opendap/src/main/java/ucar/nc2/dods/DODSNetcdfFile.java
public static String canonicalURL(String urlName)
  {
    if (urlName.startsWith("http:"))
      return "dods:" + urlName.substring(5);
    if (urlName.startsWith("https:"))
      return "dods:" + urlName.substring(6);
    return urlName;
  }
public static String canonicalURL(String urlName)
  {
    if (urlName.startsWith("http:"))
      return "dods:" + urlName.substring(5);
    if (urlName.startsWith("https:"))
      return "dods:" + urlName.substring(6);
    return urlName;
  }
Create the canonical form of the URL.
If the urlName starts with "http:" or "https:", change it to start with "dods:", otherwise
leave it alone.

@param urlName the url string
@return canonical form