<s>
Cloud	B-General_Concept
computing	I-General_Concept
architecture	I-General_Concept
refers	O
to	O
the	O
components	O
and	O
subcomponents	O
required	O
for	O
cloud	B-Architecture
computing	I-Architecture
.	O
</s>
<s>
Combined	O
,	O
these	O
components	O
make	O
up	O
cloud	B-General_Concept
computing	I-General_Concept
architecture	I-General_Concept
.	O
</s>
<s>
Cloud	B-General_Concept
computing	I-General_Concept
architectures	I-General_Concept
consist	O
of	O
front-end	O
platforms	O
called	O
clients	O
or	O
cloud	O
clients	O
.	O
</s>
<s>
These	O
clients	O
are	O
servers	O
,	O
fat	O
(	O
or	O
thick	O
)	O
clients	O
,	O
thin	O
clients	O
,	O
zero	O
clients	O
,	O
tablets	B-Device
and	O
mobile	O
devices	O
that	O
users	O
directly	O
interact	O
with	O
.	O
</s>
<s>
In	O
order	O
to	O
be	O
effective	O
,	O
the	O
cloud	O
storage	O
needs	O
to	O
be	O
agile	O
,	O
flexible	O
,	O
scalable	O
,	O
multi-tenancy	B-Architecture
,	O
and	O
secure	O
.	O
</s>
<s>
The	O
software-as-a-service	B-Architecture
(	O
SaaS	B-Architecture
)	O
service-model	O
involves	O
the	O
cloud	O
provider	O
installing	O
and	O
maintaining	O
software	B-Architecture
in	I-Architecture
the	I-Architecture
cloud	I-Architecture
and	O
users	O
running	O
the	O
software	O
from	O
cloud	O
over	O
the	O
Internet	O
(	O
or	O
Intranet	O
)	O
.	O
</s>
<s>
The	O
users	O
 '	O
client	O
machines	O
require	O
no	O
installation	O
of	O
any	O
application-specific	O
software	O
since	O
cloud	B-Architecture
applications	I-Architecture
run	O
in	B-Architecture
the	I-Architecture
cloud	I-Architecture
.	O
</s>
<s>
SaaS	B-Architecture
is	O
scalable	O
,	O
and	O
system	O
administrators	O
may	O
load	O
the	O
applications	O
on	O
several	O
servers	O
.	O
</s>
<s>
In	O
the	O
past	O
,	O
each	O
customer	O
would	O
purchase	O
and	O
load	O
their	O
own	O
copy	O
of	O
the	O
application	O
to	O
each	O
of	O
their	O
own	O
servers	O
,	O
but	O
with	O
the	O
SaaS	B-Architecture
the	O
customer	O
can	O
access	O
the	O
application	O
without	O
installing	O
the	O
software	O
locally	O
.	O
</s>
<s>
SaaS	B-Architecture
typically	O
involves	O
a	O
monthly	O
or	O
annual	O
fee	O
.	O
</s>
<s>
Software	B-Architecture
as	I-Architecture
a	I-Architecture
service	I-Architecture
provides	O
the	O
equivalent	O
of	O
installed	O
applications	O
in	O
the	O
traditional	O
(	O
non-cloud	O
computing	O
)	O
delivery	O
of	O
applications	O
.	O
</s>
<s>
Software	B-Architecture
as	I-Architecture
a	I-Architecture
service	I-Architecture
has	O
four	O
common	O
approaches	O
:	O
</s>
<s>
Of	O
these	O
,	O
flex	O
tenancy	O
is	O
considered	O
the	O
most	O
user	O
adaptive	O
SaaS	B-Architecture
paradigm	O
in	O
designated	O
multi-input	O
four	O
way	O
manifold	O
models	O
.	O
</s>
<s>
The	O
simplicity	O
of	O
this	O
concept	O
makes	O
flex	O
tenancy	O
SaaS	B-Architecture
popular	O
among	O
those	O
without	O
informatics	O
processing	O
experience	O
,	O
such	O
as	O
basic	O
maintenance	O
and	O
custodial	O
staff	O
in	O
franchise	O
businesses	O
.	O
</s>
<s>
DaaS	O
services	O
are	O
often	O
considered	O
as	O
a	O
specialized	O
subset	O
of	O
a	O
Software	B-Architecture
as	I-Architecture
a	I-Architecture
Service	I-Architecture
(	O
SaaS	B-Architecture
)	O
offering	O
.	O
</s>
<s>
Platform	B-Application
as	I-Application
a	I-Application
service	I-Application
is	O
cloud	B-Architecture
computing	I-Architecture
service	O
which	O
provides	O
the	O
users	O
with	O
application	O
platforms	O
and	O
databases	O
as	O
a	O
service	O
.	O
</s>
<s>
Infrastructure	B-General_Concept
as	I-General_Concept
a	I-General_Concept
service	I-General_Concept
is	O
taking	O
the	O
physical	O
hardware	O
and	O
going	O
completely	O
virtual	O
(	O
e.g.	O
</s>
<s>
all	O
servers	O
,	O
networks	O
,	O
storage	O
,	O
and	O
system	O
management	O
all	O
existing	O
in	B-Architecture
the	I-Architecture
cloud	I-Architecture
)	O
.	O
</s>
<s>
This	O
is	O
the	O
equivalent	O
to	O
infrastructure	O
and	O
hardware	O
in	O
the	O
traditional	O
(	O
non-cloud	O
computing	O
)	O
method	O
running	O
in	B-Architecture
the	I-Architecture
cloud	I-Architecture
.	O
</s>
<s>
Security	O
is	O
always	O
important	O
,	O
but	O
when	O
you	O
are	O
dealing	O
with	O
multi-tenancy	B-Architecture
,	O
it	O
becomes	O
much	O
more	O
important	O
because	O
you	O
're	O
dealing	O
with	O
segregating	O
multiple	O
customers	O
.	O
</s>
