Sistem Basis Data Lanjut. Sistem Manajemen Basis Data Web

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Sistem Manajemen

Basis Data Web

Tim Penyusun :

Pengajar Universitas Gunadarma 2008

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Outline

• Web sebagai Platform Aplikasi

Basis Data

• Data semi terstruktur

• Pengenalan XML

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Internet

• Interconnected Networks

– Kumpulan dari jaringan komputer di seluruh dunia yg saling

ter-hubung via TCP(Transmission

Control Protocol), IP(Internet Protocol)

– TCP bertanggungjawab menjamin pengiriman pesan dari satu komputer dgn yg lain, secara benar.

– IP mengelola pengiriman dan

penerimaan paket data antara satu mesin dgn yg lain.

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Sejarah Internet

• Mulai dibangun pada thn 60an & 70an oleh Departemen Pertahanan AS.

– disebut ARPANET (Advanced

Research Projects Agency NETwork)

– Poyek membangun jaringan yg dapat menahan serangan secara fisik.

• 1982: TCP/IP diadopsi sebagai protocol standar untuk ARPANET

• 1986: proyek dipindahkan dari militer ke pemerintahan/universitas dengan dana

National Science Foundation

– Disebut NSFNET (National Science

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Intranet & Extranet

• Intranet : suatu web site atau kumpulan web site dari suatu

organisasi, yg dapat diakses hanya oleh anggota dari organisasi

tersebut (via firewall)

• Extranet : intranet yg dapat diakses sebagian oleh pengguna (diberi

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eCommerce & eBusiness

• eCommerce

Pelanggan dapat menempatkan & membayar pesanan via web site • eBusiness

Integrasi yg lengkap dari tehnologi internet ke dalam infrastruktur ekonomi bisnis

• Ecosystem

Proses bisnis secara keseluruhan

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Web

• Sistem berbasis hipermedia, yg menyediakan ‘point and click’ berarti browsing informasi pada internet menggunakan hyperlink

• Informasi pada halaman Web terdiri atas teks, grafik, gambar, & suara. • Terdapat pula hyperlink ke halaman

web lainnya, dimana pengguna dapat menelusuri dengan cara non-sekuensial melalui informasi.

• Dokumen2 web ditulis meng-gunakan HTML.

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Web (lanj.)

• Web terdiri atas jaringan komputer yg dpt berperan sebagai

– Server, menyediakan informasi;

Contoh, Apache HTTP Server, Microsoft Internet Information Server, Netscape Enterprise Server, WebLogic Server & NCSA HTTPd

– Client (browsers), memohon informasi.

Contoh, Microsoft Internet Explorer, Netscape Navigator & NCSA Mosaic

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Web (lanj.)

• Protocol yg mengatur pertukaran informasi antara server & browser web adalah HTTP

• Lokasi dengan dokumen2 diiden-tifikasikan sebagai URL.

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HyperText Transfer Protocol

(HTTP)

• Protokol yg digunakan untuk men-transfer halaman web melalui

internet.

• Berbasis paradigma

request-response :

– Connection - Client berkoneksi dengan

Web server.

– Request - Client mengirim permohonan ke web server.

– Response – web server mengirim respon (dokumen HTML) pada client. – Close - Koneksi ditutup oleh web

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MIME types

Multipurpose Internet Mail

Extensions

• Digunakan oleh HTTP header utk menentukan penanganan tipe

media yg multipel

• Contoh:

teks/html (dokumen html; *.html)

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HTTP Request

HTTP header mengindikasikan :

1. Tipe permohonan

– GET: mendapat sumber yg diminta

– POST: mentransfer data ke data yg

posted data pada sumber tertentu

– HEAD: sama seperti GET tapi hanya

mengembalikan HTTP header

– PUT (HTTP/1.1): upload sumber ke

server

– DELETE (HTTP/1.1): menghapus

sumber dari server

– OPTIONS (HTTP/1.1):memohon

pilihan konfigurasi server

2. Nama sumber 3. Versi HTTP

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HTTP Response

HTTP header mengindikasikan:

1. Versi HTTP 2. Status respon

3. Informasi utk mengontrol perilaku respon

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HyperText Markup Language

(HTML)

• Bahasa yg memformat dokumen

digunakan utk merancang halaman web.

• Bahasa yg sederhana, punya

kekuatan, bahasa dokumen yg tidak bergantung pada platform tertentu. • HTML merupakan aplikasi dari

Standardized Generalized Markup Language (SGML), sistem yg

mendefinisikan tipe dokumen yg terstruktur & markup language utk merepresentasikan instance2 dari tipe2 dokumen tsb.

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Uniform Resource Locators

(URLs)

• URL terdiri atas 3 bagian:

– protokol yg digunakan utk koneksi

– Nama host

– Nama path pada host dimana sumber disimpan.

• Can optionally specify:

– port through which connection to host should be made,

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Kebutuhan Untuk Integrasi

Web-DBMS

• Kemampuan utk mengakses data yg berharga dengan cara yg aman. • Konektivitas data & vendor yg tidak

bergantung sehingga terdapat

kebebasan untuk memilih DBMS. • Ability to interface to database

independent of any proprietary browser or Web server.

• Connectivity solution that takes

advantage of all the features of an organization’s DBMS.

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• Open architecture to allow

interoperability with a variety of systems and technologies. For example:

– different Web servers;

– Microsoft's (Distributed) Common Object

Model (DCOM/COM);

– CORBA/IIOP (Internet Inter-ORB protocol); – Java/Remote Method Invocation (RMI).

• Cost-effective solution that

allows for scalability, growth, and changes in strategic directions,

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Arsitektur

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Arsitektur

Three-Tier Client-Server

• Client side presented two

problems preventing true

scalability:

– ‘Fat’ client, requiring considerable resources on client’s computer to run effectively.

– Significant client side

administration overhead.

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• Advantages:

– ‘Thin’ client, requiring less expensive hardware.

– Application maintenance centralized.

– Easier to modify or replace one tier without affecting others.

– Separating business logic from database functions makes it easier to implement load balancing.

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Advantages of Web-DBMS

Approach

Web sebagai platform sistem basis data • DBMS advantages

• Simplicity

• Platform independence • Graphical User Interface • Standardization

• Cross-platform support

• Transparent network access • Scalable deployment

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Disadvantages of Web-DBMS

Approach

• Reliability • Security • Cost • Scalability • Limited functionality of HTML • Statelessness • Bandwidth • Performance

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Pendekatan2 Untuk

Mengintegrasikan Web &

SMBD

• Scripting Languages.

• Common Gateway Interface (CGI). • HTTP Cookies.

• Extending the Web Server.

• Java, JDBC, SQLJ, Servlets, and JSP.

• Microsoft Web Solution Platform: ASP and ADO.

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Scripting Languages

(JavaScript and VBScript)

• Scripting languages can be used to

extend browser and Web server with database functionality.

• As script code is embedded in HTML, it

is downloaded every time page is accessed.

• Updating browser is simply a matter of

changing Web document on server.

• Some popular scripting languages are:

JavaScript, VBScript, Perl, and PHP.

• They are interpreted languages, not

compiled, making it easy to create small applications.

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Common Gateway Interface

(CGI)

• Specification for transferring

information between a Web server and a CGI program.

• Server only intelligent enough to

send documents and to tell browser what kind of document it is.

• But server also knows how to launch other programs.

• When server sees that URL points to a program (script), it executes

script and sends back script’s output to browser as if it were a file.

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• CGI defines how scripts

communicate with Web servers. • A CGI script is any script designed

to accept and return data that

conforms to the CGI specification. • Before server launches script,

prepares number of environment variables representing current state of the server, who is requesting the information, and so on.

• Script picks this up and reads STDIN.

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• Then performs necessary

processing and writes its output to STDOUT.

• Script responsible for sending MIME header, which allows browser to

differentiate between components. • CGI scripts can be written in almost

any language, provided it supports reading and writing of an operating system’s environment variables.

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• CGI is the de facto standard

for interfacing Web servers

with external applications.

• Possibly most commonly

used method for interfacing

Web applications to data

sources.

• Advantages:

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Keuntungan CGI

• Communication between client and database server must always go through Web server.

• Lack of efficiency and transaction support, and difficulty validating

user input inherited from statelessness of HTTP protocol.

• HTTP never intended for long exchanges or interactivity.

• Server has to generate a new process or thread for each CGI script.

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HTTP Cookies

• Cookies can make CGI scripts more

interactive.

• Cookies are small text files stored on

Web client.

• CGI script creates cookie and has Web

server send it to client’s browser to store on hard disk.

• Later, when client revisits Web site and

uses a CGI script that requests this cookie, client’s browser sends information stored in the cookie.

• Cookies can be used to store

registration information or preferences (e.g. for virtual shopping cart).

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Referensi

1. Korth, H.; Database System Concept,

Mc Graw Hill, 4th edition, New York, 2002