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DBin and CKC@WWW2007 Brainlet Tutorial
The CKC Brainlet, based on the DBin platform, allows to browse, collaboratively edit and share RDF(S) data.
This tutorial will guide you trough the basic DBin startup settings and shows the capabilities of the CKC Brainlet.
Once the followed the steps described in the release notes (for mac users), start DBin (as a .exe or .app).
The first time DBin is run it requires you to set up an identity, that will be attached to each information you will insert into DBin.
The identity wizard is shown in Illustration 1.
Illustration 1
Each user in DBin is identified by a URI. If you choose the first option, your identity URI will be generated automatically from the nickname provided.
Otherwise you can choose the expert mode and use a custom URI (e.g. mailto:YOURMAIL).
Once you press the next button, DBin creates a public and a private PGP certificates (for this you'll need to choose a password), which will be used to digitally sign the RDF data you will insert.
If the process succeeds DBin shows a dialog specifying a URL that you can use to get your public PGP key via HTTP: now you have an identity and can author information with DBin.
The KnowledgeGrowth perspective (Illustration 2) allows you to join topic groups, sharing your RDF data and importing what others are sharing in the same group.
On the left side you see a list of servers (currently there should be only one), providing hook-ups to the groups.
Select the SeMedia server and a list of groups will be shown on the right.
By double clicking on a group (or by selecting and pressing the "start agent" button) you will join it.
Illustration 2
To join a p2p topic group in DBin means to share those information you have in your local client which are "of interest" for the group (based on a "semantic" definition).
Join the CKC@WWW2007 group from those listed and you will now redirected to the CKC Brainlet.
Your "Knowledge Agent" is now running and collecting information from the p2p channel, you can monitor its activity the Knowledge Agents view.
This view shows statistics and info such as how many pieces of information you have taken or given out in the p2p channel and the uptime.
You can switch back to the KnowledgeGrowth perspective by clicking the double arrow button in the top menu.
Use the "plus" button on the right of the top menu bar to go to the CKC Brainlet (Illustration 3).
Illustration 3
The rest of this tutorial explains how to use the CKC Brainlet (Illustration 4).
Illustration 4
Focusing on a resource
The Ontology View, left side, shows the hierarchy of classes in the ontology starting from the Root Class, and, for each class, its instances.
Classes are represented as orange circles, while instances are green squares.
Once a resource (class or instance) has been selected, the "focus" of the Brainlet will be set to that resource.
This means that the other views (Properties, Annotations and so on) will have as input such a resource and show "something about it".
At each time you can see what is been focused in the Focusing On view and, using the top-right button you can copy its URI to the system clipboard.
This view also provides a focus history and back and forward buttons (much like a web browser).
Browsing and editing properties
The Properties View shows the properties attached to the focused resource and their values.
By double-clicking a property or a value (which in RDFS are resources as well) you will set the focus on it.
You can use this view to browse the classes, properties and instances of the ontology or to add properties to the focused resource.
Clicking the "add a Property" button the interface in Illustration 5 will be shown.
Select one of the properties from the combo box, which are the properties allowed for the selected resource (based on its type).
Illustration 5
Then you can enter a value for the property in different ways:
By selecting from the second combo box one of the resources which are already in DBin and that are allowed as values of the chosen property;
By using the NEW button. A URI Wizard (see later in this tutorial) will guide you in creating a new instance of the right type, supported by the ontology.
By entering a literal value.
By right clicking on a property value and choosing "revoke statement" you will remove it from the knowledge base.
Some words needs to be spent about revoking information in DBin.
Revoking information
Each time you revoke some data in DBin it does not imply to actually delete it from the database.
As in DBin information is shared in a decentralized way, no user has the power to really delete something.
A revocation is a piece of RDF that points to an other one and "remove it", it is an information itself and its signed by the author.
Such revocations are shared in the p2p groups along with other information.
This means that if you revoke something and then connect to the CKC group, the revocation will also take effect on other DBin clients connected to the same group.
DBin automatically hides knowledge that has been revoked by you or remotely by other users.
You still have a chance to see the overall knowledge, including revoked stuff, by the Knowledge Filters perspective (semaphore button in the top menu bar).
Check the "Show All" option to visualized revoked data, “Apply all revocations” to go back to the default mode.
When you revoke something sometimes DBin asks you to delete some other information for the revocation to be effective.
This happens when ontological relations are revoked, as in RDFS there might be other relations from which they can be inferred.
Finally, some data in DBin are read only so you cannot revoke them (e.g., base ontologies).
Adding "annotations"
The Annotations View allows you to add and browse special annotations (e.g. binary attachments, images).
The CKC Brainlet allows (long) textual comments and images to be attached.
By selecting an annotation from the list, details are shown in the Annotation Details view.
The internal browser
The Browser view always shows the web location attached to the selected resource by means of the built in hasWebSite property.
If you want to attach a web location to a resource use the Properties view and add a value for this property.
Editing ontology classes and instances
By right clicking an item in the Ontology View you can choose to:
If the item is a Class:
Add an instance of the selected class;
Add a sub-class to the selected class;
Add a super-class to the selected class;
Add an attribute to the selected class. (In RDFS this means a property with the selected class as rdfs:domain);
Remove as sub-class.
That is stating that the selected resource it is not a sub-class of its parent node in the tree.
Note this does not mean to remove the class, other information about it will remain (e.g., its attributes, label, annotation properties, and so on).
If the item is an instance:
Remove the selected instance, stating that it is not an instance of the parent node in the tree.
Also in this case other information about the resource will remain in the DB.
Illustration 6
Adding an instance
Choose add Instance from the right click menu. This will guide you to the URI Wizard.
URI Wizards are simple assisted procedures that help users in choosing a URI to identify a new resource they want to create.
In this case you have three choices (Illustration 7).
Illustration 7
The first two options allow you to simply enter a name for the resource (a label) and then uses it for creating a URI.
Alternatively, choose the expert mode to directly typing in a URI (e.g. a URL for a web site).
Adding a sub-class or a super-class
Choose add sub-class from the right click menu. Now you will be required to choose the class that will be transformed into a sub-class of the selected one.
You can select it among the existing classes (combo box in Illustration 8) or create a new class ("New" button) by means of a URI Wizard as the one in Illustration 7.
After the wizard has been closed, the new class is automatically added to the combo box and selected. Press ok to make changes effective.
Illustration 8
Adding an attribute to a class
To add an attribute means to create a property that can then be attached to each instance of the selected class (via Properties View as already explained).
This procedure in DBin is similar to the previous ones and allows you to enter the URI Wizard and create a new Property, as well as to choose from a list of already defined properties.
WARNING: we suggest to create a new property instead of using an existing one as it might create unexpected behaviors.
Removing a sub-class
This action allows to remove the sub-class relation between the selected class and its parent node in the tree.
This will make the class disappear from the GUI, but will not remove the class itself and other relations it might be involved in.
For example if it is a sub-class of more than one class, it will remain in the taxonomy until you do not remove all its sub-class relations.
Removing an instance
This action is similar to the previous one, but removes the “instance-of” relation between the selected instance and its parent node in the tree.
Other relations or annotation that the instance might have will not be removed.
Removing a class or an instance
With this action you will completely remove the class or instance you selected.
This means that no reference to or relation involving the resource will remain in your knowledge base.
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