Take a Groovy REST

Take a Groovy REST!
by Guillaume Laforge
@glaforge

Promo Code: ctwjavaone
http://www.manning.com/koenig2/
GROOVY
IN ACTION
2ND EDITION

We know
about
APIs!
http://restlet.com

@glaforge
APISpark — sign-up!
4
http://restlet.com

ROY FIELDING
RESTDISSERTATION
Principled design
of the modern
Web architecture

@glaforge
Representational State Transfer
Architectural properties
• Performance
• Scalability
• Simplicity
• Modifiability
• Visibility
• Portability
• Reliability
Architectural constraints
• Client-server
• Stateless
• Cacheable
• Layered system
• Code on demand (optional)
• Uniform interface
8

@glaforge
REST — Uniform interface
• Identification of resources
• Manipulation of resources  
through representations
• Self-descriptive messages
• HATEOAS  
(Hypermedia As The Engine  
Of Application State)
9

@glaforge
• HATEOAS  
9
Resource as URIs
http://api.co/cars/123

@glaforge
• HATEOAS  
9
Resource as URIs
JSON, XML…

@glaforge
• HATEOAS  
9
Resource as URIs
JSON, XML…
HTTP GET, POST, PUT, DELETE
media types, cacheability…

@glaforge
• HATEOAS  
9
Resource as URIs
JSON, XML…
HTTP GET, POST, PUT, DELETE
media types, cacheability…
Hypermedia APIs
HAL, JSON-LD, Siren…

@glaforge
HTTP methods / URIs for collection/item
10
GET
POST
PUT
DELETE
http://api.co/v2/cars/ http://api.co/v2/cars/1234
List all the cars Retrieve an individual car
Create a new car
Replace the entire collection
with a whole new list of cars
Replace or create
an individual car
Delete all the cars Delete an individual car

@glaforge
Common HTTP Status Codes — 1xx
11

@glaforge
12

@glaforge
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@glaforge
14

@glaforge
15

@glaforge
Solutions for your REST backend
• Grails
• Ratpack
• Spring Boot
• gServ
• Restlet Framework
• any other  
Web framework!
17

May the Groovy
force be with you!

@glaforge
gServ
19
def gserv = new GServ() 
 
def bkResource = gserv.resource("/people") { 
get ":id", { id -> 
def person = personService.get( id ) 
writeJson person 
} 
 
get "/", { -> 
def persons = personService.all() 
responseHeader "content-type", "application/json" 
writeJSON persons 
} 
} 
 
gserv.http { 
static_root '/public/webapp' 
get '/faq', file("App.faq.html") 
 
}.start(8080)

@glaforge
Restlet Framework
20
@GrabResolver('http://maven.restlet.com') 
@Grab('org.restlet.jse:org.restlet:2.3.2') 
import org.restlet.* 
import org.restlet.resource.* 
import org.restlet.data.* 
import org.restlet.routing.* 
import static org.restlet.data.MediaType.* 
 
class PeopleResource extends ServerResource { 
@Get('json') 
String toString() { "{'name': 'Luke Skywalker’}" } 
} 
 
new Server(Protocol.HTTP, 8183, PeopleResource).with { server -> 
start() 
new Router(server.context).attach("/people/{user}", PeopleResource) 
 
assert new ClientResource('http://localhost:8183/people/1') 
.get(APPLICATION_JSON).text.contains('Luke Skywalker') 
 
stop() 
}

@glaforge
Restlet Framework
20
import org.restlet.* 
import org.restlet.data.* 
import org.restlet.routing.* 
 
class PeopleResource extends ServerResource { 
@Get('json') 
String toString() { "{'name': 'Luke Skywalker’}" } 
} 
 
new Server(Protocol.HTTP, 8183, PeopleResource).with { server -> 
start() 
new Router(server.context).attach("/people/{user}", PeopleResource) 
 
assert new ClientResource('http://localhost:8183/people/1') 
.get(APPLICATION_JSON).text.contains('Luke Skywalker') 
 
stop() 
}
Starts in
milliseconds

@glaforge
Ratpack
21
@Grab('io.ratpack:ratpack-groovy:0.9.17') 
import static ratpack.groovy.Groovy.ratpack 
import static groovy.json.JsonOutput.toJson 
 
ratpack { 
handlers { 
get("/people/:id") { 
respond byContent.json { 
response.send toJson( 
[name: 'Luke Skywalker']) 
} 
} 
} 
}

@glaforge
Ratpack
21
@Grab('io.ratpack:ratpack-groovy:0.9.17') 
import static ratpack.groovy.Groovy.ratpack 
import static groovy.json.JsonOutput.toJson 
 
ratpack { 
handlers { 
get("/people/:id") { 
respond byContent.json { 
response.send toJson( 
[name: 'Luke Skywalker']) 
} 
} 
} 
}
Booh! Ratpack
0.9.17???

@glaforge
Ratpack 1.0 is out!
22

@glaforge
Ratpack
23
@Grab(’org.slf4j:slf4j-simple:1.7.12’)
@Grab(’io.ratpack:ratpack-groovy:1.0.0’)
import static ratpack.groovy.Groovy.ratpack
import static ratpack.groovy.Groovy.htmlBuilder as h
import static ratpack.jackson.Jackson.json as j
ratpack {
handlers {
get { render "foo"}
get("people/:id") {
byContent {
json {
render j(name: "Luke Skywalker")
}
html {
render h {
p "Luke Skywalker"
}
}

Beep, let’s move to
the client side of the
REST force!

@glaforge
REST clients — Web, Java, Android
Web browser 
(client-side JavaScript)
• Raw AJAX, jQuery
• Angular’s http request,
Restangular
• Restful.js
+ GrooScript! :-)
Java-based app  
(Android or Java backend)
• Groovy wslite
• Groovy HTTPBuilder
• RetroFit / OkHttp
• Restlet Framework
27

@glaforge
Restful.js (+ GrooScript ?)
29

@glaforge
new URL(‘…’).text… or not?
31
'https://starwars.apispark.net/v1/people/1'.toURL().text

@glaforge
new URL(‘…’).text… or not?
31
'https://starwars.apispark.net/v1/people/1'.toURL().text
getText() will do
an HTTP GET
on the URL

403The API doesn’t
accept a Java user
agent

@glaforge
new URL(‘…’).text… take 2!
34
'https://starwars.apispark.net/v1/people/1' 
.toURL() 
.getText(requestProperties: 
['User-Agent': 'Firefox',  
'Accept' : 'application/json'])

@glaforge
new URL(‘…’).text… take 2!
34
.toURL() 
'Accept' : 'application/json'])
Let’s ask for
JSON payload

@glaforge
Now JSON-parsed…
35
import groovy.json.* 
 
assert new JsonSlurper().parseText( 
.toURL() 
'Accept': 'application/json']) 
).name == 'Luke Skywalker'

@glaforge
…and spockified!
36
class StarWars extends Specification { 
def "retrieve Luke"() { 
given: "a URL to the resource" 
def url = 'https://starwars.apispark.net/v1'.toURL() 
 
when: "I retrieve and parse the people/1" 
def parsed = url.getText(requestProperties: 
 
then: "I expect to get Luke" 
parsed.contains "Luke Skywalker" 
} 
}

@glaforge
…and spockified!
36
 
 
} 
}
Neat for GET,
but not other
methods
supported

@glaforge
…and spockified!
36
 
 
} 
}
Neat for GET,
but not other
methods
supported
Raw text, no
JSON parsing

@glaforge
Groovy wslite
37
@Grab('com.github.groovy-wslite:groovy-wslite:1.1.0') 
import wslite.rest.* 
import wslite.http.* 
 
class StarWars3 extends Specification { 
static endpoint = 'https://starwars.apispark.net/v1' 
 
given: "a connection to the API" 
def client = new RESTClient(endpoint) 
 
when: "I retrieve the people/1" 
def result = client.get(path: '/people/1', headers: 
['User-Agent': 'Firefox', 'Accept': 'application/json']) 
 
result.json.name == "Luke Skywalker" 
} 
}

@glaforge
Groovy wslite
37
@Grab('com.github.groovy-wslite:groovy-wslite:1.1.0') 
import wslite.rest.* 
import wslite.http.* 
 
 
 
 
result.json.name == "Luke Skywalker" 
} 
}
Transparent
JSON parsing

@glaforge
Groovy wslite
38
 
 
 
 
 
 
 
 
 
 
 
 
 
result.json.name == "Luke Skywalker"

@glaforge
Groovy HTTPBuilder
39
@Grab('org.codehaus.groovy.modules.http-builder:http-builder:0.7.1') 
import groovyx.net.http.RESTClient 
import static groovyx.net.http.ContentType.JSON 
 
static endpoint = 'https://starwars.apispark.net/v1/' 
 
 
def result = client.get(path: ‘people/1', contentType: JSON, 
headers: ['User-Agent': 'Firefox']) 
 
result.data.name == "Luke Skywalker" 
} 
}

@glaforge
Groovy HTTPBuilder
40
 
 
 
 
 
 
 
 
 
 
 
def result = client.get(path: ‘people/1', contentType: JSON, 
headers: ['User-Agent': 'Firefox']) 
 
 
result.data.name == "Luke Skywalker"

@glaforge
Restlet Framework client
41
 
 
given: "I create a people resource" 
def resource = new ClientResource("${endpoint}/people/1") 
 
when: "I retrieve the resource" 
def representation = resource.get(APPLICATION_JSON) 
 
then: "I expect that resource to be Luke!" 
representation.text.contains "Luke Skywalker" 
} 
}

@glaforge
41
 
 
given: "I create a people resource" 
 
when: "I retrieve the resource" 
 
then: "I expect that resource to be Luke!" 
representation.text.contains "Luke Skywalker" 
} 
}
Raw text, no
JSON parsing

@glaforge
42
 
 
 
 
 
 
 
 
 
 
 
 
 
 
representation.text.contains "Luke Skywalker"

@glaforge
RetroFit
43
@Grab('com.squareup.retrofit:retrofit:1.9.0') 
import retrofit.* 
import retrofit.http.* 
 
interface StarWarsService { 
@Headers(["Accept: application/json", 
"User-Agent: Firefox"]) 
@Get('/people/{id}') 
People retrieve(@Path('id') String id) 
} 
 
class People { String name } 
 
def restAdapter = new RestAdapter.Builder() 
.setEndpoint('https://starwars.apispark.net/v1/')
.build() 
 
def service = restAdapter.create(StarWarsService) 
assert service.retrieve('1').name == 'Luke Skywalker'

@glaforge
DHC by Restlet
45
http://bit.ly/dhctuto

@glaforge
REST-assured
47
@Grab('com.jayway.restassured:rest-assured:2.4.1') 
import static com.jayway.restassured.RestAssured.* 
import static org.hamcrest.Matchers.* 
 
when(). 
get('https://starwars.apispark.net/v1/people/1'). 
then(). 
statusCode(200). 
body('name', equalTo('Luke Skywalker')). 
body('gender', equalTo('male'))

@glaforge
REST-assured — a Spock approach
48
@Grab('org.spockframework:spock-core:1.0-groovy-2.4') 
import spock.lang.* 
 
@Grab('com.jayway.restassured:rest-assured:2.4.1') 
import static com.jayway.restassured.RestAssured.* 
import static org.hamcrest.Matchers.* 
 
class starwars_rest_assured_spock extends Specification { 
def "rest assured and spock"() { 
expect: 
get('https://starwars.apispark.net/v1/people/1').then().with { 
statusCode 200 
body 'name', equalTo('Luke Skywalker') 
} 
} 
}

Arg! The Groovy REST
force is too strong!

@glaforge 56
Help us move Groovy forward!
Thanks!
Take a Groovy REST!
@glaforge

Take a Groovy REST

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