1. A method for handling a user request for invoking a computer service through an Application Programming Interface, comprising: receiving by a computer an unstructured request from a client to use or invoke a computer service, wherein the unstructured request comprises natural language (NL) containing one or more NL components; performing by a computer natural language analysis on the unstructured request to extract one or more of the NL components; matching by a computer the one or more NL components to one or more elements of at least one Hyper Text Transfer Protocol signature-based structured Application Programming Interface (API), wherein each structured API corresponds to the corresponding computer service, and wherein each API element corresponds to a parameter or argument to invoke the corresponding service; constructing by a computer a structured API call by mapping the one or more extracted NL components to one or more of the API elements; and performing by a computer one or more operations selected from the group consisting of submitting the constructed structured API call to a corresponding computer service on behalf of the client, returning the constructed structured API call to the client, and returning a result from an invoked corresponding computer service to the requesting client.