<s>
The	O
Croquet	B-Protocol
Project	I-Protocol
is	O
a	O
software	O
project	O
that	O
preceded	O
Croquet	O
,	O
and	O
was	O
intended	O
to	O
promote	O
the	O
continued	O
development	O
of	O
the	O
Croquet	O
open-source	B-Application
software	I-Application
development	B-Application
kit	I-Application
to	O
create	O
and	O
deliver	O
collaborative	O
multi-user	B-Operating_System
online	O
applications	B-Application
.	O
</s>
<s>
Implemented	O
in	O
Squeak	B-Operating_System
Smalltalk	I-Operating_System
,	O
Croquet	O
supports	O
communication	O
,	O
collaboration	O
,	O
resource	O
sharing	O
,	O
and	O
synchronous	O
computation	O
among	O
multiple	B-Operating_System
users	I-Operating_System
.	O
</s>
<s>
Applications	B-Application
created	O
with	O
the	O
Croquet	O
software	B-Application
development	I-Application
kit	I-Application
(	O
SDK	B-Application
)	O
can	O
be	O
used	O
to	O
support	O
highly	O
scalable	O
collaborative	O
data	O
visualization	O
,	O
virtual	O
learning	O
and	O
problem	O
solving	O
environments	O
,	O
3D	O
wikis	B-Protocol
,	O
online	O
gaming	O
environments	O
(	O
massively	B-Protocol
multiplayer	I-Protocol
online	I-Protocol
role-playing	I-Protocol
games	I-Protocol
(	O
MMORPGs	B-Protocol
)	O
,	O
and	O
privately	O
maintained	O
or	O
interconnected	O
multiuser	B-Operating_System
virtual	O
environments	O
.	O
</s>
<s>
Further	O
development	O
of	O
the	O
technology	O
has	O
also	O
branched	O
into	O
the	O
Open	B-Protocol
Cobalt	I-Protocol
and	O
Open	O
Croquet	O
efforts	O
.	O
</s>
<s>
Croquet	O
is	O
a	O
software	B-Application
development	I-Application
kit	I-Application
(	O
SDK	B-Application
)	O
for	O
use	O
in	O
developing	O
collaborative	O
virtual	B-Application
world	I-Application
applications	B-Application
.	O
</s>
<s>
Applications	B-Application
created	O
using	O
the	O
Croquet	O
SDK	B-Application
are	O
automatically	O
collaborative	O
since	O
application	O
objects	O
in	O
Croquet	O
share	O
a	O
common	O
protocol	O
allowing	O
them	O
to	O
cooperate	O
with	O
each	O
other	O
by	O
employing	O
the	O
principle	O
of	O
replicated	O
computation	O
(	O
synchronization	O
)	O
together	O
with	O
a	O
peer-based	O
messaging	O
protocol	O
.	O
</s>
<s>
The	O
technology	O
is	O
designed	O
to	O
facilitate	O
such	O
replication	O
between	O
peers	O
,	O
to	O
greatly	O
reduce	O
the	O
overhead	O
needed	O
for	O
widespread	O
deployment	O
of	O
collaborative	O
virtual	B-Application
worlds	I-Application
.	O
</s>
<s>
This	O
efficiency	O
,	O
combined	O
with	O
the	O
ability	O
to	O
deploy	O
Croquet-based	O
virtual	B-Application
worlds	I-Application
on	O
consumer-level	O
hardware	O
,	O
makes	O
it	O
possible	O
for	O
developers	O
to	O
deploy	O
large-scale	O
and	O
highly	O
participatory	O
collaborative	O
worlds	O
at	O
very	O
low	O
cost	O
compared	O
with	O
virtual	B-Application
world	I-Application
technologies	O
that	O
are	O
entirely	O
dependent	O
on	O
server-based	O
infrastructures	O
to	O
support	O
the	O
activities	O
of	O
their	O
users	O
.	O
</s>
<s>
Croquet	O
's	O
virtual	B-Architecture
machine	I-Architecture
(	O
VM	O
)	O
runs	O
bit	O
identically	O
on	O
multiple	O
platforms	O
,	O
and	O
supports	O
multiple	O
abilities	O
that	O
could	O
only	O
be	O
provided	O
by	O
a	O
true	O
late	O
bound	O
,	O
message	O
sending	O
language	O
.	O
</s>
<s>
Croquet	O
's	O
relationship	O
to	O
Squeak	B-Operating_System
gives	O
Croquet	O
the	O
property	O
of	O
a	O
purely	O
object-oriented	B-Language
system	O
allowing	O
for	O
significant	O
flexibility	O
in	O
the	O
design	O
and	O
the	O
nature	O
of	O
the	O
protocols	O
and	O
architectures	O
that	O
have	O
been	O
developed	O
for	O
the	O
system	O
.	O
</s>
<s>
Croquet	O
's	O
time-based	O
synchronization	O
abilities	O
enable	O
real-time	B-General_Concept
,	O
identical	O
interactions	O
between	O
groups	O
of	O
users	O
while	O
dramatically	O
reducing	O
the	O
need	O
for	O
server	O
infrastructures	O
to	O
support	O
virtual	B-Application
world	I-Application
deployment	O
.	O
</s>
<s>
Croquet	O
's	O
architecture	O
makes	O
it	O
easy	O
to	O
develop	O
deeply	O
collaborative	O
applications	B-Application
without	O
having	O
to	O
spend	O
a	O
lot	O
of	O
effort	O
and	O
expertise	O
in	O
understanding	O
how	O
replicated	O
applications	B-Application
work	O
.	O
</s>
<s>
TeaTime	O
is	O
a	O
scalable	O
real-time	B-General_Concept
multi-user	B-Operating_System
architecture	O
that	O
is	O
the	O
basis	O
for	O
Croquet	O
's	O
object-object	O
communication	O
and	O
synchronization	O
.	O
</s>
<s>
It	O
is	O
designed	O
to	O
support	O
multi-user	B-Operating_System
applications	B-Application
that	O
can	O
be	O
scaled	O
to	O
massive	O
numbers	O
of	O
concurrently	O
interacting	O
users	O
in	O
a	O
shared	O
virtual	O
space	O
.	O
</s>
<s>
This	O
messaging	O
protocol	O
supports	O
a	O
coordinated	O
distributed	O
two-phase	B-General_Concept
commit	I-General_Concept
that	O
is	O
used	O
to	O
control	O
the	O
progression	O
of	O
computations	O
at	O
participating	O
user	O
sites	O
.	O
</s>
<s>
It	O
is	O
a	O
framework	O
of	O
abstraction	O
that	O
works	O
over	O
a	O
range	O
of	O
implementations	O
and	O
that	O
can	O
be	O
evolved	O
and	O
tuned	O
over	O
time	O
,	O
both	O
within	O
an	O
application	O
and	O
across	O
applications	B-Application
.	O
</s>
<s>
David	O
P	O
.	O
Reed	O
,	O
Andreas	B-Operating_System
Raab	I-Operating_System
,	O
Julian	O
Lombardi	O
,	O
and	O
Mark	O
McCahill	O
.	O
</s>
<s>
The	O
present	O
identity	O
of	O
the	O
project	O
has	O
its	O
origins	O
in	O
a	O
conversation	O
between	O
Smith	O
and	O
Kay	O
in	O
1990	O
,	O
where	O
both	O
expressed	O
their	O
frustration	O
with	O
the	O
state	O
of	O
operating	B-General_Concept
systems	I-General_Concept
at	O
the	O
time	O
.	O
</s>
<s>
Also	O
in	O
1994	O
Mark	O
McCahill	O
's	O
team	O
at	O
the	O
University	O
of	O
Minnesota	O
developed	O
GopherVR	B-Protocol
,	O
a	O
3D	O
user	O
interface	O
to	O
Internet	B-Protocol
Gopher	I-Protocol
to	O
explore	O
how	O
spatial	O
metaphors	O
could	O
be	O
used	O
to	O
organize	O
information	O
and	O
create	O
social	O
spaces	O
.	O
</s>
<s>
One	O
of	O
these	O
implementations	O
was	O
a	O
prototype	O
implementation	O
of	O
ViOS	O
,	O
a	O
way	O
to	O
spatially	O
organize	O
all	O
Internet-deliverable	O
resources	O
(	O
including	O
web	O
pages	O
)	O
into	O
a	O
massively-scaled	O
multiuser	B-Operating_System
3D	O
environment	O
.	O
</s>
<s>
Smith	O
and	O
Kay	O
officially	O
started	O
the	O
Croquet	B-Protocol
Project	I-Protocol
in	O
late	O
2001	O
and	O
were	O
immediately	O
joined	O
by	O
David	O
Reed	O
and	O
Andreas	B-Operating_System
Raab	I-Operating_System
.	O
</s>
<s>
Simultaneously	O
and	O
independently	O
,	O
Lombardi	O
and	O
McCahill	O
began	O
collaborating	O
on	O
defining	O
and	O
implementing	O
highly	O
scalable	O
and	O
enterprise-integrated	O
architectures	O
for	O
multi-user	B-Operating_System
collaboration	O
and	O
were	O
invited	O
by	O
Kay	O
to	O
join	O
the	O
core	O
architectural	O
group	O
in	O
2003	O
.	O
</s>
<s>
On	O
April	O
18	O
,	O
2006	O
,	O
the	O
project	O
released	O
a	O
beta	O
version	O
of	O
the	O
in	O
the	O
open-source	B-Application
.	O
</s>
<s>
Since	O
then	O
,	O
the	O
Croquet	O
technology	O
infrastructure	O
has	O
been	O
successfully	O
used	O
by	O
private	O
industry	O
to	O
build	O
and	O
to	O
deploy	O
commercial-grade	O
closed	O
source	O
collaborative	O
applications	B-Application
.	O
</s>
<s>
,	O
continued	O
development	O
of	O
the	O
original	O
Croquet	O
technology	O
has	O
also	O
taken	O
place	O
through	O
the	O
Open	B-Protocol
Cobalt	I-Protocol
and	O
Open	O
Croquet	B-Protocol
projects	I-Protocol
.	O
</s>
<s>
In	O
2018	O
,	O
Alan	O
Kay	O
’s	O
team	O
of	O
engineers	O
,	O
Vanessa	O
Freudenberg	O
,	O
Aran	O
Lunzer	O
,	O
Yoshiki	O
Ohshima	O
,	O
as	O
well	O
as	O
Smith	O
’s	O
collaborator	O
from	O
Red	O
Storm	O
Entertainment	O
,	O
Brian	O
Upton	O
,	O
joined	O
Smith	O
as	O
co-founders	O
of	O
Croquet	O
Corporation	O
,	O
to	O
build	O
a	O
software	O
system	O
for	O
creating	O
multiuser	B-Operating_System
digital	O
experiences	O
on	O
the	O
web	O
.	O
</s>
<s>
Croquet	O
lets	O
developers	O
build	O
real	O
time	O
multiuser	B-Operating_System
apps	O
without	O
writing	O
a	O
single	O
line	O
of	O
server	O
code	O
,	O
or	O
deploying	O
or	O
managing	O
any	O
servers	O
.	O
</s>
<s>
Croquet	O
consists	O
of	O
a	O
JavaScript	B-Language
library	I-Language
that	O
grants	O
access	O
to	O
its	O
global	O
network	O
of	O
public	O
reflectors	O
.	O
</s>
