Pengantar Teknologi WEB

Pengantar Internet (HTTP)

LAN

•          LAN consists of the following components:

–        LAN file server is a repository of various software and data files for the network (optional)

–        Nodes are the client machines on the LAN

–        Wired or wireless communication media that connects the devices

•          LAN network interface card (NIC) is a special adapter that links an individual device to the communication medium and specifies:

–        The rate of data transmission;

–        The size of the message units;

–        Addressing information attached to each message

–        The network topology

WAN + WIRELESS

•          Wide area networks (WANs) are networks that cover large geographic areas.

–        WANs typically connect multiple LANs

–        WANs have large capacity and combine multiple channels (fiber optic, satellite, microwave, etc.)

–        WANs are provided by common carriers, such as telephone companies (Sprint, AT&T, etc.)

•          Wireless:

–        Wifi - simple wireless networks

–        WLAN - expanding the wireless connection

–        WiMax - Long-range wirelessWHAT IS INTERNET

WHAT IS INTERNET ?

INTERNET – EXTERNET

•          Intranet: is a private enterprise network for information gathering and distribution within an organization.

•          Extranet: is a community of interest created by extending an intranet to selected entities external to an organization.INTERNET

•          Inter-connections network

–        Memiliki bnyk sub network

–        Komputer yg berbeda-beda, media penghubung yg berbeda-beda = heterogen

•          Internet = hardware, WWW (web) = software

•          Beberapa komponen:

–        Router, client, server, modem, DNS, protocol, TCP/IP

•          Router: hardware yang mengatur jalur data sebuah paket (message)

•          Client: bagian yg meminta layanan ke server

•          Server: bagian yg melayani client (response)

•          Modem (modulator/demodulator):

–        Modulator merupakan bagian yang mengubah sinyal informasi kedalam sinyal pembawa (Carrier) dan siap untuk dikirimkan.

–        Demodulator adalah bagian yang memisahkan sinyal informasi (yang berisi data atau pesan) dari sinyal pembawa (carrier) yang diterima sehingga informasi tersebut dapat diterima dengan baik.

•          DNS : Domain Name Services

–        Mengasosiasikan setiap node (komputer) yg terhubung ke Internet dengan sebuah nama yg “human readable”

–        Mis: 202.134.201.137 => google.com

•          Protocol: aturan komunikasi data

•          TCP/IP: Transmission Control Protocol / Internet Protocol

–        Protocol untuk Internet

•          TCP: mengatur transmisi data

–        Data dibagi menjadi paket2 kecil (~1.5kb)

–        Paket tsb dikirim lwt router

•          IP: menerjemahkan aturan dari satu network ke network yg lain

–        Memungkinkan antar jaringan berbeda saling berkomunikasi

PENJELASAN

•          Protokol application layer: bertanggung jawab untuk menyediakan akses kepada aplikasi terhadap layanan jaringan TCP/IP.

•          Protokol host to network: berguna untuk membuat komunikasi menggunakan sesi koneksi yang bersifat connection-oriented atau broadcast yang bersifat connectionless.

•          Protokol lapisan network: bertanggung jawab untuk melakukan pemetaan (routing) dan enkapsulasi paket-paket data jaringan menjadi paket-paket IP.

•          Protokol lapisan physical: bertanggung jawab untuk meletakkan frame-frame jaringan di atas media jaringan yang digunakan.

DOMAIN

•          Adalah alamat permanen situs di dunia internet

•          Identifikasi sebuah situs  Istilah yang umum digunakan adalah URL.

               http://www.fppti.or.id

               http://www.ipi.or.id
               http://www.iwapi-jabar.or.id

GENERIC DOMAINS

Tata Nama

•          xxx.com : commercial                          

http://ujungkulonwild.com

•           xxx.edu : dunia pendidikan

http://www.upi.edu

•          xxx.ac.id : pendidikan

http://unsera.ac.id

•           xxx.go.id : pemerintahan

http://www.bantenprov.go.id

•          xxx.org :organisasi non profit

http://www.ujungkulon.org

CENTURY SPECIFIC DOMAIN

•          Berektensi dua huruf second level domain)

–        Indonesia  berekstensi  id

http://www.itb.ac.id

–        Australia au

http://nla.gov.au

–        Jepang berekstensi .jp  

http://www.jla.or.jp

•          Di Indonesia: dikenal dengan domain-co.id, .ac.id, .go.id, .mil.id, .or.id

Type OF WEBSITE

•          Portal Web site- www.yahoo.com

•          News Web site- www.cnn.com

•          Informational web site- www.smidec.gov.my

•          Business/ Marketing web site- www.kraft.com

•          Educational website- www.resepi.mesra.net

•          Entertainment web site- www.shockwave.com

•          Advocacy web site- www.hsus.org

•          Personal web site- www.ukm.my/radzuan

•          Blog

HTTP

•          Hypertext Transport Protocol (RFC 1945)

•          Tim Berners-Lee, 1991

•          Language of the Web

–        Protocol yang digunakan untuk komunikasi antara web browsers dan web servers

–        Since 1990

•          TCP port 80

•          Penyempurnaan HTTP 1.0 menjadi versi 1.1 dispesifikasikan oleh IETF dengan RFC 2616

•          HTTP merupakan implementasi dari protokol TCP

•          Bersifat “Stateless”

–        Tidak ada informasi yang disimpan

–        Solusi? Cookies & Session

•          HTTP bersifat request – response:

–        HTTP client (user agent misalnya) mengirimkan permintaan (request) ke HTTP server dan server meresponse sesuai request tersebut

•          User agent: Mozilla, Netscape, Microsoft Internet Explorer atau browser berbasis teks, Lynx atau links

•          Perbedaan mendasar antara HTTP/1.1 dengan HTTP/1.0 adalah penggunaan hubungan persistent.

•          HTTP/1.0 membuka satu koneksi untuk tiap permintaan URI

–        header = Connection: close

•          HTTP/1.1 dapat menggunakan sebuah koneksi TCP untuk beberapa permintaan URI (persistent)

–        header = Connection: Keep-Alive

kecuali jika client menyatakan tidak hendak menggunakan hubungan persistent (header = Connection: close).

HTTP CLIENT BROWSER

•          NCSA Mosaic (M. Andreesen)

•          Netscape Navigator (M. Andreesen)

•          Microsoft Internet Explorer

•          Browser Wars of the 1990's

•          Mozilla (Netscape Open Sourced)

•          Now Mozilla Firefox

•          Apple Safari (from Konqueror)

•          Others (Opera, Lynx)

Universal Resource Location (URL)

http://www.stanford.edu:80/class/cs193i/schedule.html 

Protocol (Scheme)

http://www.stanford.edu:80/class/cs193i/schedule.html

                Host Name

http://www.stanford.edu:80/class/cs193i/schedule.html

                                     Port

http://www.stanford.edu:80/class/cs193i/schedule.html

                                                               Path

URL PATH = FILE SYSTEM PATH

•          URL Path “/” maps to Document Root

•          Let’s say Document Root is C:\htdocs\

/ => C:\htdocs\

/images/ => C:\htdocs\images\

/a/X.html => C:\htdocs\a\X.html

HTTP 1.0 is Stateless

•          Each request/response pair uses its own connection; doesn't know about other pairs

•          "One-Shot"

–        Server Fulfills Request, and closes connection

+ Simple

─ Hard to design pages that are "logically connected" (e.g. Amazon checkout)

What is the URL path?

•          http://foo.com:8080/a/b/bar.html?hello.there#binky

•          query begins with ?

–        hello.there

•          fragment begins with #

–        binky

•          So, path is between host and query/fragment

–        /a/b/bar.html

•          But Request-Line includes Query

Fragment

•          Used by client side to scroll to named anchors

•          ...

•          http://foo.com/b.html#Chapter1

Request String

•          The path & query part of the URL

•          NOT the fragment part

•          http://foo.com/dir/b.html?info=extra&hello

–        /dir/b.html?info=extra&hello is the Request String

HTTP Request Messages

•          GET – retrieve document specified by URL

•          PUT – store specified document under given URL

•          HEAD – retrieve info. about document specified by URL

•          POST – give information (eg. annotation) to the server

•          DELETE – remove document specified  by URL

•          CONNECT – for use by caches

Example Request / Response

•          Client requests

                                http://solaria.stanford.edu/food/index.html

•          Client sends

GET /food/index.html HTTP/1.0\r\n\r\n

•          Server sees request with path /food/index.html

•          Server maps onto Document Root

G:/webroot + /food/index.html

•          Server sends back file over HTTP (e.g. HTML file)