The use of diverse web services has simplified routine tasks but it has resulted in loss of direct control over the data. This shift from traditional self-controlled databases to heterogeneous, autonomous web services can be increasingly seen among small and medium scale enterprises. Enterprises depen- dent on web services require a generic approach to integrate with multiple web services. The classical mediation approach from the data integration field provides a uniform query interface to diverse data sources hiding the underlying heterogeneity, but its utilization with current generation web services API has several research and industrial challenges which will be described in this article.