<s>
Data	B-General_Concept
scraping	I-General_Concept
is	O
a	O
technique	O
where	O
a	O
computer	B-Application
program	I-Application
extracts	O
data	O
from	O
human-readable	B-General_Concept
output	O
coming	O
from	O
another	O
program	O
.	O
</s>
<s>
Normally	O
,	O
data	O
transfer	O
between	O
programs	O
is	O
accomplished	O
using	O
data	B-General_Concept
structures	I-General_Concept
suited	O
for	O
automated	B-Application
processing	O
by	O
computers	O
,	O
not	O
people	O
.	O
</s>
<s>
Such	O
interchange	O
formats	O
and	O
protocols	O
are	O
typically	O
rigidly	O
structured	O
,	O
well-documented	O
,	O
easily	O
parsed	B-Language
,	O
and	O
minimize	O
ambiguity	O
.	O
</s>
<s>
Very	O
often	O
,	O
these	O
transmissions	O
are	O
not	O
human-readable	B-General_Concept
at	O
all	O
.	O
</s>
<s>
Thus	O
,	O
the	O
key	O
element	O
that	O
distinguishes	O
data	B-General_Concept
scraping	I-General_Concept
from	O
regular	O
parsing	B-Language
is	O
that	O
the	O
output	O
being	O
scraped	O
is	O
intended	O
for	O
display	B-Device
to	O
an	O
end-user	O
,	O
rather	O
than	O
as	O
an	O
input	O
to	O
another	O
program	O
.	O
</s>
<s>
It	O
is	O
therefore	O
usually	O
neither	O
documented	O
nor	O
structured	O
for	O
convenient	O
parsing	B-Language
.	O
</s>
<s>
Data	B-General_Concept
scraping	I-General_Concept
often	O
involves	O
ignoring	O
binary	O
data	O
(	O
usually	O
images	O
or	O
multimedia	O
data	O
)	O
,	O
display	B-Device
formatting	O
,	O
redundant	O
labels	O
,	O
superfluous	O
commentary	O
,	O
and	O
other	O
information	O
which	O
is	O
either	O
irrelevant	O
or	O
hinders	O
automated	B-Application
processing	O
.	O
</s>
<s>
Data	B-General_Concept
scraping	I-General_Concept
is	O
most	O
often	O
done	O
either	O
to	O
interface	O
to	O
a	O
legacy	B-Device
system	I-Device
,	O
which	O
has	O
no	O
other	O
mechanism	O
which	O
is	O
compatible	O
with	O
current	O
hardware	B-Architecture
,	O
or	O
to	O
interface	O
to	O
a	O
third-party	O
system	O
which	O
does	O
not	O
provide	O
a	O
more	O
convenient	O
API	B-Application
.	O
</s>
<s>
In	O
the	O
second	O
case	O
,	O
the	O
operator	O
of	O
the	O
third-party	O
system	O
will	O
often	O
see	O
screen	B-Device
scraping	O
as	O
unwanted	O
,	O
due	O
to	O
reasons	O
such	O
as	O
increased	O
system	B-Operating_System
load	I-Operating_System
,	O
the	O
loss	O
of	O
advertisement	O
revenue	O
,	O
or	O
the	O
loss	O
of	O
control	O
of	O
the	O
information	O
content	O
.	O
</s>
<s>
Data	B-General_Concept
scraping	I-General_Concept
is	O
generally	O
considered	O
an	O
ad	O
hoc	O
,	O
inelegant	O
technique	O
,	O
often	O
used	O
only	O
as	O
a	O
"	O
last	O
resort	O
"	O
when	O
no	O
other	O
mechanism	O
for	O
data	O
interchange	O
is	O
available	O
.	O
</s>
<s>
Aside	O
from	O
the	O
higher	O
programming	B-General_Concept
and	O
processing	O
overhead	O
,	O
output	O
displays	O
intended	O
for	O
human	O
consumption	O
often	O
change	O
structure	O
frequently	O
.	O
</s>
<s>
Humans	O
can	O
cope	O
with	O
this	O
easily	O
,	O
but	O
a	O
computer	B-Application
program	I-Application
will	O
fail	O
.	O
</s>
<s>
Depending	O
on	O
the	O
quality	O
and	O
the	O
extent	O
of	O
error	B-General_Concept
handling	I-General_Concept
logic	O
present	O
in	O
the	O
computer	O
,	O
this	O
failure	O
can	O
result	O
in	O
error	O
messages	O
,	O
corrupted	O
output	O
or	O
even	O
program	B-General_Concept
crashes	I-General_Concept
.	O
</s>
<s>
Although	O
the	O
use	O
of	O
physical	O
"	O
dumb	O
terminal	B-General_Concept
"	O
IBM	O
3270s	O
is	O
slowly	O
diminishing	O
,	O
as	O
more	O
and	O
more	O
mainframe	O
applications	O
acquire	O
Web	O
interfaces	O
,	O
some	O
Web	O
applications	O
merely	O
continue	O
to	O
use	O
the	O
technique	O
of	O
screen	B-Device
scraping	O
to	O
capture	O
old	O
screens	O
and	O
transfer	O
the	O
data	O
to	O
modern	O
front-ends	O
.	O
</s>
<s>
Screen	B-Device
scraping	O
is	O
normally	O
associated	O
with	O
the	O
programmatic	O
collection	O
of	O
visual	O
data	O
from	O
a	O
source	O
,	O
instead	O
of	O
parsing	B-Language
data	O
as	O
in	O
web	B-Application
scraping	I-Application
.	O
</s>
<s>
Originally	O
,	O
screen	B-Device
scraping	O
referred	O
to	O
the	O
practice	O
of	O
reading	O
text	O
data	O
from	O
a	O
computer	O
display	B-Device
terminal	I-Device
's	O
screen	B-Device
.	O
</s>
<s>
This	O
was	O
generally	O
done	O
by	O
reading	O
the	O
terminal	B-General_Concept
's	O
memory	B-General_Concept
through	O
its	O
auxiliary	O
port	B-Protocol
,	O
or	O
by	O
connecting	O
the	O
terminal	B-General_Concept
output	O
port	B-Protocol
of	O
one	O
computer	O
system	O
to	O
an	O
input	O
port	B-Protocol
on	O
another	O
.	O
</s>
<s>
The	O
term	O
screen	B-Device
scraping	O
is	O
also	O
commonly	O
used	O
to	O
refer	O
to	O
the	O
bidirectional	O
exchange	O
of	O
data	O
.	O
</s>
<s>
This	O
could	O
be	O
the	O
simple	O
cases	O
where	O
the	O
controlling	O
program	O
navigates	O
through	O
the	O
user	B-Application
interface	I-Application
,	O
or	O
more	O
complex	O
scenarios	O
where	O
the	O
controlling	O
program	O
is	O
entering	O
data	O
into	O
an	O
interface	O
meant	O
to	O
be	O
used	O
by	O
a	O
human	O
.	O
</s>
<s>
As	O
a	O
concrete	O
example	O
of	O
a	O
classic	O
screen	B-Device
scraper	O
,	O
consider	O
a	O
hypothetical	O
legacy	B-Device
system	I-Device
dating	O
from	O
the	O
1960s	O
—	O
the	O
dawn	O
of	O
computerized	O
data	B-General_Concept
processing	I-General_Concept
.	O
</s>
<s>
Computer	O
to	O
user	B-Application
interfaces	I-Application
from	O
that	O
era	O
were	O
often	O
simply	O
text-based	O
dumb	O
terminals	O
which	O
were	O
not	O
much	O
more	O
than	O
virtual	O
teleprinters	O
(	O
such	O
systems	O
are	O
still	O
in	O
use	O
,	O
for	O
various	O
reasons	O
)	O
.	O
</s>
<s>
A	O
robust	B-Application
solution	O
will	O
often	O
require	O
things	O
no	O
longer	O
available	O
,	O
such	O
as	O
source	O
code	O
,	O
system	O
documentation	O
,	O
APIs	B-Application
,	O
or	O
programmers	B-Application
with	O
experience	O
in	O
a	O
50-year-old	O
computer	O
system	O
.	O
</s>
<s>
In	O
such	O
cases	O
,	O
the	O
only	O
feasible	O
solution	O
may	O
be	O
to	O
write	O
a	O
screen	B-Device
scraper	O
that	O
"	O
pretends	O
"	O
to	O
be	O
a	O
user	O
at	O
a	O
terminal	B-General_Concept
.	O
</s>
<s>
The	O
screen	B-Device
scraper	O
might	O
connect	O
to	O
the	O
legacy	B-Device
system	I-Device
via	O
Telnet	B-Protocol
,	O
emulate	B-Application
the	O
keystrokes	O
needed	O
to	O
navigate	O
the	O
old	O
user	B-Application
interface	I-Application
,	O
process	O
the	O
resulting	O
display	B-Device
output	O
,	O
extract	O
the	O
desired	O
data	O
,	O
and	O
pass	O
it	O
on	O
to	O
the	O
modern	O
system	O
.	O
</s>
<s>
change	O
control	O
,	O
security	O
,	O
user	O
management	O
,	O
data	O
protection	O
,	O
operational	O
audit	O
,	O
load	B-Operating_System
balancing	O
,	O
and	O
queue	B-Device
management	O
,	O
etc.	O
—	O
could	O
be	O
said	O
to	O
be	O
an	O
example	O
of	O
robotic	B-Application
process	I-Application
automation	I-Application
software	O
,	O
called	O
RPA	O
or	O
RPAAI	O
for	O
self-guided	O
RPA	O
2.0	O
based	O
on	O
artificial	B-Application
intelligence	I-Application
.	I-Application
</s>
<s>
Users	O
of	O
this	O
data	O
,	O
particularly	O
investment	O
banks	O
,	O
wrote	O
applications	O
to	O
capture	O
and	O
convert	O
this	O
character	O
data	O
as	O
numeric	O
data	O
for	O
inclusion	O
into	O
calculations	O
for	O
trading	O
decisions	O
without	O
re-keying	B-General_Concept
the	O
data	O
.	O
</s>
<s>
Internally	O
Reuters	O
used	O
the	O
term	O
'	O
logicized	O
 '	O
for	O
this	O
conversion	O
process	O
,	O
running	O
a	O
sophisticated	O
computer	O
system	O
on	O
VAX/VMS	B-Operating_System
called	O
the	O
Logicizer	O
.	O
</s>
<s>
More	O
modern	O
screen	B-Device
scraping	O
techniques	O
include	O
capturing	O
the	O
bitmap	O
data	O
from	O
the	O
screen	B-Device
and	O
running	O
it	O
through	O
an	O
OCR	B-Application
engine	O
,	O
or	O
for	O
some	O
specialised	O
automated	B-Application
testing	O
systems	O
,	O
matching	O
the	O
screen	B-Device
's	O
bitmap	O
data	O
against	O
expected	O
results	O
.	O
</s>
<s>
This	O
can	O
be	O
combined	O
in	O
the	O
case	O
of	O
GUI	B-Application
applications	O
,	O
with	O
querying	O
the	O
graphical	O
controls	O
by	O
programmatically	O
obtaining	O
references	O
to	O
their	O
underlying	O
programming	B-Language
objects	I-Language
.	O
</s>
<s>
There	O
are	O
many	O
tools	O
that	O
can	O
be	O
used	O
for	O
screen	B-Device
scraping	O
.	O
</s>
<s>
Web	O
pages	O
are	O
built	O
using	O
text-based	O
mark-up	O
languages	O
(	O
HTML	B-Language
and	O
XHTML	B-Language
)	O
,	O
and	O
frequently	O
contain	O
a	O
wealth	O
of	O
useful	O
data	O
in	O
text	O
form	O
.	O
</s>
<s>
However	O
,	O
most	O
web	O
pages	O
are	O
designed	O
for	O
human	O
end-users	O
and	O
not	O
for	O
ease	O
of	O
automated	B-Application
use	O
.	O
</s>
<s>
A	O
web	B-Application
scraper	I-Application
is	O
an	O
API	B-Application
or	O
tool	O
to	O
extract	O
data	O
from	O
a	O
website	O
.	O
</s>
<s>
Companies	O
like	O
Amazon	B-Application
AWS	I-Application
and	O
Google	B-Application
provide	O
web	B-Application
scraping	I-Application
tools	O
,	O
services	O
,	O
and	O
public	O
data	O
available	O
free	O
of	O
cost	O
to	O
end-users	O
.	O
</s>
<s>
Newer	O
forms	O
of	O
web	B-Application
scraping	I-Application
involve	O
listening	O
to	O
data	O
feeds	O
from	O
web	O
servers	O
.	O
</s>
<s>
For	O
example	O
,	O
JSON	B-General_Concept
is	O
commonly	O
used	O
as	O
a	O
transport	O
storage	O
mechanism	O
between	O
the	O
client	O
and	O
the	O
webserver	O
.	O
</s>
<s>
Recently	O
,	O
companies	O
have	O
developed	O
web	B-Application
scraping	I-Application
systems	O
that	O
rely	O
on	O
using	O
techniques	O
in	O
DOM	O
parsing	B-Language
,	O
computer	B-Application
vision	I-Application
and	O
natural	B-Language
language	I-Language
processing	I-Language
to	O
simulate	O
the	O
human	O
processing	O
that	O
occurs	O
when	O
viewing	O
a	O
webpage	O
to	O
automatically	O
extract	O
useful	O
information	O
.	O
</s>
<s>
Large	O
websites	O
usually	O
use	O
defensive	O
algorithms	O
to	O
protect	O
their	O
data	O
from	O
web	B-Application
scrapers	I-Application
and	O
to	O
limit	O
the	O
number	O
of	O
requests	O
an	O
IP	O
or	O
IP	O
network	O
may	O
send	O
.	O
</s>
<s>
This	O
has	O
caused	O
an	O
ongoing	O
battle	O
between	O
website	O
developers	B-Application
and	O
scraping	O
developers	B-Application
.	O
</s>
<s>
Report	O
mining	O
is	O
the	O
extraction	O
of	O
data	O
from	O
human-readable	B-General_Concept
computer	O
reports	O
.	O
</s>
<s>
Conventional	O
data	B-General_Concept
extraction	I-General_Concept
requires	O
a	O
connection	O
to	O
a	O
working	O
source	O
system	O
,	O
suitable	O
connectivity	B-General_Concept
standards	O
or	O
an	O
API	B-Application
,	O
and	O
usually	O
complex	O
querying	O
.	O
</s>
<s>
By	O
using	O
the	O
source	O
system	O
's	O
standard	O
reporting	O
options	O
,	O
and	O
directing	O
the	O
output	O
to	O
a	O
spool	B-Device
file	I-Device
instead	O
of	O
to	O
a	O
printer	O
,	O
static	O
reports	O
can	O
be	O
generated	O
suitable	O
for	O
offline	O
analysis	O
via	O
report	O
mining	O
.	O
</s>
<s>
This	O
approach	O
can	O
avoid	O
intensive	O
CPU	B-General_Concept
usage	O
during	O
business	O
hours	O
,	O
can	O
minimise	O
end-user	O
licence	O
costs	O
for	O
ERP	O
customers	O
,	O
and	O
can	O
offer	O
very	O
rapid	O
prototyping	O
and	O
development	O
of	O
custom	O
reports	O
.	O
</s>
<s>
Whereas	O
data	B-General_Concept
scraping	I-General_Concept
and	O
web	B-Application
scraping	I-Application
involve	O
interacting	O
with	O
dynamic	O
output	O
,	O
report	O
mining	O
involves	O
extracting	O
data	O
from	O
files	O
in	O
a	O
human-readable	B-General_Concept
format	I-General_Concept
,	O
such	O
as	O
HTML	B-Language
,	O
PDF	O
,	O
or	O
text	O
.	O
</s>
<s>
This	O
approach	O
can	O
provide	O
a	O
quick	O
and	O
simple	O
route	O
to	O
obtaining	O
data	O
without	O
the	O
need	O
to	O
program	O
an	O
API	B-Application
to	O
the	O
source	O
system	O
.	O
</s>
