Integrating service description, discovery, and invocation functionalities presents several fundamental problems in the management of web services and is a basic problem for composing web services over a network. In this paper, we present the design of a system called "Semantic service, Wrapper, and Invocation Manager" (SSWiM) which provides these key functionalities. In particular, SSWiM manages ... [Show full abstract] storage of and queries over service descriptions in a service registry, wraps existing REST services with WSDL service interfaces, and supports for service invocation at run time. We describe WSDL services based on two levels of ontologies: a domain ontology for data sets and a service ontology for services. The input/output messages (data) and the functionality of a (WSDL) service are mapped to the domain ontology and the service ontology, respectively. We developed the data mapping methodology and the mapping algorithm. Service descriptions are registered in our service registry which supports a set of service discovery queries. The wrapper builder in SSWiM can generate WSDL services automatically from REST services so that services can be invoked uniformly in WSDL format.