Presentation from JavaOne 2015. This session, which covers use cases of JSR 356 (Java API for WebSocket) and some features of Oracle’s implementation related to enterprise applications, contains description of standard use cases and recommends optimizations and best practices for using the JSR 356 API. After that, it presents more-complex schemes involving authentication support, fallback support, and clustering.

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5. WebSocket
in
Enterprise
apps
Pavel
Bucek
(pavel.bucek@oracle.com)
Oracle
October
28,
2015
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Safe
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Statement
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The
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Program
Agenda
EvoluFon
–
REST,
Polling,
SSE,
WebSocket
Does
HTTP/2
make
WebSocket
obsolete?
When
to
use
WebSocket?
Java
EE
–
WebSocket
API
Advanced
architectures/usecases
1
2
3
4
5
7

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EvoluFon
–
REST
• Basic
soaware
architecture
/
scheme
• Exposes
Resources
(URIs),
which
handle
METHODs
– GET/PUT/POST/DELETE/HEAD/OPTIONS/TRACE/PATCH/…
• MediaType
(Accept/Content-­‐Type)
– text/plain,
text/html,
applicaFon/json,
…
• Caching
(GET,
HEAD),
Hyperlinking,
…
Representa7onal
State
Transfer
8

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EvoluFon
–
REST
Representa7onal
State
Transfer
9
Client
Server
GET
/hello
HTTP/1.1
Header:
value
…
HTTP/1.1
200
OK
Header:
value
…
<enFty>

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EvoluFon
–
Polling
10
Client
Server
GET
/hello
HTTP/1.1
Header:
value
…
HTTP/1.1
200
OK
Header:
value
…
<enFty>

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EvoluFon
–
Long-­‐Polling
11
Client
Server
GET
/hello
HTTP/1.1
Header:
value
…
HTTP/1.1
200
OK
Header:
value
…
<enFty
-­‐
CHUNK>
<enFty
-­‐
CHUNK>

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EvoluFon
–
SSE
• Channel
for
sending
events
from
server
to
the
client
• One-­‐way,
text
protocol
• Very
similar
to
long
polling
– (actually,
it’s
exactly
same,
but
this
Fme
it
has
own
RFC)
• Accept:
text/event-­‐stream
• Semi-­‐permanent
connecFon
– Clients
are
required
to
reconnect
when
the
connecFon
is
lost
• Limited
browser
support
(no
IE,
no
Android)
Server
Sent
Events
12

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EvoluFon
–
WebSocket
• RFC
6455
(December
2011)
• Bi-­‐direcFonal
communicaFon
• Uses
HTTP/1.1
for
iniFal
handshake
– Completely
different
protocol
aaerwards
• “Server”
and
“client”
endpoints
are
equal
aaer
handshake
• Text
or
binary
payload
• Supported
in
all
modern
browsers
13

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EvoluFon
–
WebSocket
WebSocket
Frame
14

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WebSocket
vs
REST
• Might
seem
to
be
similar
and
some
people
even
think
about
WebSocket
as
about
another
“RevoluFon”
–
like
SOAP
-­‐-­‐>
REST
• In
reality,
these
are
two
different
concepts
which
COMPLEMENT
each
other.
• REST
can
be
sFll
used
for
most
of
the
implementaFon
part
–
web,
forms,
…
• WebSocket
provides
bi-­‐direcFonal
channel,
suitable
for
exchanging
“short”
messages
with
the
browser.
– (the
scope
is
not
limited,
you
can
re-­‐implement
all
your
communicaFon
with
server,
but
there
is
no
point
in
doing
that..)
15

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WebSocket
vs
HTTP/2
• Same
semanFcs
as
HTTP/1.1
• Binary
protocol
• MulFplexed
protocol
– Single
TCP
connecFon
to
single
origin,
shared
for
consequent/parallel
requests
• Compressed
headers
– HTTP/2
introduces
HPACK
(compression
algorithm)
• Server
Push
– Server
can
push
(cacheable)
content
to
the
client
before
client
asks
HTTP/2
Key
Features
16

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WebSocket
vs
HTTP/2
• Pushed
resources
are
cached
on
client
side
• When
client
decides
it
needs
something
(image,
..),
it
looks
into
the
cache
– Doesn’t
need
to
be
image,
but
all
cool
demos
are
using
that
(remember
SPDY)
• Server
push
has
its
own
issues
– What
if
client
does
not
need
pushed
resource?
(there
might
be
other
caches,
…)
• Push
is
not
“interacFve”
message
exchange
WebSocket
vs
Server
push
17

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WebSocket
and
HTTP/2
Standards..
18
• Currently,
WebSocket
is
not
defined
in
HTTP/2
world
• WebSocket
uses
UPGRADE
header,
which
gives
complete
control
over
TCP
connecFon
• HTTP/2
Streams
could
support
WS
mulFplex

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When
to
use
WebSocket
• Bi-­‐direcFonal
communicaFon
– “messaging”
• InteracFve
applicaFons
– Any
Fme,
you
need
fast
data
exchange
with
the
backend
• Time-­‐criFcal
data
delivery
– Stock
quotes
19

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WebSocket
usecases
20
• Chat-­‐like
applicaFons
– Various
implementaFons
opFons
– XMPP
(Jabber)
over
WebSocket
• Trading
and
transacFons
– Fast
feedback/execuFon
• Real-­‐Fme
monitoring
– Depends
on
the
data
source
– InteracFon
with
monitored
object
– (SSE?)
• Remote
control
– Input
with
“real-­‐Fme”
feedback
– From
industry
applicaFon
to
fun
apps
• Games
– HTML5
“naFve”
transport
– Supported
by
improvements
in
browsers
2D/3D
canvas
support
• General
collaboraFon
– Customer
service,
Social
apps,
…

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WebSocket
usecases
• RFC
7118
–
SIP
over
WebSocket
• RFC
7355
–
SIP
&
CLF
(Common
Log
Format)
over
WebSocket
• RFC
7395
–
XMPP
over
WebSocket
• Draas
– MSRP
(Message
Session
Relay
Protocol)
over
WebSocket
– SDP
(Session
DescripFon
Protocol)
over
WebSocket
– Remote
Framebuffer
Protocol
over
WebSocket
– <anything>
over
WebSocket
Subprotocols
21

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Java
API
for
WebSocket
• JSR
356
–
Part
of
Java
EE
7
– 1.0
(May
2013)
– 1.1
(August
2014)
• Annotated
and
programmaFc
way
how
to
deploy
and
access
WebSocket
endpoints
• Event-­‐driven
model
-­‐
@OnOpen,
@OnMessage,
@OnError,
@OnClose
• Encoders/Decoders,
Path/Query
parameter
handling,
Handshake
headers
interceptors,
CDI
integraFon,
…

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Java
API
for
WebSocket
–
Annotated
Endpoint

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Java
API
for
WebSocket
–
ProgrammaFc
Endpoint

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WebSocket
vs
Java
8,
9
/
JDK
1.8,
1.9
• Some
classes
in
the
WebSocket
API
could
be
replaced
/
disassembled
to
separate
Java
8
Consumer<T>s
– MessageHandlers
already
can
be
wriQen
as
lambda
funcFons
• Default
Methods,
CompleFonStage<T>,
Method
Parameter
ReflecFon,
Streams,
…
• JDK
9
–
JEP
110:
HTTP/2
Client:
hQp://openjdk.java.net/jeps/110
– Define
a
new
HTTP
client
API
that
implements
HTTP/2
and
WebSocket,
…
Lambdas,
WebSocket
client
25

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WebSocket
and
Clustering
• Different
to
“classic”
cluster
– We’d
like
to
talk
to
other
sessions
(clients)
directly
• Clustered
environment
present
different
challenges
– “Finding
a
WebSocket
Session”
might
not
be
as
trivial
as
it
seem
• Broadcast
(mass-­‐noFficaFon)
is
common
usecase
• Clustering
can
help
– BroadcasFng
to
“all
sessions”
can
be
faster
in
clustered
environment
26

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WebSocket
and
Clustering
27
JMS,
JCache,
Coherence,
…
Load
Balancer

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WebSocket
and
Clustering
28
JMS,
JCache,
Coherence,
…
Load
Balancer

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WebSocket
and
Clustering
29
JMS,
JCache,
Coherence,
…
Load
Balancer

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WebSocket
and
Clustering
30
JMS,
JCache,
Coherence,
…
Load
Balancer

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WebSocket
and
Clustering
• Different
requirements
• Load
balancers
might
need
to
manage
more
open
connecFons
• Cannot
re-­‐balance
when
session
is
already
created
– Node
is
added
–
ok,
but
I
cannot
easily
decrease
load
on
other
nodes,
I
can
use
the
new
node
only
for
new
connecFons
• Node
going
down
is
not
transparent
to
client
– Robust
clients
can
hide
this,
but
for
now,
this
requires
custom
soluFon
– WLS
12.2.1
offers
a
soluFon
for
this..
31

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WebSocket
and
Clustering
32
JMS,
JCache,
Coherence,
…
Load
Balancer

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WebSocket
and
Clustering
33
JMS,
JCache,
Coherence,
…
Load
Balancer

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WebSocket
and
Clustering
• Might
require
more
applicaFon
code
– Proper
handling
on
client
side
– Even
more
code
when
you
want
to
have
something
like
auto
reconnect
+
“session
recovery”
• Infrastructure
requirements
– Similar
to
SSL
(persistent
connecFon,
…)
• Much
more
effecFve
when
compared
to
the
same
app
implemented
using
long-­‐polling
34

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Contacts/QA
• Pavel
Bucek
(pavel.bucek@oracle.com)
• RFC
6455:
The
WebSocket
Protocol
hQps://tools.iez.org/html/rfc6455
• JSR
356:
WebSocket
API
for
Java
hQps://java.net/projects/websocket-­‐spec/
• Tyrus
/
WebSocket
RI
:
hQp://tyrus.java.net
– users@tyrus.java.net
Feel
free
to
ask
any
quesFons
now
or
contact
me
later.
35

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