Pemrograman Jaringan: Pengenalan Java A R M I N L A W I P R O G R A M P A S C A S A R A J A N U N H A S

Pemrograman Jaringan: Pengenalan Java ARMIN LAWI PROGRAM PASCASARAJAN UNHAS

Pengenalan java 2

 Menerapkan compiler dan interpreter program.java

javac program.java

public class myCetak { public static void main(String args[]) { System.out.println(“Hello World!”); } }

compiler

11010101

java program

interprete r

program.class -------------------------------------------------------------------------------------------------------------------------------------------------------

bytecode

Karakteristik Multi-platform 3

program.java

program.class

public class myCetak { public static void main(String args[]) { System.out.println(“Hello World!”); } }

-------------------------------------------------------------------------------------------------------------------------------------------------------

interpreter

compiler

interpreter

interpreter

interpreter

JVM

Windows

Linux

Solaris

MacOS

Software yang dibutuhkan 4

 Java Standrd Edition (SE) Development Kit (JDK) Dapat didownload gratis di http://developers.sun.com/downloads/  JDK yang digunakan pada MK ini adalah versi terbaru saat ini: JDK1.6.0 update 10  Text Editor: Notepad, Edit, dll

Java IDE: Jcreator, Eclipse, NetBeans, dll

OOP dan Java 5

 Java adalah bahasa pemrograman murni berbasis

object-oriented (OO)  OOP: Program bekerja atas interaksi atau

komunikasi antar obyek (object interprocess)  OO-program dapat dipandang sebagai sistem

tersebar (distributed system)

Apa itu obyek? 6

 Segala sesuatu dapat dipandang sbg obyek  Karateristik obyek  Memiliki atribut sebagai status (state/variable)  Memiliki tingkah laku (behavior) atau method

variabel/ state

method/ behavior

Object model

Bagaimana membuat obyek 7

 Obyek dikonstruksi/dirancang dari prototipe atau

blueprint yang telah ditetapkan (class)  Contoh: resep  class kue  obyek Resep

Kue 1

Bahan: 1 kg gula 2 sdk mentega dan sterusnya. Cara Membuat: Campur semua lalu panaskan dan seterusnya

Kue 2

Contoh oop dalam java 8 class mhs { private String nama; private String nim; private String ttl; private String agama; public mhs(String nama, String nim, String m, String agama) { this.nama = nama; this.nim = nim; this.ttl = ttl; this.agama = agama; } public String getNama() { return this.nama; } public String getNim() { return nim; } public static void main(String args[]) { mhs m = new mhs(“Armin”, “132133693”, “19”, “Islam”); System.out.println(“Nama =“ + m.getNama()); }

}

variabel/ state konstruktor

method/ behavior

obyek m

Ciri-ciri oop 9

 Abstraksi (abstraction) Pengabstrakan atau penyembunyian kerumitan dari suatu proses  Pembungkusan (encapsulation) Abstraksi dilakukan dengan cara pembungkusan (kapsulasi) semua kode dan data kedalam satu entitas tunggal (obyek)  Pewarisan (inheritance) Implementasi khusus dalam OOP yang dapat menurunkan prilaku ke sub-class atau menerima prilaku dari super-class

 Kebanyak-rupaan (polymorphism) Kemampuan obyek mengungkap banyak hal melalui suatu cara yang sama. Obyek dapat menjalankan prilaku-prilaku atau metode-metode yang diturunkan dari beberapa superclassnya

Important Java Packages java.net TCP/IP networking java.io

I/O streams & utilities

java.rmi Remote Method Invocation

java.security Security policies java.lang

10

Threading classes

Netprog 2000 - Java Network Programming

Java Sockets Programming  Java uses BSD-style sockets to interface with TCP/IP

services (java.net package)  Java distinguishes between UDP, TCP server & TCP client sockets  Behind-the-scenes classes do the actual work & can be updated or swapped out transparently

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IP Addresses & Hostnames  java.net.InetAddress class

 Represents a single IP address  Factory class – no public constructor  Performs transparent DNS lookups or reverse

lookups  java.net.UnkownHostException thrown if DNS system can’t find IP address for specific host

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TCP Server Sockets  java.net.ServerSocket class

 Binds to a local port to listen for initial connections  Can be bound to a local IP for multi-homed

machines  accept() method returns a java.net.Socket, not an integer descriptor

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TCP Client Sockets  java.net.Socket class

 Combines socket with socket options (timeout,

linger, keep alive, no delay, etc)  Encapsulates a java.io.InputStream and a java.io.OutputStream – can be retrieved for use in a layered I/O system

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UDP Sockets  java.net.DatagramSocket class

 Java makes no distinction between client/server for

UDP sockets  Connected mode UDP supported in Java 2  Can be bound to both a local port & a local IP address – multi-homed support  Supports some socket options (timeout, buffer size)

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UDP Datagrams  java.net.DatagramPacket class

 Expects a byte array of data  Address optional for connected-mode UDP  This class is final – can’t be extended!  java.net.DatagramSocket instances can only

send instances of java.net.DatagramPacket

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Threading  Java doesn’t support the notion of forking

processes; how do we support concurrency?

– Java was designed to support multithreading! – In server environments we can spawn new threads to handle each client – Thread groups allow for collective control of many threads 17


Java Servlets  Servlets are the Java analog to CGI

 Advantages of servlets: full access to other Java APIs,

persistence between invocations, guaranteed portability  Servlets can be generic services or specific to HTTP

18


HTTP Servlets  javax.servlet.http.HttpServlet class  Uses HTTP to receive requests and generate

responses  Full support for all HTTP methods, cookies, sessions, persistent connections  Servlets can be chained – example: de-blink servlet

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Java Applets  Client-side Java programs that run in a browser

 Applets have special security restrictions called the

applet sandbox  Only applets loaded over the network are subject to the applet sandbox  The applet sandbox is controlled by a java.lang.SecurityManager

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Applet Sandbox  Can’t load libraries or define native methods  Can’t access local host filesystem

 Can’t open sockets to hosts other than

originating host  Can’t use Runtime.exec()  Applet windows have a unique appearance  Restricted access to certain system properties

21


Escaping the Applet Sandbox  Browsers can define their own security policy via a

new security manager  Applets can be signed and executed as trusted content  Security policies may vary from browser to browser, even for signed applets

22


Remote Method Invocation (RMI)  RMI is the Java analog to RPC

 RMI servers use a naming service (rmiregistry) to

register remote objects  RMI servers use a special security policy implemented by RMISecurityManager  The default RMI transport mechanism is via TCP sockets – this is transparent to RMI code!  Any object transferred in an RMI call must implement the Serializable interface

23


Java Naming & Directory Interface (JNDI)  JNDI provides a generic API that can be used to

interface with any naming system  JNDI uses SPIs (service provider interfaces) to access many different types of naming & directory services from the JNDI API  Sun supplies JNDI SPIs for LDAP, NIS, COS (CORBA naming), RMI registry & local filesystem

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Pemrograman Jaringan: Pengenalan Java A R M I N L A W I P R O G R A M P A S C A S A R A J A N U N H A S

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