverflow.com/example#"
    xml:base="http://www.stackoverflow.com/example">


    <rdfs:Class rdf:ID="User"></rdfs:Class>

    <rdfs:Class rdf:ID="Project"></rdfs:Class>

    <rdf:Property rdf:ID="email"></rdf:Property>

    <rdf:Property rdf:ID="name"></rdf:Property>

    <rdf:Property rdf:ID="surname"></rdf:Property>

    <rdf:Property rdf:ID="description"></rdf:Property>

    <rdf:Property rdf:ID="customer"></rdf:Property>

    <rdf:Property rdf:ID="insertProject">
        <rdfs:domain rdf:resource="http://www.stackoverflow.com/example#User"/>
        <rdfs:range rdf:resource="http://www.stackoverflow.com/example#Project"/>
    </rdf:Property>

</rdf:RDF>

And this is the Java class:

public class MY_ONTOLOGY {

    private static final OntModel M = ModelFactory.createOntologyModel(OntModelSpec.RDFS_MEM);

    private static final String NS = "http://www.stackoverflow.com/example#";

    private static final String BASE_URI = "http://www.stackoverflow.com/example/";

    public static final OntClass USER = M.createClass(NS + "User");

    public static final OntClass PROJECT = M.createClass(NS + "Project");

    public static final OntProperty EMAIL = M.createOntProperty(NS + "hasEmail");

    public static final OntProperty NAME = M.createOntProperty(NS + "hasName");

    public static final OntProperty SURNAME = M.createOntProperty(NS + "hasSurname");

    public static final OntProperty DESCRIPTION = M.createOntProperty(NS + "hasDescription");

    public static final OntProperty CUSTOMER = M.createOntProperty(NS + "hasCustomer");

    public static final OntProperty INSERTS_PROJECT = M.createOntProperty(NS + "insertsProject");

    public static final String getBaseURI() {
        return BASE_URI;
    }

}

Then I've created a directory on my PC where I want to store the data, like C:\\MyTDBdataset .
To store data inside it, I use the following code:

String directory = "C:\\MyTDBdataset";
Dataset dataset = TDBFactory.createDataset(directory);


dataset.begin(ReadWrite.WRITE);
try {
    Model m = dataset.getDefaultModel();
    Resource user = m.createResource(MY_ONTOLOGY.getBaseURI() + "Ronnie", MY_ONTOLOGY.USER);
    user.addProperty(MY_ONTOLOGY.NAME, "Ronald");
    user.addProperty(MY_ONTOLOGY.SURNNAME, "Red");
    user.addProperty(MY_ONTOLOGY.EMAIL, "ronnie@myemail.com");  

    Resource project = m.createResource(MY_ONTOLOGY.getBaseURI() + "MyProject", MY_ONTOLOGY.PROJECT);
    project.addProperty(MY_ONTOLOGY.DESCRIPTION, "This project is fantastic");
    project.addProperty(MY_ONTOLOGY.CUSTOMER, "Customer & Co");

    m.add(user, MY_ONTOLOGY.INSERTS_PROJECT, project);
    dataset.commit();
} finally {
    dataset.end();
}

If I want to read statements in my TDB, I can use something like this:

dataset.begin(ReadWrite.READ);

try {
    Model m = dataset.getDefaultModel();
    StmtIterator iter = m.listStatements();


    while (iter.hasNext()) {
        Statement stmt = iter.nextStatement();
        Resource subject = stmt.getSubject();
        Property predicate = stmt.getPredicate();
        RDFNode object = stmt.getObject();


        System.out.println(subject);
        System.out.println("\t" + predicate);
        System.out.println("\t\t" + object);
        System.out.println("");
   }
    m.write(System.out, "RDF/XML"); //IF YOU WANT TO SEE AT CONSOLE YOUR DATA AS RDF/XML
} finally {
    dataset.end();
}

If you want to navigate your model in different ways, look at this tutorial provided by Apache.
If you want to remove specific statements in your model, you can write something like this:

dataset.begin(ReadWrite.WRITE);
try {
    Model m = dataset.getDefaultModel();
    m.remove(m.createResource("http://http://www.stackoverflow.com/example/Ronnie"), MY_ONTOLOGY.NAME, m.createLiteral("Ronald"));
    dataset.commit();
} finally {
    dataset.end();
}

That's all! Bye!