Internetware intends to be a paradigm of Web-based software development. At present, researches on Internetware have gained daily expanding attentions and interests. This paper proposes an agent based framework for Internetware computing. Four principles are presented that are followed by this framework. They are the autonomy principle, the abstract principle, the explicitness principle and the competence principle. Three types of agents with di?erent responsibilities are designed and specified. They are the capability providing agents, the capability planning agents and the capability consuming agents. In this sense, capability decomposition and satisfaction turns to be a key issue for this framework and becomes a communication protocol among these distributed and heterogenous agents. A capability conceptualization is proposed and based on the conceptualization, an agent coalition formation mechanism has been developed. This mechanism features that (1) all the participants make their one decisions on whether or not joining the coalition based on the capability realization pattern generated by the capability planning agents as well as the benefits they can obtain; and (2) the coalition selection is conducted by a negotiation process for satisfying the expectations of all the participants as the complexity of this problem has been proven to be NP-complete.