Towards a similarity-based web service discovery through soft constraint satisfaction problems

In this paper, we focus on the discovery process of Web Services (WSs) by basing the search on the similarities among the service requirements and candidate search results, in order to cope with over-constrained queries or to find satisfactory alternatives for user requirements. This discovery process needs to involve the so-called Soft Constraint Satisfaction Problems (SCSPs). First we represent both WSs and the search query of the user as Rooted Trees, i.e., a particular form of Conceptual Graphs. Then, we find a homomorphism between these two trees as a solution of an SCSP. The main contribution of this paper is the enhanced expressiveness offered by this "softness": in over-constrained scenarios, when a user query cannot be satisfied, classical crisp constraints (i.e., CSP) are not expressive enough to find "close" solutions to meet the users' needs.