<s>
Apache	B-General_Concept
Storm	I-General_Concept
is	O
a	O
distributed	B-Architecture
stream	B-Application
processing	I-Application
computation	O
framework	O
written	O
predominantly	O
in	O
the	O
Clojure	B-Language
programming	O
language	O
.	O
</s>
<s>
It	O
uses	O
custom	O
created	O
"	O
spouts	O
"	O
and	O
"	O
bolts	O
"	O
to	O
define	O
information	O
sources	O
and	O
manipulations	O
to	O
allow	O
batch	O
,	O
distributed	B-Architecture
processing	I-Architecture
of	O
streaming	O
data	O
.	O
</s>
<s>
At	O
a	O
superficial	O
level	O
the	O
general	O
topology	O
structure	O
is	O
similar	O
to	O
a	O
MapReduce	B-Operating_System
job	O
,	O
with	O
the	O
main	O
difference	O
being	O
that	O
data	O
is	O
processed	O
in	O
real	O
time	O
as	O
opposed	O
to	O
in	O
individual	O
batches	O
.	O
</s>
<s>
Additionally	O
,	O
Storm	O
topologies	O
run	O
indefinitely	O
until	O
killed	O
,	O
while	O
a	O
MapReduce	B-Operating_System
job	O
DAG	O
must	O
eventually	O
end	O
.	O
</s>
<s>
Storm	O
became	O
an	O
Apache	O
Top-Level	O
Project	O
in	O
September	O
2014	O
and	O
was	O
previously	O
in	O
incubation	B-Application
since	O
September	O
2013	O
.	O
</s>
<s>
Apache	B-General_Concept
Storm	I-General_Concept
is	O
developed	O
under	O
the	O
Apache	B-Application
License	I-Application
,	O
making	O
it	O
available	O
to	O
most	O
companies	O
to	O
use	O
.	O
</s>
<s>
Git	O
is	O
used	O
for	O
version	O
control	O
and	O
Atlassian	O
JIRA	O
for	O
issue	O
tracking	O
,	O
under	O
the	O
Apache	B-Application
Incubator	I-Application
program	O
.	O
</s>
<s>
The	O
Apache	B-General_Concept
Storm	I-General_Concept
cluster	O
comprises	O
following	O
critical	O
components	O
:	O
</s>
<s>
Storm	O
is	O
but	O
one	O
of	O
dozens	O
of	O
stream	B-Application
processing	I-Application
engines	O
,	O
for	O
a	O
more	O
complete	O
list	O
see	O
Stream	B-Application
processing	I-Application
.	O
</s>
<s>
Twitter	O
announced	O
Heron	B-Application
on	O
June	O
2	O
,	O
2015	O
which	O
is	O
API	O
compatible	O
with	O
Storm	O
.	O
</s>
<s>
There	O
are	O
other	O
comparable	O
streaming	O
data	O
engines	O
such	O
as	O
Spark	O
Streaming	O
and	O
Flink	B-Application
.	O
</s>
