Development/Tutorials/Metadata/Nepomuk/NepomukServer: Difference between revisions

Revision as of 19:06, 3 April 2008

Nepomuk Server

Tutorial Series	Nepomuk
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Further Reading	Introduction to RDF and Ontologies, Handling Resources with Nepomuk

The Nepomuk Server

The Nepomuk Server is a daemon which hosts all Nepomuk service including the main Nepomuk data repository. The main repository is an RDF database using Soprano including a Soprano full text index. The interface of the repository is exported via DBus (The DBus interface is defined by Soprano). When using the Soprano DBus interface from within a KDE application there is no need to bother with QDBus. Soprano provides the Soprano::Client::DBusModel class which wraps all DBus communication into a nice Soprano::Model interface.

There are two ways to access this wrapper model:

1. Use Soprano::Client::DBusClient to create a connection to the Nepomuk Server:

Soprano::Client::DBusClient* client = new Soprano::Client::DBusClient( "org.kde.NepomukStorage" ); Soprano::Model* model = client->createModel( "main" );

The Nepomuk Server registers as DBus service org.kde.NepomukStorage and the name of the main data repository is main.

2. Use the Nepomuk library, i.e. ResourceManager to access the main model:

Soprano::Model* model = Nepomuk::ResourceManager::instance()->mainModel();

The advantage of the first version is that there is no need to link to libnepomuk. On the other hand the main model as provided by libnepomuk connects via a local socket if available which is faster. Also, it provides an automatic re-connect feature.

So all in all the easy way is also the recommended one: use libnepomuk and the ResourceManager to access the data.

@@ Line 9: / Line 9: @@
 ==The Nepomuk Server==
-The Nepomuk Server is a KDED module which hosts the main Nepomuk data repository. The main repository is an RDF database using [http://soprano.sf.net Soprano] including a [http://api.kde.org/kdesupport-api/kdesupport-apidocs/soprano/html/namespaceSoprano_1_1Index.html Soprano full text index]. The interface of the repository is exported via DBus (The DBus interface is defined by [http://api.kde.org/kdesupport-api/kdesupport-apidocs/soprano/html/soprano_server_dbus.html Soprano]). When using the Soprano DBus interface from within a KDE application there is no need to bother with QDBus. Soprano provides the [http://api.kde.org/kdesupport-api/kdesupport-apidocs/soprano/html/classSoprano_1_1Client_1_1DBusModel.html Soprano::Client::DBusModel] class which wraps all DBus communication into a nice [http://api.kde.org/kdesupport-api/kdesupport-apidocs/soprano/html/classSoprano_1_1Model.html Soprano::Model] interface.
+The Nepomuk Server is a daemon which hosts all Nepomuk service including the main Nepomuk data repository. The main repository is an RDF database using [http://soprano.sf.net Soprano] including a [http://api.kde.org/kdesupport-api/kdesupport-apidocs/soprano/html/namespaceSoprano_1_1Index.html Soprano full text index]. The interface of the repository is exported via DBus (The DBus interface is defined by [http://api.kde.org/kdesupport-api/kdesupport-apidocs/soprano/html/soprano_server_dbus.html Soprano]). When using the Soprano DBus interface from within a KDE application there is no need to bother with QDBus. Soprano provides the [http://api.kde.org/kdesupport-api/kdesupport-apidocs/soprano/html/classSoprano_1_1Client_1_1DBusModel.html Soprano::Client::DBusModel] class which wraps all DBus communication into a nice [http://api.kde.org/kdesupport-api/kdesupport-apidocs/soprano/html/classSoprano_1_1Model.html Soprano::Model] interface.
 There are two ways to access this wrapper model:
@@ Line 16: / Line 16: @@
 <code cppqt>
-Soprano::Client::DBusClient* client = new Soprano::Client::DBusClient( "org.kde.NepomukServer" );
+Soprano::Client::DBusClient* client = new Soprano::Client::DBusClient( "org.kde.NepomukStorage" );
 Soprano::Model* model = client->createModel( "main" );
 </code>
-The Nepomuk Server registers as DBus service ''org.kde.NepomukServer'' and the name of the main data repository is ''main''.
+The Nepomuk Server registers as DBus service ''org.kde.NepomukStorage'' and the name of the main data repository is ''main''.
 . Use the Nepomuk library, i.e. [http://api.kde.org/4.x-api/kdelibs-apidocs/nepomuk/core/html/classNepomuk_1_1ResourceManager.html ResourceManager] to access the main model:
@@ Line 28: / Line 28: @@
 </code>
-The advantage of the first version is that there is no need to link to libnepomuk.
+The advantage of the first version is that there is no need to link to libnepomuk. On the other hand the main model as provided by libnepomuk connects via a local socket if available which is faster. Also, it provides an automatic re-connect feature.
+So all in all the easy way is also the recommended one: use libnepomuk and the ResourceManager to access the data.