Borland International, Inc.

Raymond S Kiuchi

Randolph T Solton

Conrad Herrmann

Peter Johnson

A client/server system providing methods of utilizing information stored locally on a client even after the client has modified data on the server is described. A client stores data from the server in a local 'read-only' buffer(s), to speed up access to the data and reduce network traffic. Since the buffer is treated as a 'read only' buffer, no locks are taken out at the server by the client. Accesses to particular data records are satisfied by looking first to the local buffer or cache. The client may proceed to modify the data records and commit changes back to the server. Moreover, the client updates or 'writes through' the 'read-only' buffer(s) with the changes so that the local buffer remains valid. The methods of updating data stored locally on the client provide significant performance increases as the client does not have to refresh data from the server.

System and methods for optimized access in a multi-user environment

A system of the present invention includes a server connected to one or more workstations or 'clients' through a computer network. Methods are provided whereby network data access operations, such as are common in shared data processing, are minimized to only those which are necessary for system operation. In all other instances (i.e., time periods when updating is not needed), a workstation may gain access to the data from a local copy stored in a local buffer, preferably a rapid-access memory of the client. At periodic intervals, a workstation is interrupted for marking its local copy of the data as 'invalid'--that is, the copy may be inconsistent with a corresponding version stored on the server. With the next access to the data, the local copy is updated from the version resident on the server. Additional optimization may be added for determining whether the server version has been 'touched' (i.e., changed) since last transferred to the local buffer, with the local copy being updated only when such a change has been detected. By maintaining data locally, the penalty incurred with frequent, large data transfers across a network connection is avoided.

System and methods are provided whereby screen write operations, such as common in data processing, are performed at a frequency matched to a user's ability to perceive such information. Specifically, screen writing operations are minimized to only those which are really necessary for perception by the user. In all other instances (i.e., time periods when updating is not needed), image information is written to rapid-access memory. At periodic intervals, the system is interrupted so that a display image (maintained in video memory) is updated from the image stored in the rapid-access memory. A screen device (CRT) coupled to the video memory is updated accordingly (upon the next scan of video memory). By maintaining image data locally, the penalty incurred with frequent, large data transfers to video or display memory is avoided.

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Santa Cruz, CA, United States of America

Raymond S Kiuchi