The use case proposed to demostrate the application of RP to the event processing context is an example of sentiment analysis.
From the Wikipedia definition:
Sentiment analysis (also known as opinion mining) refers to the use of natural language processing, text analysis and computational linguistics to identify and extract subjective information in source materials.
The requirements the the application needs to satisfy are the following:
NB: This approach to sentiment analysis is for sure oversimplified and not correct at all, but in this thesis author's hopinion what really matters about this case study is not the correctness of the analysis method, but the application of the abstractions introduced in this thesis to solve problems.