<s>
The	O
Communicating	O
(	O
Stream	O
)	O
X-Machine	B-Application
is	O
a	O
model	O
of	O
computation	O
introduced	O
by	O
various	O
researchers	O
in	O
the	O
1990s	O
to	O
model	O
systems	O
composed	O
of	O
communicating	O
agents	O
.	O
</s>
<s>
The	O
model	O
exists	O
in	O
several	O
variants	O
,	O
which	O
are	O
either	O
based	O
directly	O
on	O
Samuel	O
Eilenberg	O
's	O
X-machine	B-Application
or	O
on	O
Gilbert	O
Laycock	O
's	O
later	O
Stream	O
X-Machine	B-Application
.	O
</s>
