Add on failure identification

Hi Experts,

We have developed some add on for our customer.Now my customer is asking if incase of any failure of add on we should block the transactions for SAP till the user reconnects the Add on

I tried to convince him that he will get system message when add on is not connected.But he stills says if the user ignores it he can post the wrong transactions to the system,

Please help in this regard

Thank You

Regards

Md.nazeer Shaikh