<s>
In	O
the	O
fields	O
of	O
information	B-General_Concept
technology	I-General_Concept
and	O
systems	B-Application
management	I-Application
,	O
application	B-Application
performance	I-Application
management	I-Application
(	O
APM	O
)	O
is	O
the	O
monitoring	O
and	O
management	O
of	O
the	O
performance	O
and	O
availability	O
of	O
software	O
applications	O
.	O
</s>
<s>
APM	O
strives	O
to	O
detect	O
and	O
diagnose	O
complex	O
application	B-Application
performance	I-Application
problems	O
to	O
maintain	O
an	O
expected	O
level	O
of	O
service	O
.	O
</s>
<s>
The	O
second	O
set	O
of	O
performance	O
metrics	O
measures	O
the	O
computational	B-General_Concept
resources	I-General_Concept
used	O
by	O
the	O
application	O
for	O
the	O
load	O
,	O
indicating	O
whether	O
there	O
is	O
adequate	O
capacity	O
to	O
support	O
the	O
load	O
,	O
as	O
well	O
as	O
possible	O
locations	O
of	O
a	O
performance	O
bottleneck	O
.	O
</s>
<s>
Changes	O
in	O
performance	O
can	O
be	O
correlated	O
with	O
external	O
events	O
and	O
subsequently	O
used	O
to	O
predict	O
future	O
changes	O
in	O
application	B-Application
performance	I-Application
.	O
</s>
<s>
There	O
also	O
exist	O
HTTP	B-Protocol
appliances	O
that	O
can	O
decode	O
transaction-specific	O
response	O
times	O
at	O
the	O
Web	O
server	O
layer	O
of	O
the	O
application	O
.	O
</s>
<s>
Reporting	O
&	O
Application	O
data	B-General_Concept
analytics	I-General_Concept
.	O
</s>
<s>
This	O
has	O
caused	O
an	O
upheaval	O
in	O
the	O
marketplace	O
with	O
vendors	O
from	O
unrelated	O
backgrounds	O
(	O
including	O
network	O
monitoring	O
,	O
systems	B-Application
management	I-Application
,	O
application	O
instrumentation	O
,	O
and	O
web	O
performance	O
monitoring	O
)	O
adopting	O
messaging	O
around	O
APM	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
the	O
term	O
APM	O
has	O
become	O
diluted	O
and	O
has	O
evolved	O
into	O
a	O
concept	O
for	O
managing	O
application	B-Application
performance	I-Application
across	O
many	O
diverse	O
computing	O
platforms	O
,	O
rather	O
than	O
a	O
single	O
market	O
.	O
</s>
<s>
Two	O
challenges	O
for	O
implementing	O
APM	O
are	O
(	O
1	O
)	O
it	O
can	O
be	O
difficult	O
to	O
instrument	O
an	O
application	O
to	O
monitor	O
application	B-Application
performance	I-Application
,	O
especially	O
among	O
components	O
of	O
an	O
application	O
,	O
and	O
(	O
2	O
)	O
applications	O
can	O
be	O
virtualized	B-General_Concept
,	O
which	O
increases	O
the	O
variability	O
of	O
the	O
measurements	O
.	O
</s>
<s>
To	O
alleviate	O
the	O
first	O
problem	O
application	B-Application
service	I-Application
management	I-Application
(	O
ASM	O
)	O
provides	O
an	O
application-centric	O
approach	O
,	O
where	O
business	O
service	O
performance	O
visibility	O
is	O
a	O
key	O
objective	O
.	O
</s>
<s>
The	O
second	O
aspect	O
present	O
in	O
distributed	O
,	O
virtual	O
and	O
cloud-based	B-Architecture
applications	O
poses	O
a	O
unique	O
challenge	O
for	O
application	B-Application
performance	I-Application
monitoring	O
because	O
most	O
of	O
the	O
key	O
system	O
components	O
are	O
no	O
longer	O
hosted	O
on	O
a	O
single	O
machine	O
.	O
</s>
<s>
Each	O
function	O
is	O
now	O
likely	O
to	O
have	O
been	O
designed	O
as	O
an	O
Internet	O
service	O
that	O
runs	O
on	O
multiple	O
virtualized	B-General_Concept
systems	O
.	O
</s>
<s>
Applications	O
themselves	O
are	O
becoming	O
increasingly	O
difficult	O
to	O
manage	O
as	O
they	O
move	O
toward	O
highly	O
distributed	O
,	O
multi-tier	O
,	O
multi-element	O
constructs	O
that	O
in	O
many	O
cases	O
rely	O
on	O
application	O
development	O
frameworks	O
such	O
as	O
.NET	B-Application
or	O
Java	O
.	O
</s>
<s>
The	O
outcome	O
of	O
this	O
measuring	O
is	O
referred	O
to	O
as	O
Real-time	O
Application	B-Application
monitoring	I-Application
(	O
aka	O
Top-Down	O
monitoring	O
)	O
,	O
which	O
has	O
two	O
components	O
,	O
passive	O
and	O
active	O
.	O
</s>
<s>
Passive	O
monitoring	O
is	O
usually	O
an	O
agentless	O
appliance	O
implemented	O
using	O
network	B-Protocol
port	I-Protocol
mirroring	I-Protocol
.	O
</s>
<s>
User	B-Application
experience	I-Application
management	O
(	O
UEM	O
)	O
is	O
a	O
subcategory	O
that	O
emerged	O
from	O
the	O
EUE	O
dimension	O
to	O
monitor	O
the	O
behavioral	O
context	O
of	O
the	O
user	O
.	O
</s>
<s>
UEM	O
is	O
considered	O
another	O
facet	O
of	O
Real-time	O
Application	B-Application
monitoring	I-Application
.	O
</s>
<s>
This	O
allows	O
for	O
meaningful	O
SLA	O
reports	O
,	O
and	O
provides	O
trending	O
information	O
on	O
application	B-Application
performance	I-Application
from	O
a	O
business	O
perspective	O
:	O
start	O
with	O
broad	O
categories	O
and	O
refine	O
them	O
over	O
time	O
.	O
</s>
<s>
For	O
a	O
deeper	O
understanding	O
,	O
see	O
Business	B-Application
transaction	I-Application
management	I-Application
.	O
</s>
<s>
Deep	O
dive	O
component	O
monitoring	O
(	O
DDCM	O
)	O
requires	O
an	O
agent	O
installation	O
and	O
is	O
generally	O
targeted	O
at	O
middleware	B-General_Concept
,	O
focusing	O
on	O
web	O
,	O
application	O
,	O
and	O
messaging	O
servers	O
.	O
</s>
<s>
It	O
should	O
provide	O
a	O
real-time	O
view	O
of	O
the	O
J2EE	B-Language
and	O
.NET	B-Application
stacks	O
,	O
tying	O
them	O
back	O
to	O
the	O
user-defined	O
business	O
transactions	O
.	O
</s>
<s>
It	O
is	O
important	O
to	O
arrive	O
at	O
a	O
common	O
set	O
of	O
metrics	O
to	O
collect	O
and	O
report	O
on	O
for	O
each	O
application	O
,	O
then	O
standardize	O
on	O
a	O
common	O
view	O
on	O
how	O
to	O
present	O
the	O
application	B-Application
performance	I-Application
data	O
.	O
</s>
