In this paper we outlined the different challenges faced by autonomous Web Services. Furthermore, we showed how DAML-S tackles these challenges by providing the information that allows Web Services to connect and interact autonomously with little intervention from the programmers. Finally, we propose a Web Service architecture that takes advantage of DAML-S information to support automatic discovery and interaction between Web Services.
In our presentation and implementations we concentrated on the feasibility of using DAML-S for the interaction with Web services. While we showed that indeed it is possible to use DAML-S to control such interaction, we also show that to take full advantage of the power of DAML-S the Web service needs to incorporate a computational model that supports non-deterministic reasoning such as the HITAP planner. It is still an open question what compromises we need to make to lower the computational requirements and proceed with a simpler computational model.
In the demonstrations we presented, we naïvely assumed that Web services will negotiate agreements and strike deals. Ultimately, we assumed a world of perfectly honest Web services that deliver every time they receive an order, and that pay every time they receive goods. Such an ideal world does not correspond to reality. Ultimately, we will need to introduce notions like commitments and contracts to back the transaction with legal guarantees. Preconditions and effects of processes can be used to express contracts and commitments, for instance a precondition to the execution of a process is that may be that the receiver signs a contract, while the effect is a commitment to deliver goods by an established date. We are currently investigating these problems.