<s>
Lightstreamer	B-Application
is	O
a	O
web-based	O
asynchronous	B-Application
messaging	I-Application
project	O
,	O
implementing	O
the	O
WebSocket	B-Protocol
protocol	O
,	O
the	O
Comet	B-General_Concept
model	O
,	O
the	O
push	B-General_Concept
technology	I-General_Concept
paradigm	O
,	O
and	O
the	O
real-time	B-Application
web	I-Application
practices	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
Lightstreamer	B-Application
was	O
created	O
at	O
the	O
end	O
of	O
2000	O
,	O
as	O
one	O
of	O
the	O
first	O
attempts	O
to	O
implement	O
real-time	O
data	O
push	O
to	O
HTML	B-Language
pages	O
without	O
employing	O
Java	B-Application
applets	I-Application
.	O
</s>
<s>
The	O
application	O
domain	O
driving	O
most	O
of	O
the	O
interest	O
in	O
push	B-General_Concept
technology	I-General_Concept
at	O
that	O
time	O
was	O
market	O
data	O
distribution	O
for	O
the	O
financial	O
services	O
industry	O
.	O
</s>
<s>
In	O
the	O
following	O
years	O
,	O
Lightstreamer	B-Application
was	O
used	O
within	O
other	O
application	O
domains	O
too	O
,	O
including	O
aerospace	O
telemetry	O
,	O
where	O
NASA	O
chose	O
Lightstreamer	B-Application
to	O
push	O
live	O
telemetry	O
data	O
for	O
the	O
International	O
Space	O
Station	O
.	O
</s>
<s>
The	O
Lightstreamer	B-Application
Server	O
is	O
a	O
high-performance	O
engine	O
that	O
manages	O
all	O
the	O
connections	O
with	O
the	O
clients	O
through	O
the	O
Internet	O
.	O
</s>
<s>
The	O
Data	O
Adapter	O
receives	O
the	O
real-time	O
data	O
flow	O
from	O
the	O
data	O
feed	O
and	O
injects	O
it	O
into	O
the	O
Lightstreamer	B-Application
Server	O
.	O
</s>
<s>
Lightstreamer	B-Application
Server	O
is	O
made	O
up	O
of	O
three	O
logical	O
layers	O
:	O
</s>
<s>
Lightstreamer	B-Application
implements	O
a	O
bi-directional	O
transport	O
based	O
on	O
standard	O
Web	O
protocols	O
.	O
</s>
<s>
This	O
means	O
it	O
uses	O
several	O
underlying	O
techniques	O
(	O
WebSocket	B-Protocol
,	O
Comet	B-General_Concept
,	O
HTTP	B-General_Concept
streaming	I-General_Concept
,	O
etc	O
.	O
)	O
</s>
<s>
Lightstreamer	B-Application
implements	O
a	O
publish	B-Operating_System
–	I-Operating_System
subscribe	I-Operating_System
pattern	I-Operating_System
,	O
suitable	O
for	O
both	O
one-to-many	O
fan-out	O
scenarios	O
and	O
one-to-one	O
messaging	O
needs	O
.	O
</s>
<s>
on	O
the	O
top	O
of	O
publish-subscribe	B-Operating_System
.	O
</s>
