<s>
SignalR	B-Language
is	O
a	O
free	B-License
and	I-License
open-source	I-License
software	I-License
library	O
for	O
Microsoft	B-Application
ASP.NET	I-Application
that	O
allows	O
server	O
code	O
to	O
send	O
asynchronous	O
notifications	O
to	O
client-side	O
web	B-Application
applications	I-Application
.	O
</s>
<s>
The	O
library	O
includes	O
server-side	O
and	O
client-side	O
JavaScript	B-Language
components	O
.	O
</s>
<s>
ASP.NET	B-Language
SignalR	I-Language
is	O
a	O
library	O
for	O
ASP.NET	B-Application
developers	O
to	O
add	O
real-time	O
web	O
functionality	O
to	O
their	O
applications	O
.	O
</s>
<s>
SignalR	B-Language
takes	O
advantage	O
of	O
several	O
transports	O
,	O
automatically	O
selecting	O
the	O
best	O
available	O
transport	O
given	O
the	O
client	O
's	O
and	O
server	O
's	O
capabilities	O
.	O
</s>
<s>
SignalR	B-Language
takes	O
advantage	O
of	O
WebSocket	B-Protocol
,	O
an	O
HTML5	B-Application
API	B-General_Concept
that	O
enables	O
bi-directional	O
communication	O
between	O
the	O
browser	O
and	O
server	O
.	O
</s>
<s>
SignalR	B-Language
will	O
use	O
WebSockets	B-Protocol
under	O
the	O
covers	O
when	O
it	O
's	O
available	O
,	O
and	O
gracefully	O
fall	O
back	O
to	O
other	O
techniques	O
and	O
technologies	O
when	O
it	O
is	O
n't	O
,	O
while	O
the	O
application	O
code	O
remains	O
the	O
same	O
.	O
</s>
<s>
SignalR	B-Language
also	O
provides	O
a	O
simple	O
,	O
high-level	O
API	B-General_Concept
for	O
doing	O
server-to-client	O
RPC	B-Operating_System
(	O
call	O
JavaScript	B-Language
functions	O
in	O
a	O
client	O
's	O
browser	O
from	O
server-side	O
.NET	B-Application
code	O
)	O
in	O
an	O
ASP.NET	B-Application
application	O
,	O
as	O
well	O
as	O
adding	O
useful	O
hooks	O
for	O
management	O
,	O
such	O
as	O
connect/disconnect	O
events	O
,	O
grouping	O
connections	O
,	O
authorization	O
.	O
</s>
