We present a simple and uniform communication framework for an agent-based market infrastructure, the goal of which is to enable automation of consumer goods markets distributed over the Internet. The framework consists of an information model for participant interests and an interaction model that defines a basic vocabulary for advertising, searching, negotiating and settling deals. The information model is based on structured documents representing contracts and representations of constrained sets of contracts called interests. The interaction model is asynchronous message communication in a speech act based language, similar to, but simpler than, KQML [7] and FIPA ACL [8]. We also discuss integration of an agent-based market infrastructure with the web.