Patent ID: 7581168

Claim:
A method for determining whether to reproduce a chart image from the contents of a spreadsheet application workbook on a server, comprising: calculating chart data for rendering a chart image from workbook data retrieved from the spreadsheet application workbook; generating an extensible markup language (XML) representation of the chaff data; generating a hash value from the generated XML representation of the chart data; caching the XML representation of the chart data and the generated hash value, wherein the hash value serves as a unique identifier for the chart data calculated from the spreadsheet application workbook; calculating an identifier for the XML representation of the chart data, wherein the identifier is calculated from the XML representation of the chaff data including chart series points and chart series point values within the XML representation of the chart data; comparing the calculated identifier to a previously stored identifier on the server; if the calculated identifier is equal to the previously stored identifier, then retrieving a previously produced chaff image based on the XML representation of the chart data from the server; if the calculated identifier is not equal to the previously stored identifier, then producing a chaff image from the XML representation of the chart data; and displaying the chart image in a web browser on a client computer.