Re: C: in ncml

Ethan Davis wrote:
> John Caron wrote:
> > Allowable forms of the referenced dataset location are:
> >
> >    * an absolute HTTP URL (eg http://server/myfile.nc)
> >    * An absolute file URL with an absolute path (eg 
> > file:/usr/local/data/mine.nc). You can sometimes omit the file: 
> > prefix, but not always, so we recommend using the file: prefix.
>
> What does that second  sentence above mean? Can we just drop that 
> sentence? As it is, seems like it will cause more confusion than it is 
> worth. Also, seems like it would conflict with the item two bullets down 
> (a URL relative to the NcML document base).
>
> Is it even a file URL if it doesn't have the "file:" prefix?

in the absence of a file prefix, i think it will try it as a file if all else fails. The 
C: interferes, since it makes it look like a URL with schema "C"

> >    * An absolute file URL with a relative path (eg file:data/mine.nc). 
> > The file will be opened reletive to the working directory.
>
> Is this a valid file URL? In Java I can get a URL and URI for this 
> string. But it fails when I try to get a File. I hate to document the 
> use of a form of file URL that isn't a good file URL.

im not sure if thats standard usage, since "file:" is particularly ill-defined 
("opaque"). Its quite useful when you want the NcML to refer to a file in the same 
directory.


> >    * A relative URL resolved against the NcML location (eg 
> > subdir/mydata.nc). You must not use a file: prefix in this case.
>
> Ethan

http://www.unidata.ucar.edu/software/netcdf-java/reference/DatasetUrls.html#NcML

has been modified. any further suggestions welcome