<s>
Responsibility-driven	B-Application
design	I-Application
is	O
a	O
design	O
technique	O
in	O
object-oriented	B-Language
programming	I-Language
,	O
which	O
improves	O
encapsulation	B-Application
by	O
using	O
the	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
model	I-Operating_System
.	O
</s>
<s>
Responsibility-driven	B-Application
design	I-Application
is	O
in	O
direct	O
contrast	O
with	O
data-driven	B-Application
design	I-Application
,	O
which	O
promotes	O
defining	O
the	O
behavior	O
of	O
a	O
class	O
along	O
with	O
the	O
data	O
that	O
it	O
holds	O
.	O
</s>
<s>
Data-driven	B-Application
design	I-Application
is	O
not	O
the	O
same	O
as	O
data-driven	B-Application
programming	I-Application
,	O
which	O
is	O
concerned	O
with	O
using	O
data	O
to	O
determine	O
the	O
control	O
flow	O
,	O
not	O
class	O
design	O
.	O
</s>
<s>
In	O
the	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
model	I-Operating_System
they	O
refer	O
to	O
,	O
both	O
the	O
client	O
and	O
the	O
server	O
are	O
classes	O
or	O
instances	O
of	O
classes	O
.	O
</s>
<s>
Thus	O
,	O
responsibility-driven	B-Application
design	I-Application
tries	O
to	O
avoid	O
dealing	O
with	O
details	O
,	O
such	O
as	O
the	O
way	O
in	O
which	O
requests	O
are	O
carried	O
out	O
,	O
by	O
instead	O
only	O
specifying	O
the	O
intent	O
of	O
a	O
certain	O
request	O
.	O
</s>
<s>
The	O
benefit	O
is	O
increased	O
encapsulation	B-Application
,	O
since	O
the	O
specification	O
of	O
the	O
exact	O
way	O
in	O
which	O
a	O
request	O
is	O
carried	O
out	O
is	O
private	O
to	O
the	O
server	O
.	O
</s>
<s>
To	O
further	O
the	O
encapsulation	B-Application
of	O
the	O
server	O
,	O
Wirfs-Brock	O
and	O
Wilkerson	O
call	O
for	O
language	O
features	O
that	O
limit	O
outside	O
influence	O
to	O
the	O
behavior	O
of	O
a	O
class	O
.	O
</s>
<s>
They	O
demand	O
that	O
the	O
visibility	O
of	O
members	O
and	O
functions	O
should	O
be	O
finely	O
grained	O
,	O
such	O
as	O
in	O
Eiffel	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
Even	O
finer	O
control	O
of	O
the	O
visibility	O
of	O
even	O
classes	O
is	O
available	O
in	O
the	O
Newspeak	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
Responsibility-driven	B-Application
design	I-Application
focuses	O
on	O
the	O
objects	O
as	O
which	O
are	O
characterized	O
by	O
their	O
responsibilities	O
.	O
</s>
<s>
This	O
makes	O
the	O
design	O
follow	O
type	O
hierarchy	O
for	O
inheritance	O
which	O
improves	O
encapsulation	B-Application
and	O
makes	O
it	O
easier	O
to	O
identify	O
abstract	O
classes	O
.	O
</s>
<s>
A	O
good	O
object-oriented	B-Language
design	O
involves	O
an	O
early	O
focus	O
on	O
behaviors	O
to	O
realize	O
the	O
capabilities	O
meeting	O
the	O
stated	O
requirements	O
and	O
a	O
late	O
binding	O
of	O
implementation	O
details	O
to	O
the	O
requirements	O
.	O
</s>
<s>
Similarly	O
,	O
it	O
can	O
help	O
to	O
design	O
and	O
maintain	O
explanation	O
facilities	O
for	O
cognitive	O
models	O
,	O
intelligent	B-General_Concept
agents	I-General_Concept
,	O
and	O
other	O
knowledge-based	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
In	O
their	O
book	O
Object	O
Design	O
:	O
Roles	O
,	O
Responsibilities	O
and	O
Collaborations	O
,	O
the	O
authors	O
describe	O
the	O
following	O
building	O
blocks	O
that	O
make	O
up	O
responsibility-driven	B-Application
design	I-Application
.	O
</s>
<s>
It	O
is	O
mainly	O
used	O
for	O
encapsulating	O
non-object-oriented	O
APIs	O
and	O
does	O
not	O
collaborate	O
a	O
lot	O
.	O
</s>
<s>
An	O
important	O
part	O
in	O
the	O
responsibility-driven	B-Application
design	I-Application
process	O
is	O
the	O
distribution	O
of	O
control	O
responsibilities	O
that	O
results	O
in	O
developing	O
a	O
control	O
style	O
.	O
</s>
<s>
Interrupt-driven	O
model	O
:	O
There	O
will	O
be	O
the	O
interrupt	B-Application
handler	O
to	O
process	O
the	O
interrupt	B-Application
and	O
passes	O
to	O
some	O
object	O
to	O
process	O
it	O
.	O
</s>
