<s>
Upload	B-Application
components	I-Application
are	O
software	O
products	O
that	O
are	O
designed	O
to	O
be	O
embedded	O
into	O
a	O
web	O
site	O
to	O
add	O
upload	B-Application
functionality	O
to	O
it	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
are	O
designed	O
to	O
replace	O
the	O
standard	O
HTML4	O
upload	B-Application
mechanism	O
.	O
</s>
<s>
Compared	O
with	O
HTML4	O
,	O
Upload	B-Application
Components	I-Application
have	O
a	O
more	O
user-friendly	B-General_Concept
interface	O
and	O
support	O
a	O
wider	O
range	O
of	O
features	O
.	O
</s>
<s>
The	O
HTML4	O
standard	O
supports	O
requesting	O
data	O
to	O
be	O
requested	O
from	O
a	O
client	O
computer	O
and	O
uploaded	B-Application
to	O
a	O
server	B-Application
.	O
</s>
<s>
The	O
standard	O
mechanism	O
for	O
this	O
type	O
of	O
data	O
transmission	O
is	O
HTML	B-Language
forms	O
.	O
</s>
<s>
With	O
HTML	B-Language
forms	O
a	O
user	O
's	O
files	O
can	O
be	O
uploaded	B-Application
by	O
employing	O
tag	B-General_Concept
with	O
different	O
attributes	O
.	O
</s>
<s>
This	O
method	O
allows	O
web	O
site	O
developers	O
to	O
implement	O
basic	O
upload	B-Application
functionality	O
.	O
</s>
<s>
Multiple	O
files	O
upload	B-Application
is	O
not	O
available	O
–	O
a	O
user	O
can	O
upload	B-Application
only	O
1	O
file	O
a	O
time	O
.	O
</s>
<s>
Limited	O
upload	B-Application
size	O
-	O
it	O
is	O
usually	O
impossible	O
to	O
send	O
files	O
up	O
to	O
dozens	O
of	O
megabytes	O
(	O
MB	O
)	O
via	O
HTTP	O
.	O
</s>
<s>
No	O
optimization	O
before	O
uploading	B-Application
files	O
is	O
available	O
.	O
</s>
<s>
Poor	O
visualization	O
–	O
a	O
user	O
cannot	O
see	O
any	O
information	O
about	O
the	O
upload	B-Application
progress	O
and	O
estimated	O
upload	B-Application
time	O
.	O
</s>
<s>
Awkward	O
look	O
and	O
feel	O
–	O
the	O
way	O
a	O
user	O
selects	O
files	O
for	O
upload	B-Application
is	O
inconvenient	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
allow	O
for	O
bypassing	O
the	O
HTML	B-Language
upload	B-Application
restrictions	O
and	O
disadvantages	O
noted	O
previously	O
.	O
</s>
<s>
An	O
upload	B-Application
component	O
is	O
a	O
plug-in	B-Application
which	O
allows	O
uploading	B-Application
files	O
from	O
a	O
client	O
to	O
a	O
server	B-Application
.	O
</s>
<s>
Usually	O
upload	B-Application
components	I-Application
are	O
developed	O
by	O
third	O
party	O
companies	O
and	O
can	O
be	O
integrated	O
with	O
any	O
website	O
on	O
any	O
platform	B-Device
.	O
</s>
<s>
The	O
user	O
's	O
Web	B-Application
browser	I-Application
will	O
display	O
the	O
embedded	O
upload	B-Application
component	O
as	O
a	O
part	O
of	O
the	O
web	O
page	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
can	O
be	O
built	O
with	O
various	O
technologies	O
:	O
Flash	B-Operating_System
,	O
Silverlight	B-Application
,	O
Java	B-Language
,	O
ActiveX	B-Application
,	O
and	O
HTML5	B-Application
.	O
</s>
<s>
The	O
W3C	O
community	O
is	O
in	O
the	O
process	O
of	O
developing	O
a	O
HTML5	B-Application
standard	O
,	O
the	O
full	O
specification	O
of	O
which	O
is	O
expected	O
by	O
2014	O
.	O
</s>
<s>
HTML5	B-Application
is	O
supposed	O
to	O
support	O
multimedia	O
content	O
without	O
any	O
plug-ins	B-Application
or	O
components	O
.	O
</s>
<s>
For	O
upload	B-Application
functionality	O
,	O
new	O
HTML5	B-Application
APIs	B-Application
offer	O
a	O
wide	O
variety	O
of	O
new	O
features	O
,	O
including	O
access	O
to	O
the	O
client	O
's	O
file	O
system	O
and	O
dynamic	O
request-generating	O
and	O
processing	O
of	O
images	O
.	O
</s>
<s>
The	O
new	O
HTML5	B-Application
features	O
could	O
be	O
a	O
good	O
basis	O
for	O
implementing	O
upload	B-Application
components	I-Application
with	O
a	O
sophisticated	O
user	O
interface	O
and	O
the	O
ability	O
to	O
upload	B-Application
any	O
amount	O
of	O
data	O
.	O
</s>
<s>
Unfortunately	O
,	O
at	O
the	O
moment	O
browsers	B-Application
support	O
those	O
features	O
partially	O
and	O
differently	O
,	O
which	O
is	O
a	O
serious	O
obstacle	O
.	O
</s>
<s>
The	O
situation	O
becomes	O
worse	O
if	O
we	O
remember	O
that	O
large	O
numbers	O
of	O
users	O
still	O
use	O
Windows	B-Application
XP	I-Application
(	O
28%	O
)	O
and	O
obsolete	O
Internet	B-Application
Explorer	I-Application
versions	O
(	O
11%	O
)	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
can	O
be	O
developed	O
on	O
the	O
basis	O
of	O
various	O
technologies	O
aimed	O
at	O
extending	O
browser	B-Application
functionality	O
.	O
</s>
<s>
Depending	O
on	O
the	O
technology	O
and	O
its	O
features	O
,	O
upload	B-Application
components	I-Application
can	O
support	O
more	O
or	O
less	O
functionality	O
,	O
be	O
more	O
or	O
less	O
configurable	O
,	O
and	O
be	O
easier	O
to	O
use	O
.	O
</s>
<s>
Microsoft	O
technologies	O
are	O
preferable	O
Internet	B-Application
Explorer	I-Application
,	O
Firefox	B-Application
,	O
Chrome	B-Application
,	O
Safari	B-Application
,	O
Opera	B-Application
Windows	O
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
Linux	B-Application
(	O
Moonlight	B-Language
)	O
No	O
support	O
Silverlight	B-Application
plug-inHTML5	O
controls	O
Chrome	B-Application
,	O
Firefox	B-Application
,	O
Opera	B-Application
,	O
Safari	B-Application
,	O
Internet	B-Application
Explorer	I-Application
,	O
</s>
<s>
Limited	O
support	O
Windows	O
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
Linux	B-Application
iOS	B-Application
,	O
Android	B-Application
,	O
Windows	B-Protocol
Phone	I-Protocol
7	O
,	O
</s>
<s>
Java	B-Application
Applets	I-Application
are	O
components	O
running	O
in	O
a	O
web	B-Application
browser	I-Application
.	O
</s>
<s>
They	O
are	O
developed	O
in	O
the	O
form	O
of	O
Java	B-Language
byte	O
code	O
.	O
</s>
<s>
The	O
applets	O
are	O
supported	O
by	O
most	O
modern	O
operating	B-General_Concept
systems	I-General_Concept
and	O
browsers	B-Application
.	O
</s>
<s>
Java	B-Application
applets	I-Application
have	O
high	B-Application
performance	I-Application
similar	O
to	O
native	O
installed	O
software	O
.	O
</s>
<s>
Java	B-Application
applets	I-Application
are	O
signed	O
with	O
security	O
certificates	O
to	O
become	O
trusted	O
software	O
,	O
which	O
allows	O
automatic	O
redistribution	O
from	O
a	O
web	O
site	O
and	O
installation	O
on	O
client	O
computers	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
can	O
be	O
implemented	O
as	O
Adobe	B-Operating_System
Flash	I-Operating_System
controls	O
.	O
</s>
<s>
Flash	B-Operating_System
is	O
a	O
framework	O
for	O
running	O
rich-media	O
applications	O
on	O
the	O
Internet	O
.	O
</s>
<s>
24%	O
of	O
all	O
web	O
sites	O
use	O
Flash	B-Operating_System
components	I-Operating_System
,	O
and	O
the	O
Flash	B-Operating_System
player	O
is	O
installed	O
on	O
99%	O
of	O
Internet-enabled	O
PC	O
's	O
.	O
</s>
<s>
Flash	B-Operating_System
is	O
a	O
cross-platform	O
and	O
a	O
cross-browser	O
technology	O
that	O
allows	O
Flash	B-Operating_System
upload	B-Application
components	I-Application
to	O
work	O
in	O
various	O
browsers	B-Application
,	O
with	O
the	O
exception	O
of	O
mobile	B-Application
platforms	I-Application
.	O
</s>
<s>
Another	O
type	O
of	O
upload	B-Application
components	I-Application
is	O
Silverlight	B-Application
which	O
is	O
a	O
Microsoft	O
technology	O
requiring	O
a	O
browser	B-Application
plug-in	B-Application
to	O
be	O
installed	O
.	O
</s>
<s>
In	O
features	O
it	O
is	O
very	O
similar	O
to	O
Adobe	B-Operating_System
Flash	I-Operating_System
and	O
it	O
is	O
supported	O
by	O
most	O
modern	O
browsers	B-Application
and	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
There	O
are	O
versions	O
of	O
Silverlight	B-Application
for	O
Windows	O
and	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
and	O
there	O
is	O
also	O
a	O
version	O
for	O
Linux	B-Application
called	O
Moonlight	B-Language
.	O
</s>
<s>
Silverlight	B-Application
is	O
one	O
of	O
the	O
basic	O
technologies	O
used	O
for	O
Windows	B-Protocol
Phone	I-Protocol
applications	O
development	O
.	O
</s>
<s>
HTML5	B-Application
is	O
a	O
new	O
HTML	B-Language
standard	O
developed	O
to	O
add	O
multimedia	O
support	O
to	O
HTML	B-Language
.	O
</s>
<s>
It	O
is	O
supported	O
on	O
Windows	O
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
Linux	B-Application
,	O
iOS	B-Application
,	O
Android	B-Application
,	O
and	O
Windows	B-Protocol
Phone	I-Protocol
.	O
</s>
<s>
Since	O
the	O
format	O
is	O
still	O
under	O
development	O
and	O
some	O
of	O
the	O
features	O
employed	O
for	O
uploading	B-Application
files	O
are	O
still	O
not	O
part	O
of	O
the	O
standard	O
,	O
HTML5	B-Application
upload	B-Application
components	I-Application
are	O
not	O
common	O
at	O
the	O
moment	O
.	O
</s>
<s>
Their	O
support	O
is	O
restricted	O
to	O
a	O
subset	O
of	O
browsers	B-Application
.	O
</s>
<s>
HTML5	B-Application
support	O
has	O
been	O
steadily	O
improving	O
.	O
</s>
<s>
The	O
best	O
coverage	O
of	O
HTML5	B-Application
features	O
is	O
provided	O
by	O
the	O
latest	O
version	O
of	O
Chrome	B-Application
,	O
Firefox	B-Application
,	O
Safari	B-Application
and	O
Opera	B-Application
.	O
</s>
<s>
Internet	B-Application
Explorer	I-Application
provides	O
the	O
least	O
support	O
.	O
</s>
<s>
Internet	B-Application
Explorer	I-Application
10	I-Application
has	O
less	O
support	O
than	O
versions	O
of	O
other	O
browsers	B-Application
;	O
however	O
the	O
coverage	O
will	O
be	O
twice	O
as	O
good	O
as	O
Internet	B-Application
Explorer	I-Application
9	I-Application
.	O
</s>
<s>
iOS	B-Operating_System
5	I-Operating_System
has	O
a	O
sufficiently	O
high	O
level	O
of	O
HTML5	B-Application
support	O
;	O
however	O
,	O
its	O
level	O
of	O
support	O
remains	O
lower	O
than	O
for	O
desktop	O
browsers	B-Application
.	O
</s>
<s>
Windows	B-Protocol
Phone	I-Protocol
7.5	O
"	O
Mango	O
"	O
has	O
slight	O
support	O
for	O
HTML5	B-Application
,	O
which	O
makes	O
it	O
comparable	O
to	O
desktop	O
Internet	B-Application
Explorer	I-Application
9	I-Application
's	O
lack	O
of	O
support	O
for	O
the	O
standard	O
.	O
</s>
<s>
The	O
latest	O
Android	B-Application
5.0	I-Application
supports	O
many	O
more	O
HTML5	B-Application
features	O
than	O
Windows	B-Protocol
Phone	I-Protocol
,	O
but	O
less	O
than	O
iOS	B-Application
.	O
</s>
<s>
Mobile	O
browsers’	O
HTML5	B-Application
support	O
remains	O
a	O
work	O
in	O
progress	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
bring	O
additional	O
features	O
and	O
a	O
user	O
experience	O
that	O
cannot	O
be	O
provided	O
by	O
pure	O
HTML4	O
.	O
</s>
<s>
Progress	O
bars	O
are	O
used	O
to	O
inform	O
users	O
about	O
upload	B-Application
progress	O
details	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
support	O
progress	O
bars	O
displaying	O
such	O
parameters	O
as	O
file	O
names	O
,	O
file	O
sizes	O
,	O
upload	B-Application
speed	O
,	O
etc	O
.	O
</s>
<s>
Some	O
websites	O
require	O
support	O
for	O
uploading	B-Application
multiple	O
files	O
at	O
once	O
.	O
</s>
<s>
This	O
feature	O
is	O
extremely	O
important	O
for	O
upload	B-Application
components	I-Application
on	O
social	O
networks	O
,	O
photo	B-Algorithm
galleries	I-Algorithm
,	O
file	O
sharing	O
,	O
etc	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
support	O
multiple	O
file	B-Application
uploads	I-Application
in	O
a	O
more	O
flexible	O
fashion	O
,	O
for	O
example	O
by	O
allowing	O
a	O
simpler	O
selection	O
of	O
files	O
to	O
be	O
uploaded	B-Application
simultaneously	O
from	O
several	O
folders	O
.	O
</s>
<s>
Uploading	B-Application
a	O
huge	O
amount	O
of	O
data	O
is	O
always	O
a	O
problem	O
,	O
as	O
the	O
request	O
size	O
can	O
be	O
too	O
large	O
for	O
the	O
upload	B-Application
process	O
to	O
successfully	O
complete	O
,	O
possibly	O
because	O
of	O
slow	O
or	O
unstable	O
Internet	O
connections	O
.	O
</s>
<s>
On	O
the	O
server	B-Application
side	O
there	O
can	O
be	O
restrictions	O
applied	O
to	O
the	O
maximum	O
size	O
of	O
HTTP	O
requests	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
have	O
to	O
find	O
a	O
balance	O
between	O
the	O
client	O
’s	O
needs	O
on	O
one	O
hand	O
and	O
server	B-Application
and	O
channel	O
resources	O
and	O
restrictions	O
on	O
the	O
other	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
delivering	O
huge	O
files	O
to	O
server	B-Application
components	O
a	O
so-called	O
"	O
chunk	O
upload	B-Application
"	O
divides	O
a	O
file	O
into	O
several	O
parts	O
(	O
chunks	O
)	O
before	O
the	O
upload	B-Application
process	O
starts	O
.	O
</s>
<s>
Each	O
chunk	O
is	O
sent	O
in	O
response	O
to	O
a	O
single	O
request	O
;	O
after	O
all	O
chunks	O
arrive	O
at	O
a	O
server	B-Application
the	O
original	O
file	O
is	O
reassembled	O
.	O
</s>
<s>
During	O
an	O
upload	B-Application
process	O
some	O
unexpected	O
problems	O
or	O
malfunctions	O
can	O
occur	O
,	O
leading	O
to	O
upload	B-Application
failure	O
and	O
file	O
corruption	O
.	O
</s>
<s>
To	O
address	O
these	O
problems	O
upload	B-Application
components	I-Application
have	O
fail-safe	O
mechanisms	O
sporting	O
features	O
such	O
as	O
automatic	O
resumption	O
of	O
the	O
upload	B-Application
process	O
,	O
sending	O
files	O
individually	O
in	O
a	O
single	O
package	O
,	O
and	O
chunk	O
uploads	B-Application
.	O
</s>
<s>
Sometimes	O
it	O
is	O
useful	O
to	O
send	O
additional	O
data	O
along	O
with	O
a	O
file	O
,	O
such	O
as	O
informational	O
descriptions	O
or	O
Exif/IPTC	O
fields	O
,	O
or	O
Hash	B-Error_Name
sums	I-Error_Name
to	O
identify	O
whether	O
a	O
file	O
was	O
corrupted	O
or	O
damaged	O
during	O
the	O
upload	B-Application
process	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
can	O
have	O
a	O
concurrent	O
upload	B-Application
feature	O
–	O
sending	O
upload	B-Application
packages	O
in	O
multiple	O
threads	B-Operating_System
.	O
</s>
<s>
In	O
some	O
cases	O
the	O
upload	B-Application
process	O
benefits	O
by	O
increasing	O
overall	O
upload	B-Application
speed	O
,	O
decreasing	O
upload	B-Application
time	O
,	O
and	O
using	O
computer	O
resources	O
in	O
a	O
more	O
effective	O
way	O
.	O
</s>
<s>
This	O
approach	O
allows	O
the	O
upload	B-Application
of	O
files	O
to	O
start	O
right	O
after	O
they	O
are	O
added	O
to	O
an	O
upload	B-Application
queue	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
can	O
upload	B-Application
files	I-Application
to	O
cloud	O
storage	O
.	O
</s>
<s>
Drag-n-Drop	O
is	O
a	O
form	O
of	O
user-program	O
graphical	B-Application
interface	I-Application
interaction	O
which	O
involves	O
selecting	O
one	O
object	O
and	O
dragging	O
it	O
onto	O
another	O
object	O
.	O
</s>
<s>
Drag-n-Drop	O
is	O
widespread	O
as	O
it	O
helps	O
to	O
increase	O
program	O
usability	B-General_Concept
.	O
</s>
<s>
Upload	B-Application
components	I-Application
support	O
customizing	O
the	O
components	O
 '	O
appearance	O
to	O
fit	O
into	O
a	O
web	O
site	O
design	O
through	O
such	O
configurations	O
as	O
font	O
styles	O
,	O
sizes	O
,	O
colors	O
,	O
or	O
view	O
modes	O
among	O
others	O
.	O
</s>
<s>
Once	O
an	O
upload	B-Application
component	O
enters	O
the	O
international	O
market	O
,	O
it	O
needs	O
support	O
translating	O
the	O
interface	O
's	O
text	O
labels	O
and	O
messages	O
to	O
other	O
languages	O
.	O
</s>
<s>
Usually	O
upload	B-Application
components	I-Application
have	O
configurable	O
support	O
for	O
the	O
most	O
widely	O
used	O
languages	O
.	O
</s>
<s>
To	O
save	O
server-side	O
resources	O
upload	B-Application
components	I-Application
can	O
apply	O
client-side	O
validation	O
to	O
files	O
selected	O
for	O
upload	B-Application
in	O
several	O
groups	O
:	O
file	O
types	O
(	O
which	O
can	O
be	O
selectively	O
defined	O
or	O
barred	O
by	O
the	O
developer	O
)	O
,	O
file	O
size	O
(	O
which	O
can	O
be	O
set	O
to	O
minimum/maximum	O
allowed	O
sizes	O
)	O
,	O
and	O
image	B-Algorithm
size	I-Algorithm
(	O
which	O
can	O
have	O
minimum/maximum	O
sizes	O
configured	O
among	O
other	O
parameters	O
)	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
are	O
used	O
for	O
uploading	B-Application
images	O
,	O
so	O
there	O
are	O
components	O
that	O
have	O
additional	O
features	O
for	O
image	O
pre-upload	O
processing	O
.	O
</s>
<s>
Photos	O
taken	O
with	O
modern	O
digital	O
cameras	O
are	O
high	B-Algorithm
resolution	I-Algorithm
,	O
but	O
most	O
websites	O
need	O
the	O
images	B-Algorithm
resized	I-Algorithm
to	O
conserve	O
bandwidth	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
allow	O
images	O
to	O
be	O
automatically	O
resized	O
and	O
uploaded	B-Application
,	O
with	O
or	O
without	O
the	O
original	O
file	O
,	O
or	O
a	O
thumbnail	O
copy	O
for	O
use	O
as	O
an	O
avatar	O
,	O
etc	O
.	O
</s>
<s>
Image	O
rotation	B-General_Concept
is	O
a	O
very	O
important	O
feature	O
for	O
websites	O
giving	O
users	O
basic	O
image	O
editing	O
abilities	O
.	O
</s>
<s>
A	O
watermark	B-General_Concept
is	O
a	O
text	O
message	O
,	O
or	O
image	O
put	O
over	O
an	O
original	O
image	O
,	O
and	O
is	O
used	O
to	O
protect	O
intellectual	O
property	O
or	O
specify	O
important	O
information	O
,	O
such	O
as	O
date	O
when	O
the	O
image	O
was	O
taken	O
,	O
text	O
comments	O
,	O
or	O
copyright	O
.	O
</s>
<s>
Upload	B-Application
components	I-Application
can	O
include	O
a	O
feature	O
to	O
add	O
watermarks	B-General_Concept
to	O
all	O
uploaded	B-Application
images	O
.	O
</s>
<s>
It	O
is	O
extremely	O
important	O
for	O
upload	B-Application
components	I-Application
to	O
preserve	O
original	O
image	O
metadata	O
in	O
the	O
upload	B-Application
process	O
.	O
</s>
<s>
An	O
example	O
of	O
quality	O
meter	O
usage	O
can	O
be	O
a	O
photo	O
printing	O
web	O
site	O
with	O
a	O
built-in	O
upload	B-Application
component	O
that	O
notifies	O
users	O
if	O
an	O
image	B-Algorithm
resolution	I-Algorithm
is	O
not	O
right	O
for	O
it	O
to	O
be	O
printed	O
in	O
a	O
selected	O
format	O
.	O
</s>
