The Experimentation Command and Control Interface (XC2I) project has developed an architecture for a Web-service based viewer/controller for use with distributed simulations supporting military experiments. As part of this activity, a capability for Interest Management with three functions is being created. The functions are Role-Based Access Control (RBAC), Area of Interest Management (AOIM), and Aggregation Interest Management (AGIM). While the approach is compatible with High Level Architecture (HLA) for Modeling and Simulation, primary information exchange takes place using the Web services, i.e. software-to-software messaging interfaces that operate over Web protocols such as XML/SOAP. This paper presents a Web Services Internet Management (WSIM) architecture designed to achieve these capabilities in a way that is compatible with simulations using the HLA. The protocols and information flow structure are described, along with the architecture's design rationale, interest management rules, and plans for its implementation. The paper concludes with a description of potential for future development of WSIM, including adoption of the Command and Control Information Exchange Data Model (C2IEDM) and use of Overlay Multicast for data distribution.