This paper proposes an SAMD(Synchronization Algorithms based on Message Digest)algorithm based on message digest in
order to facilitate data synchronization between a server-side database and a mobile database. The SAMD algorithm makes the
images at the server-side database and the mobile database uses message digest tables to compare two images in order to select
the rows needed for synchronization. If the two images are different, the synchronization progresses according to synchronization
policy. The SAMD algorithm does not use techniques that are dependent on specific database venders; neither does it use
triggers, stored procedures or timestamps. The SAMD uses only the standard SQL functions for the synchronization. Therefore
the SAMD algorithm can be used in any combinations of server-side database and mobile database because of its independence
of database vender. This feature is important in order to build efficient mobile business systems because the upcoming mobile
business environment has heterogeneous characteristics in which diverse mobile devices, mobile databases, and RDBMS exist.
INTRODUCTION
Recent advances in mobile technology and equipment haveled to the emergence of a new computing
environment and avariety of small sized mobile devices such as PDAs (personaldigital assistants), smart mobile
phones, HPCs (handheld PCs)and Pocket PCs have been popularized. As various networktechnologies are
increasingly being associated with suchmobile devices, the processing of business information can beavailable using
mobile devices. As a result, business modelsthat rely on mobile technologies are appeared .Mobile devices do not
have much computing power andrely on batteries. Additionally, constant access to network isdifficult due to narrow
bandwidth . Therefore, it is noteasy to process a large size of stored data and maintain acontinuous connection with
the server-side database. For thesereasons, mobile devices have mobile databases in order toachieve stable data
processing. Mobile devices downloadreplications of limited data from a connected server-sidedatabase using a
synchronization device that has a stable wirecommunication function. Mobile devices process various tasksusing the
data downloaded in an off-line state. The work onthe network disconnected condition is a crucial point formobility
support. In a disconnected environment, there areinevitable inconsistencies between the server-side databaseand the
mobile database. Synchronization techniques cansolve the data inconsistencies and guarantee the integrity ofthe
data. Consequently, synchronization is an essential subjectin mobile device computing environments.