<s>
MUMPS	B-Language
is	O
a	O
high	O
performance	O
transaction	O
processing	O
key	O
–	O
value	O
database	O
with	O
integrated	O
programming	O
language	O
.	O
</s>
<s>
MUMPS	B-Language
allows	O
multiple	O
commands	O
to	O
appear	O
on	O
a	O
line	O
,	O
grouped	O
into	O
procedures	O
(	O
subroutines	O
)	O
in	O
a	O
fashion	O
similar	O
to	O
most	O
structured	B-Language
programming	I-Language
systems	O
.	O
</s>
<s>
There	O
have	O
been	O
several	O
revisions	O
to	O
the	O
MUMPS	B-Language
language	I-Language
standard	O
between	O
1975	O
and	O
1999	O
.	O
</s>
<s>
MUMPS	B-Language
was	O
early	O
used	O
for	O
multi-user	O
and	O
multi-tasking	O
work	O
.	O
</s>
<s>
Today	O
,	O
a	O
PC	O
running	O
MUMPS	B-Language
can	O
behave	O
much	O
as	O
a	O
large	O
minicomputer	O
of	O
former	O
years	O
.	O
</s>
<s>
Early	O
versions	O
of	O
MUMPS	B-Language
did	O
not	O
require	O
large	O
memory	O
or	O
disk	O
capacities	O
and	O
so	O
were	O
practical	O
on	O
smaller	O
machines	O
than	O
some	O
other	O
systems	O
required	O
.	O
</s>
<s>
In	O
MUMPS	B-Language
syntax	I-Language
,	O
some	O
spaces	O
are	O
significant	O
;	O
they	O
are	O
not	O
merely	O
whitespace	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
space	O
(	O
called	O
ls	O
in	O
the	O
formal	O
MUMPS	B-Language
standard	O
)	O
separates	O
a	O
tag	O
on	O
a	O
line	O
from	O
the	O
commands	O
that	O
make	O
up	O
that	O
line	O
.	O
</s>
<s>
Where	O
some	O
languages	O
have	O
a	O
requirement	O
to	O
put	O
semicolons	O
at	O
the	O
end	O
of	O
commands	O
,	O
MUMPS	B-Language
uses	O
the	O
space	O
or	O
line-terminator	O
to	O
end	O
the	O
command	O
.	O
</s>
<s>
While	O
other	O
languages	O
have	O
larger	O
ways	O
of	O
grouping	O
commands	O
,	O
such	O
as	O
statements	O
and	O
blocks	O
,	O
MUMPS	B-Language
does	O
not	O
have	O
these	O
,	O
only	O
the	O
line	O
scope	O
.	O
</s>
<s>
Unlike	O
Fortran	B-Application
and	O
some	O
other	O
languages	O
which	O
had	O
fixed-length	O
lines	O
,	O
lines	O
have	O
variable	O
length	O
up	O
to	O
the	O
limit	O
of	O
the	O
implementation	O
.	O
</s>
<s>
A	O
typical	O
M	B-Language
procedure	O
(	O
a	O
"	O
routine	O
"	O
in	O
MUMPS	B-Language
terminology	O
)	O
is	O
analogous	O
to	O
a	O
source	O
file	O
in	O
C	O
(	O
in	O
that	O
the	O
subroutines	O
and	O
functions	O
relevant	O
to	O
a	O
particular	O
task	O
or	O
category	O
are	O
grouped	O
together	O
,	O
for	O
instance	O
)	O
and	O
consists	O
of	O
lines	O
of	O
MUMPS	B-Language
code	O
.	O
</s>
<s>
MUMPS	B-Language
also	O
allows	O
the	O
programmer	O
to	O
jump	O
to	O
an	O
arbitrary	O
line	O
within	O
a	O
subroutine	O
.	O
</s>
<s>
MUMPS	B-Language
does	O
not	O
require	O
declaration	O
of	O
variables	O
,	O
and	O
is	O
untyped	O
:	O
all	O
variables	O
,	O
including	O
numbers	O
,	O
are	O
effectively	O
strings	O
.	O
</s>
<s>
MUMPS	B-Language
has	O
a	O
large	O
set	O
of	O
string	O
manipulation	O
operators	O
,	O
and	O
its	O
hierarchical	O
variable	O
management	O
system	O
extends	O
to	O
both	O
RAM-based	O
and	O
disk-based	O
variables	O
.	O
</s>
<s>
All	O
variables	O
are	O
considered	O
to	O
be	O
sparse	B-Algorithm
arrays	I-Algorithm
.	O
</s>
<s>
In	O
a	O
MUMPS	B-Language
context	O
,	O
this	O
means	O
that	O
there	O
is	O
no	O
requirement	O
for	O
sequential	O
nodes	O
to	O
exist	O
—	O
A(1 )	O
,	O
A(99 )	O
and	O
A(100 )	O
may	O
be	O
used	O
without	O
defining	O
,	O
allocating	O
space	O
for	O
,	O
or	O
using	O
any	O
space	O
for	O
nodes	O
2	O
through	O
98	O
.	O
</s>
<s>
The	O
MUMPS	B-Language
term	O
globals	O
does	O
not	O
refer	O
strictly	O
to	O
unscoped	O
variables	O
,	O
as	O
in	O
the	O
C	O
tradition	O
.	O
</s>
<s>
MUMPS	B-Language
Globals	O
are	O
variables	O
which	O
are	O
automatically	O
and	O
transparently	O
stored	O
on	O
disk	O
and	O
persist	O
beyond	O
program	O
,	O
routine	O
,	O
or	O
process	O
completion	O
.	O
</s>
<s>
It	O
is	O
persistent	O
,	O
just	O
as	O
a	O
file	O
persists	O
in	O
most	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Globals	O
are	O
stored	O
in	O
structured	O
data	O
files	O
by	O
MUMPS	B-Language
,	O
and	O
accessed	O
only	O
as	O
MUMPS	B-Language
globals	O
.	O
</s>
<s>
MUMPS	B-Language
has	O
a	O
long	O
history	O
of	O
cached	O
,	O
journaled	O
,	O
and	O
balanced	O
B-tree	O
key/value	O
disk	O
storage	O
,	O
including	O
transaction	O
control	O
for	O
multiple	O
file	O
transaction	O
'	O
commit	O
 '	O
and	O
'	O
roll-back	O
'	O
at	O
the	O
language/operating	O
system	O
level	O
.	O
</s>
<s>
Real-world	O
databases	O
can	O
often	O
grow	O
unpredictably	O
(	O
such	O
as	O
having	O
20	O
patients	O
with	O
a	O
last	O
name	O
of	O
'	O
Anderson	O
 '	O
before	O
you	O
get	O
any	O
with	O
surnames	O
starting	O
with	O
'	O
B	O
 '	O
)	O
,	O
but	O
modern	O
MUMPS	B-Language
implementations	O
are	O
designed	O
to	O
structure	O
the	O
database	O
efficiently	O
as	O
it	O
grows	O
.	O
</s>
<s>
For	O
all	O
of	O
these	O
reasons	O
,	O
one	O
of	O
the	O
most	O
common	O
MUMPS	B-Language
applications	O
is	O
database	O
management	O
.	O
</s>
<s>
MUMPS	B-Language
provides	O
the	O
classic	O
ACID	O
properties	O
as	O
part	O
of	O
any	O
standard	O
MUMPS	B-Language
implementation	O
.	O
</s>
<s>
FileMan	B-Language
is	O
an	O
example	O
of	O
a	O
DBMS	O
built	O
with	O
MUMPS	B-Language
.	O
</s>
<s>
The	O
InterSystems	B-Language
Caché	I-Language
implementation	O
allows	O
dual	O
views	O
of	O
selected	O
data	O
structures	O
—	O
as	O
MUMPS	B-Language
globals	O
,	O
or	O
as	O
SQL	B-Language
data	O
—	O
and	O
has	O
SQL	B-Language
built	O
in	O
(	O
called	O
M/SQL	O
)	O
.	O
</s>
<s>
Since	O
MUMPS	B-Language
's	O
global	O
variables	O
are	O
stored	O
on	O
disk	O
,	O
they	O
are	O
immediately	O
visible	O
to	O
and	O
modifiable	O
by	O
any	O
other	O
running	O
program	O
once	O
they	O
are	O
created	O
.	O
</s>
<s>
A	O
declared	O
variable	O
is	O
accessible	O
at	O
the	O
stack	B-General_Concept
level	I-General_Concept
it	O
was	O
declared	O
,	O
and	O
remains	O
accessible	O
as	O
long	O
as	O
that	O
stack	B-General_Concept
level	I-General_Concept
exists	O
.	O
</s>
<s>
It	O
cannot	O
prevent	O
routines	O
it	O
calls	O
from	O
modifying	O
its	O
own	O
variables	O
,	O
so	O
good	O
MUMPS	B-Language
programming	O
practice	O
is	O
to	O
have	O
every	O
routine	O
'	O
new	O
 '	O
the	O
variables	O
it	O
uses	O
.	O
</s>
<s>
MUMPS	B-Language
allowed	O
multi-user	O
operation	O
at	O
a	O
time	O
when	O
memory	O
was	O
measured	O
in	O
kilobytes	O
,	O
processor	O
time	O
was	O
scarce	O
,	O
and	O
processors	O
themselves	O
were	O
considerably	O
slower	O
than	O
those	O
found	O
today	O
.	O
</s>
<s>
Many	O
MUMPS	B-Language
implementations	O
included	O
full	O
support	O
for	O
multi-tasking	O
,	O
multi-user	O
,	O
multi-machine	O
programming	O
even	O
when	O
the	O
host	O
operating	B-General_Concept
system	I-General_Concept
itself	O
did	O
not	O
.	O
</s>
<s>
For	O
instance	O
,	O
a	O
single	O
PC	O
running	O
MUMPS	B-Language
under	O
MS-DOS	O
and	O
equipped	O
with	O
multiple	O
RS232	O
ports	O
,	O
behaved	O
as	O
a	O
large	O
minicomputer	O
serving	O
multiple	O
ASCII	O
terminals	O
,	O
with	O
proper	O
data	O
sharing	O
and	O
protection	O
.	O
</s>
<s>
Another	O
use	O
of	O
MUMPS	B-Language
in	O
more	O
recent	O
times	O
has	O
been	O
to	O
create	O
object	B-Application
databases	I-Application
.	O
</s>
<s>
The	O
InterSystems	B-Language
Caché	I-Language
implementation	O
,	O
for	O
instance	O
,	O
includes	O
such	O
features	O
natively	O
.	O
</s>
<s>
MUMPS	B-Language
can	O
generate	O
text	O
in	O
HTML	O
or	O
XML	O
format	O
as	O
well	O
,	O
and	O
can	O
be	O
called	O
via	O
the	O
CGI	O
interface	O
to	O
serve	O
web	O
pages	O
directly	O
from	O
the	O
database	O
.	O
</s>
<s>
It	O
can	O
also	O
be	O
used	O
as	O
a	O
backend	O
for	O
web	O
applications	O
using	O
AJAX	B-General_Concept
background	O
communication	O
.	O
</s>
