A Visual Environment for Developing Defeasible Rule Bases for the Semantic Web
VDR-Device is a visual integrated environment for developing (creating, editing, running, testing and deploying) defeasible rule bases for the Semantic Web. The following is a brief tutorial to get you started with the use and functionality of the VDR-Device system, accompanied by a number of screenshots, aiming at a better depth of understanding.
*Please note that VDR-Device
is still under development and, therefore, a number of its features require
some “polishing”, while many more are planned to be added in future releases.
This tutorial covers the following aspects of VDR-Device:
·
The Main Window of the program
·
Compiling & Running a Set of Rules
The Main Window
of the Program
The main window of the program is composed of two
major parts:
(a) the upper part
includes the menu bar, which contains the program menus, and the toolbar that
includes icons, representing the most common utilities of the rule editor, and
(b) the central and more
“bulky” part is the primary frame of the main window and is in turn divided
into two panels.
|
main window |
The left panel displays the rule base in XML-tree
format, which is the most intuitive means of displaying RuleML-like
syntax, because of its hierarchical nature. The user has the option of navigating
through the entire tree and can add to or remove elements from the tree. However,
since each rule base is backed by a DTD document (compatible to RuleML v. 0.85), potential
addition or removal of tree elements has to obey the DTD limitations. Therefore,
the rule editor allows a limited number of operations performed on each
element, according to the element's meaning within the rule tree.
The right panel shows a table, which contains the
attributes that correspond each time to the selected tree node in the left-hand
area. The user can also perform editing functions on the attributes, by
altering the value for each attribute in the panel that appears below the
attributes table on the right-hand side. The values that the user can insert
are obviously limited by the chosen attribute each time.
Each new project created by VDR-Device
determines a separate folder,
dedicated for the storage of the rule base as well as the various
relevant files created during compilation. The next time any of these files are
needed, they can be directly loaded, improving speed
considerably (running a compiled project is up to 10 times faster).
There are 3 types of new projects, depending on the
location and type of the corresponding rule base: Projects with remote rule
base, projects with local rule base and projects with blank rule
base. If, for example, the former project type is selected, then the user
has to input the project name and the location of the rule base in the dialog
box that opens immediately afterwards:
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|
creating
a new project with remote rule base |
VDR-Device
loads the rule base and displays it in tree format in the left-hand frame. The
project and rule base names are displayed in the upper part of the main window
and the attributes of the rule base can be viewed and edited in the right-hand
panel.
An existing project can also be accessed, by clicking
on the respective icon in the toolbar and selecting the desired directory in
the dialog panel that appears immediately afterwards. This
results in the project rule base being loaded and displayed in the
left-hand frame, as well as the relevant project and rule base names displayed
in the upper part of the main window.
|
opening an existing project |
Another important aspect of the VDR-Device
system is the namespace dialog window, where the user determines which RDF/XML
namespaces will be used by the rule base. Namespace declarations are treated as
addresses of input RDF Schema ontologies that contain the vocabulary for the
input RDF documents, over which the rules of the rule base will be run.
|
the namespaces window |
The namespaces entered by the user, as well as those
contained in the input RDF documents are then analyzed, in order to extract all
the allowed class and property names for the rule base being developed. These
names are then used throughout the authoring phase of the RuleML
rule base, constraining the corresponding allowed names that can be applied and
narrowing the possibility for errors on behalf of the user.
As can be observed in the screenshot, the “rdf” and “rdfs”
namespaces are already included in the namespace dialog window, indicating that
the authoring of a VDR-Device rule base is compliant
to the two aforementioned specifications. The user can, however, append as many
additional namespace declarations as he/she wishes.
Compiling
& Running a Set of Rules
When the project parameters have been set up and a
valid rule base is created (or loaded), the user can compile and run the
rules, in order to obtain a result. More specifically, the compilation of the
rule base transforms the rules from the RuleML-like
syntax of VDR-Device into CLIPS production rules,
which are then executed by the reasoning system and an output is produced. The
exported results as well as the execution trace of the compilation and running
processes can then be displayed to the user.
results |
trace |