1. A program product, the program product comprising: computer readable media; and a converting mechanism stored on the computer readable media, the converting mechanism being applied to a business process integration system, the business process integration system being equipped with first and second information processing systems and a message switching system, the business process integration system exchanging a plurality of messages between the first and the second information processing systems through the message switching system in the performance of an implicit business process, said implicit business process being a process which is performed by at least one legacy application not managed by a workflow system, each message of said plurality of messages exchanged between the first and second information processing systems through the message switching system being generated by said at least one legacy application to perform a function in relation to a respective task in said implicit business process; wherein said converting mechanism monitors execution of said implicit business process for occurrences of messages of said plurality of messages, said converting mechanism monitoring execution by a process separate from said at least one legacy application and without modification to said at least one legacy application, and responsive to each occurrence of a message of said plurality of messages detected by monitoring execution of said implicit business process, generates a respective event in a progress model of said implicit business process, the respective event being of a type associated with the message said converting mechanism generating a respective event in a progress model of said implicit business process a process separate from said at least one legacy application and without modification to said at least one legacy application; and a judging mechanism also stored on the computer readable media, the judging mechanism being used for judging the progress of the business process based on said events generated in said progress model.