Rest dengan restlet

REZA LESMANA
Universitas Gunadarma

Saturday, February 5, 2011

REST
Using Restlet Framework

REST
Representational State Transfer


WHAT IS REST?
GAYA ARSITEKTUR SOFTWARE UNTUK ARSITEKTUR
APLIKASI BERBASIS JARINGAN

BASICALLY
WEB SERVICES ARCHITECTURE


WHY USE REST?
UNIFORM INTERFACE

SEMUA KOMPONEN APLIKASI DALAM WEB SERVICES
BERINTERAKSI DENGAN CARA YANG SAMA


UNIFORM INTERFACE
one of the feature of REST


UNIFORM INTERFACE
Resource Identiﬁcation [1]

RESOURCE
informasi yang dibutuhkan oleh user untuk
menjalankan proses bisnis dari suatu aplikasi


UNIFORM INTERFACE

Uniform Resource Identiﬁer
(URI)
Contoh : HTTP URL


UNIFORM INTERFACE
URI Template

http://contohaja.com/message/{index}


RESTLET FRAMEWORK
application building block


RESTLET FRAMEWORK
servlet conﬁguration (web.xml)

<context-param>
<param-name>org.restlet.application</param-name>
<param-value>
com.helloworld.main.MainApplication
</param-value>
</context-param>


<servlet>
<servlet-name>RestletServlet</servlet-name>
<servlet-class>
org.restlet.ext.servlet.ServerServlet
</servlet-class>
</servlet>


<servlet-mapping>
<servlet-name>RestletServlet</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>

UNIFORM INTERFACE
aplikasi penyimpanan pesan dalam stack

• Daftar Pesan ---> • “/” ---> MessagesResource

• Top of Stack ---> • “/message/ ---> MessageResource

• Pesan Tunggal ---> • “/message/{index} ---> MessageResource


RESTLET FRAMEWORK
MainApplication
public class MainApplication extends Application {

public MainApplication(Context parentContext) {
super(parentContext);
}

@Override
public synchronized Restlet createInboundRoot() {
Router router = new Router(getContext());

router.attach("/", MessagesResource.class);
router.attach("/message/", MessageResource.class);
router.attach("/message/{messageIndex}", MessageResource.class);

return router;
}
}


UNIFORM INTERFACE
Manipulation Through Representation [1]

REPRESENTATION

representasi dari resource


UNIFORM INTERFACE
HTTP METHOD as Popular Practices

• HTTP POST ---> • membuat Resource baru (Create)

• HTTP GET ---> • mendapatkan Resource (Read)

• HTTP PUT ---> • mengubah Resource (Update)

• HTTP DELETE ---> • menghapus Resource (Delete)


UNIFORM INTERFACE
Another Protocol?

• Gunakan standar protokol komunikasi sesuai dengan
spesiﬁkasinya

• Perhatikan Safety dan Idempotency dari method

• Safety : tidak menghasilkan “efek samping” pada resource

• Idempotency : dilakukan berulang-ulang hasilnya sama


UNIFORM INTERFACE
Standardized Document Structure as Representation

• XHTML • MPEG

• XML • MP3

• Atom Pub • AVI

• OData • Text/Audio/Video Streaming


UNIFORM INTERFACE
Not Only HTTP

TEXT/AUDIO/VIDEO STREAMING
Contoh : VoIP

Using SIP or XMPP


RESTLET FRAMEWORK
public class MessageResource extends ServerResource {

@Post
public Representation addMessage(Representation entity) {
StringRepresentation representation = null;

String result = "";
try {
result = HelloBusiness.create(entity.getText());
} catch (IOException e) {
setStatus(Status.SERVER_ERROR_INTERNAL );
}

representation = new StringRepresentation
(result, MediaType.APPLICATION_XML);

return representation;
}


RESTLET FRAMEWORK
@Get("xml")
public Representation get(){
String index = (String)getRequest().getAttributes().get("messageIndex");
String result = "";
try{
if(index != "" && index != null){
result = HelloBusiness.get(Integer.parseInt(index));
}else{
result = HelloBusiness.get();
}
}catch(Exception e){
setStatus(Status.CLIENT_ERROR_NOT_FOUND);
("no item found", MediaType.TEXT_PLAIN);
}
}


RESTLET FRAMEWORK
@Put
public Representation put(Representation entity){

String result = "";
try {

result = HelloBusiness.update(entity.getText());

} catch (IOException e) {
setStatus(Status.SERVER_ERROR_INTERNAL );
}


}

RESTLET FRAMEWORK
@Delete
public Representation delete(){
String result = "";
try {
result = HelloBusiness.delete();
}catch(NoMoreItemException ne){
setStatus(Status.CLIENT_ERROR_FORBIDDEN);
("Tidak boleh, udah kosong", MediaType.TEXT_PLAIN);
}
}


UNIFORM INTERFACE
Self-Descriptive Messages [1]

TWO FACTORS

The Protocol Message
The Media Type (Type of Representation)


UNIFORM INTERFACE
The Protocol Message

• HTTP Header --> Content Negotiation
• Contoh : Accept : application/xml

• Status Respon :
• Contoh : HTTP 1.1 / 200 OK ,HTTP 1.1 / 403 FORBIDDEN


UNIFORM INTERFACE
The Media Type
• Struktur Dokumen Bisa Mudah Diolah
• Contoh :
• XML (application/xml)
• Atom Pub (application/atom+xml)

Contoh MediaType XML
<messages>
<message>
<messageid>120</messageid>
<author>Reza</author>
<created>2011/02/04 08:20:12</created>
<value>Hello, World!</value>
<link>/message/120</link>
<message>
........
........
<messages>


Contoh MediaType Atom
<entry>
<id>urn:uuid:95506d98-aae9-4d34-a8f4-1ff30bece80c</id>
<title type=ʹ′ʹ′textʹ′ʹ′>product created</title>
<updated>2009-07-05T10:25:00Z</updated>
<link rel=ʹ′ʹ′selfʹ′ʹ′ href=ʹ′ʹ′http://starbucks.com/products/notiﬁcations/95506d98-aae9-4d34-
a8f4-1ff30bece80cʹ′ʹ′/>
<link rel=ʹ′ʹ′relatedʹ′ʹ′ href=ʹ′ʹ′http://starbucks.com/products/527ʹ′ʹ′/>
<category scheme=ʹ′ʹ′http://starbucks.com/products/categories/typeʹ′ʹ′ term=ʹ′ʹ′productʹ′ʹ′/>
<category scheme=ʹ′ʹ′http://starbucks.com/products/categories/statusʹ′ʹ′ term=ʹ′ʹ′newʹ′ʹ′/>
<content type=ʹ′ʹ′application/vnd.starbucks+xmlʹ′ʹ′>
<product xmlns=ʹ′ʹ′http://schemas.starbucks.com/productʹ′ʹ′
href=ʹ′ʹ′http://starbucks.com/products/527ʹ′ʹ′>
<name>Fairtrade Roma Coffee Beans</name>
<size>1kg</size>
<price>10</price>
<currency>$</currency>
</product>
</content>
</entry>


RESTLET FRAMEWORK
Self-Descriptive Message [1]
@Get("xml")
public Representation get(){
String index = (String)getRequest().getAttributes().get("messageIndex");
String result = "";
try{
if(index != "" && index != null){
result = HelloBusiness.get(Integer.parseInt(index));
}else{
result = HelloBusiness.get();
}
}catch(NotFoundException e){
setStatus(Status.CLIENT_ERROR_NOT_FOUND);
("no item found", MediaType.TEXT_PLAIN);
}
}


RESTLET FRAMEWORK
Self-Descriptive Message [2]
<messages>
<request>GET : ALL</request>
<message>
<request>GET</request>
<value>Hello, World!</value>
</message>
<message>
<value>Halo, Dunia!</value>
</message>
<message>
<value>Apa Kabar?</value>
</message>
</messages>


UNIFORM INTERFACE
Hypermedia as The Engine of Application
State (HATEOAS) [1]

or
Hypermedia constraints


UNIFORM INTERFACE
Hypermedia Constraint [1]

• Inti dari Representational State Transfer
• Menyatukan informasi proses bisnis dalam
representasi resource


UNIFORM INTERFACE
explains why named as “representational state transfer”


UNIFORM INTERFACE
execution of business process

“Consumers in a hypermedia system cause state
transitions by visiting and manipulating resource
state. Interestingly, the application state changes that
result from a consumer driving a hypermedia system
resemble the execution of a business process. This
suggests that our services can advertise workﬂows
using hypermedia.” - Jim Webber - REST In Practice


UNIFORM INTERFACE
Best Practices

• Menambahkan informasi possible next states
langsung di dalam Representation
• Caranya (untuk saat ini) :
• possible next states ----> hyperlinks


UNIFORM INTERFACE
examples
<entry>
<order xmlns=ʹ′ʹ′http://schemas.starbucks.comʹ′ʹ′>
<location>takeAway</location>
<item>
<name>latte</name>
<quantity>1</quantity>
<milk>whole</milk>
<size>small</size>
</item>
<cost>2.0</cost>
<status>payment-expected</status>
<link rel=ʹ′ʹ′http://relations.restbucks.com/paymentʹ′ʹ′
href=ʹ′ʹ′https://restbucks.com/payment/1234ʹ′ʹ′/>
<link rel=ʹ′ʹ′http://relations.restbucks.com/special-offerʹ′ʹ′
href=ʹ′ʹ′http://restbucks.com/offers/cookie/1234ʹ′ʹ′/>
</entry>


UNIFORM INTERFACE
hypermedia support in MediaType

• Lebih baik jangan gunakan MediaType XML untuk
menambahkan hyperlinks di dalamnya.
• Tidak ada dukungan langsung (native link tag) untuk hyperlinks

• Gunakan Hypermedia Types (-Mike Amundsen)
• Contoh : Atom
• http://amundsen.com/hypermedia/

RESTLET FRAMEWORK
Hypermedia Constraints [1]

• Native support untuk mempermudah manajemen
hypermedia constraints terdapat pada Restlet
versi 2.1 (dalam pengembangan)
• Solusi : Tambahkan secara manual ! :D
• Solusi : Pakai versi 2.1 dengan resiko sendiri


CONTOH APLIKASI LAIN
SOCIAL COMMERCE [1]

• Indeks Aplikasi Memuat :

• Daftar Toko Online (dengan link masing-masing)

• Link ke User Proﬁle

• Link ke Pengaturan Toko Online milik user


SOCIAL COMMERCE [2]

• Masuk ke salah satu Toko Online (melalui link). Memuat :

• Proﬁl singkat penjual (dengan link ke proﬁl lengkap)

• Daftar Deskripsi Singkat Produk (dengan link masing-
masing untuk deskripsi lengkap)

• Link ke Indeks


SOCIAL COMMERCE [3]

• Lihat deskripsi lengkap produk (melalui link). Memuat :

• Informasi produk

• Link untuk memesan

• Link kembali ke Toko Online


SOCIAL COMMERCE [4]


SOCIAL COMMERCE [5]


SOCIAL COMMERCE [6]


SOCIAL COMMERCE [7]


THANK YOU !

QUESTION?


Rest dengan restlet

More Related Content

What's hot (18)

Viewers also liked (7)

Similar to Rest dengan restlet (20)

Recently uploaded (20)

Rest dengan restlet