A first character string in a logic, wherein the logic is a rule which analyzes input text and extracts additional information used for the text analysis, used for the text analysis with a second character string which is different form the first character string is replaced using a mapping between the first character string and the second character string. The first character string being a character or a combination of characters in a logic. A first character string is searched for in a target document for the text analysis and the first character string, if found, is replaced with the second character string, using the mapping. The logic is sent after the replacement to a server computer. The target document after the replacement is sent to the server computer. A text analysis result for the target document after the replacement is received form the server computer.