<s>
Software	O
as	O
a	O
service	O
(	O
SaaS	O
)	O
is	O
a	O
software	B-License
licensing	I-License
and	O
delivery	B-Application
model	O
in	O
which	O
software	O
is	O
licensed	O
on	O
a	O
subscription	O
basis	O
and	O
is	O
centrally	O
hosted	O
.	O
</s>
<s>
SaaS	O
is	O
also	O
known	O
as	O
on-demand	O
software	O
,	O
web-based	B-Application
software	O
,	O
or	O
web-hosted	O
software	O
.	O
</s>
<s>
SaaS	O
is	O
considered	O
to	O
be	O
part	O
of	O
cloud	B-Architecture
computing	I-Architecture
,	O
along	O
with	O
infrastructure	B-General_Concept
as	I-General_Concept
a	I-General_Concept
service	I-General_Concept
(	O
IaaS	B-General_Concept
)	O
,	O
platform	B-Application
as	I-Application
a	I-Application
service	I-Application
(	O
PaaS	B-Application
)	O
,	O
desktop	B-Protocol
as	I-Protocol
a	I-Protocol
service	I-Protocol
(	O
DaaS	O
)	O
,	O
managed	O
software	O
as	O
a	O
service	O
(	O
MSaaS	O
)	O
,	O
mobile	B-Application
backend	I-Application
as	I-Application
a	I-Application
service	I-Application
(	O
MBaaS	B-Application
)	O
,	O
data	B-Operating_System
center	I-Operating_System
as	O
a	O
service	O
(	O
DCaaS	O
)	O
,	O
integration	B-General_Concept
platform	I-General_Concept
as	I-General_Concept
a	I-General_Concept
service	I-General_Concept
(	O
iPaaS	B-General_Concept
)	O
,	O
and	O
information	B-General_Concept
technology	I-General_Concept
management	O
as	O
a	O
service	O
(	O
ITMaaS	O
)	O
.	O
</s>
<s>
SaaS	O
apps	O
are	O
typically	O
accessed	O
by	O
users	O
of	O
a	O
web	B-Application
browser	I-Application
(	O
a	O
thin	B-Device
client	I-Device
)	O
.	O
</s>
<s>
SaaS	O
became	O
a	O
common	O
delivery	B-Application
model	O
for	O
many	O
business	B-Application
applications	I-Application
,	O
including	O
office	B-Application
software	I-Application
,	O
messaging	B-Application
software	I-Application
,	O
payroll	O
processing	O
software	O
,	O
DBMS	O
software	O
,	O
management	O
software	O
,	O
CAD	B-Application
software	I-Application
,	O
development	O
software	O
,	O
gamification	O
,	O
virtualization	B-General_Concept
,	O
accounting	B-Application
,	O
collaboration	B-Application
,	O
customer	O
relationship	O
management	O
(	O
CRM	O
)	O
,	O
management	B-Application
information	I-Application
systems	I-Application
(	O
MIS	O
)	O
,	O
enterprise	O
resource	O
planning	O
(	O
ERP	O
)	O
,	O
invoicing	O
,	O
field	O
service	O
management	O
,	O
human	O
resource	O
management	O
(	O
HRM	O
)	O
,	O
talent	O
acquisition	O
,	O
learning	B-Application
management	I-Application
systems	I-Application
,	O
content	B-Protocol
management	I-Protocol
(	O
CM	O
)	O
,	O
geographic	B-Application
information	I-Application
systems	I-Application
(	O
GIS	B-Application
)	O
,	O
and	O
service	O
desk	O
management	O
.	O
</s>
<s>
SaaS	O
has	O
been	O
incorporated	O
into	O
the	O
strategies	O
of	O
nearly	O
all	O
enterprise	B-Application
software	I-Application
companies	O
.	O
</s>
<s>
Centralized	O
hosting	O
of	O
business	B-Application
applications	I-Application
dates	O
back	O
to	O
the	O
1960s	O
.	O
</s>
<s>
Starting	O
in	O
that	O
decade	O
,	O
IBM	O
and	O
other	O
mainframe	B-Architecture
computer	I-Architecture
providers	O
conducted	O
a	O
service	O
bureau	O
business	O
,	O
often	O
referred	O
to	O
as	O
time-sharing	B-General_Concept
or	O
utility	B-Operating_System
computing	I-Operating_System
.	O
</s>
<s>
Such	O
services	O
included	O
offering	O
computing	O
power	O
and	O
database	O
storage	O
to	O
banks	O
and	O
other	O
large	O
organizations	O
from	O
their	O
worldwide	O
data	B-Operating_System
centers	I-Operating_System
.	O
</s>
<s>
The	O
expansion	O
of	O
the	O
Internet	O
during	O
the	O
1990s	O
brought	O
about	O
a	O
new	O
class	O
of	O
centralized	B-General_Concept
computing	I-General_Concept
,	O
called	O
application	O
service	O
providers	O
(	O
ASP	O
)	O
.	O
</s>
<s>
ASPs	O
provided	O
businesses	O
with	O
the	O
service	O
of	O
hosting	O
and	O
managing	O
specialized	O
business	B-Application
applications	I-Application
to	O
reduce	O
costs	O
through	O
central	O
administration	O
and	O
the	O
provider	O
's	O
specialization	O
in	O
a	O
particular	O
business	B-Application
application	I-Application
.	O
</s>
<s>
While	O
most	O
initial	O
ASPs	O
focused	O
on	O
managing	O
and	O
hosting	O
third-party	O
independent	B-Application
software	I-Application
vendors	I-Application
 '	O
software	O
,	O
contemporary	O
SaaS	O
offerings	O
are	O
typically	O
provided	O
by	O
the	O
software	O
developer	O
.	O
</s>
<s>
Whereas	O
many	O
initial	O
ASPs	O
offered	O
more	O
traditional	O
client-server	B-Operating_System
applications	O
,	O
which	O
require	O
the	O
installation	O
of	O
software	O
on	O
users	O
 '	O
personal	B-Device
computers	I-Device
,	O
later	O
implementations	O
can	O
be	O
Web	B-Application
applications	I-Application
that	O
only	O
require	O
a	O
web	B-Application
browser	I-Application
to	O
use	O
.	O
</s>
<s>
Whereas	O
the	O
software	B-Architecture
architecture	I-Architecture
used	O
by	O
most	O
initial	O
ASPs	O
mandated	O
maintaining	O
a	O
separate	O
instance	O
of	O
the	O
application	O
for	O
each	O
business	O
,	O
SaaS	O
services	O
can	O
utilize	O
a	O
multi-tenant	B-Architecture
architecture	O
,	O
in	O
which	O
the	O
application	O
serves	O
multiple	O
businesses	O
and	O
users	O
,	O
and	O
partitions	O
its	O
data	O
accordingly	O
.	O
</s>
<s>
Unlike	O
traditional	O
software	O
,	O
which	O
is	O
conventionally	O
sold	O
as	O
a	O
perpetual	B-License
license	I-License
with	O
an	O
up-front	O
cost	O
(	O
and	O
an	O
optional	O
ongoing	O
support	O
fee	O
)	O
,	O
SaaS	O
providers	O
generally	O
price	O
applications	O
using	O
a	O
subscription	O
fee	O
,	O
most	O
commonly	O
a	O
monthly	O
fee	O
or	O
an	O
annual	O
fee	O
.	O
</s>
<s>
Consequently	O
,	O
the	O
initial	O
setup	O
cost	O
for	O
SaaS	O
is	O
typically	O
lower	O
than	O
the	O
equivalent	O
enterprise	B-Application
software	I-Application
.	O
</s>
<s>
The	O
relatively	O
low	O
cost	O
for	O
user	O
provisioning	O
(	O
i.e.	O
,	O
setting	O
up	O
a	O
new	O
customer	O
)	O
in	O
a	O
multi-tenant	B-Architecture
environment	O
enables	O
some	O
SaaS	O
vendors	O
to	O
offer	O
applications	O
using	O
the	O
freemium	O
model	O
.	O
</s>
<s>
This	O
is	O
consistent	O
with	O
the	O
traditional	O
rationale	O
for	O
outsourcing	O
IT	B-General_Concept
systems	I-General_Concept
,	O
which	O
involves	O
applying	O
economies	O
of	O
scale	O
to	O
application	O
operation	O
,	O
i.e.	O
,	O
an	O
outside	O
service	O
provider	O
may	O
be	O
able	O
to	O
offer	O
better	O
,	O
cheaper	O
,	O
more	O
reliable	O
applications	O
.	O
</s>
<s>
Most	O
SaaS	O
providers	O
offer	O
a	O
multi-tenant	B-Architecture
architecture	O
.	O
</s>
<s>
With	O
this	O
model	O
,	O
a	O
single	O
version	O
of	O
the	O
application	O
,	O
with	O
a	O
single	O
configuration	B-General_Concept
(	O
hardware	B-Architecture
,	O
network	B-Architecture
,	O
operating	B-General_Concept
system	I-General_Concept
)	O
,	O
is	O
used	O
for	O
all	O
customers	O
(	O
"	O
tenants	O
"	O
)	O
.	O
</s>
<s>
To	O
support	O
scalability	B-Architecture
,	O
the	O
application	O
can	O
be	O
installed	O
on	O
multiple	O
machines	O
(	O
called	O
horizontal	O
scaling	B-Architecture
)	O
.	O
</s>
<s>
This	O
is	O
contrasted	O
with	O
traditional	O
software	O
,	O
where	O
multiple	O
physical	O
copies	O
of	O
the	O
software	O
—	O
each	O
potentially	O
of	O
a	O
different	O
version	O
,	O
with	O
a	O
potentially	O
different	O
configuration	B-General_Concept
,	O
and	O
often	O
customized	O
—	O
are	O
installed	O
across	O
various	O
customer	O
sites	O
.	O
</s>
<s>
Although	O
an	O
exception	O
rather	O
than	O
the	O
norm	O
,	O
some	O
SaaS	O
providers	O
use	O
mechanisms	O
such	O
as	O
virtualization	B-General_Concept
to	O
manage	O
a	O
large	O
number	O
of	O
customers	O
in	O
place	O
of	O
multitenancy	B-Architecture
.	O
</s>
<s>
Whether	O
multitenancy	B-Architecture
is	O
a	O
necessary	O
component	O
of	O
software	O
as	O
a	O
service	O
is	O
debatable	O
.	O
</s>
<s>
Horizontal	O
SaaS	O
and	O
vertical	O
SaaS	O
are	O
different	O
models	O
of	O
cloud	B-Architecture
computing	I-Architecture
services	O
.	O
</s>
<s>
Some	O
popular	O
examples	O
of	O
horizontal	O
SaaS	O
vendors	O
are	O
Salesforce	B-Application
and	O
HubSpot	O
.	O
</s>
<s>
The	O
application	O
only	O
has	O
a	O
single	O
configuration	B-General_Concept
,	O
making	O
development	O
testing	O
faster	O
.	O
</s>
<s>
Accelerated	O
feature	O
delivery	B-Application
is	O
further	O
enabled	O
by	O
agile	O
software	O
development	O
methodologies	O
.	O
</s>
<s>
Such	O
methodologies	O
,	O
which	O
evolved	O
in	O
the	O
mid-1990s	O
,	O
provide	O
a	O
set	O
of	O
software	B-Application
development	I-Application
tools	I-Application
and	O
practices	O
to	O
support	O
frequent	O
software	O
releases	O
.	O
</s>
<s>
SaaS	O
applications	O
predominantly	O
offer	O
integration	O
protocols	O
and	O
application	B-Application
programming	I-Application
interfaces	I-Application
(	O
APIs	B-General_Concept
)	O
that	O
operate	O
over	O
a	O
wide	O
area	O
network	B-Architecture
.	O
</s>
<s>
The	O
ubiquity	O
of	O
SaaS	O
applications	O
and	O
other	O
Internet	O
services	O
and	O
the	O
standardization	O
of	O
their	O
API	B-General_Concept
technology	O
has	O
spawned	O
the	O
development	O
of	O
mashups	B-Application
,	O
which	O
are	O
lightweight	O
applications	O
that	O
combine	O
data	O
,	O
presentation	O
,	O
and	O
functionality	O
from	O
multiple	O
services	O
,	O
creating	O
a	O
compound	O
service	O
.	O
</s>
<s>
Mashups	B-Application
further	O
differentiate	O
SaaS	O
applications	O
from	O
on-premises	O
software	O
as	O
the	O
latter	O
cannot	O
be	O
easily	O
integrated	O
outside	O
a	O
company	O
's	O
firewall	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
many	O
project	O
management	O
applications	O
delivered	O
in	O
the	O
SaaS	O
model	O
offer	O
—	O
in	O
addition	O
to	O
traditional	O
project	O
planning	O
functionality	O
—	O
collaboration	B-Application
features	O
letting	O
users	O
comment	O
on	O
tasks	O
and	O
plans	O
and	O
share	O
documents	O
within	O
and	O
outside	O
an	O
organization	O
.	O
</s>
<s>
Although	O
some	O
collaboration-related	O
functionality	O
is	O
also	O
integrated	O
into	O
on-premises	O
software	O
,	O
(	O
implicit	O
or	O
explicit	O
)	O
collaboration	B-Application
between	O
users	O
or	O
different	O
customers	O
is	O
only	O
possible	O
with	O
centrally	O
hosted	O
software	O
.	O
</s>
<s>
OpenSaaS	B-Application
refers	O
to	O
software	O
as	O
a	O
service	O
(	O
SaaS	O
)	O
based	O
on	O
open-source	B-Application
code	O
.	O
</s>
<s>
Like	O
SaaS	O
applications	O
,	O
Open	O
SaaS	O
is	O
a	O
web-based	B-Application
application	I-Application
hosted	O
,	O
supported	O
,	O
and	O
maintained	O
by	O
a	O
service	O
provider	O
.	O
</s>
<s>
The	O
term	O
was	O
coined	O
in	O
2011	O
by	O
Dries	O
Buytaert	O
,	O
creator	O
of	O
the	O
Drupal	B-Application
content	B-Protocol
management	I-Protocol
framework	O
.	O
</s>
<s>
Andrew	O
Hoppin	O
,	O
a	O
former	O
Chief	O
Information	O
Officer	O
for	O
the	O
New	O
York	O
State	O
Senate	O
,	O
has	O
been	O
a	O
vocal	O
advocate	O
of	O
OpenSaaS	B-Application
for	O
government	O
,	O
calling	O
it	O
"	O
the	O
future	O
of	O
government	O
innovation.	O
"	O
</s>
<s>
He	O
points	O
to	O
WordPress	B-Application
and	O
Why	O
Unified	O
as	O
a	O
successful	O
example	O
of	O
an	O
OpenSaaS	B-Application
software	B-Application
delivery	I-Application
model	O
that	O
gives	O
customers	O
"	O
the	O
best	O
of	O
both	O
worlds	O
,	O
and	O
more	O
options	O
.	O
</s>
<s>
The	O
fact	O
that	O
it	O
is	O
open	O
source	O
means	O
that	O
they	O
can	O
start	O
building	O
their	O
websites	O
by	O
self-hosting	O
WordPress	B-Application
and	O
customizing	O
their	O
website	O
to	O
their	O
heart	O
's	O
content	O
.	O
</s>
<s>
Concurrently	O
,	O
the	O
fact	O
that	O
WordPress	B-Application
is	O
SaaS	O
means	O
that	O
they	O
do	O
n't	O
have	O
to	O
manage	O
the	O
website	O
at	O
all	O
--	O
they	O
can	O
simply	O
pay	O
WordPress.com	O
to	O
host	O
it.	O
"	O
</s>
<s>
The	O
growing	O
use	O
of	O
web-based	B-Application
user	B-Application
interfaces	I-Application
by	O
applications	O
,	O
along	O
with	O
the	O
proliferation	O
of	O
associated	O
practices	O
(	O
e.g.	O
,	O
web	O
design	O
)	O
,	O
continuously	O
decreased	O
the	O
need	O
for	O
traditional	O
client-server	B-Operating_System
applications	O
.	O
</s>
<s>
Consequently	O
,	O
traditional	O
software	O
vendor	O
's	O
investment	O
in	O
software	O
based	O
on	O
fat	B-Protocol
clients	I-Protocol
has	O
become	O
a	O
disadvantage	O
(	O
mandating	O
ongoing	O
support	O
)	O
,	O
opening	O
the	O
door	O
for	O
new	O
software	O
vendors	O
 '	O
offering	O
a	O
user	B-Application
experience	I-Application
perceived	O
as	O
more	O
"	O
modern	O
"	O
.	O
</s>
<s>
The	O
standardization	O
of	O
web	O
page	O
technologies	O
(	O
HTML	B-Language
,	O
JavaScript	B-Language
,	O
CSS	B-Language
)	O
,	O
the	O
increasing	O
popularity	O
of	O
web	O
development	O
as	O
a	O
practice	O
,	O
and	O
the	O
introduction	O
and	O
ubiquity	O
of	O
web	B-Application
application	I-Application
frameworks	I-Application
like	O
Ruby	B-Application
on	I-Application
Rails	I-Application
or	O
Laravel	B-Language
(	O
PHP	B-Application
)	O
gradually	O
reduced	O
the	O
cost	O
of	O
developing	O
new	O
software	O
services	O
and	O
enabled	O
new	O
providers	O
to	O
challenge	O
traditional	O
vendors	O
.	O
</s>
<s>
The	O
standardization	O
of	O
the	O
HTTPS	B-Protocol
protocol	O
as	O
part	O
of	O
the	O
web	O
stack	O
provided	O
universally	O
available	O
lightweight	O
security	O
that	O
is	O
sufficient	O
for	O
most	O
everyday	O
applications	O
.	O
</s>
<s>
The	O
introduction	O
and	O
wide	O
acceptance	O
of	O
lightweight	O
integration	O
protocols	O
such	O
as	O
Representational	B-Protocol
State	I-Protocol
Transfer	I-Protocol
(	O
REST	O
)	O
and	O
SOAP	O
enabled	O
affordable	O
integration	O
between	O
SaaS	O
applications	O
(	O
residing	O
in	B-Architecture
the	I-Architecture
cloud	I-Architecture
)	O
with	O
internal	O
applications	O
over	O
wide	O
area	O
networks	O
and	O
with	O
other	O
SaaS	O
applications	O
.	O
</s>
<s>
SaaS	O
applications	O
are	O
hosted	O
in	B-Architecture
the	I-Architecture
cloud	I-Architecture
,	O
far	O
away	O
from	O
the	O
application	O
users	O
.	O
</s>
<s>
This	O
introduces	O
latency	O
into	O
the	O
environment	O
;	O
for	O
example	O
,	O
the	O
SaaS	O
model	O
is	O
not	O
suitable	O
for	O
applications	O
that	O
demand	O
response	O
times	O
in	O
milliseconds	O
(	O
OLTP	B-General_Concept
)	O
.	O
</s>
<s>
Multi-tenant	B-Architecture
architectures	O
,	O
which	O
drive	O
cost	O
efficiency	O
for	O
service	O
providers	O
,	O
limit	O
customization	O
of	O
applications	O
for	O
large	O
clients	O
,	O
inhibiting	O
such	O
applications	O
from	O
being	O
used	O
in	O
scenarios	O
(	O
applicable	O
mostly	O
to	O
large	O
enterprises	O
)	O
for	O
which	O
such	O
customization	O
is	O
necessary	O
.	O
</s>
<s>
Some	O
business	B-Application
applications	I-Application
require	O
access	O
to	O
or	O
integration	O
with	O
customers	O
 '	O
current	O
data	O
.	O
</s>
<s>
end-user	O
'	O
s	O
personal	O
information	O
)	O
,	O
integrating	O
them	O
with	O
remotely	O
hosted	O
software	O
can	O
be	O
costly	O
or	O
risky	O
or	O
can	O
conflict	O
with	O
data	B-General_Concept
governance	I-General_Concept
regulations	O
.	O
</s>
<s>
Relying	O
on	O
an	O
Internet	O
connection	O
means	O
that	O
data	O
is	O
transferred	O
to	O
and	O
from	O
a	O
SaaS	O
firm	O
at	O
Internet	O
speeds	O
rather	O
than	O
the	O
potentially	O
higher	O
speeds	O
of	O
a	O
firm	O
's	O
internal	O
network	B-Architecture
.	O
</s>
<s>
These	O
disparate	O
applications	O
and	O
services	O
can	O
become	O
challenging	O
to	O
maintain	O
technically	O
and	O
administratively	O
,	O
leading	O
to	O
the	O
proliferation	O
of	O
shadow	B-Application
IT	I-Application
.	O
</s>
<s>
Compatibility	O
with	O
hardware	B-Architecture
,	O
other	O
software	O
,	O
and	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
According	O
to	O
a	O
survey	O
by	O
the	O
Healthcare	O
Information	O
and	O
Management	O
Systems	O
Society	O
,	O
83%	O
of	O
US	O
IT	O
healthcare	O
organizations	O
are	O
now	O
using	O
cloud	B-Architecture
services	I-Architecture
,	O
with	O
9.3	O
%	O
planning	O
to	O
,	O
whereas	O
67%	O
of	O
IT	O
healthcare	O
organizations	O
are	O
currently	O
running	O
SaaS-based	O
applications	O
.	O
</s>
<s>
It	O
allows	O
companies	O
to	O
protect	O
and	O
ensure	O
all	O
the	O
data	O
that	O
resides	O
within	O
SaaS	O
applications	O
,	O
protecting	O
against	O
data	B-General_Concept
loss	I-General_Concept
.	O
</s>
<s>
There	O
are	O
many	O
and	O
varied	O
reasons	O
for	O
considering	O
SaaS	O
data	O
escrow	O
,	O
including	O
concerns	O
about	O
vendor	O
bankruptcy	O
,	O
unplanned	O
service	O
outages	O
,	O
and	O
potential	O
data	B-General_Concept
loss	I-General_Concept
or	O
corruption	O
.	O
</s>
<s>
Many	O
businesses	O
either	O
ensure	O
that	O
they	O
are	O
complying	O
with	O
their	O
data	B-General_Concept
governance	I-General_Concept
standards	O
or	O
try	O
to	O
enhance	O
their	O
reporting	O
and	O
business	B-Algorithm
analytics	I-Algorithm
against	O
their	O
SaaS	O
data	O
.	O
</s>
<s>
One	O
notable	O
criticism	O
of	O
SaaS	O
comes	O
from	O
Richard	O
Stallman	O
of	O
the	B-Operating_System
Free	I-Operating_System
Software	I-Operating_System
Foundation	I-Operating_System
,	O
who	O
refers	O
to	O
it	O
as	O
Service	O
as	O
a	O
Software	O
Substitute	O
(	O
SaaSS	O
)	O
.	O
</s>
<s>
He	O
considers	O
the	O
use	O
of	O
SaaSS	O
to	O
be	O
a	O
violation	O
of	O
the	O
principles	O
of	O
free	B-Application
software	I-Application
.	O
</s>
