is it possible to connect to the a line desktop API and communicate through the line application?
No, you can't. There is no desktop API. You can only use messaging api and talk with other users using your bot. To send message to a spesific user, the user and your bot should be friend relationship. For more detail, see https://developers.line.biz/en/reference/messaging-api/#send-push-message.
Also, you should probably get channel access token via LINE Developer console site. It's neccessary to send message and pass auth. Plz take a look at the sites.
Thank you very mush ksyt. Looks like I will have to investigate bots more