Patent Publication Number: US-2003229654-A1

Title: PDASync - a synching method between a PDA (Personal Digital Assistant) client or clients and a host computer supporting one-to-many and many-to-one database synchronization

Description:
BACKGROUND OF INVENTION  
       [0001] Radio-frequency (RF) is a very widely used method for providing real-time transfer of information between handheld devices and central computers. However, there are drawbacks. Without purchasing special equipment (repeaters, antennas, etc.), the signal range is not very long. Also, any environments which require the users to be on the road, for instance trucking, are not capable of employing RF solutions. Furthermore, RF signals are very prone to interference. If someone is working with a radio frequency device in such an inhospitable environment, there is a good chance that data will not reach its destination.  
       [0002] This situation can be avoided by employing a batch process, whereby data is stored on the handheld unit until the unit is docked into a cradle connected to a desktop or laptop computer via a serial or USB interface, or even through a wireless connection. Any data can then be synched back to the PC.  
       [0003] This invention employs batch processing to allow data incorporated locally on the handheld to be synched back to the database on the desktop/laptop. It accomplishes this by creating a table on the handheld which is a subset of a database table on the desktop. Only the fields which are needed by the handheld are included in the table. Data is written to a corresponding table on the PC, then a set of basic instructions is executed which moves data from this temporary table into the actual data table.  
       SUMMARY OF INVENTION  
       [0004] It is the object of this invention to allow a primary database, stored on a host computer (laptop device or desktop device) to be updated with information stored in a database on a handheld computer (PDA). The data on the handheld can be updated as well.  
       [0005] Please note: The secondary database is not of the same structure or type as the primary database. Therefore, PDASync will work with any database types. 
     
    
    
     DETAILED DESCRIPTION  
     [0006] The solution is based on having a local copy or a subset of the Host (Desktop/Server) database in the PDA. The Synch process should function based on the following:  
     [0007] 1. Host Sync program will keep track of tables that are read only for the PDA. Sync program will synch these tables from Host to PDA only.  
     [0008] 2. All database PDA operations will be written to a log file (table) as well as to the local database. Host Synch program will read the log file from the PDA and re-run it on its own database. That way there is no actual synchronization between the Host Tables and the PDA Tables. What there is a re-run of the PDA operations on the Host data base. The result is updated tables in the Host. After Host tables were updated, the Host will now update the PDA with one way Synch (any record that is different or missing will be re-written by the Host into the PDA, this is done by having a version column).  
     [0009] Collision can be handled automatically or by Admin. The Host will merge the Log file from the PDA to the Host Log file either by direct merge or by induced merge (via the re-run).  
     [0010] Terms and More Definitions:  
     [0011] Log file (table): The log file includes information of all fields (from all tables) that can be changed by the PDA plus a time stamp. Any operation that change a field or fields in the PDA will also add new entry to the log file and fill the value(s) of the changing fields in this new log file entry, in addition a time stamp value will populate this new entry, all other unchanged fields will remain blank (all blank fields are a signal to the Host not to change these fields).  
     [0012] Data type: Handling of more complex data as pictures, PDF, doc etc. can be done by saving them in a folder while the PDA database field will point to them. The type is not important, since the file name extension will indicate what program/function to use to open it. These fields will be saved as a files as follows: &lt;column_name&gt;.&lt;fieldname&gt;.&lt;type&gt;. For instance, if in the host we have a database named MyDB with a Table named Items an a column name Image with the value of a picture Mypicture,jpg then this will be stored in the PDA as: root\MyDB\Items\Image.Mypicture.jpg. The PDA will save the path for this in the corresponding field.  
     [0013] The host synch process will update these files from the host database to the PDA in a standard sync fashion (any file that have been changed will be replaced).