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Matakuliah
Tahun
Versi
: T0206-Sistem Basisdata
: 2005
: 1.0/0.0
Minggu 12, Pertemuan 24
Web Technology and DBMSs
(Chapter 28.1-3, 3rd ed.)
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan
mahasiswa dapat dapat menjelaskan
penggunaan basisdata di dalam
lingkungan internet/web (C2)
2
Outline Materi
• Basics of Internet, Web, HTTP, HTML, URLs.
• Difference between two-tier and three-tier clientserver architecture.
• Advantages and disadvantages of Web as a
database platform.
• Approaches for integrating databases into Web
3
Introduction
• Web most popular and powerful
networked information system to date.
• As architecture of Web was designed
to be platform-independent, can
significantly lower deployment and
training costs.
• Organizations using Web as strategic
platform for innovative business
solutions, in effect becoming Webcentric.
4
Introduction
• Many Web sites today are file-based
where each Web document is stored in
separate file.
• For large sites, this can lead to significant
management problems.
• Also many Web sites now contain more
dynamic information, such as product and
pricing data.
• Maintaining such data in both a database
and in separate HTML files is problematic.
• Accessing database directly from Web
would be a better approach.
5
Internet
Worldwide
networks.
collection
of
interconnected
• Began in late ‘60s in ARPANET, a US DOD
project, investigating how to build networks
that could withstand partial outages.
• Starting with a few nodes, Internet estimated
to have over 100 million users in 1997, and
over 390 million users in over 100 countries in
2001.
• May be 640 million users of Web by year 2003.
• About 2.5 billion documents on Internet (550
billion if intranets/extranets included).
6
Intranet and Extranet
• Intranet - Web site or group of sites
belonging to an organization,
accessible only by members of that
organization.
• Extranet
- An intranet that is partially
accessible to authorized outsiders.
• Whereas intranet resides behind firewall
and is accessible only to people who
are members of same organization,
extranet provides various levels of
accessibility to outsiders.
7
eCommerce and eBusiness
• eCommerce - Customers can place and
pay for orders via the business’s Web site.
• eBusiness - Complete integration of
Internet
technology
into
economic
infrastructure of the business.
• Business-to-business transactions
reach $1.3 trillion by 2003.
may
• eCommerce may account for $3.2 trillion
in worldwide corporate revenue by 2003
and could represent 5% of sales in the
global economy.
8
The Web
Hypermedia-based system that provides a
simple ‘point and click’ means of
browsing information on the Internet
using hyperlinks.
• Information presented on Web pages,
which can contain text, graphics, pictures,
sound, and video.
• Can also contain hyperlinks to other Web
pages, which allow users to navigate in a
non-sequential way through information.
• Web documents written using HTML.
9
The Web
• Web consists of network of computers
that can act in two roles:
– as servers, providing information;
– as
clients
(browsers),
requesting
information.
• Protocol that governs exchange of
information between Web server and
browser is HTTP and locations within
documents identified as a URL.
• Much of Web’s success is due to its
simplicity and platform-independence.
10
Basic Components of Web
Environment
11
HyperText Transfer Protocol
(HTTP)
Protocol used to transfer Web pages
through Internet.
• Based on request-response paradigm:
Connection - Client establishes connection with
Web
server.
Request - Client sends request to Web server.
Response - Web server sends response (HTML
document) to client.
Close -
Connection closed by Web server.
12
HyperText
(HTTP)
Transfer
Protocol
• HTTP/1.0 is stateless protocol - each
connection is closed once server
provides response.
• This makes it difficult to support
concept of a session that is essential
to basic DBMS transactions.
13
HyperText Markup Language
(HTML)
Document formatting language used to
design most Web pages.
• A simple, yet powerful, platformindependent document language.
• HTML is an application of Standardized
Generalized Markup Language (SGML), a
system for defining structured document
types and markup languages to represent
instances of those document types.
14
HyperText Markup Language
(HTML)
15
HyperText Markup Language
(HTML)
16
Uniform Resource Locators
(URLs)
String of alphanumeric characters that
represents location or address of a resource
on Internet and how that resource should be
accessed.
• Defines
uniquely
where
documents
(resources) can be found.
• Uniform Resource Identifiers (URIs) - generic
set of all Internet resource names/addresses.
• Uniform
Resource
Names
(URNs)
persistent,
location-independent
name.
Relies on name lookup services.
17
Uniform
(URLs)
Resource
Locators
• URL consists of three basic parts:
– protocol used for the connection,
– host name,
– path name on host where resource stored.
• Can optionally specify:
– port through which connection to host should be
made,
– query string.
http://www.w3.org/Markup/MarkUp.html
18
Static and Dynamic Web Pages
• HTML document stored in file is static
Web page.
• Content of dynamic Web page is
generated each time it is accessed.
• Thus, dynamic Web page can:
– respond to user input from browser;
– be customized by and for each user.
• Requires hypertext to be generated by
servers.
• Need scripts that perform conversions
from different data formats into HTML
‘on-the-fly’.
19
Requirements for Web-DBMS
Integration
• Ability to access valuable corporate data
in a secure manner.
• Data- and vendor-independent
connectivity to allow freedom of choice
in DBMS selection.
• 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.
20
Requirements for Web-DBMS
Integration
• 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, and helps reduce applications
development costs.
21
Requirements for Web-DBMS
Integration
• Support for transactions that span
multiple HTTP requests.
• Support for session- and applicationbased authentication.
• Acceptable performance.
• Minimal administration overhead.
• Set of high-level productivity tools to
allow applications to be developed,
maintained, and deployed with relative
ease and speed.
22
Two-Tier Client-Server
Architecture
23
Three-Tier Client-Server
Architecture
• 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.
• By 1995, three layers proposed, each
potentially running on a different
platform.
24
Three-Tier Client-Server
Architecture
• 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.
– Maps quite naturally to Web environment.
25
Three-Tier Client-Server
Architecture
26
Advantages of Web-DBMS
Approach
•
•
•
•
•
•
•
•
•
DBMS advantages
Simplicity
Platform independence
Graphical User Interface
Standardization
Cross-platform support
Transparent network access
Scalable deployment
Innovation
27
Disadvantages of Web-DBMS
Approach
•
•
•
•
•
•
•
•
•
Reliability
Security
Cost
Scalability
Limited functionality of HTML
Statelessness
Bandwidth
Performance
Immaturity of development tools
28
Approaches to Integrating Web
and DBMSs
•
•
•
•
•
•
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.
• Oracle Internet Platform.
29