There are many Twitter libraries, but as far as I know they require user authentication for use. I’m building an application for a single user, and the application should be able to automatically log in, so as to not make the owner have to walk over to the machine every day and every time the application restarts. The app should be able to post tweets on owner’s behalf.
EDIT: Found the perfect example: http://www.davidortinau.com/blog/create_a_twitter_oauth_application_with_tweetr_using_single_access_token/
The example only goes with read-level method, but by using access token with write permission I can post a tweet.