<s>
BOINC	B-Operating_System
client	I-Operating_System
–	I-Operating_System
server	I-Operating_System
technology	I-Operating_System
refers	O
to	O
the	O
model	O
under	O
which	O
BOINC	B-Operating_System
works	O
.	O
</s>
<s>
The	O
BOINC	B-Operating_System
framework	B-Architecture
consists	O
of	O
two	O
layers	O
which	O
operate	O
under	O
the	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
architecture	I-Operating_System
.	O
</s>
<s>
Once	O
the	O
BOINC	B-Operating_System
software	O
is	O
installed	O
in	O
a	O
machine	O
,	O
the	O
server	B-Application
starts	O
sending	O
tasks	O
to	O
the	O
client	B-Protocol
.	O
</s>
<s>
The	O
operations	O
are	O
performed	O
client-side	B-Operating_System
and	O
the	O
results	O
are	O
uploaded	O
to	O
the	O
server-side	B-Application
.	O
</s>
<s>
BOINC	B-Operating_System
is	O
designed	O
to	O
be	O
a	O
free	O
structure	O
for	O
anyone	O
wishing	O
to	O
start	O
a	O
distributed	O
computing	O
project	O
.	O
</s>
<s>
BOINC	B-Operating_System
consists	O
of	O
a	O
server	B-Application
system	O
and	O
client	B-Protocol
software	I-Protocol
that	O
communicate	O
with	O
each	O
other	O
to	O
distribute	O
,	O
process	B-Operating_System
,	O
and	O
return	O
workunits	O
.	O
</s>
<s>
A	O
major	O
part	O
of	O
the	O
BOINC	B-Operating_System
system	O
is	O
the	O
backend	O
server	B-Application
.	O
</s>
<s>
The	O
server	B-Application
can	O
run	O
on	O
one	O
or	O
many	O
machines	O
to	O
allow	O
BOINC	B-Operating_System
to	O
scale	O
easily	O
to	O
projects	O
of	O
any	O
size	O
.	O
</s>
<s>
BOINC	B-Operating_System
servers	O
run	O
on	O
Linux-based	O
computers	O
and	O
use	O
Apache	B-Application
,	O
PHP	B-Application
,	O
and	O
MySQL	B-Application
for	O
their	O
web	O
and	O
database	O
systems	O
.	O
</s>
<s>
After	O
uploading	O
from	O
the	O
user	O
's	O
client	B-Protocol
to	O
a	O
science	O
investigator	O
's	O
database	O
,	O
the	O
backend	O
server	B-Application
validates	O
and	O
analyzes	O
the	O
results	O
.	O
</s>
<s>
The	O
validation	O
process	B-Operating_System
involves	O
running	O
all	O
tasks	O
on	O
multiple	O
contributor	O
PCs	O
and	O
comparing	O
the	O
results	O
.	O
</s>
<s>
BOINC	B-Operating_System
servers	O
also	O
provide	O
these	O
features	O
:	O
</s>
<s>
The	O
server	B-Application
consists	O
of	O
two	O
CGI	B-Language
programs	O
and	O
(	O
normally	O
)	O
five	O
daemons	B-Operating_System
,	O
written	O
in	O
C++	B-Language
.	O
</s>
<s>
A	O
project	O
does	O
not	O
explicitly	O
create	O
results	O
;	O
the	O
server	B-Application
creates	O
them	O
automatically	O
from	O
workunits	O
.	O
</s>
<s>
The	O
scheduler	O
CGI	B-Language
program	O
handles	O
requests	O
from	O
clients	O
,	O
receiving	O
completed	O
results	O
and	O
sending	O
new	O
work	O
to	O
compute	O
.	O
</s>
<s>
Instead	O
,	O
a	O
feeder	O
daemon	B-Operating_System
loads	O
tasks	O
from	O
the	O
database	O
and	O
keeps	O
them	O
in	O
a	O
shared-memory	B-Operating_System
block	O
,	O
which	O
the	O
scheduler	O
reads	O
.	O
</s>
<s>
The	O
feeder	O
periodically	O
fills	O
empty	O
"	O
slots	O
"	O
in	O
the	O
shared-memory	B-Operating_System
block	O
after	O
the	O
scheduler	O
has	O
sent	O
those	O
results	O
to	O
a	O
client	B-Protocol
.	O
</s>
<s>
If	O
the	O
validator	O
determines	O
that	O
at	O
least	O
some	O
of	O
the	O
results	O
are	O
valid	O
,	O
it	O
marks	O
the	O
work	O
unit	O
and	O
the	O
valid	O
results	O
as	O
valid	O
,	O
users	O
who	O
returned	O
legitimate	O
results	O
are	O
granted	O
credit	B-Operating_System
for	O
it	O
,	O
and	O
a	O
"	O
canonical	O
result	O
"	O
is	O
chosen	O
.	O
</s>
<s>
If	O
the	O
results	O
do	O
n't	O
agree	O
,	O
or	O
if	O
one	O
of	O
the	O
results	O
is	O
not	O
reported	O
by	O
its	O
deadline	O
,	O
the	O
server	B-Application
generates	O
an	O
additional	O
instance	O
of	O
the	O
job	O
,	O
and	O
sends	O
it	O
to	O
a	O
third	O
host	O
.	O
</s>
<s>
Next	O
,	O
the	O
assimilator	O
daemon	B-Operating_System
processes	O
the	O
canonical	O
result	O
using	O
project-specific	O
code	O
.	O
</s>
<s>
The	O
file_deleter	O
daemon	B-Operating_System
deletes	O
output	O
files	O
after	O
the	O
assimilator	O
has	O
processed	O
them	O
,	O
and	O
deletes	O
input	O
files	O
that	O
are	O
n't	O
needed	O
anymore	O
.	O
</s>
<s>
The	O
transitioner	O
daemon	B-Operating_System
handles	O
state	O
transitions	O
of	O
workunits	O
and	O
results	O
.	O
</s>
<s>
BOINC	B-Operating_System
on	O
the	O
client	B-Protocol
is	O
structured	O
into	O
a	O
number	O
of	O
separate	O
applications	O
.	O
</s>
<s>
These	O
intercommunicate	O
using	O
the	O
BOINC	B-Operating_System
remote	B-Operating_System
procedure	I-Operating_System
call	I-Operating_System
(	O
RPC	O
)	O
mechanism	O
.	O
</s>
<s>
The	O
program	O
(	O
or	O
)	O
is	O
the	O
core	O
client	B-Protocol
.	O
</s>
<s>
The	O
core	O
client	B-Protocol
is	O
a	O
process	B-Operating_System
which	O
:	O
</s>
<s>
Takes	O
care	O
of	O
communications	O
between	O
the	O
client	B-Protocol
and	O
the	O
server	B-Application
.	O
</s>
<s>
The	O
core	O
client	B-Protocol
also	O
downloads	O
science	O
applications	O
,	O
provides	O
a	O
unified	O
logging	O
mechanism	O
,	O
makes	O
sure	O
science	O
application	O
binaries	O
are	O
up-to-date	O
,	O
and	O
schedules	O
CPU	O
resources	O
between	O
science	O
applications	O
(	O
if	O
several	O
are	O
installed	O
)	O
.	O
</s>
<s>
Although	O
the	O
core	O
client	B-Protocol
is	O
capable	O
of	O
downloading	O
new	O
science	O
applications	O
,	O
it	O
does	O
not	O
update	O
itself	O
.	O
</s>
<s>
BOINC	B-Operating_System
's	O
authors	O
felt	O
doing	O
so	O
posed	O
an	O
unacceptable	O
security	O
risk	O
,	O
as	O
well	O
as	O
all	O
of	O
the	O
risks	O
that	O
automatic	O
update	O
procedures	O
have	O
in	O
computing	O
.	O
</s>
<s>
On	O
Unix	B-Application
,	O
the	O
core	O
client	B-Protocol
is	O
generally	O
run	O
as	O
a	O
daemon	B-Operating_System
(	O
or	O
occasionally	O
as	O
a	O
cron	B-General_Concept
job	I-General_Concept
)	O
.	O
</s>
<s>
On	O
Windows	O
,	O
BOINC	B-Operating_System
initially	O
was	O
not	O
a	O
Windows	O
service	O
,	O
but	O
an	O
ordinary	O
application	O
.	O
</s>
<s>
BOINC	B-Operating_System
Client	B-Protocol
for	O
Windows	O
,	O
Versions	O
5.2.13	O
and	O
higher	O
add	O
,	O
during	O
installation	O
,	O
the	O
option	O
of	O
"	O
Service	O
Installation	O
"	O
.	O
</s>
<s>
Depending	O
on	O
how	O
the	O
BOINC	B-Operating_System
client	B-Protocol
software	I-Protocol
was	O
installed	O
,	O
it	O
can	O
either	O
run	O
in	O
the	O
background	O
like	O
a	O
daemon	B-Operating_System
,	O
or	O
starts	O
when	O
an	O
individual	O
user	O
logs	O
in	O
(	O
and	O
is	O
stopped	O
when	O
the	O
user	O
logs	O
out	O
)	O
.	O
</s>
<s>
The	O
software	O
version	O
management	O
and	O
work-unit	O
handling	O
provided	O
by	O
the	O
core	O
client	B-Protocol
greatly	O
simplifies	O
the	O
coding	O
of	O
science	O
applications	O
.	O
</s>
<s>
There	O
is	O
a	O
specific	O
science	O
application	O
for	O
each	O
of	O
the	O
distributed	O
computation	O
projects	O
which	O
use	O
the	O
BOINC	B-Operating_System
framework	B-Architecture
.	O
</s>
<s>
Science	O
applications	O
use	O
the	O
BOINC	B-Operating_System
daemon	B-Operating_System
to	O
upload	O
and	O
download	O
workunits	O
,	O
and	O
to	O
exchange	O
statistics	O
with	O
the	O
server	B-Application
.	O
</s>
<s>
(	O
or	O
)	O
,	O
a	O
GUI	B-Application
which	O
communicates	O
with	O
the	O
core	O
application	O
using	O
remote	B-Operating_System
procedure	I-Operating_System
calls	I-Operating_System
.	O
</s>
<s>
By	O
default	O
a	O
core	O
client	B-Protocol
only	O
allows	O
connections	O
from	O
the	O
same	O
computer	O
,	O
but	O
it	O
can	O
be	O
configured	O
to	O
allow	O
connections	O
from	O
other	O
computers	O
(	O
optionally	O
using	O
password	O
authentication	O
)	O
;	O
this	O
mechanism	O
allows	O
one	O
person	O
to	O
manage	O
a	O
farm	O
of	O
BOINC	B-Operating_System
installations	O
from	O
a	O
single	O
workstation	O
.	O
</s>
<s>
The	O
GUI	B-Application
is	O
written	O
using	O
the	O
cross-platform	O
WxWidgets	B-Language
toolkit	O
,	O
providing	O
the	O
same	O
user	O
experience	O
on	O
different	O
platforms	B-Device
.	O
</s>
<s>
Users	O
can	O
connect	O
to	O
BOINC	B-Operating_System
core	O
clients	O
,	O
can	O
instruct	O
those	O
clients	O
to	O
install	O
new	O
science	O
applications	O
,	O
can	O
monitor	O
the	O
progress	O
of	O
ongoing	O
calculations	O
,	O
and	O
can	O
view	O
the	O
BOINC	B-Operating_System
system	O
message	O
logs	O
.	O
</s>
<s>
The	O
BOINC	B-Operating_System
screensaver	B-General_Concept
.	O
</s>
<s>
This	O
provides	O
a	O
framework	B-Architecture
whereby	O
science	O
applications	O
can	O
display	O
graphics	O
in	O
the	O
user	O
's	O
screensaver	B-General_Concept
window	O
.	O
</s>
<s>
BOINC	B-Operating_System
screensavers	B-General_Concept
are	O
coded	O
using	O
the	O
BOINC	B-Operating_System
graphics	O
API	O
,	O
OpenGL	B-Application
,	O
and	O
the	O
GLUT	B-Library
toolkit	O
.	O
</s>
<s>
Typically	O
BOINC	B-Operating_System
screensavers	B-General_Concept
show	O
animated	O
graphics	O
detailing	O
the	O
work	O
underway	O
,	O
perhaps	O
showing	O
graphs	O
or	O
charts	O
or	O
other	O
data	O
visualisation	O
graphics	O
.	O
</s>
<s>
Some	O
science	O
applications	O
do	O
not	O
provide	O
screensaver	B-General_Concept
functionality	O
(	O
or	O
stop	O
providing	O
screensaver	B-General_Concept
images	O
when	O
they	O
are	O
idle	O
)	O
.	O
</s>
<s>
In	O
this	O
circumstance	O
the	O
screensaver	B-General_Concept
shows	O
a	O
small	O
BOINC	B-Operating_System
logo	O
which	O
bounces	O
around	O
the	O
screen	O
.	O
</s>
<s>
Since	O
BOINC	B-Operating_System
has	O
features	O
that	O
can	O
render	O
it	O
invisible	O
to	O
the	O
typical	O
user	O
,	O
there	O
is	O
risk	O
that	O
unauthorized	O
and	O
difficult	O
to	O
detect	O
installations	O
may	O
occur	O
.	O
</s>
<s>
This	O
would	O
aid	O
the	O
accumulation	O
of	O
BOINC-credit	O
points	O
by	O
hobbyists	O
who	O
are	O
competing	O
with	O
others	O
for	O
status	O
within	O
the	O
BOINC-credit	O
subculture	O
.	O
</s>
<s>
Operating	O
systemHardwareExamplesStatusLinuxIA-32	O
and	O
AMD64PCs	O
and	O
serversMost	O
Linux	B-Application
projects	O
require	O
64-bit	O
Linux	B-Application
.	O
</s>
<s>
32-bit	O
Linux	B-Application
projects	O
could	O
require	O
installation	O
of	O
32-bit	O
libraries	O
if	O
they	O
are	O
run	O
on	O
64-bit	O
Linux.macOSX86-64	O
,	O
ARMv8Different	O
BOINC	B-Operating_System
clients	O
used	O
to	O
be	O
available	O
for	O
PowerPC	O
,	O
IA-32	B-Device
,	O
and	O
AMD64	B-Device
.	O
</s>
<s>
The	O
AMD64	B-Device
client	B-Protocol
was	O
capable	O
of	O
running	O
IA-32	B-Device
applications	O
if	O
the	O
BOINC	B-Operating_System
server	B-Application
supports	O
this	O
.	O
</s>
<s>
BOINC	B-Operating_System
Manager	O
7.16.13	O
is	O
for	O
both	O
X-86-64	O
and	O
ARMv8.WindowsIA-32	O
and	O
AMD64Different	O
BOINC	B-Operating_System
clients	O
are	O
available	O
for	O
IA-32	B-Device
and	O
AMD64	B-Device
.	O
</s>
<s>
The	O
64-bit	O
client	B-Protocol
will	O
run	O
32-bit	O
applications	O
if	O
the	O
BOINC	B-Operating_System
server	B-Application
supports	O
this.Raspbian	O
(	O
Linux	B-Application
)	O
ARMRaspberry	O
PiVery	O
few	O
client	B-Protocol
applications	I-Protocol
availableAndroid	O
(	O
Linux	B-Application
)	O
ARM	B-Architecture
,	O
MIPS	B-Device
,	O
or	O
IA-32Smartphones	O
and	O
tabletsFew	O
client	B-Protocol
applications	I-Protocol
available	O
.	O
</s>
