[SalesForce] REST service in salesforce (FORBIDDEN)

I am writing a REST service in apex, and getting the below error message.

<Errors>
<Error>
<errorCode>FORBIDDEN</errorCode>
<message>
You do not have access to the Apex class named: JobOrderFeedXML
</message>
</Error>
</Errors>

Basically, below is my class structure.

@RestResource(urlMapping='/myFeedXML/*')
global class myFeedXML 
{
    @HttpGet
    global static void doGet() 
    {
        RestRequest req = RestContext.request;
        RestResponse res = RestContext.response;

        //generate xml
        .....

        res.addHeader('Content-Type', 'text/xml');
        res.responseBody = Blob.valueOf(xmlOutput);
    }
}

Anything wrong with the code?
Any input will be so helpful.

Best Answer

In the case of a Force.com Site the Apex class must be enabled on the special Guest profile associated with the site.

Setup > Develop > Sites > [your site label] > Public Access Settings > Enabled Apex Classes