<s>
A	O
data	B-Application
model	I-Application
is	O
an	O
abstract	O
model	O
that	O
organizes	O
elements	O
of	O
data	O
and	O
standardizes	O
how	O
they	O
relate	O
to	O
one	O
another	O
and	O
to	O
the	O
properties	O
of	O
real-world	O
entities	B-Architecture
.	O
</s>
<s>
For	O
instance	O
,	O
a	O
data	B-Application
model	I-Application
may	O
specify	O
that	O
the	O
data	O
element	O
representing	O
a	O
car	O
be	O
composed	O
of	O
a	O
number	O
of	O
other	O
elements	O
which	O
,	O
in	O
turn	O
,	O
represent	O
the	O
color	O
and	O
size	O
of	O
the	O
car	O
and	O
define	O
its	O
owner	O
.	O
</s>
<s>
The	O
term	O
data	B-Application
model	I-Application
can	O
refer	O
to	O
two	O
distinct	O
but	O
closely	O
related	O
concepts	O
.	O
</s>
<s>
At	O
other	O
times	O
it	O
refers	O
to	O
the	O
set	O
of	O
concepts	O
used	O
in	O
defining	O
such	O
formalizations	O
:	O
for	O
example	O
concepts	O
such	O
as	O
entities	B-Architecture
,	O
attributes	O
,	O
relations	O
,	O
or	O
tables	O
.	O
</s>
<s>
So	O
the	O
"	O
data	B-Application
model	I-Application
"	O
of	O
a	O
banking	O
application	O
may	O
be	O
defined	O
using	O
the	O
entity	O
–	O
relationship	B-Architecture
"	O
data	B-Application
model	I-Application
"	O
.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
explicitly	O
determines	O
the	O
structure	O
of	O
data	O
.	O
</s>
<s>
Data	B-Application
models	I-Application
are	O
typically	O
specified	O
by	O
a	O
data	O
specialist	O
,	O
data	O
librarian	O
,	O
or	O
a	O
digital	O
humanities	O
scholar	O
in	O
a	O
data	B-Application
modeling	I-Application
notation	O
.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
can	O
sometimes	O
be	O
referred	O
to	O
as	O
a	O
data	B-General_Concept
structure	I-General_Concept
,	O
especially	O
in	O
the	O
context	O
of	O
programming	O
languages	O
.	O
</s>
<s>
Data	B-Application
models	I-Application
are	O
often	O
complemented	O
by	O
function	O
models	O
,	O
especially	O
in	O
the	O
context	O
of	O
enterprise	O
models	O
.	O
</s>
<s>
Managing	O
large	O
quantities	O
of	O
structured	O
and	O
unstructured	B-Application
data	I-Application
is	O
a	O
primary	O
function	O
of	O
information	O
systems	O
.	O
</s>
<s>
Data	B-Application
models	I-Application
describe	O
the	O
structure	O
,	O
manipulation	O
,	O
and	O
integrity	O
aspects	O
of	O
the	O
data	O
stored	O
in	O
data	O
management	O
systems	O
such	O
as	O
relational	B-Application
databases	I-Application
.	O
</s>
<s>
They	O
may	O
also	O
describe	O
data	O
with	O
a	O
looser	O
structure	O
,	O
such	O
as	O
word	B-General_Concept
processing	I-General_Concept
documents	O
,	O
email	O
messages	O
,	O
pictures	O
,	O
digital	O
audio	O
,	O
and	O
video	O
:	O
XDM	B-Application
,	O
for	O
example	O
,	O
provides	O
a	O
data	B-Application
model	I-Application
for	O
XML	B-Protocol
documents	I-Protocol
.	O
</s>
<s>
The	O
main	O
aim	O
of	O
data	B-Application
models	I-Application
is	O
to	O
support	O
the	O
development	O
of	O
information	O
systems	O
by	O
providing	O
the	O
definition	O
and	O
format	O
of	O
data	O
.	O
</s>
<s>
If	O
the	O
same	O
data	B-General_Concept
structures	I-General_Concept
are	O
used	O
to	O
store	O
and	O
access	O
data	O
then	O
different	O
applications	O
can	O
share	O
data	O
.	O
</s>
<s>
A	O
major	O
cause	O
is	O
that	O
the	O
quality	O
of	O
the	O
data	B-Application
models	I-Application
implemented	O
in	O
systems	O
and	O
interfaces	O
is	O
poor	O
"	O
.	O
</s>
<s>
"	O
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
can	O
lead	O
to	O
replication	O
of	O
data	O
,	O
data	B-General_Concept
structure	I-General_Concept
,	O
and	O
functionality	O
,	O
together	O
with	O
the	O
attendant	O
costs	O
of	O
that	O
duplication	O
in	O
development	O
and	O
maintenance	O
"	O
.	O
</s>
<s>
"	O
Data	B-Application
models	I-Application
for	O
different	O
systems	O
are	O
arbitrarily	O
different	O
.	O
</s>
<s>
The	O
reason	O
for	O
these	O
problems	O
is	O
a	O
lack	O
of	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>
A	O
data	B-Application
model	I-Application
explicitly	O
determines	O
the	O
structure	O
of	O
data	O
.	O
</s>
<s>
Typical	O
applications	O
of	O
data	B-Application
models	I-Application
include	O
database	B-General_Concept
models	I-General_Concept
,	O
design	O
of	O
information	O
systems	O
,	O
and	O
enabling	O
exchange	O
of	O
data	O
.	O
</s>
<s>
Usually	O
,	O
data	B-Application
models	I-Application
are	O
specified	O
in	O
a	O
data	B-Language
modeling	I-Language
language	I-Language
.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
instance	O
may	O
be	O
one	O
of	O
three	O
kinds	O
according	O
to	O
ANSI	O
in	O
1975	O
:	O
</s>
<s>
Conceptual	B-Application
data	I-Application
model	I-Application
:	O
describes	O
the	O
semantics	B-Application
of	O
a	O
domain	O
,	O
being	O
the	O
scope	O
of	O
the	O
model	O
.	O
</s>
<s>
This	O
consists	O
of	O
entity	O
classes	O
,	O
representing	O
kinds	O
of	O
things	O
of	O
significance	O
in	O
the	O
domain	O
,	O
and	O
relationship	B-Architecture
assertions	O
about	O
associations	O
between	O
pairs	O
of	O
entity	O
classes	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>
Logical	B-Application
data	I-Application
model	I-Application
:	O
describes	O
the	O
semantics	B-Application
,	O
as	O
represented	O
by	O
a	O
particular	O
data	O
manipulation	O
technology	O
.	O
</s>
<s>
This	O
consists	O
of	O
descriptions	O
of	O
tables	O
and	O
columns	O
,	O
object	B-Language
oriented	I-Language
classes	O
,	O
and	O
XML	B-Protocol
tags	O
,	O
among	O
other	O
things	O
.	O
</s>
<s>
Physical	B-Application
data	I-Application
model	I-Application
:	O
describes	O
the	O
physical	O
means	O
by	O
which	O
data	O
are	O
stored	O
.	O
</s>
<s>
The	O
table/column	O
structure	O
may	O
be	O
different	O
from	O
a	O
direct	O
translation	O
of	O
the	O
entity	O
classes	O
and	O
attributes	O
,	O
but	O
it	O
must	O
ultimately	O
carry	O
out	O
the	O
objectives	O
of	O
the	O
conceptual	O
entity	B-Architecture
class	I-Architecture
structure	O
.	O
</s>
<s>
Early	O
phases	O
of	O
many	O
software	O
development	O
projects	O
emphasize	O
the	O
design	O
of	O
a	O
conceptual	B-Application
data	I-Application
model	I-Application
.	O
</s>
<s>
Such	O
a	O
design	O
can	O
be	O
detailed	O
into	O
a	O
logical	B-Application
data	I-Application
model	I-Application
.	O
</s>
<s>
In	O
later	O
stages	O
,	O
this	O
model	O
may	O
be	O
translated	O
into	O
physical	B-Application
data	I-Application
model	I-Application
.	O
</s>
<s>
One	O
of	O
the	O
earliest	O
pioneering	O
works	O
in	O
modeling	O
information	O
systems	O
was	O
done	O
by	O
Young	O
and	O
Kent	O
(	O
1958	O
)	O
,	O
who	O
argued	O
for	O
"	O
a	O
precise	O
and	O
abstract	O
way	O
of	O
specifying	O
the	O
informational	O
and	O
time	O
characteristics	O
of	O
a	O
data	B-General_Concept
processing	I-General_Concept
problem	O
"	O
.	O
</s>
<s>
They	O
wanted	O
to	O
create	O
"	O
a	O
notation	O
that	O
should	O
enable	O
the	O
analyst	O
to	O
organize	O
the	O
problem	O
around	O
any	O
piece	O
of	O
hardware	B-Architecture
"	O
.	O
</s>
<s>
Their	O
work	O
was	O
the	O
first	O
effort	O
to	O
create	O
an	O
abstract	O
specification	O
and	O
invariant	O
basis	O
for	O
designing	O
different	O
alternative	O
implementations	O
using	O
different	O
hardware	B-Architecture
components	O
.	O
</s>
<s>
The	O
next	O
step	O
in	O
IS	O
modeling	O
was	O
taken	O
by	O
CODASYL	B-Language
,	O
an	O
IT	O
industry	O
consortium	O
formed	O
in	O
1959	O
,	O
who	O
essentially	O
aimed	O
at	O
the	O
same	O
thing	O
as	O
Young	O
and	O
Kent	O
:	O
the	O
development	O
of	O
"	O
a	O
proper	O
structure	O
for	O
machine-independent	O
problem	O
definition	O
language	O
,	O
at	O
the	O
system	O
level	O
of	O
data	B-General_Concept
processing	I-General_Concept
"	O
.	O
</s>
<s>
In	O
the	O
1960s	O
data	B-Application
modeling	I-Application
gained	O
more	O
significance	O
with	O
the	O
initiation	O
of	O
the	O
management	B-Application
information	I-Application
system	I-Application
(	O
MIS	O
)	O
concept	O
.	O
</s>
<s>
The	O
first	O
generation	O
database	B-Application
system	I-Application
,	O
called	O
Integrated	B-Application
Data	I-Application
Store	I-Application
(	O
IDS	O
)	O
,	O
was	O
designed	O
by	O
Charles	O
Bachman	O
at	O
General	O
Electric	O
.	O
</s>
<s>
Two	O
famous	O
database	B-General_Concept
models	I-General_Concept
,	O
the	O
network	B-General_Concept
data	I-General_Concept
model	I-General_Concept
and	O
the	O
hierarchical	B-General_Concept
data	I-General_Concept
model	I-General_Concept
,	O
were	O
proposed	O
during	O
this	O
period	O
of	O
time	O
"	O
.	O
</s>
<s>
Towards	O
the	O
end	O
of	O
the	O
1960s	O
,	O
Edgar	O
F	O
.	O
Codd	O
worked	O
out	O
his	O
theories	O
of	O
data	O
arrangement	O
,	O
and	O
proposed	O
the	O
relational	B-Architecture
model	I-Architecture
for	O
database	B-Application
management	I-Application
based	O
on	O
first-order	O
predicate	O
logic	O
.	O
</s>
<s>
In	O
the	O
1970s	O
entity	O
–	O
relationship	B-Architecture
modeling	O
emerged	O
as	O
a	O
new	O
type	O
of	O
conceptual	O
data	B-Application
modeling	I-Application
,	O
originally	O
formalized	O
in	O
1976	O
by	O
Peter	O
Chen	O
.	O
</s>
<s>
Entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
models	I-Architecture
were	O
being	O
used	O
in	O
the	O
first	O
stage	O
of	O
information	O
system	O
design	O
during	O
the	O
requirements	O
analysis	O
to	O
describe	O
information	O
needs	O
or	O
the	O
type	O
of	O
information	O
that	O
is	O
to	O
be	O
stored	O
in	O
a	O
database	O
.	O
</s>
<s>
This	O
technique	O
can	O
describe	O
any	O
ontology	O
,	O
i.e.	O
,	O
an	O
overview	O
and	O
classification	O
of	O
concepts	O
and	O
their	O
relationships	O
,	O
for	O
a	O
certain	O
area	B-Algorithm
of	I-Algorithm
interest	I-Algorithm
.	O
</s>
<s>
Nijssen	O
developed	O
"	O
Natural	B-Application
Language	I-Application
Information	I-Application
Analysis	I-Application
Method	I-Application
"	O
(	O
NIAM	B-Application
)	O
method	O
,	O
and	O
developed	O
this	O
in	O
the	O
1980s	O
in	O
cooperation	O
with	O
Terry	O
Halpin	O
into	O
Object-Role	B-Application
Modeling	I-Application
(	O
ORM	O
)	O
.	O
</s>
<s>
However	O
,	O
it	O
was	O
Terry	O
Halpin	O
's	O
1989	O
PhD	O
thesis	O
that	O
created	O
the	O
formal	O
foundation	O
on	O
which	O
Object-Role	B-Application
Modeling	I-Application
is	O
based	O
.	O
</s>
<s>
Bill	O
Kent	O
,	O
in	O
his	O
1978	O
book	O
Data	O
and	O
Reality	O
,	O
compared	O
a	O
data	B-Application
model	I-Application
to	O
a	O
map	O
of	O
a	O
territory	O
,	O
emphasizing	O
that	O
in	O
the	O
real	O
world	O
,	O
"	O
highways	O
are	O
not	O
painted	O
red	O
,	O
rivers	O
do	O
n't	O
have	O
county	O
lines	O
running	O
down	O
the	O
middle	O
,	O
and	O
you	O
ca	O
n't	O
see	O
contour	O
lines	O
on	O
a	O
mountain	O
"	O
.	O
</s>
<s>
In	O
the	O
1980s	O
,	O
according	O
to	O
Jan	O
L	O
.	O
Harrington	O
(	O
2000	O
)	O
,	O
"	O
the	O
development	O
of	O
the	O
object-oriented	B-Language
paradigm	O
brought	O
about	O
a	O
fundamental	O
change	O
in	O
the	O
way	O
we	O
look	O
at	O
data	O
and	O
the	O
procedures	O
that	O
operate	O
on	O
data	O
.	O
</s>
<s>
Traditionally	O
,	O
data	O
and	O
procedures	O
have	O
been	O
stored	O
separately	O
:	O
the	O
data	O
and	O
their	O
relationship	B-Architecture
in	O
a	O
database	O
,	O
the	O
procedures	O
in	O
an	O
application	O
program	O
.	O
</s>
<s>
They	O
focused	O
more	O
on	O
the	O
communication	O
part	O
of	O
the	O
semantics	B-Application
.	O
</s>
<s>
In	O
1997	O
they	O
formalized	O
the	O
method	O
Fully	B-Application
Communication	I-Application
Oriented	I-Application
Information	I-Application
Modeling	I-Application
FCO-IM	B-Application
.	O
</s>
<s>
A	O
database	B-General_Concept
model	I-General_Concept
is	O
a	O
specification	O
describing	O
how	O
a	O
database	O
is	O
structured	O
and	O
used	O
.	O
</s>
<s>
This	O
may	O
not	O
strictly	O
qualify	O
as	O
a	O
data	B-Application
model	I-Application
.	O
</s>
<s>
The	O
hierarchical	B-General_Concept
model	I-General_Concept
is	O
similar	O
to	O
the	O
network	B-General_Concept
model	I-General_Concept
except	O
that	O
links	O
in	O
the	O
hierarchical	B-General_Concept
model	I-General_Concept
form	O
a	O
tree	O
structure	O
,	O
while	O
the	O
network	B-General_Concept
model	I-General_Concept
allows	O
arbitrary	O
graph	O
.	O
</s>
<s>
The	O
network	B-General_Concept
data	I-General_Concept
model	I-General_Concept
is	O
an	O
abstraction	B-Application
of	O
the	O
design	O
concept	O
used	O
in	O
the	O
implementation	O
of	O
databases	B-Application
.	O
</s>
<s>
is	O
a	O
database	B-General_Concept
model	I-General_Concept
based	O
on	O
first-order	O
predicate	O
logic	O
.	O
</s>
<s>
The	O
power	O
of	O
the	O
relational	B-Architecture
data	I-Architecture
model	I-Architecture
lies	O
in	O
its	O
mathematical	O
foundations	O
and	O
a	O
simple	O
user-level	O
paradigm	O
.	O
</s>
<s>
Similar	O
to	O
a	O
relational	B-Architecture
database	I-Architecture
model	I-Architecture
,	O
but	O
objects	O
,	O
classes	O
,	O
and	O
inheritance	B-Language
are	O
directly	O
supported	O
in	O
database	B-Application
schemas	I-Application
and	O
in	O
the	O
query	O
language	O
.	O
</s>
<s>
A	O
method	O
of	O
data	B-Application
modeling	I-Application
that	O
has	O
been	O
defined	O
as	O
"	O
attribute	B-General_Concept
free	O
"	O
,	O
and	O
"	O
fact-based	O
"	O
.	O
</s>
<s>
The	O
result	O
is	O
a	O
verifiably	O
correct	O
system	O
,	O
from	O
which	O
other	O
common	O
artifacts	O
,	O
such	O
as	O
ERD	O
,	O
UML	B-Language
,	O
and	O
semantic	O
models	O
may	O
be	O
derived	O
.	O
</s>
<s>
Associations	O
between	O
data	O
objects	O
are	O
described	O
during	O
the	O
database	B-General_Concept
design	I-General_Concept
procedure	O
,	O
such	O
that	O
normalization	O
is	O
an	O
inevitable	O
result	O
of	O
the	O
process	O
.	O
</s>
<s>
The	O
simplest	O
style	O
of	O
data	O
warehouse	O
schema	B-Application
.	O
</s>
<s>
The	O
star	B-Application
schema	I-Application
consists	O
of	O
a	O
few	O
"	O
fact	O
tables	O
"	O
(	O
possibly	O
only	O
one	O
,	O
justifying	O
the	O
name	O
)	O
referencing	O
any	O
number	O
of	O
"	O
dimension	O
tables	O
"	O
.	O
</s>
<s>
The	O
star	B-Application
schema	I-Application
is	O
considered	O
an	O
important	O
special	O
case	O
of	O
the	O
snowflake	B-Language
schema	I-Language
.	O
</s>
<s>
A	O
data	B-General_Concept
structure	I-General_Concept
diagram	O
(	O
DSD	O
)	O
is	O
a	O
diagram	O
and	O
data	B-Application
model	I-Application
used	O
to	O
describe	O
conceptual	B-Application
data	I-Application
models	I-Application
by	O
providing	O
graphical	O
notations	O
which	O
document	O
entities	B-Architecture
and	O
their	O
relationships	O
,	O
and	O
the	O
constraints	O
that	O
bind	O
them	O
.	O
</s>
<s>
The	O
basic	O
graphic	O
elements	O
of	O
DSDs	O
are	O
boxes	O
,	O
representing	O
entities	B-Architecture
,	O
and	O
arrows	O
,	O
representing	O
relationships	O
.	O
</s>
<s>
Data	B-General_Concept
structure	I-General_Concept
diagrams	O
are	O
most	O
useful	O
for	O
documenting	O
complex	O
data	O
entities	B-Architecture
.	O
</s>
<s>
Data	B-General_Concept
structure	I-General_Concept
diagrams	O
are	O
an	O
extension	O
of	O
the	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
model	I-Architecture
(	O
ER	B-Architecture
model	I-Architecture
)	O
.	O
</s>
<s>
In	O
DSDs	O
,	O
attributes	O
are	O
specified	O
inside	O
the	O
entity	O
boxes	O
rather	O
than	O
outside	O
of	O
them	O
,	O
while	O
relationships	O
are	O
drawn	O
as	O
boxes	O
composed	O
of	O
attributes	O
which	O
specify	O
the	O
constraints	O
that	O
bind	O
entities	B-Architecture
together	O
.	O
</s>
<s>
DSDs	O
differ	O
from	O
the	O
ER	B-Architecture
model	I-Architecture
in	O
that	O
the	O
ER	B-Architecture
model	I-Architecture
focuses	O
on	O
the	O
relationships	O
between	O
different	O
entities	B-Architecture
,	O
whereas	O
DSDs	O
focus	O
on	O
the	O
relationships	O
of	O
the	O
elements	O
within	O
an	O
entity	O
and	O
enable	O
users	O
to	O
fully	O
see	O
the	O
links	O
and	O
relationships	O
between	O
each	O
entity	O
.	O
</s>
<s>
There	O
are	O
several	O
styles	O
for	O
representing	O
data	B-General_Concept
structure	I-General_Concept
diagrams	O
,	O
with	O
the	O
notable	O
difference	O
in	O
the	O
manner	O
of	O
defining	O
cardinality	B-Application
.	O
</s>
<s>
The	O
choices	O
are	O
between	O
arrow	O
heads	O
,	O
inverted	O
arrow	O
heads	O
(	O
crow	B-Architecture
's	I-Architecture
feet	I-Architecture
)	O
,	O
or	O
numerical	O
representation	O
of	O
the	O
cardinality	B-Application
.	O
</s>
<s>
An	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
model	I-Architecture
(	O
ERM	O
)	O
,	O
sometimes	O
referred	O
to	O
as	O
an	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
diagram	I-Architecture
(	O
ERD	O
)	O
,	O
could	O
be	O
used	O
to	O
represent	O
an	O
abstract	O
conceptual	B-Application
data	I-Application
model	I-Application
(	O
or	O
semantic	O
data	B-Application
model	I-Application
or	O
physical	B-Application
data	I-Application
model	I-Application
)	O
used	O
in	O
software	B-General_Concept
engineering	I-General_Concept
to	O
represent	O
structured	B-Application
data	I-Application
.	O
</s>
<s>
Like	O
DSD	O
's	O
,	O
attributes	O
are	O
specified	O
inside	O
the	O
entity	O
boxes	O
rather	O
than	O
outside	O
of	O
them	O
,	O
while	O
relationships	O
are	O
drawn	O
as	O
lines	O
,	O
with	O
the	O
relationship	B-Architecture
constraints	O
as	O
descriptions	O
on	O
the	O
line	O
.	O
</s>
<s>
The	O
E-R	B-Architecture
model	I-Architecture
,	O
while	O
robust	O
,	O
can	O
become	O
visually	O
cumbersome	O
when	O
representing	O
entities	B-Architecture
with	O
several	O
attributes	O
.	O
</s>
<s>
There	O
are	O
several	O
styles	O
for	O
representing	O
data	B-General_Concept
structure	I-General_Concept
diagrams	O
,	O
with	O
a	O
notable	O
difference	O
in	O
the	O
manner	O
of	O
defining	O
cardinality	B-Application
.	O
</s>
<s>
The	O
choices	O
are	O
between	O
arrow	O
heads	O
,	O
inverted	O
arrow	O
heads	O
(	O
crow	B-Architecture
's	I-Architecture
feet	I-Architecture
)	O
,	O
or	O
numerical	O
representation	O
of	O
the	O
cardinality	B-Application
.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
in	O
Geographic	B-Application
information	I-Application
systems	I-Application
is	O
a	O
mathematical	O
construct	O
for	O
representing	O
geographic	O
objects	O
or	O
surfaces	O
as	O
data	O
.	O
</s>
<s>
the	O
raster	O
data	B-Application
model	I-Application
represents	O
geography	O
as	O
cell	O
matrixes	O
that	O
store	O
numeric	O
values	O
;	O
</s>
<s>
and	O
the	O
Triangulated	B-Algorithm
irregular	I-Algorithm
network	I-Algorithm
(	O
TIN	O
)	O
data	B-Application
model	I-Application
represents	O
geography	O
as	O
sets	O
of	O
contiguous	O
,	O
nonoverlapping	O
triangles	O
.	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>
Generic	O
data	B-Application
models	I-Application
are	O
developed	O
as	O
an	O
approach	O
to	O
solving	O
some	O
shortcomings	O
of	O
conventional	O
data	B-Application
models	I-Application
.	O
</s>
<s>
For	O
example	O
,	O
different	O
modelers	O
usually	O
produce	O
different	O
conventional	O
data	B-Application
models	I-Application
of	O
the	O
same	O
domain	O
.	O
</s>
<s>
Invariably	O
,	O
however	O
,	O
this	O
difference	O
is	O
attributable	O
to	O
different	O
levels	O
of	O
abstraction	B-Application
in	O
the	O
models	O
and	O
differences	O
in	O
the	O
kinds	O
of	O
facts	O
that	O
can	O
be	O
instantiated	O
(	O
the	O
semantic	O
expression	O
capabilities	O
of	O
the	O
models	O
)	O
.	O
</s>
<s>
A	O
semantic	O
data	B-Application
model	I-Application
in	O
software	B-General_Concept
engineering	I-General_Concept
is	O
a	O
technique	O
to	O
define	O
the	O
meaning	O
of	O
data	O
within	O
the	O
context	O
of	O
its	O
interrelationships	O
with	O
other	O
data	O
.	O
</s>
<s>
A	O
semantic	O
data	B-Application
model	I-Application
is	O
an	O
abstraction	B-Application
that	O
defines	O
how	O
the	O
stored	O
symbols	O
relate	O
to	O
the	O
real	O
world	O
.	O
</s>
<s>
A	O
semantic	O
data	B-Application
model	I-Application
is	O
sometimes	O
called	O
a	O
conceptual	B-Application
data	I-Application
model	I-Application
.	O
</s>
<s>
The	O
logical	O
data	B-General_Concept
structure	I-General_Concept
of	O
a	O
database	B-Application
management	I-Application
system	I-Application
(	O
DBMS	O
)	O
,	O
whether	O
hierarchical	B-General_Concept
,	O
network	B-General_Concept
,	O
or	O
relational	B-Architecture
,	O
cannot	O
totally	O
satisfy	O
the	O
requirements	O
for	O
a	O
conceptual	O
definition	O
of	O
data	O
because	O
it	O
is	O
limited	O
in	O
scope	O
and	O
biased	O
toward	O
the	O
implementation	O
strategy	O
employed	O
by	O
the	O
DBMS	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
need	O
to	O
define	O
data	O
from	O
a	O
conceptual	B-Application
view	I-Application
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
that	O
defines	O
how	O
the	O
stored	O
symbols	O
relate	O
to	O
the	O
real	O
world	O
.	O
</s>
<s>
It	O
is	O
usually	O
one	O
of	O
several	O
architecture	B-Architecture
domains	I-Architecture
that	O
form	O
the	O
pillars	O
of	O
an	O
enterprise	O
architecture	O
or	O
solution	B-Architecture
architecture	I-Architecture
.	O
</s>
<s>
A	O
data	O
architecture	O
describes	O
the	O
data	B-General_Concept
structures	I-General_Concept
used	O
by	O
a	O
business	O
and/or	O
its	O
applications	O
.	O
</s>
<s>
It	O
provides	O
criteria	O
for	O
data	B-General_Concept
processing	I-General_Concept
operations	O
that	O
make	O
it	O
possible	O
to	O
design	O
data	O
flows	O
and	O
also	O
control	O
the	O
flow	O
of	O
data	O
in	O
the	O
system	O
.	O
</s>
<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
by	O
applying	O
formal	O
data	B-Application
model	I-Application
descriptions	O
using	O
data	B-Application
modeling	I-Application
techniques	O
.	O
</s>
<s>
Data	B-Application
modeling	I-Application
is	O
a	O
technique	O
for	O
defining	O
business	O
requirements	O
for	O
a	O
database	O
.	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>
The	O
figure	O
illustrates	O
the	O
way	O
data	B-Application
models	I-Application
are	O
developed	O
and	O
used	O
today	O
.	O
</s>
<s>
A	O
conceptual	B-Application
data	I-Application
model	I-Application
is	O
developed	O
based	O
on	O
the	O
data	O
requirements	O
for	O
the	O
application	O
that	O
is	O
being	O
developed	O
,	O
perhaps	O
in	O
the	O
context	O
of	O
an	O
activity	O
model	O
.	O
</s>
<s>
The	O
data	B-Application
model	I-Application
will	O
normally	O
consist	O
of	O
entity	O
types	O
,	O
attributes	O
,	O
relationships	O
,	O
integrity	O
rules	O
,	O
and	O
the	O
definitions	O
of	O
those	O
objects	O
.	O
</s>
<s>
This	O
is	O
then	O
used	O
as	O
the	O
start	O
point	O
for	O
interface	O
or	O
database	B-General_Concept
design	I-General_Concept
.	O
</s>
<s>
Another	O
kind	O
of	O
data	B-Application
model	I-Application
describes	O
how	O
to	O
organize	O
data	O
using	O
a	O
database	B-Application
management	I-Application
system	I-Application
or	O
other	O
data	O
management	O
technology	O
.	O
</s>
<s>
It	O
describes	O
,	O
for	O
example	O
,	O
relational	B-Architecture
tables	O
and	O
columns	O
or	O
object-oriented	B-Language
classes	O
and	O
attributes	O
.	O
</s>
<s>
Such	O
a	O
data	B-Application
model	I-Application
is	O
sometimes	O
referred	O
to	O
as	O
the	O
physical	B-Application
data	I-Application
model	I-Application
,	O
but	O
in	O
the	O
original	O
ANSI	O
three	O
schema	B-Application
architecture	O
,	O
it	O
is	O
called	O
"	O
logical	O
"	O
.	O
</s>
<s>
Ideally	O
,	O
this	O
model	O
is	O
derived	O
from	O
the	O
more	O
conceptual	B-Application
data	I-Application
model	I-Application
described	O
above	O
.	O
</s>
<s>
While	O
data	O
analysis	O
is	O
a	O
common	O
term	O
for	O
data	B-Application
modeling	I-Application
,	O
the	O
activity	O
actually	O
has	O
more	O
in	O
common	O
with	O
the	O
ideas	O
and	O
methods	O
of	O
synthesis	O
(	O
inferring	O
general	O
concepts	O
from	O
particular	O
instances	O
)	O
than	O
it	O
does	O
with	O
analysis	O
(	O
identifying	O
component	O
concepts	O
from	O
more	O
general	O
ones	O
)	O
.	O
</s>
<s>
Data	B-Application
modeling	I-Application
strives	O
to	O
bring	O
the	O
data	B-General_Concept
structures	I-General_Concept
of	O
interest	O
together	O
into	O
a	O
cohesive	O
,	O
inseparable	O
,	O
whole	O
by	O
eliminating	O
unnecessary	O
data	O
redundancies	O
and	O
by	O
relating	O
data	B-General_Concept
structures	I-General_Concept
with	O
relationships	O
.	O
</s>
<s>
A	O
different	O
approach	O
is	O
to	O
use	O
adaptive	O
systems	O
such	O
as	O
artificial	B-Architecture
neural	I-Architecture
networks	I-Architecture
that	O
can	O
autonomously	O
create	O
implicit	O
models	O
of	O
data	O
.	O
</s>
<s>
A	O
data	B-General_Concept
structure	I-General_Concept
is	O
a	O
way	O
of	O
storing	O
data	O
in	O
a	O
computer	O
so	O
that	O
it	O
can	O
be	O
used	O
efficiently	O
.	O
</s>
<s>
Often	O
a	O
carefully	O
chosen	O
data	B-General_Concept
structure	I-General_Concept
will	O
allow	O
the	O
most	O
efficient	B-General_Concept
algorithm	I-General_Concept
to	O
be	O
used	O
.	O
</s>
<s>
The	O
choice	O
of	O
the	O
data	B-General_Concept
structure	I-General_Concept
often	O
begins	O
from	O
the	O
choice	O
of	O
an	O
abstract	O
data	O
type	O
.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
describes	O
the	O
structure	O
of	O
the	O
data	O
within	O
a	O
given	O
domain	O
and	O
,	O
by	O
implication	O
,	O
the	O
underlying	O
structure	O
of	O
that	O
domain	O
itself	O
.	O
</s>
<s>
This	O
means	O
that	O
a	O
data	B-Application
model	I-Application
in	O
fact	O
specifies	O
a	O
dedicated	O
grammar	O
for	O
a	O
dedicated	O
artificial	O
language	O
for	O
that	O
domain	O
.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
represents	O
classes	O
of	O
entities	B-Architecture
(	O
kinds	O
of	O
things	O
)	O
about	O
which	O
a	O
company	O
wishes	O
to	O
hold	O
information	O
,	O
the	O
attributes	O
of	O
that	O
information	O
,	O
and	O
relationships	O
among	O
those	O
entities	B-Architecture
and	O
(	O
often	O
implicit	O
)	O
relationships	O
among	O
those	O
attributes	O
.	O
</s>
<s>
The	O
entities	B-Architecture
represented	O
by	O
a	O
data	B-Application
model	I-Application
can	O
be	O
the	O
tangible	O
entities	B-Architecture
,	O
but	O
models	O
that	O
include	O
such	O
concrete	O
entity	O
classes	O
tend	O
to	O
change	O
over	O
time	O
.	O
</s>
<s>
Robust	O
data	B-Application
models	I-Application
often	O
identify	O
abstractions	B-Application
of	O
such	O
entities	B-Architecture
.	O
</s>
<s>
For	O
example	O
,	O
a	O
data	B-Application
model	I-Application
might	O
include	O
an	O
entity	B-Architecture
class	I-Architecture
called	O
"	O
Person	O
"	O
,	O
representing	O
all	O
the	O
people	O
who	O
interact	O
with	O
an	O
organization	O
.	O
</s>
<s>
Such	O
an	O
abstract	O
entity	B-Architecture
class	I-Architecture
is	O
typically	O
more	O
appropriate	O
than	O
ones	O
called	O
"	O
Vendor	O
"	O
or	O
"	O
Employee	O
"	O
,	O
which	O
identify	O
specific	O
roles	O
played	O
by	O
those	O
people	O
.	O
</s>
<s>
The	O
term	O
data	B-Application
model	I-Application
can	O
have	O
two	O
meanings	O
:	O
</s>
<s>
A	O
data	B-Application
model	I-Application
theory	O
,	O
i.e.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
instance	O
,	O
i.e.	O
</s>
<s>
applying	O
a	O
data	B-Application
model	I-Application
theory	O
to	O
create	O
a	O
practical	O
data	B-Application
model	I-Application
instance	O
for	O
some	O
particular	O
application	O
.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
theory	O
has	O
three	O
main	O
components	O
:	O
</s>
<s>
The	O
structural	O
part	O
:	O
a	O
collection	O
of	O
data	B-General_Concept
structures	I-General_Concept
which	O
are	O
used	O
to	O
create	O
databases	B-Application
representing	O
the	O
entities	B-Architecture
or	O
objects	O
modeled	O
by	O
the	O
database	O
.	O
</s>
<s>
The	O
integrity	O
part	O
:	O
a	O
collection	O
of	O
rules	O
governing	O
the	O
constraints	O
placed	O
on	O
these	O
data	B-General_Concept
structures	I-General_Concept
to	O
ensure	O
structural	O
integrity	O
.	O
</s>
<s>
The	O
manipulation	O
part	O
:	O
a	O
collection	O
of	O
operators	O
which	O
can	O
be	O
applied	O
to	O
the	O
data	B-General_Concept
structures	I-General_Concept
,	O
to	O
update	O
and	O
query	O
the	O
data	O
contained	O
in	O
the	O
database	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
relational	B-Architecture
model	I-Architecture
,	O
the	O
structural	O
part	O
is	O
based	O
on	O
a	O
modified	O
concept	O
of	O
the	O
mathematical	B-Algorithm
relation	I-Algorithm
;	O
the	O
integrity	O
part	O
is	O
expressed	O
in	O
first-order	O
logic	O
and	O
the	O
manipulation	O
part	O
is	O
expressed	O
using	O
the	O
relational	B-Algorithm
algebra	I-Algorithm
,	O
tuple	B-Application
calculus	I-Application
and	O
domain	B-Application
calculus	I-Application
.	O
</s>
<s>
A	O
data	B-Application
model	I-Application
instance	O
is	O
created	O
by	O
applying	O
a	O
data	B-Application
model	I-Application
theory	O
.	O
</s>
<s>
Business	O
requirements	O
are	O
normally	O
captured	O
by	O
a	O
semantic	O
logical	B-Application
data	I-Application
model	I-Application
.	O
</s>
<s>
This	O
is	O
transformed	O
into	O
a	O
physical	B-Application
data	I-Application
model	I-Application
instance	O
from	O
which	O
is	O
generated	O
a	O
physical	O
database	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
data	O
modeler	O
may	O
use	O
a	O
data	B-Application
modeling	I-Application
tool	O
to	O
create	O
an	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
model	I-Architecture
of	O
the	O
corporate	O
data	O
repository	O
of	O
some	O
business	O
enterprise	O
.	O
</s>
<s>
This	O
model	O
is	O
transformed	O
into	O
a	O
relational	B-Architecture
model	I-Architecture
,	O
which	O
in	O
turn	O
generates	O
a	O
relational	B-Application
database	I-Application
.	O
</s>
<s>
Patterns	O
are	O
common	O
data	B-Application
modeling	I-Application
structures	O
that	O
occur	O
in	O
many	O
data	B-Application
models	I-Application
.	O
</s>
<s>
It	O
differs	O
from	O
the	O
flowchart	B-Language
as	O
it	O
shows	O
the	O
data	O
flow	O
instead	O
of	O
the	O
control	O
flow	O
of	O
the	O
program	O
.	O
</s>
<s>
A	O
data-flow	O
diagram	O
can	O
also	O
be	O
used	O
for	O
the	O
visualization	B-Application
of	O
data	B-General_Concept
processing	I-General_Concept
(	O
structured	O
design	O
)	O
.	O
</s>
<s>
It	O
is	O
common	O
practice	O
to	O
draw	O
a	O
context-level	B-Application
data-flow	I-Application
diagram	I-Application
first	O
which	O
shows	O
the	O
interaction	O
between	O
the	O
system	O
and	O
outside	O
entities	B-Architecture
.	O
</s>
<s>
An	O
Information	B-Application
model	I-Application
is	O
not	O
a	O
type	O
of	O
data	B-Application
model	I-Application
,	O
but	O
more	O
or	O
less	O
an	O
alternative	O
model	O
.	O
</s>
<s>
Within	O
the	O
field	O
of	O
software	B-General_Concept
engineering	I-General_Concept
,	O
both	O
a	O
data	B-Application
model	I-Application
and	O
an	O
information	B-Application
model	I-Application
can	O
be	O
abstract	O
,	O
formal	O
representations	O
of	O
entity	O
types	O
that	O
include	O
their	O
properties	O
,	O
relationships	O
and	O
the	O
operations	O
that	O
can	O
be	O
performed	O
on	O
them	O
.	O
</s>
<s>
The	O
entity	O
types	O
in	O
the	O
model	O
may	O
be	O
kinds	O
of	O
real-world	O
objects	O
,	O
such	O
as	O
devices	O
in	O
a	O
network	B-General_Concept
,	O
or	O
they	O
may	O
themselves	O
be	O
abstract	O
,	O
such	O
as	O
for	O
the	O
entities	B-Architecture
used	O
in	O
a	O
billing	O
system	O
.	O
</s>
<s>
According	O
to	O
Lee	O
(	O
1999	O
)	O
an	O
information	B-Application
model	I-Application
is	O
a	O
representation	O
of	O
concepts	O
,	O
relationships	O
,	O
constraints	O
,	O
rules	O
,	O
and	O
operations	O
to	O
specify	O
data	O
semantics	B-Application
for	O
a	O
chosen	O
domain	B-Algorithm
of	I-Algorithm
discourse	I-Algorithm
.	O
</s>
<s>
More	O
in	O
general	O
the	O
term	O
information	B-Application
model	I-Application
is	O
used	O
for	O
models	O
of	O
individual	O
things	O
,	O
such	O
as	O
facilities	O
,	O
buildings	O
,	O
process	O
plants	O
,	O
etc	O
.	O
</s>
<s>
In	O
those	O
cases	O
the	O
concept	O
is	O
specialised	O
to	O
Facility	B-Application
Information	I-Application
Model	I-Application
,	O
Building	B-Architecture
Information	I-Architecture
Model	I-Architecture
,	O
Plant	O
Information	B-Application
Model	I-Application
,	O
etc	O
.	O
</s>
<s>
Such	O
an	O
information	B-Application
model	I-Application
is	O
an	O
integration	O
of	O
a	O
model	O
of	O
the	O
facility	O
with	O
the	O
data	O
and	O
documents	O
about	O
the	O
facility	O
.	O
</s>
<s>
An	O
information	B-Application
model	I-Application
provides	O
formalism	O
to	O
the	O
description	O
of	O
a	O
problem	O
domain	O
without	O
constraining	O
how	O
that	O
description	O
is	O
mapped	O
to	O
an	O
actual	O
implementation	O
in	O
software	B-Application
.	I-Application
</s>
<s>
There	O
may	O
be	O
many	O
mappings	O
of	O
the	O
information	B-Application
model	I-Application
.	O
</s>
<s>
Such	O
mappings	O
are	O
called	O
data	B-Application
models	I-Application
,	O
irrespective	O
of	O
whether	O
they	O
are	O
object	B-Application
models	I-Application
(	O
e.g.	O
</s>
<s>
using	O
UML	B-Language
)	O
,	O
entity	B-Architecture
–	I-Architecture
relationship	I-Architecture
models	I-Architecture
or	O
XML	B-Language
schemas	I-Language
.	O
</s>
<s>
An	O
object	B-Application
model	I-Application
in	O
computer	O
science	O
is	O
a	O
collection	O
of	O
objects	O
or	O
classes	O
through	O
which	O
a	O
program	O
can	O
examine	O
and	O
manipulate	O
some	O
specific	O
parts	O
of	O
its	O
world	O
.	O
</s>
<s>
In	O
other	O
words	O
,	O
the	O
object-oriented	B-Language
interface	O
to	O
some	O
service	O
or	O
system	O
.	O
</s>
<s>
Such	O
an	O
interface	O
is	O
said	O
to	O
be	O
the	O
object	B-Application
model	I-Application
of	O
the	O
represented	O
service	O
or	O
system	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
(	O
DOM	B-General_Concept
)	O
is	O
a	O
collection	O
of	O
objects	O
that	O
represent	O
a	O
page	O
in	O
a	O
web	B-Application
browser	I-Application
,	O
used	O
by	O
script	B-Language
programs	O
to	O
examine	O
and	O
dynamically	O
change	O
the	O
page	O
.	O
</s>
<s>
There	O
is	O
a	O
Microsoft	B-Application
Excel	I-Application
object	B-Application
model	I-Application
for	O
controlling	O
Microsoft	B-Application
Excel	I-Application
from	O
another	O
program	O
,	O
and	O
the	O
ASCOM	B-Application
Telescope	O
Driver	O
is	O
an	O
object	B-Application
model	I-Application
for	O
controlling	O
an	O
astronomical	O
telescope	O
.	O
</s>
<s>
In	O
computing	O
the	O
term	O
object	B-Application
model	I-Application
has	O
a	O
distinct	O
second	O
meaning	O
of	O
the	O
general	O
properties	O
of	O
objects	O
in	O
a	O
specific	O
computer	O
programming	O
language	O
,	O
technology	O
,	O
notation	O
or	O
methodology	O
that	O
uses	O
them	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
Java	B-Language
object	B-Application
model	I-Application
,	O
the	O
COM	B-Application
object	B-Application
model	I-Application
,	O
or	O
the	O
object	B-Application
model	I-Application
of	O
OMT	B-Application
.	O
</s>
<s>
Such	O
object	B-Application
models	I-Application
are	O
usually	O
defined	O
using	O
concepts	O
such	O
as	O
class	O
,	O
message	O
,	O
inheritance	B-Language
,	O
polymorphism	B-Application
,	O
and	O
encapsulation	B-Application
.	O
</s>
<s>
There	O
is	O
an	O
extensive	O
literature	O
on	O
formalized	O
object	B-Application
models	I-Application
as	O
a	O
subset	O
of	O
the	O
formal	B-Application
semantics	I-Application
of	I-Application
programming	I-Application
languages	I-Application
.	O
</s>
<s>
Object-Role	B-Application
Modeling	I-Application
(	O
ORM	O
)	O
is	O
a	O
method	O
for	O
conceptual	O
modeling	O
,	O
and	O
can	O
be	O
used	O
as	O
a	O
tool	O
for	O
information	O
and	O
rules	O
analysis	O
.	O
</s>
<s>
Object-Role	B-Application
Modeling	I-Application
is	O
a	O
fact-oriented	O
method	O
for	O
performing	O
systems	O
analysis	O
at	O
the	O
conceptual	O
level	O
.	O
</s>
<s>
The	O
conceptual	O
design	O
may	O
include	O
data	O
,	O
process	O
and	O
behavioral	O
perspectives	O
,	O
and	O
the	O
actual	O
DBMS	O
used	O
to	O
implement	O
the	O
design	O
might	O
be	O
based	O
on	O
one	O
of	O
many	O
logical	B-Application
data	I-Application
models	I-Application
(	O
relational	B-Architecture
,	O
hierarchic	O
,	O
network	B-General_Concept
,	O
object-oriented	B-Language
,	O
etc	O
.	O
</s>
<s>
The	O
Unified	B-Language
Modeling	I-Language
Language	I-Language
(	O
UML	B-Language
)	O
is	O
a	O
standardized	O
general-purpose	O
modeling	B-Language
language	I-Language
in	O
the	O
field	O
of	O
software	B-General_Concept
engineering	I-General_Concept
.	O
</s>
<s>
The	O
Unified	B-Language
Modeling	I-Language
Language	I-Language
offers	O
a	O
standard	O
way	O
to	O
write	O
a	O
system	O
's	O
blueprints	O
,	O
including	O
:	O
</s>
<s>
Reusable	O
software	B-Architecture
components	I-Architecture
.	O
</s>
<s>
UML	B-Language
offers	O
a	O
mix	O
of	O
functional	O
models	O
,	O
data	B-Application
models	I-Application
,	O
and	O
database	B-General_Concept
models	I-General_Concept
.	O
</s>
