Method of Replicating Data Between Computing Devices

Abstract

A system and method of replicating database records for use in resource constrained wireless computing devices. The replication method has a low processing burden and is well suited to low-bandwidth, unreliable connections found in many wireless networks. To reduce the amount of memory used on the wireless device only a change log record is time-stamped, not every database record. The change log defines what data is to be replicated and needs to sent to a main server that hosts a master copy of the database. The change log is made compact to reduce the amount of data that needs to be sent for data replication by only requiring the field that has changed in a record and a timestamp to be sent, not the entire record in which the change was made.

1 . A method of replicating data from computing devices, in which a first computing device is given responsibility for determining whether data received from a wireless, portable computing device over a wireless network is replicated or not; wherein the method comprises the steps of the wireless, portable computing device: 
 (a) generating a change log, the change log including data only for records that have changed;    (b) sending those change logs to the first computing device in order to replicate data in the change log in a master copy database running on the first computing device; and    (c) registering one or more metadata definitions with the first computing device said metadata definition defining how change logs relating to a new application will be presented by the wireless computing device, said metadata definition comprising a description of a property type used by said new application.    
     
     
         2 . The method of  claim 1  in which the change log comprises a time stamp that indicates the time a change to a record was made, the time being measured using a real time clock on the wireless computing device.  
     
     
         3 . The method of  claim 1  in which the change log only records changes to the field of a given record that has changed and not the entire record.  
     
     
         4 . The method of  claim 1  comprising the step of the change log recording only changes that have occurred since the last data replication between the wireless computing device and the first computing device.  
     
     
         5 . The method of  claim 1  comprising the step of the wireless computing device and the first computing device sharing metadata that defines the proper interpretation of the change log.  
     
     
         6 . The method of  claim 1  comprising the step of the change log being populated with data identifying the data that has been changed, how it was changed and when it was changed on the wireless computing device.  
     
     
         7 . The method of  claim 1  comprising the step of the change log being automatically sent by the wireless computing device to the first computing device without any user intervention.  
     
     
         8 . The method of  claim 1  comprising the step of the wireless computing device sending the change log automatically (a) at pre-defined periodic intervals, (b) at pre-defined times or (c) continuously whenever a change log is created.  
     
     
         9 . The method of  claim 1  comprising the step of the wireless computing device batching up multiple change logs.  
     
     
         10 . The method of  claim 9  comprising the step of the wireless computing device sending batched change logs at times which depend on the importance of the change log being rapidly processed by the first computing device, with low priority change logs being sent at times of lower network traffic.  
     
     
         11 . The method of  claim 1  comprising the step of the wireless computing device sending records in a change log at times which depend on the importance of the records being rapidly processed by the first computing device, with low priority records being sent at times of lower network traffic.  
     
     
         12 . A wireless, portable computing device programmed to send data to a first computing device over a wireless network, in order for the first computing device to replicate that data; wherein the device is programmed to: 
 (a) generate and store time stamps in a change log, the change log including data only for records that have changed;    (b) send those change logs to the first computing device in order to replicate data in the change log in a master copy database running on the first computing device; and    (c) register 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, said metadata definitions comprising a description of a property type used by said new application.