• A Web service knows only about itself — not about its users, clients, or customers.
• Web services are not designed to use and reconcile ontologies among each other or with their clients.
• Web services are passive until invoked; they can't provide alerts or updates when new information becomes available.
• Web services do not cooperate with each other or self-organize, although they can be composed by external systems.
• getting information into the appropriate format;
• scaling Semantic Web technology to handle "Web size" data;
• creating, maintaining, and integrating ontologies;
• using the Semantic Web to describe and compose Web services;
• handling inconsistent data; and
• determining what to trust.