Why Grails?
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This document introduces Grails, a web framework based on Java, Groovy, Spring, and GORM. It discusses how Grails enables rapid development through scaffolding and plugins, supports modern browsers, and allows rendering objects to JSON and XML. The document also provides an overview of Groovy and its similarities to Java, and demonstrates Grails through examples of parallel computing with GPars and calling Clojure code from Grails services.
![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))](https://image.slidesharecdn.com/whygrails-12695675387175-phpapp01/85/Why-Grails-9-320.jpg)
![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
}}](https://image.slidesharecdn.com/whygrails-12695675387175-phpapp01/85/Why-Grails-13-320.jpg)
Why Grails?
- 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 }}