<s>
Meteor	O
,	O
or	O
MeteorJS	O
,	O
is	O
a	O
partly	O
proprietary	O
,	O
mostly	O
free	B-License
and	I-License
open-source	I-License
isomorphic	B-Language
JavaScript	I-Language
web	B-Application
framework	I-Application
written	O
using	O
Node.js	B-Language
.	O
</s>
<s>
Meteor	O
allows	O
for	O
rapid	O
prototyping	O
and	O
produces	O
cross-platform	B-Operating_System
(	O
Android	B-Application
,	O
iOS	B-Application
,	O
Web	O
)	O
code	O
.	O
</s>
<s>
The	O
server-side	O
MongoDB	B-Application
program	O
is	O
the	O
only	O
proprietary	O
component	O
of	O
Meteor	O
and	O
is	O
part	O
of	O
the	O
Meteor	O
download	O
bundle	O
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
use	O
Meteor	O
without	O
using	O
the	O
server-side	O
MongoDB	B-Application
.	O
</s>
<s>
It	O
uses	O
the	O
Distributed	B-Protocol
Data	I-Protocol
Protocol	I-Protocol
and	O
a	O
publish	B-Operating_System
–	I-Operating_System
subscribe	I-Operating_System
pattern	I-Operating_System
to	O
automatically	O
propagate	O
data	O
changes	O
to	O
clients	O
without	O
requiring	O
the	O
developer	O
to	O
write	O
any	O
synchronization	O
code	O
.	O
</s>
<s>
On	O
the	O
client	O
,	O
Meteor	O
can	O
be	O
used	O
with	O
any	O
popular	O
front-end	O
JS	O
framework	O
,	O
Vue	B-Language
,	O
React	O
,	O
Svelte	B-Language
,	O
Angular	O
,	O
or	O
Blaze	O
.	O
</s>
<s>
From	O
2016	O
the	O
Meteor	O
Development	O
Group	O
(	O
the	O
open	O
source	O
organisation	O
powering	O
Meteor	O
)	O
started	O
working	O
on	O
a	O
new	O
backend	O
layer	O
based	O
on	O
GraphQL	B-Language
to	O
gradually	O
replace	O
their	O
pub/sub	B-Operating_System
system	O
,	O
largely	O
isolated	O
in	O
the	O
whole	O
node.js	B-Language
ecosystem	O
:	O
the	O
Apollo	O
framework	O
.	O
</s>
<s>
Distributed	B-Protocol
Data	I-Protocol
Protocol	I-Protocol
(	O
or	O
DDP	O
)	O
is	O
a	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
protocol	O
for	O
querying	O
and	O
updating	O
a	O
server-side	O
database	O
and	O
for	O
synchronizing	O
such	O
updates	O
among	O
clients	O
.	O
</s>
<s>
It	O
uses	O
the	O
publish	B-Operating_System
–	I-Operating_System
subscribe	I-Operating_System
messaging	O
pattern	O
.	O
</s>
<s>
It	O
was	O
created	O
for	O
use	O
by	O
the	O
Meteor	O
JavaScript	B-Language
framework	I-Language
.	O
</s>
