Title: An ObjectBased Architecture For WAPCompliant Application
1An Object-Based Architecture ForWAP-Compliant
Application
- ??Mario Cannataro Domenico Pascuzzi
- ??IEEE (JNL) / 2000
- ??? csshu
- ??2000/11/26
2Outline
- Abstract
- Introduction
- An architecture to deploy portable WAP-compliant
application - Future Work
3Abstract
- WAP suite have been developed, it lacks a
complete general architecture integrating
software components of both the Internet and
wireless contexts in a transparent way. - Presents a general architecture framework to
develop and deploy portable application and
services.
4Introduction
- Constrains of the wireless networks-Low
bandwidth-High latency-Unsteady
connection-High Transmission Bit Error
Rate-Low predictable services availability
5Introduction(CONT.)
- Constrains of the wireless terminals-Small, low
resolution display and limited user-input
facilities-Limited computational
resources-Many kinds of terminals
6Basic Component Of The WAP Framework
- µ browser
- Hosted by the mobile terminal.
- WAP gateway
- Allow the interworking operation between the
wireless network and others kinds of data
networks. - A layered stack of protocols
- Specific designed for wireless environments.
7The Development Of WAP-compliant Application
- Classical approach in developing WAP-compliant
Application comprises the following choices - Localisation of the application
- Content format(static or dynamic)
8Localisation
- A WAP application may be localised either on
- The WAP gateway
- WAP gateway acts as a server
- Realized the encode/decode function
- Host the static and dynamic WML content
- The Application Server
- WAP Gateway behaves as HTTP Proxy
- Apart from the encode/decode function, WAP
Gateway realizes protocol conversion - The application content can be coded in HTML or
WML
9Content Format
10An Architecture To Deploy Portable WAP Application
- The four layers(figure 1)
- User Layer
- A mobile terminal with a WML µ-browser
- Network Layer
- Represented by the WAP gateway which act as a
HTTP client - Application Layer
- Composed by the Application Server implementing
the business logic - Data Layer
- Composed by the DBMS server and the hosted
database
11An Architecture To Deploy Portable WAP
Application(2)
Figure 1. Architecture integrating WAP and WWW
12An Architecture To Deploy Portable WAP
Application(3)
Table 1. The Communication Interface between
adjacent layer
13An Architecture To Deploy Portable WAP
Application(4)
- In author design, the WAP gateway operates as
proxy whereas the Application Server is executed
on a different host have following advantages - To separate the WAP-based connectivity operations
by application implementation - To implement the application Server using open
standard object-based technologiesex Enterprise
JavaBeans - To provide an open and portable solution based on
the use of standard APIs
14An Architecture To Deploy Portable WAP
Application(5)
- The Application Server is comprised the following
layers - Servlets
- Manage the HTTP communication with the WAP
gateway - Care of the dynamic WML/HTML code generation
- Session Beans
- Manage the maintaining of the application state
15An Architecture To Deploy Portable WAP
Application(6)
- Entity Beans
- Encapsulate the data source and offer an
object-oriented interface to the data model - This layer access data via JDBC
- The Application layer (Figure 2.)
16An Architecture To Deploy Portable WAP
Application(7)
Web Container
EJB Container
J D B C
Seeion Beans
Servlets
WML HTML Static Contents
Entity Beans
WML/HTML generation
Session management Data access
EJB low level services(HTTP,..)
Figure 2. The Application Layer
17Object-based Approach
- In this architecture the development of a WAP
application comprises the following steps - Data model definition
- Mapping of the data model using entity beans
- Discovery and definition of the business rules
- Mapping the business rules using session beans
- Definition of the servlets for dynamic(WML/HTML)
code generation - Component compilation
- Application Deployment in the Application server
18Maintaining The State Of Wireless Application
Against Terminal Disconnections
- Static Session Identifier(SSI)
- It is used to identify a client and its current
session - SSI has the following features
- Uniqueness
- Temporal invariance
- Temporal validity
- Username is used as SSI in the proposed model
19Maintaining The State Of Wireless Application
Against Terminal Disconnections(CONT.)
- The proposed model consists of the following
components - An auxiliary database
- Used to store information about sessions and
state of the application - A Session Manager(SM) process
- Used to manage sessions and disconnections
20Auxiliary Database
- Comprised the Session table and State table
- Session table
- Keep trace of user sessions
- Contain the following attribute
- User username chosen by the user
- Date the date of creation/last access of the
session - URL storing the last URL invoked by client
21Auxiliary Database(CONT.)
- State table
- Store state variables, related to a specific user
session - ltparameter, valuegt
- The removal of a session causes the cascading
eliminating of all the state information related
to it
22Session Manager Process
- Independent of the application
- Offers a sets of session/state management
services accessible by APIs or class method - Session Manager primitives
- Table 2
23Session Manager Process(CONT.)
Table 2 Session manager primitives
24Session Manager Process(CONT.)
- Session Manager is involved
- During a connection(normal mode)
- After a client disconnection (recovery mode)
- SM manages session lifecycle which is based on
the use of two timers (Timer1, Timer2) with
associated timeout (Timeout1, Timerout2) see
figure 3
25Session Manager Process(CONT.)
Close
NEW
Operation
Destroy
ACTIVE
Reconnection ! Resume
Reconnection Resume
Timeout1
Suspend
Recovery
Destroy
Timeout2
SUSPENDED
REMOVED
Destroy
Figure 3. Session state transition diagram
26Implementation
- A system prototype for sales force automation has
been implementation. - Client
- Nokia 7110, Nokia WAP Toolkit
- Network Layer
- Nokia WAP Gateway
- Application Layer
- Java 2 Platform Enterprise Edition
- Data Layer
- SQLServer, Oracle DBMS
27Future Work
- To complete implementation of the Session
Manager - Development of rewriting techniques to simplify
the use of its functions
28References
- The demand for Mobile value-Added Service -----
Nokia White Paper - Wireless Application Protocol Architecture
Specification WAP Forum. - Wireless Application Environment Specification
- Thomas Enderes, Design and Implementation of a
Multiplexing Framework for the Wireless
Application Protocol, Tech. Rep., University of
Karlsruhe-Institute for Communication
Engineering, May 27, 1999 - Kyriacos Sabatakais, Marcel Zumbhl, Steffen
Krotsch, Mobile eCommerce - Juha Leppanen, Timo Laakko, Markuu Kylanpaa,
Prototype development for the WAP application,
VTT Information Technology, Finland