How to get the conversation id/any unique id for each chat comes to servicenow

I am working in integrating one of our product with Servicenow on a chat runtime. 

So, for the purpose we need to know about the conversation id/ interaction id of each such chat going between the end user and agents. Is there any APIs from which I can directly get the data based on the application scope, queue name or any other input?

In which table do we store all the ongoing chats ?