The number of diverse web services that we use regularly is significantly increasing. Most of these services are managed by autonomous service providers. However it has become very difficult to get a unified view of this widespread data, which in all likelihood is substantially important to enterprises. A classical approach followed by the enterprises is to write applications using imperative languages making use of the web service API. Such an approach is not scalable and is difficult to maintain considering the ever-evolving web services landscape. This tutorial explores a semi-automated declarative approach to information extraction from the web services using a classical virtual data integration approach, namely mediation, that relies on a well-known query rewriting algorithm, namely the inverse-rules algorithm. It is targeted to audience from both industry as well as academia and requires a basic understanding of database principles and web technologies.