How to Stop ongoing process

Question

im sending datas using resetful API..

 

for example im trying to send 500 datas.. so im getting those 500datas from database and storing in datatable.. and by using for-loop, sending row by row ... everything working fine..

 

but here my task .. i need to stop that process whenever i need,,

 

for example, currently 124th or 325th or 98th or any position.... data is runing in for-loop, so when i click on "stop" button, the for-loop should get break and stop sending data's...

 

how to stop the process??

 

my code   is running in server side .. i need to stop that..

 

i tried like, mainted one variable and validating that variable inside the for-loop, when the variable value is 0 it continue to run, if the variable value is 1 i want break the loop...

 

how to do that??