<s>
Hypermedia	B-Operating_System
as	I-Operating_System
the	I-Operating_System
Engine	I-Operating_System
of	I-Operating_System
Application	I-Operating_System
State	I-Operating_System
(	O
HATEOAS	B-Operating_System
)	O
is	O
a	O
constraint	O
of	O
the	O
REST	B-Protocol
application	I-Protocol
architecture	I-Protocol
that	O
distinguishes	O
it	O
from	O
other	O
network	O
application	B-Architecture
architectures	I-Architecture
.	O
</s>
<s>
With	O
HATEOAS	B-Operating_System
,	O
a	O
client	O
interacts	O
with	O
a	O
network	O
application	O
whose	O
application	O
servers	O
provide	O
information	O
dynamically	O
through	O
hypermedia	O
.	O
</s>
<s>
By	O
contrast	O
,	O
clients	O
and	O
servers	O
in	O
Common	B-Architecture
Object	I-Architecture
Request	I-Architecture
Broker	I-Architecture
Architecture	I-Architecture
(	O
CORBA	B-Architecture
)	O
interact	O
through	O
a	O
fixed	O
interface	B-Application
shared	O
through	O
documentation	O
or	O
an	O
interface	B-General_Concept
description	I-General_Concept
language	I-General_Concept
(	O
IDL	O
)	O
.	O
</s>
<s>
The	O
restrictions	O
imposed	O
by	O
HATEOAS	B-Operating_System
decouple	O
client	O
and	O
server	O
.	O
</s>
<s>
A	O
user-agent	O
makes	O
an	O
HTTP	O
request	O
to	O
a	O
REST	B-Protocol
API	I-Protocol
through	O
an	O
entry	O
point	O
URL	O
.	O
</s>
<s>
The	O
media	B-Application
types	I-Application
used	O
for	O
these	O
representations	O
,	O
and	O
the	O
link	B-General_Concept
relations	I-General_Concept
they	O
may	O
contain	O
,	O
are	O
part	O
of	O
the	O
API	O
.	O
</s>
<s>
The	O
client	O
transitions	O
through	O
application	O
states	O
by	O
selecting	O
from	O
the	O
links	O
within	O
a	O
representation	O
or	O
by	O
manipulating	O
the	O
representation	O
in	O
other	O
ways	O
afforded	O
by	O
its	O
media	B-Application
type	I-Application
.	O
</s>
<s>
In	O
this	O
way	O
,	O
RESTful	B-Protocol
interaction	O
is	O
driven	O
by	O
hypermedia	O
,	O
rather	O
than	O
out-of-band	O
information	O
.	O
</s>
<s>
A	O
client	O
does	O
not	O
need	O
to	O
understand	O
every	O
media	B-Application
type	I-Application
and	O
communication	O
mechanism	O
offered	O
by	O
the	O
server	O
.	O
</s>
<s>
The	O
ability	O
to	O
understand	O
new	O
media	B-Application
types	I-Application
may	O
be	O
acquired	O
at	O
run-time	O
through	O
"	O
code-on-demand	B-Protocol
"	O
provided	O
to	O
the	O
client	O
by	O
the	O
server	O
.	O
</s>
<s>
The	O
HATEOAS	B-Operating_System
constraint	O
is	O
an	O
essential	O
part	O
of	O
the	O
"	O
uniform	O
interface	B-Application
"	O
feature	O
of	O
REST	O
,	O
as	O
defined	O
in	O
Roy	O
Fielding	O
's	O
doctoral	O
dissertation	O
.	O
</s>
