Web service discovery requires matching techniques for comparing and selecting web service descriptions based on user constraints. Semantic-based approaches achieve higher recall than other approaches (such as syntax-based approaches), because they employ ontological reasoning mechanisms to match syntactically heterogeneous descriptions. However, existing semantic-based approaches are not scalable as they perform an exhaustive search to locate composite services that conform to global constraints. This paper proposes a semantic-based matching technique that locates composite services. It relates attributes of services to a common attribute to ensure that they have the same scope. This enables the assigned values to be compared and evaluated against a given global constraint. Conforming composite services are located in polynomial time with a three-dimensional data structure that indexes services based on their types, attributes and the assigned values. Simulation results indicate that the proposed approach achieves higher recall than syntax-based approaches and is more scalable than existing semantic-based approaches.