service monitioring utility in ROS

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Hi, I am having some 10 services which are running continuously but next day some of these might be active and some of these might not be active , now i need to calculate the delta out of this in order to know exact name of active and inactive services so that based on this service registration and de-registration decision can be taken up .Apart from this i also want to keep on polling to roscore so that newly added service can be known on run time. Could you suggest any API/utility for the same?