<s>
Data	B-Application
modeling	I-Application
in	O
software	B-General_Concept
engineering	I-General_Concept
is	O
the	O
process	O
of	O
creating	O
a	O
data	B-Application
model	I-Application
for	O
an	O
information	O
system	O
by	O
applying	O
certain	O
formal	O
techniques	O
.	O
</s>
<s>
Data	B-Application
modeling	I-Application
is	O
a	O
process	O
used	O
to	O
define	O
and	O
analyze	O
data	O
requirements	O
needed	O
to	O
support	O
the	O
business	O
processes	O
within	O
the	O
scope	O
of	O
corresponding	O
information	O
systems	O
in	O
organizations	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
process	O
of	O
data	B-Application
modeling	I-Application
involves	O
professional	O
data	O
modelers	O
working	O
closely	O
with	O
business	O
stakeholders	O
,	O
as	O
well	O
as	O
potential	O
users	O
of	O
the	O
information	O
system	O
.	O
</s>
<s>
There	O
are	O
three	O
different	O
types	O
of	O
data	B-Application
models	I-Application
produced	O
while	O
progressing	O
from	O
requirements	O
to	O
the	O
actual	O
database	O
to	O
be	O
used	O
for	O
the	O
information	O
system	O
.	O
</s>
<s>
The	O
data	O
requirements	O
are	O
initially	O
recorded	O
as	O
a	O
conceptual	B-Application
data	I-Application
model	I-Application
which	O
is	O
essentially	O
a	O
set	O
of	O
technology	O
independent	O
specifications	O
about	O
the	O
data	O
and	O
is	O
used	O
to	O
discuss	O
initial	O
requirements	O
with	O
the	O
business	O
stakeholders	O
.	O
</s>
<s>
The	O
conceptual	O
model	O
is	O
then	O
translated	O
into	O
a	O
logical	B-Application
data	I-Application
model	I-Application
,	O
which	O
documents	O
structures	O
of	O
the	O
data	O
that	O
can	O
be	O
implemented	O
in	O
databases	B-Application
.	O
</s>
<s>
Implementation	O
of	O
one	O
conceptual	B-Application
data	I-Application
model	I-Application
may	O
require	O
multiple	O
logical	B-Application
data	I-Application
models	I-Application
.	O
</s>
<s>
The	O
last	O
step	O
in	O
data	B-Application
modeling	I-Application
is	O
transforming	O
the	O
logical	B-Application
data	I-Application
model	I-Application
to	O
a	O
physical	B-Application
data	I-Application
model	I-Application
that	O
organizes	O
the	O
data	O
into	O
tables	B-Application
,	O
and	O
accounts	O
for	O
access	O
,	O
performance	O
and	O
storage	O
details	O
.	O
</s>
<s>
Data	B-Application
modeling	I-Application
defines	O
not	O
just	O
data	O
elements	O
,	O
but	O
also	O
their	O
structures	O
and	O
the	O
relationships	O
between	O
them	O
.	O
</s>
<s>
Data	B-Application
modeling	I-Application
techniques	O
and	O
methodologies	O
are	O
used	O
to	O
model	O
data	O
in	O
a	O
standard	O
,	O
consistent	O
,	O
predictable	O
manner	O
in	O
order	O
to	O
manage	O
it	O
as	O
a	O
resource	O
.	O
</s>
<s>
The	O
use	O
of	O
data	B-Application
modeling	I-Application
standards	O
is	O
strongly	O
recommended	O
for	O
all	O
projects	O
requiring	O
a	O
standard	O
means	O
of	O
defining	O
and	O
analyzing	O
data	O
within	O
an	O
organization	O
,	O
e.g.	O
,	O
using	O
data	B-Application
modeling	I-Application
:	O
</s>
<s>
Data	B-Application
modeling	I-Application
may	O
be	O
performed	O
during	O
various	O
types	O
of	O
projects	O
and	O
in	O
multiple	O
phases	O
of	O
projects	O
.	O
</s>
<s>
Data	B-Application
models	I-Application
are	O
progressive	O
;	O
there	O
is	O
no	O
such	O
thing	O
as	O
the	O
final	O
data	B-Application
model	I-Application
for	O
a	O
business	O
or	O
application	O
.	O
</s>
<s>
Instead	O
a	O
data	B-Application
model	I-Application
should	O
be	O
considered	O
a	O
living	O
document	O
that	O
will	O
change	O
in	O
response	O
to	O
a	O
changing	O
business	O
.	O
</s>
<s>
The	O
data	B-Application
models	I-Application
should	O
ideally	O
be	O
stored	O
in	O
a	O
repository	O
so	O
that	O
they	O
can	O
be	O
retrieved	O
,	O
expanded	O
,	O
and	O
edited	O
over	O
time	O
.	O
</s>
<s>
(	O
2004	O
)	O
determined	O
two	O
types	O
of	O
data	B-Application
modeling	I-Application
:	O
</s>
<s>
Strategic	O
data	B-Application
modeling	I-Application
:	O
This	O
is	O
part	O
of	O
the	O
creation	O
of	O
an	O
information	O
systems	O
strategy	O
,	O
which	O
defines	O
an	O
overall	O
vision	O
and	O
architecture	O
for	O
information	O
systems	O
.	O
</s>
<s>
Information	B-Application
technology	I-Application
engineering	I-Application
is	O
a	O
methodology	O
that	O
embraces	O
this	O
approach	O
.	O
</s>
<s>
Data	B-Application
modeling	I-Application
during	O
systems	O
analysis	O
:	O
In	O
systems	O
analysis	O
logical	B-Application
data	I-Application
models	I-Application
are	O
created	O
as	O
part	O
of	O
the	O
development	O
of	O
new	O
databases	B-Application
.	O
</s>
<s>
Data	B-Application
modeling	I-Application
is	O
also	O
used	O
as	O
a	O
technique	O
for	O
detailing	O
business	O
requirements	O
for	O
specific	O
databases	B-Application
.	O
</s>
<s>
It	O
is	O
sometimes	O
called	O
database	O
modeling	O
because	O
a	O
data	B-Application
model	I-Application
is	O
eventually	O
implemented	O
in	O
a	O
database	O
.	O
</s>
<s>
Data	B-Application
models	I-Application
provide	O
a	O
framework	O
for	O
data	O
to	O
be	O
used	O
within	O
information	O
systems	O
by	O
providing	O
specific	O
definition	O
and	O
format	O
.	O
</s>
<s>
If	O
a	O
data	B-Application
model	I-Application
is	O
used	O
consistently	O
across	O
systems	O
then	O
compatibility	O
of	O
data	O
can	O
be	O
achieved	O
.	O
</s>
<s>
However	O
,	O
systems	O
and	O
interfaces	B-Application
are	O
often	O
expensive	O
to	O
build	O
,	O
operate	O
,	O
and	O
maintain	O
.	O
</s>
<s>
This	O
may	O
occur	O
when	O
the	O
quality	O
of	O
the	O
data	B-Application
models	I-Application
implemented	O
in	O
systems	O
and	O
interfaces	B-Application
is	O
poor	O
.	O
</s>
<s>
Some	O
common	O
problems	O
found	O
in	O
data	B-Application
models	I-Application
are	O
:	O
</s>
<s>
Business	O
rules	O
,	O
specific	O
to	O
how	O
things	O
are	O
done	O
in	O
a	O
particular	O
place	O
,	O
are	O
often	O
fixed	O
in	O
the	O
structure	O
of	O
a	O
data	B-Application
model	I-Application
.	O
</s>
<s>
This	O
means	O
that	O
small	O
changes	O
in	O
the	O
way	O
business	O
is	O
conducted	O
lead	O
to	O
large	O
changes	O
in	O
computer	O
systems	O
and	O
interfaces	B-Application
.	O
</s>
<s>
So	O
,	O
business	O
rules	O
need	O
to	O
be	O
implemented	O
in	O
a	O
flexible	O
way	O
that	O
does	O
not	O
result	O
in	O
complicated	O
dependencies	O
,	O
rather	O
the	O
data	B-Application
model	I-Application
should	O
be	O
flexible	O
enough	O
so	O
that	O
changes	O
in	O
the	O
business	O
can	O
be	O
implemented	O
within	O
the	O
data	B-Application
model	I-Application
in	O
a	O
relatively	O
quick	O
and	O
efficient	O
way	O
.	O
</s>
<s>
Therefore	O
,	O
data	B-Language
definitions	I-Language
should	O
be	O
made	O
as	O
explicit	O
and	O
easy	O
to	O
understand	O
as	O
possible	O
to	O
minimize	O
misinterpretation	O
and	O
duplication	O
.	O
</s>
<s>
Data	B-Application
models	I-Application
for	O
different	O
systems	O
are	O
arbitrarily	O
different	O
.	O
</s>
<s>
The	O
result	O
of	O
this	O
is	O
that	O
complex	O
interfaces	B-Application
are	O
required	O
between	O
systems	O
that	O
share	O
data	O
.	O
</s>
<s>
These	O
interfaces	B-Application
can	O
account	O
for	O
between	O
25	O
and	O
70%	O
of	O
the	O
cost	O
of	O
current	O
systems	O
.	O
</s>
<s>
Required	O
interfaces	B-Application
should	O
be	O
considered	O
inherently	O
while	O
designing	O
a	O
data	B-Application
model	I-Application
,	O
as	O
a	O
data	B-Application
model	I-Application
on	O
its	O
own	O
would	O
not	O
be	O
usable	O
without	O
interfaces	B-Application
within	O
different	O
systems	O
.	O
</s>
<s>
To	O
obtain	O
optimal	O
value	O
from	O
an	O
implemented	O
data	B-Application
model	I-Application
,	O
it	O
is	O
very	O
important	O
to	O
define	O
standards	O
that	O
will	O
ensure	O
that	O
data	B-Application
models	I-Application
will	O
both	O
meet	O
business	O
needs	O
and	O
be	O
consistent	O
.	O
</s>
<s>
Conceptual	B-Application
schema	I-Application
:	O
describes	O
the	O
semantics	O
of	O
a	O
domain	O
(	O
the	O
scope	O
of	O
the	O
model	O
)	O
.	O
</s>
<s>
A	O
conceptual	B-Application
schema	I-Application
specifies	O
the	O
kinds	O
of	O
facts	O
or	O
propositions	O
that	O
can	O
be	O
expressed	O
using	O
the	O
model	O
.	O
</s>
<s>
Simply	O
described	O
,	O
a	O
conceptual	B-Application
schema	I-Application
is	O
the	O
first	O
step	O
in	O
organizing	O
the	O
data	O
requirements	O
.	O
</s>
<s>
Logical	B-Application
schema	I-Application
:	O
describes	O
the	O
structure	O
of	O
some	O
domain	O
of	O
information	O
.	O
</s>
<s>
This	O
consists	O
of	O
descriptions	O
of	O
(	O
for	O
example	O
)	O
tables	B-Application
,	O
columns	O
,	O
object-oriented	O
classes	O
,	O
and	O
XML	O
tags	O
.	O
</s>
<s>
The	O
logical	B-Application
schema	I-Application
and	O
conceptual	B-Application
schema	I-Application
are	O
sometimes	O
implemented	O
as	O
one	O
and	O
the	O
same	O
.	O
</s>
<s>
Physical	B-Application
schema	I-Application
:	O
describes	O
the	O
physical	O
means	O
used	O
to	O
store	O
data	O
.	O
</s>
<s>
This	O
is	O
concerned	O
with	O
partitions	O
,	O
CPUs	O
,	O
tablespaces	B-General_Concept
,	O
and	O
the	O
like	O
.	O
</s>
<s>
Storage	O
technology	O
can	O
change	O
without	O
affecting	O
either	O
the	O
logical	O
or	O
the	O
conceptual	B-Application
schema	I-Application
.	O
</s>
<s>
The	O
table/column	O
structure	O
can	O
change	O
without	O
(	O
necessarily	O
)	O
affecting	O
the	O
conceptual	B-Application
schema	I-Application
.	O
</s>
<s>
In	O
each	O
case	B-Application
,	O
of	O
course	O
,	O
the	O
structures	O
must	O
remain	O
consistent	O
across	O
all	O
schemas	O
of	O
the	O
same	O
data	B-Application
model	I-Application
.	O
</s>
<s>
In	O
the	O
context	O
of	O
business	O
process	O
integration	O
(	O
see	O
figure	O
)	O
,	O
data	B-Application
modeling	I-Application
complements	O
business	O
process	O
modeling	O
,	O
and	O
ultimately	O
results	O
in	O
database	O
generation	O
.	O
</s>
<s>
The	O
database	O
design	O
documented	O
in	O
these	O
schemas	O
are	O
converted	O
through	O
a	O
Data	B-Language
Definition	I-Language
Language	I-Language
,	O
which	O
can	O
then	O
be	O
used	O
to	O
generate	O
a	O
database	O
.	O
</s>
<s>
A	O
fully	O
attributed	O
data	B-Application
model	I-Application
contains	O
detailed	O
attributes	O
(	O
descriptions	O
)	O
for	O
every	O
entity	O
within	O
it	O
.	O
</s>
<s>
The	O
term	O
"	O
database	O
design	O
"	O
can	O
describe	O
many	O
different	O
parts	O
of	O
the	O
design	O
of	O
an	O
overall	O
database	B-Application
system	I-Application
.	O
</s>
<s>
In	O
the	O
relational	B-Architecture
model	I-Architecture
these	O
are	O
the	O
tables	B-Application
and	O
views	B-Language
.	O
</s>
<s>
In	O
an	O
object	B-Application
database	I-Application
the	O
entities	O
and	O
relationships	O
map	O
directly	O
to	O
object	O
classes	O
and	O
named	O
relationships	O
.	O
</s>
<s>
However	O
,	O
the	O
term	O
"	O
database	O
design	O
"	O
could	O
also	O
be	O
used	O
to	O
apply	O
to	O
the	O
overall	O
process	O
of	O
designing	O
,	O
not	O
just	O
the	O
base	O
data	O
structures	O
,	O
but	O
also	O
the	O
forms	O
and	O
queries	O
used	O
as	O
part	O
of	O
the	O
overall	O
database	O
application	O
within	O
the	O
Database	B-Application
Management	I-Application
System	I-Application
or	O
DBMS	O
.	O
</s>
<s>
In	O
the	O
process	O
,	O
system	O
interfaces	B-Application
account	O
for	O
25%	O
to	O
70%	O
of	O
the	O
development	O
and	O
support	O
costs	O
of	O
current	O
systems	O
.	O
</s>
<s>
The	O
primary	O
reason	O
for	O
this	O
cost	O
is	O
that	O
these	O
systems	O
do	O
not	O
share	O
a	O
common	B-Application
data	I-Application
model	I-Application
.	O
</s>
<s>
If	O
data	B-Application
models	I-Application
are	O
developed	O
on	O
a	O
system	O
by	O
system	O
basis	O
,	O
then	O
not	O
only	O
is	O
the	O
same	O
analysis	O
repeated	O
in	O
overlapping	O
areas	O
,	O
but	O
further	O
analysis	O
must	O
be	O
performed	O
to	O
create	O
the	O
interfaces	B-Application
between	O
them	O
.	O
</s>
<s>
Data	B-Application
models	I-Application
represent	O
information	O
areas	O
of	O
interest	O
.	O
</s>
<s>
While	O
there	O
are	O
many	O
ways	O
to	O
create	O
data	B-Application
models	I-Application
,	O
according	O
to	O
Len	O
Silverston	O
(	O
1997	O
)	O
only	O
two	O
modeling	O
methodologies	O
stand	O
out	O
,	O
top-down	O
and	O
bottom-up	O
:	O
</s>
<s>
Top-down	O
logical	B-Application
data	I-Application
models	I-Application
,	O
on	O
the	O
other	O
hand	O
,	O
are	O
created	O
in	O
an	O
abstract	O
way	O
by	O
getting	O
information	O
from	O
people	O
who	O
know	O
the	O
subject	O
area	O
.	O
</s>
<s>
Unfortunately	O
,	O
in	O
many	O
environments	O
the	O
distinction	O
between	O
a	O
logical	B-Application
data	I-Application
model	I-Application
and	O
a	O
physical	B-Application
data	I-Application
model	I-Application
is	O
blurred	O
.	O
</s>
<s>
In	O
addition	O
,	O
some	O
CASE	B-Application
tools	O
do	O
n't	O
make	O
a	O
distinction	O
between	O
logical	O
and	O
physical	B-Application
data	I-Application
models	I-Application
.	O
</s>
<s>
There	O
are	O
several	O
notations	O
for	O
data	B-Application
modeling	I-Application
.	O
</s>
<s>
The	O
actual	O
model	O
is	O
frequently	O
called	O
"	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
model	I-Architecture
"	O
,	O
because	O
it	O
depicts	O
data	O
in	O
terms	O
of	O
the	O
entities	O
and	O
relationships	O
described	O
in	O
the	O
data	O
.	O
</s>
<s>
An	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
model	I-Architecture
(	O
ERM	O
)	O
is	O
an	O
abstract	O
conceptual	O
representation	O
of	O
structured	B-Application
data	I-Application
.	O
</s>
<s>
Entity	O
–	O
relationship	O
modeling	O
is	O
a	O
relational	O
schema	O
database	O
modeling	O
method	O
,	O
used	O
in	O
software	B-General_Concept
engineering	I-General_Concept
to	O
produce	O
a	O
type	O
of	O
conceptual	B-Application
data	I-Application
model	I-Application
(	O
or	O
semantic	O
data	B-Application
model	I-Application
)	O
of	O
a	O
system	O
,	O
often	O
a	O
relational	B-Application
database	I-Application
,	O
and	O
its	O
requirements	O
in	O
a	O
top-down	O
fashion	O
.	O
</s>
<s>
The	O
data	B-Application
modeling	I-Application
technique	O
can	O
be	O
used	O
to	O
describe	O
any	O
ontology	O
(	O
i.e.	O
</s>
<s>
an	O
overview	O
and	O
classifications	O
of	O
used	O
terms	O
and	O
their	O
relationships	O
)	O
for	O
a	O
certain	O
universe	B-Algorithm
of	I-Algorithm
discourse	I-Algorithm
i.e.	O
</s>
<s>
Several	O
techniques	O
have	O
been	O
developed	O
for	O
the	O
design	O
of	O
data	B-Application
models	I-Application
.	O
</s>
<s>
Generic	O
data	B-Application
models	I-Application
are	O
generalizations	O
of	O
conventional	O
data	B-Application
models	I-Application
.	O
</s>
<s>
The	O
definition	O
of	O
generic	O
data	B-Application
model	I-Application
is	O
similar	O
to	O
the	O
definition	O
of	O
a	O
natural	O
language	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
generic	O
data	B-Application
model	I-Application
may	O
define	O
relation	O
types	O
such	O
as	O
a	O
'	O
classification	O
relation	O
 '	O
,	O
being	O
a	O
binary	O
relation	O
between	O
an	O
individual	O
thing	O
and	O
a	O
kind	O
of	O
thing	O
(	O
a	O
class	O
)	O
and	O
a	O
'	O
part-whole	O
relation	O
 '	O
,	O
being	O
a	O
binary	O
relation	O
between	O
two	O
things	O
,	O
one	O
with	O
the	O
role	O
of	O
part	O
,	O
the	O
other	O
with	O
the	O
role	O
of	O
whole	O
,	O
regardless	O
the	O
kind	O
of	O
things	O
that	O
are	O
related	O
.	O
</s>
<s>
By	O
standardization	O
of	O
an	O
extensible	O
list	O
of	O
relation	O
types	O
,	O
a	O
generic	O
data	B-Application
model	I-Application
enables	O
the	O
expression	O
of	O
an	O
unlimited	O
number	O
of	O
kinds	O
of	O
facts	O
and	O
will	O
approach	O
the	O
capabilities	O
of	O
natural	O
languages	O
.	O
</s>
<s>
Conventional	O
data	B-Application
models	I-Application
,	O
on	O
the	O
other	O
hand	O
,	O
have	O
a	O
fixed	O
and	O
limited	O
domain	O
scope	O
,	O
because	O
the	O
instantiation	O
(	O
usage	O
)	O
of	O
such	O
a	O
model	O
only	O
allows	O
expressions	O
of	O
kinds	O
of	O
facts	O
that	O
are	O
predefined	O
in	O
the	O
model	O
.	O
</s>
<s>
That	O
is	O
unless	O
the	O
semantic	O
data	B-Application
model	I-Application
is	O
implemented	O
in	O
the	O
database	O
on	O
purpose	O
,	O
a	O
choice	O
which	O
may	O
slightly	O
impact	O
performance	O
but	O
generally	O
vastly	O
improves	O
productivity	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
need	O
to	O
define	O
data	O
from	O
a	O
conceptual	O
view	O
has	O
led	O
to	O
the	O
development	O
of	O
semantic	O
data	B-Application
modeling	I-Application
techniques	O
.	O
</s>
<s>
A	O
semantic	O
data	B-Application
model	I-Application
is	O
an	O
abstraction	B-Application
which	O
defines	O
how	O
the	O
stored	O
symbols	O
relate	O
to	O
the	O
real	O
world	O
.	O
</s>
<s>
The	O
purpose	O
of	O
semantic	O
data	B-Application
modeling	I-Application
is	O
to	O
create	O
a	O
structural	O
model	O
of	O
a	O
piece	O
of	O
the	O
real	O
world	O
,	O
called	O
"	O
universe	B-Algorithm
of	I-Algorithm
discourse	I-Algorithm
"	O
.	O
</s>
<s>
A	O
semantic	O
data	B-Application
model	I-Application
can	O
be	O
used	O
to	O
serve	O
many	O
purposes	O
,	O
such	O
as	O
:	O
</s>
<s>
The	O
overall	O
goal	O
of	O
semantic	O
data	B-Application
models	I-Application
is	O
to	O
capture	O
more	O
meaning	O
of	O
data	O
by	O
integrating	O
relational	O
concepts	O
with	O
more	O
powerful	O
abstraction	B-Application
concepts	O
known	O
from	O
the	B-Application
artificial	I-Application
intelligence	I-Application
field	O
.	O
</s>
<s>
The	O
idea	O
is	O
to	O
provide	O
high	O
level	O
modeling	O
primitives	O
as	O
integral	O
part	O
of	O
a	O
data	B-Application
model	I-Application
in	O
order	O
to	O
facilitate	O
the	O
representation	O
of	O
real	O
world	O
situations	O
.	O
</s>
