In the prior art, a user bore a heavy burden on operating together different products having the same functions. A user 102 calls a job net managing function 105 via GUI/CLI 103, and defines a job net 106. A job net execution controlling function 109 interrupts a definition of the job net 106, and sequentially executes the defined jobs. The defined jobs call not real commands directly, but switchers 110 to 114 that define regularized interfaces. The switchers, referring to environment variables 101, select adaptors 115 and 116 properly to call real commands 117 and 118 corresponding thereto.