I implemented a log file parser to catch messages when an user is (connected / disconnected) (to / from) an application running on the node. When an user is connected or disconnected, an event with the user id is generated.

What I would like to do now is to graph the number of connection to the application by using the parser and implement a kind of counter. When the parser catch the message that an user connects to the application, I would like to increment a counter and vice versa, when the parser catch the message that the same user disconnects from the application, I would like to decrement the counter. And after, I would like to graph this counter. For this, I need to get the last value of the counter, increment or decrement the value and store the new value.

I do not find the way how to do it. I am opened to all suggestions.

Thanks for your support.

Regards,

F.