REZA LESMANAUniversitas Gunadarma

Saturday, February 5, 2011

RESTUsing Restlet Framework

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RESTRepresentational State Transfer

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WHAT IS REST?

GAYA ARSITEKTUR SOFTWARE UNTUK ARSITEKTUR APLIKASI BERBASIS JARINGAN

BASICALLYWEB SERVICES ARCHITECTURE

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WHY USE REST?UNIFORM INTERFACE

SEMUA KOMPONEN APLIKASI DALAM WEB SERVICES BERINTERAKSI DENGAN CARA YANG SAMA

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UNIFORM INTERFACEone of the feature of REST

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UNIFORM INTERFACEResource Identification [1]

RESOURCEinformasi yang dibutuhkan oleh user untuk

menjalankan proses bisnis dari suatu aplikasi

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UNIFORM INTERFACEResource Identification [2]

Uniform Resource Identifier (URI)

Contoh : HTTP URL

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UNIFORM INTERFACEResource Identification [3]

URI Template

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

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RESTLET FRAMEWORKapplication building block

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RESTLET FRAMEWORKservlet configuration (web.xml)

<!-- Application class name --> <context-param> <param-name>org.restlet.application</param-name> <param-value> com.helloworld.main.MainApplication </param-value> </context-param> <!-- Restlet adapter --> <servlet> <servlet-name>RestletServlet</servlet-name> <servlet-class> org.restlet.ext.servlet.ServerServlet </servlet-class> </servlet> <!-- Catch all requests --> <servlet-mapping> <servlet-name>RestletServlet</servlet-name> <url-pattern>/*</url-pattern> </servlet-mapping>

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UNIFORM INTERFACEResource Identification [4]

aplikasi penyimpanan pesan dalam stack

•Daftar Pesan --->

• Top of Stack --->

• Pesan Tunggal --->

• “/” ---> MessagesResource

• “/message/ ---> MessageResource

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

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RESTLET FRAMEWORKMainApplication

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; }}

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UNIFORM INTERFACEManipulation Through Representation [1]

REPRESENTATION

representasi dari resource

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RESTLET FRAMEWORKapplication building block

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UNIFORM INTERFACEManipulation Through Representation [2]

HTTP METHOD as Popular Practices

• HTTP POST --->

• HTTP GET --->

• HTTP PUT --->

• HTTP DELETE --->

•membuat Resource baru (Create)

•mendapatkan Resource (Read)

•mengubah Resource (Update)

•menghapus Resource (Delete)

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UNIFORM INTERFACEManipulation Through Representation [3]

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

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UNIFORM INTERFACEManipulation Through Representation [4]

Standardized Document Structure as Representation

• XHTML

• XML

• Atom Pub

•OData

•MPEG

•MP3

• AVI

• Text/Audio/Video Streaming

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UNIFORM INTERFACEManipulation Through Representation [5]

Not Only HTTP

TEXT/AUDIO/VIDEO STREAMINGContoh : VoIP

Using SIP or XMPP

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RESTLET FRAMEWORKMainApplication

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; }}

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RESTLET FRAMEWORKManipulation Through Representation [1]

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; }

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RESTLET FRAMEWORKManipulation Through Representation [2]

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

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RESTLET FRAMEWORKManipulation Through Representation [3]

@Put public Representation put(Representation entity){ StringRepresentation representation = null; String result = ""; try { result = HelloBusiness.update(entity.getText()); } catch (IOException e) { setStatus(Status.SERVER_ERROR_INTERNAL ); } representation = new StringRepresentation (result, MediaType.APPLICATION_XML); return representation; }

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RESTLET FRAMEWORKManipulation Through Representation [4]

@Delete public Representation delete(){ StringRepresentation representation = null; String result = ""; try { result = HelloBusiness.delete(); }catch(NoMoreItemException ne){ setStatus(Status.CLIENT_ERROR_FORBIDDEN); representation = new StringRepresentation ("Tidak boleh, udah kosong", MediaType.TEXT_PLAIN); return representation; } representation = new StringRepresentation (result, MediaType.APPLICATION_XML); return representation; }

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UNIFORM INTERFACESelf-Descriptive Messages [1]

TWO FACTORS

The Protocol MessageThe Media Type (Type of Representation)

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UNIFORM INTERFACESelf-Descriptive Messages [2]

The Protocol Message

•HTTP Header --> Content Negotiation

• Contoh : Accept : application/xml

•Status Respon :

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

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UNIFORM INTERFACESelf-Descriptive Messages [3]

The Media Type

•Struktur Dokumen Bisa Mudah Diolah

•Contoh :

•XML (application/xml)

•Atom Pub (application/atom+xml)

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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>

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<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>

Contoh MediaType Atom

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RESTLET FRAMEWORKSelf-Descriptive Message [1]

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

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RESTLET FRAMEWORKSelf-Descriptive Message [2]

<messages><request>GET : ALL</request><message> <request>GET</request> <value>Hello, World!</value> <link>/message/0</link></message><message> <request>GET</request> <value>Halo, Dunia!</value> <link>/message/1</link></message><message> <request>GET</request> <value>Apa Kabar?</value> <link>/message/2</link></message></messages>

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UNIFORM INTERFACEHypermedia as The Engine of Application

State (HATEOAS) [1]

orHypermedia constraints

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UNIFORM INTERFACEHypermedia Constraint [1]

• Inti dari Representational State Transfer

•Menyatukan informasi proses bisnis dalam representasi resource

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UNIFORM INTERFACEHypermedia Constraint [2]

explains why named as “representational state transfer”

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UNIFORM INTERFACEHypermedia Constraint [3]

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

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UNIFORM INTERFACEHypermedia Constraint [3]

Best Practices

•Menambahkan informasi possible next states langsung di dalam Representation

•Caranya (untuk saat ini) :

•possible next states ----> hyperlinks

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UNIFORM INTERFACEHypermedia Constraint [4]

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>

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UNIFORM INTERFACEHypermedia Constraint [5]

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/Saturday, February 5, 2011

RESTLET FRAMEWORKHypermedia 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

Saturday, February 5, 2011

CONTOH APLIKASI LAINSOCIAL COMMERCE [1]

• Indeks Aplikasi Memuat :

•Daftar Toko Online (dengan link masing-masing)

• Link ke User Profile

• Link ke Pengaturan Toko Online milik user

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CONTOH APLIKASI LAINSOCIAL 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

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CONTOH APLIKASI LAINSOCIAL COMMERCE [3]

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

• Informasi produk

• Link untuk memesan

• Link kembali ke Toko Online

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CONTOH APLIKASI LAINSOCIAL COMMERCE [4]

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CONTOH APLIKASI LAINSOCIAL COMMERCE [5]

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CONTOH APLIKASI LAINSOCIAL COMMERCE [6]

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CONTOH APLIKASI LAINSOCIAL COMMERCE [7]

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THANK YOU !

QUESTION?

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