Opening frontend session from api

Hi all,
can anybody advise me how should i open frontend session from an api?

could you describe your intention with couple more sentences?

well, after creation of a session from api, in this session cart should reside, and in this cart i add articles from api, but the checkout process remains from a frontend

I guess you want to import a list of articles into the cart: Just like this?:

yes, but thru api, not admin. i will recieve json with article data, and i have to put those articles in an cart. afterwards, user have all those articles when he is in a checkout process on the frontend

It’s not by admin. The customer himself can import the list in frontend. We have an extended version of it and can add a special list of articles over ids.

I also do not understand this issue too.