Solution design: Retrieving conversations


As part of a research project, I am required to collect the tweets that are part of a conversations among participating users. What is the best way to design a solution such that once the user grants the necessary permissions, the system should automatically start recording their tweets in a local database as a backend service.

What would be the components of this system?
How would these components interact with each other?
What is preferred language/technology for each of these components?