<s>
The	O
Corosync	B-Operating_System
Cluster	I-Operating_System
Engine	I-Operating_System
is	O
an	O
open	B-Application
source	I-Application
implementation	O
of	O
the	O
Totem	O
Single	O
Ring	O
Ordering	O
and	O
Membership	O
protocol	O
.	O
</s>
<s>
The	O
mission	O
of	O
the	O
Corosync	B-Operating_System
effort	O
is	O
to	O
develop	O
,	O
release	O
,	O
and	O
support	O
a	O
community-defined	O
,	O
open	B-Application
source	I-Application
cluster	B-Architecture
.	O
</s>
<s>
The	O
Corosync	B-Operating_System
Cluster	I-Operating_System
Engine	I-Operating_System
is	O
a	O
group	B-Operating_System
communication	I-Operating_System
system	I-Operating_System
with	O
additional	O
features	O
for	O
implementing	O
high	O
availability	O
within	O
applications	O
.	O
</s>
<s>
The	O
project	O
provides	O
four	O
C	B-Language
API	B-Application
features	O
:	O
</s>
<s>
A	O
closed	O
process	O
group	O
communication	O
model	O
with	O
virtual	O
synchrony	O
guarantees	O
for	O
creating	O
replicated	O
state	B-Architecture
machines	I-Architecture
.	O
</s>
<s>
A	O
configuration	O
and	O
statistics	O
in-memory	B-General_Concept
database	I-General_Concept
that	O
provides	O
the	O
ability	O
to	O
set	O
,	O
retrieve	O
,	O
and	O
receive	O
change	O
notifications	O
of	O
information	O
.	O
</s>
<s>
A	O
quorum	B-General_Concept
system	I-General_Concept
that	O
notifies	O
applications	O
when	O
quorum	B-General_Concept
is	O
achieved	O
or	O
lost	O
.	O
</s>
<s>
The	O
software	O
is	O
designed	O
to	O
operate	O
on	O
UDP/IP	B-Protocol
and	O
InfiniBand	B-Architecture
networks	O
.	O
</s>
<s>
The	O
software	O
is	O
composed	O
of	O
an	O
executive	O
binary	O
which	O
uses	O
a	O
client-server	B-Operating_System
communication	O
model	O
between	O
libraries	O
and	O
service	O
engines	O
.	O
</s>
<s>
Loadable	O
modules	O
,	O
called	O
service	O
engines	O
,	O
are	O
loaded	O
into	O
the	O
Corosync	B-Operating_System
Cluster	I-Operating_System
Engine	I-Operating_System
and	O
use	O
the	O
services	O
provided	O
by	O
the	O
Corosync	B-Operating_System
Service	O
Engine	O
internal	O
API	B-Application
.	O
</s>
<s>
The	O
services	O
provided	O
by	O
the	O
Corosync	B-Operating_System
Service	O
Engine	O
internal	O
API	B-Application
are	O
:	O
</s>
<s>
The	O
coroipc	O
high	O
performance	O
shared	B-Operating_System
memory	I-Operating_System
IPC	O
system	O
.	O
</s>
<s>
An	O
object	O
database	O
that	O
implements	O
the	O
in	B-General_Concept
memory	I-General_Concept
database	I-General_Concept
model	O
.	O
</s>
<s>
Additionally	O
Corosync	B-Operating_System
provides	O
several	O
default	O
service	O
engines	O
that	O
are	O
used	O
via	O
C	B-Language
APIs	B-Application
:	O
</s>
<s>
The	O
source	O
code	O
of	O
OpenAIS	O
was	O
refactored	O
such	O
that	O
the	O
core	O
infrastructure	O
components	O
were	O
placed	O
into	O
Corosync	B-Operating_System
and	O
the	O
SA	O
Forum	O
APIs	B-Application
were	O
kept	O
in	O
OpenAIS	O
.	O
</s>
<s>
In	O
the	O
second	O
version	O
of	O
corosync	B-Operating_System
,	O
published	O
in	O
2012	O
,	O
quorum	B-General_Concept
subsystem	O
was	O
changed	O
and	O
integrated	O
into	O
the	O
daemon	O
.	O
</s>
