Since we know already how to integrate any kind of Java code into the reactive flow, we are ready to start working with Twitter streams.

To monitor Twitter for tweets that are related to the stocks we are following, we will use the Twitter4J (available at http://twitter4j.org or https://github.com/yusuke/twitter4j) library. It's a pure Java solution that provides an interface to the Twitter API through Java.

Initially, we will transform the original Twitter4J API into an Observable compatible interface. Afterward, we will plug it into the existing flow where we are monitoring stock updates.

Finally, since it will contain new textual data, we will have to make modifications to the UI so that we can show the status updates from Twitter along with stock quotes.