Lorna Mitchell has posted the last article in her look at web services - a focus on status codes.
Unlike the other posts in this series, this one is quite specific to one type of service - REST - since it deals with status codes, specifically HTTP ones. The ideas are transferrable however and other types of service can return statuses in a similar way.
She mentions things to keep in mind in returning the codes, some of the more interesting codes as well as some typical situations where things like an error code 500 would be thrown.
Status codes are like a headline to the calling entity about what happened, and are a valuable tool in the web service toolkit.