WWW Model
• The Internet WWW architecture provides a flexible and powerful programming
model.
• Applications and content are presented in standard data formats, and are browsed
by applications known as web browsers.
• The web browser is a network application, i.e., it sends requests for named data
objects to a network server and the network server responds with encoded data
using the standard formats.
The WWW standards specify several mechanisms necessary to build a general-purpose application environment which includes:
• Standard naming model.
– All servers and content on the WWW are named with an Internet-standard Uniform
Resource Locator ( URL ).
• Content typing.
– All content on the WWW is given a specific type, thereby allowing web browsers to
correctly process the content based on its type.
• Standard content formats.
– All web browsers support a set of standard content formats.
– These include (HTML), JavaScript scripting language (ECMAScript, JavaScript), and a large
number of other formats.
• Standard protocols.
– Standard networking protocols allow any web browser to communicate with any web server.
– The most commonly used protocol on the WWW is the HTTP.
– This infrastructure allows users to easily reach a large number of third party applications and
content services.
– It also allows application developers to easily create applications and content services for a
large community of clients.
The WWW protocols define three classes of servers:1. Origin server:
The server on which a given resource (content) resides or is to be created.
2. Proxy:
- An intermediary program that acts as both a server and a client for the purpose of making requests on
behalf of other clients.
- It resides between clients and servers that have no means of direct communication (e.g., across a
firewall).
- Requests are either serviced by a proxy program or passed on with possible translation to other servers.
- A proxy must implement both the client and the server requirements of WWW specifications.
3. Gateway:
- A server which acts as an intermediary for some other server.
- Unlike a proxy, a gateway receives requests as if it were the origin server for the requested resource.
- The requesting client may not be aware that it is communicating with a gateway.
The Internet Model:
• Here WWW client request a resource stored on a web server.
• On the Internet standard communication protocols, like HTTP and Transmission Control
Protocol/Internet Protocol (TCP/IP) are used.
• The content available at the web server may be static or dynamic.
• Static content is produced once and not changed or updated very often; for example, a
company presentation.
• Dynamic content is needed when the information provided by the service changes more often;
for example, timetables, news, stock quotes, and account information.
• Technologies such as Active Server Pages (ASP), Common Gateway Interface (CGI), and
Servlets allow content to be generated dynamically.
The WAP Model
• The WAP programming model is similar to the WWW programming model.
• Purpose of WAP:
To enable easy, fast delivery of relevant information and services to mobile users.
• Type of devices that use WAP:
Handheld digital wireless devices such as mobile phones, pagers, two-way radios, smart phones and
communicators -- from low-end to high-end.
• WAP works with most Wireless networks such as:
CDPD, CDMA, GSM, PDC, PHS, TDMA, FLEX, ReFLEX, iDEN, TETRA, DECT, DataTAC,
Mobitex.
The WAP Model
• WAP Gateway/Proxy is the entity that
connects the wireless domain with the
Internet.
• The request that is sent from the wireless
client to the WAP Gateway/Proxy uses the
Wireless Session Protocol (WSP).
• A mark-up language – It has been
adapted to develop optimized WAP
applications to save valuable bandwidth in
the wireless network, it can be encoded
into a compact binary format.
How WAP Model Works?
• The user selects an option on their mobile device that has a URL with Wireless Markup
language (WML) content assigned to it.
• The phone sends the URL request via the phone network to a WAP gateway using the binary
encoded WAP protocol.
• The gateway translates this WAP request into a conventional HTTP request for the specified
URL and sends it on to the Internet.
• The appropriate Web server picks up the HTTP request.
• The server processes the request just as it would any other request. If the URL refers to a static
WML file, the server delivers it. If a CGI script is requested, it is processed and the content
returned as usual.
How WAP Model Works?
• The Web server adds the HTTP header to the WML content and returns it to the gateway.
• The WAP gateway compiles the WML into binary form.
• The gateway then sends the WML response back to the phone.
• The phone receives the WML via the WAP protocol.
• The micro-browser processes the WML and displays the content on the screen.
WAP defines a set of standard components that enable communication between mobile terminals and network servers, including:
Standard naming model :
WWW-standard URLs are used to identify WAP content on origin servers. WWW-standard
URLs are used to identify local resources in a device (e.g., call control functions).
Content typing :
All WAP content is given a specifi c type consistent with WWW typing. This allows WAP
user agents to correctly process the content based on its type.
Standard content formats :
WAP content formats are based on WWW technology and include display markup,
calendar information, electronic business card objects, images, and scripting
language.
Standard protocols :
– WAP communication protocols enable the communication of browser requests from the mobile
terminal to the network web server.
– The WAP content types and protocols have been optimized for mass market, hand-held
wireless devices.
– WAP utilizes proxy technology to connect between the wireless domain and the WWW.
Hardware and Software Requirement:
• A web server with connection to the Internet
• A WML to develop WAP application
• A WAP simulator to test WAP application
• A WAP gateway
• A WAP phone for final testing.
USAGE
• Corporate Applications:
Sales force automation where sales people use their WAP enabled handsets to get instant,
direct access to the latest pricing, latest news, competitive information any time, anywhere.
• Online Services:
– Banking:
Users can get their current balance, transfer funds between accounts and receive
fax of a mini-statement.
– Electronic Commerce:
Subscribers can use their handset just like their PC to purchase products and
services over the Web.
• Tele services
- Prepaid Services:
With a WAP-enabled phone, prepaid subscribers can see their current balance with the press of a button
And can also recharge their account by entering a credit card or voucher number into the handset.
• Personal Productivity
Email: Using WAP users can keep track of their email right from their handset.
• Others include:
- Interactive Chat
- Auctions
- Games
Disadvantages:
• Small screens: For web phones, there's an incredibly small viewing area; palmtops are barely
better.
• Speed of access: All devices have slow access.
• Limited or fragmented availability: Wireless web access is sporadic in many areas and
entirely unavailable in other areas.
• Price: Many technology limitations are being addressed by higher-end devices and services.
But the entry price for a good wireless web palmtop with decent display, keyboard, and speed
is easily $700 to $900, not including monthly access.
• Lack of user habit: It takes some patience and overcoming the learning curve to get the hang
of it -- connecting, putting in an address, typing. Users just aren't used to the idea and protocol
yet.
Top Related