—The last decade has witnessed a tremendous growth of web services as a major technology for sharing data, computing
resources, and programs on the web. With increasing adoption and presence of web services, designing novel approaches for efficient
and effective web service recommendation has become of paramount importance. Most existing web service discovery and
recommendation approaches focus on either perishing UDDI registries, or keyword-dominant web service search engines, which
possess many limitations such as poor recommendation performance and heavy dependence on correct and complex queries from
users. It would be desirable for a system to recommend web services that align with users’ interests without requiring the users to
explicitly specify queries. Recent research efforts on web service recommendation center on two prominent approaches: collaborative
filtering and content-based recommendation. Unfortunately, both approaches have some drawbacks, which restrict their applicability in
web service recommendation. In this paper, we propose a novel approach that unifies collaborative filtering and content-based
recommendations. In particular, our approach considers simultaneously both rating data (e.g., QoS) and semantic content data (e.g.,
functionalities) of web services using a probabilistic generative model. In our model, unobservable user preferences are represented by
introducing a set of latent variables, which can be statistically estimated. To verify the proposed approach, we conduct experiments
using 3,693 real-world web services. The experimental results show that our approach outperforms the state-of-the-art methods on
recommendation performance.