Synchronization of Virtual Databases: A Case of Smartphone Contacts

The contact databases are stored and managed independently on different resources, hence contain inconsistencies. The inconsistencies are outcome of addition, modification and deletion of contacts. As contact database increases on daily basis, these inconsistencies also increase, and situation demands synchronization. The contact databases have simple structure (rows and columns) with simple data (tabular entries) thus there is a keen need to apply a simple solution (considering time and space complexity). This work proposes a Message Digest based user defined synchronization algorithm (UDSA). The proposed algorithm takes more than two inconsistent contact databases, one is local to the device and other from online source and synchronize them. The proposed algorithm compares the message digest values (of each row) to other database rows. After the message digest value comparison, the inconsistent rows are detected with the help of user defined data. The user defined data is embedded into the inconsistent rows. Final decision is taken according to the synchronization policy. The proposed algorithm does not depend on specific database vendors; also, does not use triggers, stored procedures or time stamps. Therefore, efficiency, extensibility, adaptability and flexibility are guaranteed when a mobile system is authorized. The proposed scheme is compared with state-of-the-art techniques in the literature and it is observed that the scheme is much better in terms of space and time complexities.