<s>
Project	B-Application
Darkstar	I-Application
was	O
an	O
open-source	B-Application
MMOG	B-Application
middleware	O
solution	O
written	O
in	O
Java	B-Language
.	O
</s>
<s>
Project	B-Application
Darkstar	I-Application
began	O
as	O
a	O
personal	O
project	O
of	O
Jeff	O
Kesselman	O
in	O
1999	O
.	O
</s>
<s>
It	O
later	O
became	O
a	O
research	O
project	O
at	O
Sun	O
Microsystems	O
,	O
and	O
aimed	O
to	O
"	O
help	O
developers	O
and	O
operators	O
avoid	O
a	O
range	O
of	O
serious	O
,	O
yet	O
typical	O
,	O
problems	O
associated	O
with	O
massive	O
scale	O
online	O
games	O
,	O
virtual	O
worlds	O
,	O
and	O
social	O
networking	O
applications	O
today	O
,	O
including	O
zone	O
overloading	O
,	O
data	O
corruption	O
,	O
and	O
server	B-Application
underutilization.	O
"	O
</s>
<s>
Project	B-Application
Darkstar	I-Application
began	O
as	O
a	O
personal	O
project	O
of	O
Jeff	O
Kesselman	O
in	O
1999	O
while	O
he	O
was	O
the	O
Senior	O
Game	O
Integration	O
Engineer	O
at	O
the	O
Total	O
Entertainment	O
Network	O
.	O
</s>
<s>
In	O
2004	O
,	O
Sun	O
's	O
Game	O
Technology	O
Group	O
was	O
formed	O
,	O
and	O
at	O
that	O
time	O
Mr.	O
Kesselman	O
brought	O
the	O
third	O
iteration	O
of	O
the	O
project	O
into	O
Sun	O
where	O
it	O
was	O
dubbed	O
the	O
Sun	O
Game	B-Application
Server	I-Application
.	O
</s>
<s>
(	O
The	O
SGS	O
moniker	O
survives	O
to	O
this	O
day	O
in	O
the	O
package	O
names	O
of	O
the	O
Project	B-Application
Darkstar	I-Application
Server	B-Application
.	O
)	O
</s>
<s>
This	O
team	O
delivered	O
what	O
is	O
now	O
known	O
as	O
the	O
Early	O
Access	O
version	O
,	O
the	O
first	O
working	O
server	B-Application
,	O
for	O
GDC	O
2005	O
.	O
</s>
<s>
A	O
number	O
of	O
members	O
of	O
the	O
Sun	O
Labs	O
team	O
and	O
a	O
number	O
of	O
members	O
of	O
the	O
Darkstar	O
community	O
worked	O
for	O
a	O
time	O
on	O
the	O
RedDwarf	O
Server	B-Application
as	O
a	O
successor	O
to	O
Darkstar	O
.	O
</s>
<s>
When	O
a	O
Project	B-Application
Darkstar	I-Application
server	B-Application
implementation	O
is	O
run	O
,	O
it	O
either	O
starts	O
a	O
new	O
network	O
or	O
joins	O
one	O
that	O
is	O
currently	O
running	O
.	O
</s>
<s>
All	O
networks	O
contain	O
clients	B-Protocol
,	O
server	B-Application
implementations	O
,	O
a	O
Project	B-Application
Darkstar	I-Application
stack	O
on	O
which	O
the	O
server	B-Application
implementations	O
run	O
,	O
and	O
several	O
meta-service	O
nodes	O
that	O
handle	O
traffic	O
between	O
each	O
node	O
in	O
the	O
server	B-Application
stack	O
.	O
</s>
<s>
A	O
server	B-Application
implementation	O
is	O
a	O
user	O
created	O
program	B-Application
written	O
with	O
the	O
Project	B-Application
Darkstar	I-Application
API	B-General_Concept
.	O
</s>
<s>
The	O
clients	B-Protocol
include	O
all	O
client-side	O
applications	O
and	O
games	O
that	O
are	O
connected	O
to	O
a	O
game	B-Application
server	I-Application
in	O
the	O
network	O
.	O
</s>
<s>
Project	B-Application
Darkstar	I-Application
is	O
being	O
developed	O
to	O
support	O
all	O
features	O
vital	O
to	O
a	O
massively	B-Application
multiplayer	I-Application
game	O
,	O
and	O
at	O
the	O
same	O
time	O
be	O
scalable	O
enough	O
to	O
support	O
non-massive	O
multiplayer	O
online	O
games	O
.	O
</s>
<s>
The	O
API	B-General_Concept
of	O
Project	B-Application
Darkstar	I-Application
is	O
the	O
key	O
component	O
for	O
developers	O
who	O
use	O
the	O
technology	O
.	O
</s>
<s>
With	O
it	O
,	O
they	O
can	O
develop	O
game	B-Application
servers	I-Application
to	O
communicate	O
correctly	O
with	O
their	O
client	O
technology	O
and	O
have	O
a	O
server	B-Application
up	O
and	O
running	O
that	O
runs	O
on	O
top	O
of	O
the	O
Project	B-Application
Darkstar	I-Application
game	O
stack	O
.	O
</s>
<s>
The	O
API	B-General_Concept
is	O
written	O
to	O
hide	O
the	O
concurrency	O
of	O
the	O
underlying	O
system	O
that	O
the	O
Project	B-Application
Darkstar	I-Application
stack	O
performs	O
for	O
the	O
developer	O
,	O
so	O
that	O
the	O
program	B-Application
can	O
be	O
written	O
with	O
the	O
illusion	O
that	O
it	O
is	O
single	O
threaded	O
,	O
even	O
though	O
the	O
stack	O
is	O
fully	O
parallel	O
.	O
</s>
<s>
The	O
main	O
parts	O
of	O
the	O
API	B-General_Concept
include	O
task	B-General_Concept
management	O
,	O
data	O
persistence	B-Application
,	O
and	O
channel	O
communication	O
.	O
</s>
<s>
Control	O
of	O
information	O
in	O
a	O
Project	B-Application
Darkstar	I-Application
server	B-Application
is	O
generally	O
handled	O
by	O
tasks	O
,	O
although	O
in	O
some	O
special	O
cases	O
they	O
are	O
not	O
necessary	O
.	O
</s>
<s>
They	O
are	O
used	O
in	O
instances	O
where	O
storage	O
or	O
retrieval	O
of	O
data	O
must	O
be	O
protected	O
from	O
a	O
server	B-Application
crash	B-General_Concept
or	O
shutdown	B-Device
,	O
as	O
tasks	O
are	O
saved	O
and	O
remembered	O
when	O
they	O
are	O
run	O
,	O
and	O
can	O
be	O
respawned	O
when	O
the	O
server	B-Application
is	O
restarted	O
in	O
the	O
same	O
state	O
as	O
they	O
were	O
in	O
before	O
the	O
crash	B-General_Concept
.	O
</s>
<s>
If	O
something	O
goes	O
wrong	O
with	O
the	O
server	B-Application
internally	O
,	O
the	O
character	O
information	O
is	O
persisted	O
and	O
on	O
a	O
server	B-Application
restart	B-General_Concept
the	O
character	O
information	O
will	O
be	O
restored	O
from	O
the	O
last	O
state	O
it	O
was	O
in	O
before	O
the	O
crash	B-General_Concept
.	O
</s>
<s>
The	O
Berkeley	B-Language
DB	I-Language
used	O
by	O
Project	B-Application
Darkstar	I-Application
stores	O
all	O
data	O
that	O
is	O
to	O
be	O
persisted	O
.	O
</s>
<s>
Anything	O
that	O
is	O
to	O
be	O
stored	O
in	O
the	O
database	O
must	O
also	O
be	O
serializable	B-Application
,	O
as	O
the	O
database	O
is	O
programmed	O
to	O
store	O
binary	O
information	O
.	O
</s>
<s>
position	O
,	O
equipment	O
)	O
to	O
internal	O
server	B-Application
data	O
and	O
control	O
logic	O
(	O
i.e.	O
</s>
<s>
The	O
usefulness	O
of	O
managed	O
objects	O
is	O
seen	O
in	O
the	O
instance	O
of	O
a	O
server	B-Application
failure	O
.	O
</s>
<s>
Since	O
managed	O
objects	O
are	O
updated	O
transactionally	O
,	O
any	O
corrupted	O
data	O
is	O
discarded	O
on	O
the	O
server	B-Application
restart	B-General_Concept
and	O
the	O
managed	O
object	O
is	O
rolled	B-Application
back	I-Application
to	O
its	O
last	O
working	O
state	O
.	O
</s>
<s>
Channels	O
give	O
developers	O
an	O
easy	O
way	O
of	O
communicating	O
with	O
many	O
clients	B-Protocol
.	O
</s>
<s>
The	O
way	O
channels	O
work	O
is	O
by	O
giving	O
clients	B-Protocol
a	O
way	O
of	O
subscribing	O
to	O
channels	O
such	O
that	O
they	O
can	O
send	O
messages	O
to	O
the	O
channel	O
and	O
receive	O
messages	O
from	O
the	O
channel	O
.	O
</s>
<s>
When	O
a	O
message	O
is	O
sent	O
to	O
the	O
channel	O
from	O
a	O
client	O
or	O
the	O
server	B-Application
,	O
the	O
message	O
is	O
multicast	O
to	O
all	O
clients	B-Protocol
who	O
are	O
subscribed	O
to	O
it	O
.	O
</s>
<s>
It	O
is	O
an	O
abstraction	O
built	O
on	O
top	O
of	O
the	O
communications	O
layer	O
to	O
assist	O
in	O
the	O
development	O
of	O
easy	O
and	O
extensible	O
communication	O
between	O
many	O
clients	B-Protocol
and	O
the	O
server	B-Application
.	O
</s>
<s>
RedDwarf	O
Server	B-Application
was	O
an	O
open-source	B-Application
middleware	O
solution	O
for	O
developing	O
the	O
server-side	B-Application
of	O
massively	B-Application
multiplayer	I-Application
online	I-Application
games	I-Application
.	O
</s>
<s>
It	O
was	O
the	O
official	O
community	O
fork	O
of	O
Project	B-Application
Darkstar	I-Application
.	O
</s>
<s>
Once	O
Oracle	O
discontinued	O
support	O
for	O
the	O
project	O
,	O
the	O
community	O
rebranded	O
the	O
latest	O
codebase	O
of	O
Project	B-Application
Darkstar	I-Application
's	O
repositories	O
and	O
released	O
it	O
as	O
RedDwarf	O
Server	B-Application
.	O
</s>
<s>
RedDwarf	O
inherited	O
the	O
Project	B-Application
Darkstar	I-Application
licensing	O
scheme	O
,	O
with	O
the	O
RedDwarf	O
Server	B-Application
distributed	O
under	O
GPLv2	O
and	O
the	O
server	B-Application
APIs	B-General_Concept
being	O
made	O
available	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
with	O
the	O
classpath	O
exception	O
.	O
</s>
<s>
The	O
Java	B-Language
and	O
C	B-Language
client	O
APIs	B-General_Concept
—	O
available	O
as	O
part	O
of	O
the	O
RedDwarf	O
project	O
—	O
were	O
distributed	O
under	O
a	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
Clients	B-Protocol
can	O
communicate	O
with	O
the	O
server	B-Application
using	O
a	O
Java	B-Language
or	O
C	B-Language
API	B-General_Concept
.	O
</s>
<s>
The	O
community	O
also	O
released	O
client	O
APIs	B-General_Concept
for	O
additional	O
platforms	O
including	O
C#	B-Application
,	O
Python	B-Language
,	O
Objective-C	B-Language
,	O
and	O
ActionScript	B-Operating_System
.	O
</s>
<s>
RedDwarf	O
Server	B-Application
uses	O
a	O
built-in	O
protocol	O
for	O
network	O
communications	O
.	O
</s>
