Data Management, Transaction Models and Enabling Technology for Mobile Commerce. In this discussion… Introduction Enabling Technology Data Management Transaction Models Query Processing Recovery. Introduction. E-commerce applications run on fixed, reliable networks.
Data Management, Transaction Models and Enabling Technology for Mobile Commerce
The WAP Architectureprovides a scalable and extensible environment for application development for mobile devices in wireless environment. Each layer of the architecture is accessible by the layers above, as well as by other applications and services
Fig 1: WAP Architecture
Wireless Application Environment (WAE):
Provides interface to build and run applications of wireless environment
Wireless Session Protocol (WSP):
Offers both connectionless and connection oriented services and Responsible for long-lived session state, sessions suspend and resume with session migration, reliable and unreliable data push.
Wireless Transaction Protocol (WTP):
Provides unreliable and reliable one-way and two-way requests and transactions, asynchronous transactions and data unit concatenation.
Wireless Transport Layer Security (WTLS):
Provides data integrity, privacy, authentication and protection to the upper layers.
Wireless Datagram Protocol (WDP):
Operates above the bearer services supported by the different networks and offers a consistent service to the upper layer protocols.
e.g. short message, circuit-switched data, and packet data.
GPRS (General Packet Radio Service)
Fig 2: GPRS Architecture
Table 1: GPRS Interfaces
3. Data Management
Global data management : network level issues such as location, addressing, replication, broadcasting etc.
Local data management: energy efficient data access management and query processing at the user level
Fig 3: Mobile database architecture
Data access management
Broadcast data organization is known as broadcast program or broadcast schedule.
Fig 4: Broadcast programs
Broadcast Disks: (Acharya et al) uses cyclic, non-flat dissemination architecture.
Data Indexing:Extra meta-data is added to data objects so that clients only need to selectively tune to broadcast channel to extract the desired data.
Data Replication and Consistency Management:
- reduces access time
- transparency of mobility
- selection of data and service stations
- updation of database
- consistency management
4. Transaction Models
Kangaroo Transaction Model(Dunham et al)
Fig 5: Kangaroo Transaction Model
Isolation-Only Transactions (Satyanarayan et al)
Two-tier Model(Gary et al)
Team Transaction model(Gore and Ghosh)
Fig 6: Team Transaction Model
Multi-database Transactions(Yeo and Zaslavsky)
Fig 7: Architecture of MDSTPM
Toggle Transactions(Dirckze and Gruenwald)
Fig 8: PRO-MOTION System Architecture
Table 2: Comparison of Transaction Models
5. Query Processing
Query By Icons(Antonio Massari)
Fig 9: QBI Architecture
Query Processing using Summary Databases(Madria et al)
Query Processing using Summary Databases(contd..)
Fig 10: Mobile Database Environment with Summary Databases
Recovery Protocols( M. M.Gore and R. K. Ghosh)
1.Timeout protocol: executed by MSS. MSS maintains a timer to measure the inactivity period of mobile host and initiates rollback for the transaction on timeout.
2.Disconnect protocol: executed by mobile host due to resource problems (like battery discharge, weak signal etc.).
3. Hand-off protocol: executed by mobile host, when it switches from one MSS to another MSS. Mobile host sends it’s new MSS address to the old MSS and conveys old MSS information to the new MSS while switching from cell to cell.
4. Migration protocol: In this protocol migration information and new settings of mobile host are communicated to the old MSS by the new MSS, before timeout or disconnect protocol execution at old MSS
Fig 11: Mobile Transaction Recovery Protocols
Recovery Guarantees(Martin and Krithi Ramamritham)