Question

I’ve got an asmx web service with the following method

    [WebMethod]
    public string LoadRegions(Guid id)
    {
        throw new NotImplementedException();
    }

When I attempt to call this method, I receive this exception:

System.InvalidOperationException: LoadRegions Web Service method 
name is not valid.
at System.Web.Services.Protocols.HttpServerProtocol.Initialize()

If I change the parameter type from Guid to, say, string, the problem disappears. Suggestions? For testing purposes, I’m calling the service with this url from Firefox:

http://localhost:81/services/ContactService.asmx/LoadRegions
?id=6C388126-5787-4B63-AAFE-5BCC4EA4DF83

Any suggestions?

Answer 1

I am trying to find formal documentation, but it appears that you cannot use a GUID as an input type on a WebMethod, because it is not something that can be validated on the way in. But I can’t find the exact documentation on it.

I would most likely leave it as a string parameter, and have the first line of your method do a Guid.Parse to validate that it is a GUID, if not, send the user an exception. This is the way I have seen it done in other implementations that require a GUID on a WebMethod.