Server apparatuses, server control programs, and client apparatuses in a computer system

A server control program recorded in a recording medium for a computer system which causes drawing data created at a server apparatus to be transmitted to a client apparatus and displayed on its display screen, the server control program causing a computer of the server apparatus to function as

• a preceding drawing data storage unit which stores drawing data on the preceding screen transmitted to the client apparatus into a memory,
• a present drawing data storage control unit which stores drawing data on a created present screen into a memory;
• an area dividing unit which divides the drawing data stored in the memory into a plurality of drawing areas;
• a comparison decision unit which compares the present drawing data stored in the memory by the present drawing data storage control unit with the preceding drawing data stored in the memory by the preceding drawing data storage control unit for each of the drawing areas divided by the area dividing unit and determines whether there is a change in the preceding drawing data for each of the drawing areas in the present drawing data;
• and
• a transmission control unit which transmits drawing data on a drawing area determined to have a change by the comparison decision unit to the client apparatus, except for a drawing area of the present drawing data determined to have no change by the comparison decision unit.

A server apparatus for a computer system which causes drawing data created at a server apparatus to be transmitted to a client apparatus and displayed on its display screen, the server apparatus comprising:

• a hardware circuit which includes a preceding drawing data storage unit which stores drawing data on the preceding screen transferred to the client apparatus, a present drawing data storage unit which stores drawing data on a created present screen, an area dividing unit which divides the drawing data into a plurality of drawing areas, and a comparison decision unit which compares the present drawing data stored in the present drawing data storage unit with the preceding drawing data stored in the preceding drawing data storage unit for each of the drawing areas divided by the area dividing unit and determines whether there is a change in the preceding drawing data for each of the drawing areas in the present drawing data;
• a software program recorded in a recording medium which causes the computer of the server apparatus to function as an area dividing unit which divides the drawing data stored in the drawing data storage unit into a plurality of drawing areas, and a comparison decision unit which compares the present drawing data stored in the present drawing data storage unit with the preceding drawing data stored in the preceding drawing data storage unit for each of the drawing areas divided by the area dividing unit and determines whether there is a change in the preceding drawing data for each of the drawing areas in the present drawing data;
• and
• a transmission control unit which uses the comparison decision unit of the hardware circuit if the drawing area of the present drawing data stored in the present drawing data storage unit is larger than a preset area size and uses the comparison decision unit of the software program if the drawing area of the present drawing data is equal to or smaller than the preset area size to determine whether there is a change in the preceding drawing data in each of the drawing areas in the present drawing data and transmits to the client apparatus the drawing data in a drawing area determined to have a change, except for a drawing area of the present drawing data determined to have no change.

A server apparatus for a computer system which causes drawing data created at a server apparatus to be transmitted to a client apparatus and displayed on its display screen, the server apparatus comprising:

• a hardware circuit which includes a preceding drawing data storage unit which stores drawing data on the preceding screen transferred to the client apparatus, a present drawing data storage unit which stores drawing data on a created present screen, an area dividing unit which divides the drawing data into a plurality of drawing areas, and a comparison decision unit which compares the present drawing data stored in the present drawing data storage unit with the preceding drawing data stored in the preceding drawing data storage unit for each of the drawing areas divided by the area dividing unit and determines whether there is a change in the preceding drawing data for each of the drawing areas in the present drawing data;
• a software program recorded in a recording medium which causes the computer of the server apparatus to function as an area dividing unit which divides the drawing data stored in the drawing data storage unit into a plurality of drawing areas, and a comparison decision unit which compares the present drawing data stored in the present drawing data storage unit with the preceding drawing data stored in the preceding drawing data storage unit for each of the drawing areas divided by the area dividing unit and determines whether there is a change in the preceding drawing data for each of the drawing areas in the present drawing data;
• and
• a transmission control unit which uses the comparison decision unit of the hardware circuit if the number of drawing colors in the present drawing data stored in the present drawing data storage unit is larger than a preset number of colors and uses the comparison decision unit of the software program if the number of drawing colors in the present drawing data is equal to or smaller than the preset number of colors to determine whether there is a change in the preceding drawing data in each of the drawing areas in the present drawing area and transmits to the client apparatus the drawing data in a drawing area determined to have a change to the client apparatus, except for a drawing area of the present drawing data determined to have no change.

A server apparatus for a computer system which causes drawing data created at a server apparatus to be transmitted to a client apparatus and displayed on its display screen, the server apparatus comprising:

• a preceding drawing data storage unit which stores drawing data on the preceding screen transferred to the client apparatus;
• a present drawing data storage unit which stores drawing data on a created present screen;
• an area dividing unit which divides the drawing data into a plurality of drawing areas;
• a specific data replacing unit which compares the present drawing data stored in the present drawing data storage unit with the preceding drawing data stored in the preceding drawing data storage unit for each of the drawing areas divided by the area dividing unit and replaces the drawing data in an unchanged part of each of the drawing areas in the present drawing data with specific data;
• a compressing unit which compresses the drawing data in each of the drawing areas in the present drawing data after the specific data replacing unit has replaced the drawing data in the unchanged part with the specific data;
• a specific area sensing unit which detects a drawing area of the present drawing data where the drawing data has been replaced with the specific data by the specific data replacing unit;
• and
• a transmission control unit which transmits to the client apparatus the drawing data in each of the drawing areas in the present drawing data compressed by the compressing unit, except for the drawing data in the drawing area detected by the specific area sensing unit.

A server control program recorded in a recording medium for a computer system which causes drawing data created at a server apparatus to be transmitted to a client apparatus and displayed on its display screen, the server control program causing a computer of the server apparatus to function as

• a preceding drawing data storage unit which stores drawing data on the preceding screen transferred to the client apparatus into a memory,
• a present drawing data storage control unit which stores drawing data on a created present screen into a memory;
• an area dividing unit which divides the drawing data stored in the memory into a plurality of drawing areas;
• a specific data replacing unit which compares the present drawing data stored in the memory by the present drawing data storage unit with the preceding drawing data stored in the memory by the preceding drawing data storage unit for each of the drawing areas divided by the area dividing unit and replaces the drawing data in an unchanged part of each of the drawing areas in the present drawing data with specific data;
• a compression control unit which causes a compression circuit to compress the drawing data in each of the drawing areas in the present drawing data after the specific data replacing unit has replaced the drawing data in the unchanged part with the specific data;
• a specific area sensing unit which detects the drawing area of the present drawing data where the drawing data has been replaced with the specific data by the specific data replacing unit;
• and
• a transmission control unit which transmits to the client apparatus the drawing data in each of the drawing areas in the present drawing data compressed by the compression control unit, except for the drawing area detected by the specific area sensing unit.

A client apparatus for a computer system which causes drawing data created at a server apparatus to be received and displayed on its display screen, the client apparatus comprising:

• a compression/decompression unit which decompresses the compressed drawing data in a drawing area of the present drawing data received from the server apparatus;
• a pixel data decision unit which reads pixel data item by pixel data item the drawing data in the drawing area decompressed by the compressing/decompressing unit and determines whether the pixel data is specific data indicating that there is no change in the drawing;
• and
• a display update control unit which updates the display on the display screen according to pixel data other than the pixel data determined to be specific data by the pixel data decision unit.