This presentation would like to convince you grails is very good and you have lots to enjoy

1. Why
Grails?
Yiguang
Hu

2. What
is
Grails?
• Grails
is
a
web
framework
based
on
– JAVA,
GROOVY,
Spring,
GORM
• Scaffolding!
• Plugin
everything!!!
– GWT,
DWR,
YUI,
ACEGI,
Google
AppEngine,
Google
Wave,
COMET,
JQuery,
Clojure,
Scala,
JSF,
Struts…
• Support
all
modern
browsers
automaRcally
• Render
object
to
JSON,
XML
free!
• MVC+IOC(services)+plugin

3. Why
Grails?
• Rapid
– Have
your
next
Web
2.0
project
done
in
weeks
instead
of
months.
Grails
delivers
a
new
age
of
Java
web
applicaRon
producRvity.
• Dynamic
– Get
instant
feedback,
see
instant
results.
Grails
is
the
premier
dynamic
language
web
framework
for
the
JVM.
• Robust
– Powered
by
Spring,
Grails
out
performs
the
compeRRon.
Dynamic,
agile
web
development
without
compromises.
• Proven
Technologies:
JAVA(Groovy),
Spring,
GORM

4. What
is
Groovy?
• Groovy
=
– JAVA+Dynamic
Typing+Closure+
DSL,
GPars,Griffon….
• Runs
on
JVM
• 0
Learning
curve
for
Java
programmer

5. Success
Stories
• The
Sites
I
personally
involved:
– Worthpoint.com
(80
million
records)
– Gsword:
h_p://www.ccimweb.org/gsword
• Web
2.0.
Highly
interacRve.
• Done
in
two
days!
– Others

6. Demo
• Install
java,
groovy,
grails
• grails
create-­‐app
interop
– Goto
dir
interop
and
see
the
dires/files
created
• Run
it!
• Add
domain
• Generate
controller/views
and
run
– SorRng,
paginaRon
are
there
already!
• Add
a
service
and
use
in
controller
• Run
it!

7. Demo…
• SOA
– Render
objects
as
JSON,
XML
etc
– Import
grails.converters.*;
• Parallel
compuRng
in
Services
using
GPars
• Using
other
languages
like
Clojure
in
grails
• …

8. Performance
Concern?
• User
Java
in
high
demanding
place
• Gpars
(Actors,
map
reducer…)
• Use
clojure
in
services
• User
Scala
in
services
• Yes.
It
is
AGILE!

9. Clojure
Demo
• grails
install-­‐plugin
clojure
• New
dir
src/clj
is
created
• Add
file
Addnumber.clj
in
src/clj
(ns
grails)
(def
twenty
20)
(defn
add_numbers
[a
b]
(+
a
b))

10. Call
Clojure
from
Service
class
ClojService
{
boolean
transacRonal
=
false
def
addNumbers(x,
y)
{
clj.add_numbers(x,
y)
}
def
addTwenty(x)
{
clj.add_numbers(x,
clj.twenty)
}
}

11. Call
Service
in
Controller
import
grails.converters.XML;
class
PlayController
{
def
index
=
{
}
def
clojService
def
cljaddnumber={
render
clojService.addNumbers(Integer.parseInt(params.a?:"5"),
Integer.parseInt(params.b?:"4"))
}
def
cljadd20={
render
clojService.addTwenty(Integer.parseInt(params.a?:"10"))
}
}

12. Gpars
Map
Reducer
Demo
//@Grab(group='org.codehaus.gpars',
module='gpars',
version='0.9')
import
staRc
groovyx.gpars.Parallelizer.*
class
ConcurrentService
{
boolean
transacRonal
=
true
def
sqr()
{
def
myNumbers
doParallel{
myNumbers
=
(1..1000).parallel.filter{it
%
2
==
0}.map{Math.sqrt
it}.collecRon
}
myNumbers
}

13. Gpars
Map
Reducer
Demo
def
search(String
key,keys){
key+":"+
keys.replaceAll(key,key.toUpperCase())
/turns
key
to
upper
case
}
def
webs=["a
b
c
d
e
f
g
h
j
k
i
o
as
da
o
sa
ds
h
vcx
aw
s
dsf
gdsg
ds
,
bbx
fdwvcx
786
",
"b
sd
sd
sd
dsfgh
fds
ewr
56y
k
o
aw
n
q
12
g
n
1
uy
t
r",
"sad
assa
sa
sa
sa
sa
456t465367
45
45
23
23
12
453
43
5
3
234
523
",
"8sdf
ds
5ue
we
123
42
hg
h
k
s
x
d
f
t
r
g
h
j
y
k
v
b
n
m
l
qw
ew
c"]
def
reducer(String
key)
{
def
rst
doParallel
{
rst
=
webs.parallel.map
{search(key,it)}.collecRon
}
rst
}}