Crawling class announcements from University's eclass platform

I have a bot that is posting text into a chat. I want to check the announcements of the classes that I'm interested into and post the new ones in the chat via the bot.

The announcements are posted in an e-class web platform. There is no api available to interact with it. I have a registered student account that I use to login to the platform through the browser using a username and a password. As a user I can "join" classes and view class menus like announcements,lab schedules,project assignments etc.

The bot is written in ruby. Is my best shot a dirty web crawling approach where I work with html/css or is there some more polished way? Given that there is no api that is. Also ruby on rails is a better option here right? I have no experience with ruby on rails.