Method of replicating data between computing devices

Abstract

Resource constrained wireless computing devices (e.g. mobile telephones) are given a replication capability for database records (e.g. to enable backing up contacts, e-mails, photographs etc. onto a remote server). This operates without undue processing burden, using low bandwidth unreliable wireless connections. This is achieved by not including a time stamp in each database record, but instead time stamping only a change log record; this approach saves considerable memory space on the wireless device since there is no need to time stamp every database record, as is usually done in the prior art. The change log defines what data is to be replicated; it alone has to be sent to a main server which hosts a master copy of the database and hence has to be kept up to date. Because the change log is compact, far less data has to be sent for data replication purposes—typically only the field which has changed, how it was be changed and when it was changed on the wireless computing device. Prior art systems typically send an entire record, even though that will contain data that has not changed.

Description

FIELD OF THE INVENTION This invention relates to a method of replicating data between computing devices, particularly data from resource constrained wireless devices (i.e. devices with limited processing power and limited battery life) such as mobile telephones and personal organisers that are synchronising to and from a server over a wireless network. DESCRIPTION OF THE PRIOR ART Data replication between computing devices occurs in many different contexts, such as synchronising documents, e-mails, contacts and calendar entries across different computing devices used by the same person. In order for data replication to be accurate, there must be some system for deciding which of two or more inconsistent data replication requests should be acted on. Take for example the situation where, at time 1, a user enters a change to his e-mail details for person X on his mobile telephone. Some time later, at time 2, the user realises that those changes were in fact wrong. He makes a further ...

AI Technical Summary

Benefits of technology

Further, because the wireless, computing device registers new metadata definitions with the first computing device to define how change logs relating to a new application will be presented by the wireless computing device, there is no need for each change log to be self-describing (as XML bases systems would be); instead, a change log can in effect just be raw data, hence minimising bandwidth requirements.

Further, the change logs may include a time stamp indicating the time of a change; this a

Problems solved by technology

However, this results in records including a ‘null’ entry in the time stamp field to indicate that no change has been made to those records or in keeping the last time stamp even though it pre-dates a synchronisation to a server keeping a ma