In an HTTP/1.1-compliant web service, the class of HTTP response status codes that indicates successful client requests is the 2xx class. These status codes signify that the client's request was successfully received, understood, and accepted by the web service. Common 2xx status codes include:

200 OK: The request was successful.

201 Created: The request was successful and a new resource was created.

202 Accepted: The request has been accepted for processing, but the processing is not yet complete.

Other status code classes like 3xx (redirection), 4xx (client errors), and 5xx (server errors) indicate different types of responses and do not signify successful request processing.

References

IETF RFC 2616: HTTP/1.1 Specification

HTTP Status Code Definitions