COLLABORATIVE ONTOLOGIES AND ITS VISUALISATION IN

CSCW SYSTEMS

Michael Vonrueden

University of Paderborn, Faculty of Electrical Engineering, Mathematics and Computer Science

Fuerstenallee 11, 33102 Paderborn, Germany

Thorsten Hampel

University of Paderborn, Faculty of Electrical Engineering, Mathematics and Computer Science

Fuerstenallee 11, 33102 Paderborn, Germany

Keywords:

Collaborative Ontology Creation, Knowledge Representation, Userinterface, Semantic Web.

Abstract:

The goal of semantic structures and especially the semantic web is to simplify knowledge retrieval in computer

based systems. The Visual Cooperative Ontology Environment - short visCOntE - aims to support the process

of a collaborative ontology creation and the mapping of an individual’s mental map into a computer based

knowledge representation. Due to the collaborative and graphical approach many requirements have to be

considered to establish such a project. Beneath a deep description of visCOntE and possible usage scenarios,

the question what is needed for a successful collaborative ontology creation and which functions a system

should make available will be determined in detail.

1 INTRODUCTION

The problem of information overload is present in

nearly every digital based system. The difﬁculty to

gain an overview and to separate the wanted from

the unwanted information, or more precisely, to trans-

form it into personal knowledge is often an enormous

cognitive performance. The latest ambitions of the

W3C towards the semantic web shows a new way to

handle these tasks (W3C, 2004a). The use of ontolo-

gies can make it easier to ﬁnd, process and associate

informations. But as an ontology is similar to a men-

tal model of an individual, a monolithic mental model

will show only a unique view to the world, which

will, in some cases, be not comprehensibly for oth-

ers. Therefore the creation of ontologies should cover

the involvement of different parties to participate and

construct an ontology in a collaborate process.

This paper outlines the problems with ontologies

which are developed in a one to many relation and

tries to ﬁnd new ways for a collaborative creation of

ontologies. After an analysis of what is needed for a

collaborative ontology creation, the current develop-

ment of a tool called visCOntE will be described. vis-

COntE (Visual Cooperative Ontology Environment)

- part of the

open

sTeam (Structuring Information in

Teams) open source environment, developed at the

University of Paderborn - is designed to edit and

browse ontologies in a collaborate environment.

The underlying high ﬂexible

open

sTeam server ar-

chitecture, provides manifold approaches to create

and structure knowledge in a cooperative manner.

Users can share and annotate their knowledge (e.g.

Documents) or separate resp. order it by creating spe-

cial rooms and access rights.

open

sTeam’s communi-

cation facilities like the shared whiteboard supports

the synchronous building of a cooperative informa-

tion space (Hampel and Keil-Slawik, 2002). The vis-

COntE project is the very ﬁrst step to integrate a new

approach of ontology based knowledge management

into this environment.

2 SEMANTIC STRUCTURES

A human sees the world not as a line up of single ob-

jects but rather as an interconnected ensemble. The

ability to structure natural objects and artifacts in hi-

erarchies and classes is one part of the preceding step

in a construction of a semantic map. The other highly

cognitive performance is to relate the items of a tax-

onomy to other items and to reason their associations.

To achieve this relations a kind of logical reasoning

has to be performed. With the resulting semantic

structure new semantical integrations can be adopted.

But the question is how to integrate such complex

structures into a computer based system. The struc-

ture of an ontology allows the creation of special

knowledge domains, which split the complex type of

a human mental model into specialized parts, which

294

Ronaghi F. (2005).

INTEGRATED PERFORMANCE MANAGEMENT.

In Proceedings of the Seventh International Conference on Enterprise Information Systems, pages 294-299

DOI: 10.5220/0002551402940299

 SciTePress

have a common base. These ontologies cover (instead

of a whole representation ) only a ﬁne granulated part

of it. This makes the processing of knowledge easier

and provides more reusability for distributed ontolo-

gies.

3 COLLABORATION AND

ONTOLOGIES

”The Semantic Web is an extension of the

current web in which information is given well-

deﬁned meaning, better enabling computers and

people to work in cooperation.” (Tim Berners-

Lee, 2001)

As mentioned above, ontologies are similar to an in-

dividuals mental model of a special domain and/or a

view of the world. The process to create such a men-

tal model is far more than a one-time procedure or a

simple adaption of other individual’s models. More-

over the development of a mental model is always in a

state of continuous movement associated with social

aspects like discussions, correction of wrong assess-

ments or simply: questions and answers. The rule of

a mental models creation could be described as fol-

lowed: Starting from a generic point of knowledge the

new adopted knowledge will become more and more

special, but never reaches a ﬁnal state.

This let us assume, that for a successful building

of knowledge two parts are essential: continuousness

and endlessness. The fact is, that this parts are not

considered in ontologies which are created from one

or a few authors for many users or recipients and those

which claim a ﬁnal state. Because of the non existing

involvement of the future users and the missing social

aspects, a collaborative approach is needed which will

support the evolution of an ontology similar to a men-

tal model.

A collaborative created ontology could bear ad-

vantages with regard to the acceptance and compre-

hension of a common knowledge domain by all par-

ties. The ability to create, modify and contribute an

individual knowledge could further affect the atten-

dance of the whole process and the gain of new or

renewed knowledge which come along with discus-

sions. Moreover a hidden advantage exists in the in-

terpretation of current states of an ontology, that could

state out the actual knowledge of a community and

outlines the way of creation up to an actual snapshot.

The resulting questions is, what should be consid-

ered to transform the idea of a collaborate creation of

ontologies into a real word scenario. In relation to the

previous conclusions, the following keywords should

be reasonable represented in this scenario: visualiza-

tion, comprehension, social exchange and usability.

4 visCOntE - VISUAL

COOPERATIVE ONTOLOGY

ENVIRONMENT

visCOntE - part of the

open

sTeam (Structuring Infor-

mation in Teams) environment, developed at the Uni-

versity of Paderborn (Hampel and Keil-Slawik, 2002)

- aims to be a web-based graphical front-end for the

collaborative creation and modiﬁcation of ontologies.

Intended are three possible kinds of editable ontolo-

gies. Due to the capabilities of the

open

sTeam Server

it is possible to provide a very global ontology for the

whole (server-wide) community, the creation of spe-

cial rooms and groups permit a shared ontology for

related users and the personal user space for private

one. In general visCOntE should act as the default

application for ﬁles in the common W3C Ontologie-

Format OWL (W3C, 2004b) , which makes it very

ﬂexible in importing existing ontologies. The envi-

ronment itself is splitted into a client and a server

module. The client, implemented in Scalable Vec-

tor Graphics, combines an ontology browser with di-

rectly accessible edit-components. With this browser

it is possible to structure the taxonomy of the ontol-

ogy and to add, remove and edit elements such as

classes and individuals or their interconnection. The

server module, responsible for storing and retrieving

the ontology data in OWL Format, communicates to

the client over a simpliﬁed XML-Format to avoid time

consuming processes. The following outlines the in

section Collaboration and Ontologies mentioned key-

words in relation to the developed tool.

4.1 Server Module

Like the

open

sTeam server itself, the server-module

is written entirely in the Pike Scripting Language.

Since Version 7.6, the Pike API offers basic capa-

bilities for the handling of RDF (Ora Lassila, 1999)

and OWL structures (Michael K. Smith, 2004) . The

visCOntE server-module builds up on this basic func-

tionality by adding a more sophisticated and linked

level which represents the structure of the low level

OWL-Elements like Classes, Individuals and Proper-

ties. This linked structure extends the meta informa-

tions of these elements, so that a class for example

knows which individuals are derived from itself or

an individual can validate if it belongs to the inher-

itance line of a special class. A controllstructure acts

as an intermediate between the elements and the tex-

tual representation on the one hand and the connec-

tion to the Pike API on the other. Further it handles

the ontology access and versioning over platform spe-

ciﬁc storage handlers.

Due to the extended element representation the ar-

chitecture supports the use of actions which can be

COLLABORATIVE ONTOLOGIES AND ITS VISUALISATION IN CSCW SYSTEMS

295

performed on hierarchical and ontology speciﬁc data

structures. These actions will take place only on the

represented elements and not on the ontology itself,

so moving a class to a new position in the tree, adding

an individual of a class to the ontology or getting an

individual with a speciﬁc property are possible with-

out touching the existing data. The above mentioned

ontology control object will save the changes only on

a explicit save call. The execution of a single ac-

tion produces a result object which is provided either

as a simpliﬁed hierarchical XML Format or in a raw

format of the above mentioned OWL-Elements. The

action model can be extended by customized actions

which makes it easier for custom interfaces to access

and edit an ontology in a very special way and with

various clients. With the package oriented design, the

insertion of custom interface and the interoperable use

of the resulting XML data structure the module is ca-

pable for other purposes or software projects.

4.2 Visualization

The Visualization of hierarchical structures like on-

tologies and the resulting large depth and/or width

often consumes to much space. Concerning to

Ben Shneiderman’s Informations Seeking Mantra:

”Overview ﬁrst, zoom and ﬁlter, then details on de-

mand” (Shneiderman, 1996) the browser’s view is di-

vided into two major parts to consider the dynamic

structure of a collaborative created ontology. The

treemap approach (Shneiderman, 1991) allows to get

a fast and good overview of deep hierarchies. The

Figure 1: Treemap View

optimal space alignment and the quick navigation to

deeper layers provide a good starting point to get a

ﬁrst overview. To distinguish the model’s hierarchy,

each tree-depth gets the same color, whereas the color

differs only in a slight amount to it’s parent color.

The second visualization, the graph view, is related

to a complex hierarchy. Especially ontologies with

their associations, parent and child classes and at-

tributes needs an easy respectively self-explanatory

visualization. To understand the enormous complex-

ity a deeper look on the construct of an ontology is

required. An ontology according to the guidelines of

Figure 2: Graph of model with parent, childs and associa-

tions

the OWL-Format is structured into classes and indi-

viduals. A class represents a more generic description

of an object, it links attributes and associations to it-

self and provides the inherited properties of its parent.

On the other side an individual or instance represents

a real world object, that is constructed from it’s cor-

responding model. To achieve an easy to understand

representation, we developed a metaphor which bears

in mind the dependencies of the model-individual re-

lation. The chosen metaphor maps the inheritance of

the models as a ﬂuid, which ﬂows from one model

to its submodel. The models layout looks like a kind

of reservoir whose ﬁlling height indicates the number

of individuals belonging to this model. If we proceed

Figure 3: Individual View of Type ”Lecture”

with this metaphor an individual could be seen as a

part of the ﬂuid, consequently this appears as a drop,

which will show up in a zoomed view of the reservoir.

Further the drops can be ﬁltered by attributes and as-

sociations to achieve clusters with common proper-

ties. However the models attributes are shown as

a box inside the reservoir, connections from this box

to other models indicate the related associations. To

keep the overview simple, only the current selected

model, its direct parent and child models and the as-

sociated models are rendered.

ICEIS 2005 - INFORMATION SYSTEMS ANALYSIS AND SPECIFICATION

296

Figure 4: Filtering of drops by different properties and as-

sociations

Figure 5: Individual in connection with properties and other

individuals

4.3 Awareness

The understanding of how an ontology evolved to

a current state is of particular importance. On the

one hand side an involved author should see which

changes are made to a model to recognize its current

progress and what intention another editor’s change

belong to. On the other hand an important case is

to provide a quick overview for future users, who

participate the collaborative process at a later time.

Therefore changes need to keep logged and facilities

for asynchronous conversations are essential. Hav-

ing much experience with Wiki-Systems we decided

to adopt the approach of logging every changed ver-

sion to provide the ability to return to a previous state.

This technique also enables an author to fork a previ-

ous version for new editing. Another media function

we will adopt is the asynchronous discussion related

to a model. With this we hope to achieve an effect of

continuous exchange between the users with the re-

sult of new respectively renewed views and in ﬁnding

a consensus.

4.4 Usability

To achieve a good usability the graphical user inter-

face is evaluated at speciﬁed milestones by students,

which indeed will be the future users. The current

framework of the in section Visualization mentioned

views provides the following components.

Tabbed Views The treemap and the graph view are

separated in different tabs. The selected model in

either one of this views will also change the current

model in the other tab. So a fast switching without

a new search of the selected model accelerate the

browsing of the ontology.

Bookmarks Adopted from World Wide Web -

Browsers, the feature of setting a bookmark for a

particular model provides a quick tie up to a previ-

ous session.

History A history navigation enables the user to keep

track of the visited models in a current session.

Address Field Due to the hierarchical nature of an

ontology an omnipresent virtual path (similar to a

ﬁlesystem path) will be printed to get informations

about the current location of a model. Further the

models are selectable which could also be used for

navigation purposes.

Zoomed Views Because of the lossless magniﬁca-

tion of Scalable Vector Graphics, zoomable views

are supported for the treemap and graph view and

also a general magniﬁcation of the whole applica-

tion which is especially useful for visually handi-

capped persons.

Directly Editable The editing is provided directly

at the speciﬁed model. Symbols like a drop or

an reservoir beneath the model indicate the result-

ing actions. The edit-forms itself are provided in

HTML, due to the text input limitations of SVG. To

create new associations a special copy stack which

holds the selected models will be initialized over

the whole session.

Related Filters As mentioned in section Visualiza-

tion, a model related ﬁlter will be provided to clus-

ter the individuals by speciﬁc attributes.

Automatic Linking Similar to the behavior of links

in Wiki-Systems, special types of links will han-

dled differently. Common WWW-links will be

considered and a direct jump to the page will be

performed. Links containing targets to pictures will

be rendered as picture instead of the textual appear-

ance. Special links to

open

sTeam items like users,

documents, groups and rooms can be entered sim-

ply by its unique id instead of a complicated URL.

Further it is planned to support the embedding of

audible and visual documents.

COLLABORATIVE ONTOLOGIES AND ITS VISUALISATION IN CSCW SYSTEMS

297

4.5 Participation

What we want to achieve is acceptance and participa-

tion for the cooperative creation of an ontology. The

challenge is to communicate the future user the ad-

vantage and gain for his own purposes. In case of on-

tologies stimuli could be to point out that the users in-

dividual knowledge will stay in conjunction to others

knowledge or that personal artifacts like Documents

can be embedded in a semantic structure to be useful

for others and in the end for the user himself. It is

surely not enough to just communicate it with words,

than with a direct response of the whole system. Fur-

ther attendance could be achieved by embedding the

system in university lectures or other workﬂow’s in

organizations. Especially organizations could proﬁt

from sharing the knowledge of its members to keep it

beyond the individuals quitting. But covering this in

detail would go to far for this paper.

5 USAGE SCENARIOS

In this section an imaginable usage scenario could

take place. The

open

sTeam is available for all faculties

of the University of Paderborn. To mention a few, the

range of faculties goes from culture studies to com-

puter science over economics up to natural science.

Faculties outside the computer science uses the sys-

tem often for accompanying lectures of a semester.

After a semester the rooms and groups more or less

gets orphaned. The chances to create an ontology at

an ongoing lecture are obvious. Either for following

groups of the same faculty or for the chance of a real

interdisciplinary study, a group related or global on-

tology could help to keep the knowledge persistent

in the system, which in turn could help students to

revise on present semantic linked documents or re-

lations. For clarity, the following ﬁctive example is

given.

5.1 Connecting knowledge domains

Imagine three courses, which will be held with sup-

port of the

open

sTeam environment. The ﬁrst courses

topic is about how to write screenplays for documen-

tations, the second deals with current development of

robotics at the university and the third is about guide-

lines of university marketing. Now the three courses

create independently from each other models for their

topics in the global ontology. They embed documents

related to a speciﬁc ﬁeld, relate these ﬁelds and doc-

uments to the involved students and to other previous

existing models of the ontology.

In the next semester an economic course should

create a short movie about the current research of

advanced technology at the university, which should

be presented to current and future investors. Now

the three above mentioned independent courses could

help to access related informations in a quick way.

Browsing the ontology to get informations about lead-

ings technologies and how to present them in attrac-

tive and for investors adequate form will help to keep

the focus on the real problems. Due to the seman-

tic structure of the ontology the students can reason

what documents are related for their tasks, who could

be a possible contact person and what else is associ-

ated. With the experience related to the creation of the

movie new associations could be developed, which

possibly connects the ﬁeld of robotic with the ﬁeld

of university marketing with the one of how to write

a screenplay.

This example should be more or less assignable to

any kind of organization which has either a broad or

a narrow spectrum of ﬁelds. Because of the ability

of every involved person to embed its experience and

knowledge, the approach in resolving a problem with

an already solved problem and the direct access of

related informations are the big chance of an ontol-

ogy. Facts like the constructive fashion and the never

reached ﬁnal state of an ontology makes the essential

difference of a collaborative created ontology in con-

trast to an expert only one.

5.2 Mapping

open

sTeam structure

Another possible scenario is the automatic mapping

of the

open

sTeam structure to an ontology. The inter-

connection of users, room and documents could be vi-

sualized in a more detailed and clearly arranged man-

ner. The addition of a special type of model could

initiate a pre deﬁned action, that performs changes in

both, the ontology and the system structure. A partic-

ular example in this case could be the administration

of the users room privileges or the relation of docu-

ments to speciﬁc rooms.

6 RELATED WORKS

One of the inspirations for visCOntE were on the one

hand Wiki Systems like its well known representa-

tive wikipedia

. Structures like the collaborative edit-

ing of linkable content as a main approach in vis-

COntE and other media elements like an asynchro-

nous item related discussion or the different handling

of URIs (like weblinks, images or email-addresses )

are adopted. Moreover the versioning of the Ontol-

ogy is much the same like it is in a Wiki - System,

visCOntE even extends this technique with the ability

http://www.wikipedia.org

ICEIS 2005 - INFORMATION SYSTEMS ANALYSIS AND SPECIFICATION

298

to work with a forked version of the ontology. On

the other hand ontology editors like Prot

and

OntoEdit



with their ﬁne granulated form based ap-

proach of ontology creation were taken into account

for the development. With the visual approach of on-

tology creation and the design goal to be a tool for

non experts visCOntE differs from these editors.

7 CONCLUSION AND FURTHER

WORK

Because of the independent format of the ontology,

the adaption is not limited to the context of the browse

and edit environment. Where visCOntE is the ﬁrst

step in creating, searching and editing of the ontol-

ogy, other services could also operate on the provided

informations of it. This could be either in the way of

an automatic editing of the ontology by special rea-

sonings or in an automatic support of user interests.

General services can operate on any kind of ontol-

ogy regardless to the real information. An imagin-

able service or agent could observe a special model

of the ontology which a user places to a list of sub-

scribed interest. On any change he/she will be in-

formed about the current addition. Related to the us-

age scenario this could be a new document dealing

about robotics or a newly associated ﬁeld. This could

help, to keep the user’s knowledge updated. A dif-

ferent service but with the same approach could be

the detection of people, who have similar interests

or problems. Especially in organization like univer-

sities this could help out to ﬁnd new learning part-

ners. Another approach could be the initiation of a

keyword based semantical search engine that in fu-

ture could be embedded in visCOntE. The mentioned

scope is directed to the informations an ontology pro-

vides. Other services like a reminder of appointments

can operate only if the ontology has a relation to time.

To initiate these kind of services a special architec-

ture which analyses the attributes of an ontology is

needed. The OWL-Standard supports the assignment

of special data types like dates but others are speci-

ﬁed by the author of the ontology. The special struc-

ture of the OWL-Format in separating datatypes from

the actual models makes it possible to provide such

architecture, that dynamically watches attributes and

relates them to special events. Perhaps, even a cre-

ation of services on the user side is possible to con-

struct a set of rules with corresponding actions. The

list could be widened by more particular examples.

What we wanted to mention is the wide ﬁeld of appli-

cation of an ontology thats reasonably needs at ﬁrst

http://protege.stanford.edu

http://www.ontoedit.de

to be constructed and in particular in a cooperative

way. Without this very ﬁrst step, services like the

above remain meaningless, because the user is con-

strained to embed himself in the whole process. The

visContE project is the very ﬁrst step to integrate a

new approach of the semantic web into the

open

sTeam

environment. Further steps could be, like mentioned

above, the integration of semantic webservices, the

sharing of the constructed ontology with other par-

ties or the representation of system characteristics or

other hierarchical based informations. Beside this, we

are looking forward to get an overview on social as-

pects and patterns of the systems user composition to

answer questions like which research ﬁelds are more

distinctive than others or how the cooperation of in-

terdisciplinary groups is possible / impossible. The

development of visContE is still in an early phase

of userinterface creation and implementation of the

server-module.

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