JavaOne session describing the qualities and structure of a Java cloud application.

1. Lightweight
Java
in
the
Cloud
Shaun
Smith
Oracle
Applica9on
Container
Cloud
shaun.smith@oracle.com
@shaunMsmith
Gerrit
Grunwald
Java
Technology
Evangelist
gerrit.grunwald@oracle.com
@hansolo_
Copyright
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2015,
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and/or
its
affiliates.
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2. Copyright
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Safe
Harbor
Statement
The
following
is
intended
to
outline
our
general
product
direc9on.
It
is
intended
for
informa9on
purposes
only,
and
may
not
be
incorporated
into
any
contract.
It
is
not
a
commitment
to
deliver
any
material,
code,
or
func9onality,
and
should
not
be
relied
upon
in
making
purchasing
decisions.
The
development,
release,
and
9ming
of
any
features
or
func9onality
described
for
Oracle’s
products
remains
at
the
sole
discre9on
of
Oracle.
2

3. Copyright
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2015,
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and/or
its
affiliates.
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Java
Cloud
• Java
SE
is
ideal
for
building
lightweight
applica9ons
and
(micro)services
• Cloud
plaTorms
offer
– High
availability
– Affordability
– Ease
of
management
– Access
to
suppor9ng
services
like
object
storage,
messaging,
and
databases
3

4. Copyright
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2015,
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What
do
we
mean
by
Cloud?
• A
wonderfully
amorphous
word!
• Clouds
offer
a
range
of
services
including
Iaas
/
SaaS
/
PaaS
• Applica9on
PlaTorm
as
a
Service—APaaS
– Focused
on
running
lightweight
applica9ons—not
heavy
weight
services
like
database
– Typically
employ
containers
to
run
applica9ons
– Many
vendors
to
choose
from
– Most,
if
not
all,
APaaS
plaTorms
support
Java
4

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Cloud
Applica9on
Architecture
5

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6

7. Copyright
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7
Configura9on

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Test
Prod
8
Dev

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Configura9on
• Applica9on
should
be
“parameterizable”—externalize
all
config
data
• Configura9on
should
be
defined
as
environment
variables
and
read
by
applica9ons
on
start
• Makes
it
easy
to
deploy
the
applica9on
to
any
environment
where
configura9ons
will
differ
• Deployment
configura9on
can
be
managed
by
Ops
post
Dev
9

10. Copyright
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10
This
includes
database
and
other
backing
service
loca9ons,
third-­‐party
creden9als
like
AWS
or
Twijer…such
configura9on
should
not
be
stored
in
the
codebase…exposes
private
resources
in
the
version
control
system.

11. Copyright
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11
Environment
variables…useful
when
the
values
are
likely
to
be
different
from
one
host
system
to
the
next…makes
the
applica9on
code
more
portable
and
flexible…cri4cal
for
wri4ng
applica4ons
that
are
easily
deployed
and
scaled

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12
Grizzly
/
Jersey

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13
Embedded
Tomcat

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14
Configura9on
Dependencies

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Dependencies
• Applica9on
dependencies
must
be
explicitly
declared
• Relying
on
the
availability
of
system
wide
libraries
in
the
run9me
environment
can
lead
problems
that
are
to
hard
to
diagnose
• Applica9ons
with
explicit
dependencies
are
easy
to
move
between
environments
• Maven
&
Gradle
provide
a
nice
way
to
declare
applica9on
dependencies
15

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16
Configura9on
Dependencies
Service
Interface

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Service
Interface
• Cloud
applica9ons
typically
expose
Web/REST/Websocket
services
using
embedded
servers
like
Tomcat,
Jejy,
or
Grizzly/Jersey/Tyrus.
• Embedded
servers
must
bind
to
the
hostname
and
port
defined
by
the
run9me
environment,
typically
in
an
environment
variable
like
$PORT
• Applica9ons
running
in
containers
will
likely
bind
to
a
local
port
that
is
receiving
load
balanced
traffic
forwarded
from
a
pubic
port
• By
exposing
func9onality
over
REST,
applica9ons
can
be
provide
services
to
other
applica9ons
(the
core
of
the
microservices
approach)
17

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18
Configura9on
Dependencies
Services
Applica9on
Interface

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Service
Dependencies
• Service
coordinates
published
in
the
run9me
environment
for
consump9on
by
applica9on
• Backing
services
should
be
pluggable
• Easy
to
change
services—restart
applica9on
to
pick
up
changes
• Treat
3rd
party
or
plaTorm
services
the
same
as
your
own
services
19

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DEMO
20

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Cloud
Applica9on
Quali9es
21

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Stateless
/
Disposable
• Applica9ons
should
be
stateless
with
all
persistent
data
stored
in
external
services
like
database
or
key/value
stores
• Stateless
applica9ons
makes
scaling
easy
(esp.
when
scaling
in
by
disposing
of
instances)
• Configura9on
changes
will
result
in
the
restar9ng
(disposing
&
crea9ng)
of
applica9on
instances
• Ephemeral
disk
is
useful
but
there
is
no
guarantee
a
subsequent
request
will
be
handled
by
the
same
instance
22

23. Copyright
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Share
Nothing
• Ideally,
applica9ons
should
be
stateless
and
share-­‐nothing
• Horizontal
scaling
of
stateless
applica9ons
by
adding
instances
to
handle
increased
load
is
simple
and
reliable
• Not
everyone
agrees
on
this
point…
23

24. Copyright
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24
Why
We
Aren’t
Joining
the
Cloud
Foundry
Founda4on
…we
are
also
working
hard
to
support
both
stateless
and
stateful
applica9ons
inside
those
containers…

25. Copyright
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25
Concurrency
in
Oracle
Java
SE
Cloud
Service
Java
SE
Docker
Java
SE
Docker
Load
Balancer
…
Messaging
Cloud
Service
Storage
Cloud
Service
Database
Cloud
Service
Java
Cloud
Service
MyApp
Java
SE
Docker

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Prac9cal
Majers
26

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Development
vs.
Deployment
• APaaS
plaTorms
are
deployment
plaTorms—you
run
apps
on
them
• Development
happens
where?
• How
to
develop
and
debug
applica9ons
targe9ng
APaaS?
27

28. Copyright
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Debug
locally
in
emulated
environment
• Define
environment
variables
to
match
target
• Use
same
JDK
release
and
version
as
in
target
• Use
tools
like
Foreman
• Challenge—”emulated”
not
iden9cal
Debug
in
Cloud
• Restrict
to
single
instance
• Remote
test
&
debug
• E.g.,
Spring
Tools
(experimental
afaik)
• Challenge—opening
up
ports
and
suppor9ng
breakpoint
callbacks
from
cloud
to
desktop
28
Debug
locally
using
same
Docker
image
as
on
APaaS
• Same
run9me
environment
as
Cloud
• Challenge—dependency
on
cloud
services
• E.g.
Heroku
(not
exactly
the
same
since
not
Docker
in
cloud)
Java
APaaS
Debug
Op9ons

29. Copyright
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Summary
• Java
is
one
of
the
best
choices
for
Cloud
applica9on
development
• Java
has
broad
support
from
APaaS
vendors
• Most
of
the
architectural
principals
of
Cloud
apps
are
simply
good
prac9ce
– Configurable
– Declared
Dependencies
– Pluggable
Service
– …
29
Configura9on
Dependencies
Applica9on
Interface
Services

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Java
is
the
PlaTorm!
• Focus
on
your
Java
applica9on
and
not
on
proprietary
plaTorm
features
• Architect
for
plaTorm
independence
• Own
the
stack—don’t
let
vendors
dictate
• Use
embedded
servers,
not
containers
to
stay
light
• Consider
the
microservices
approach
of
many
small
services
assembled
to
provide
a
complete
solu9on
30

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31