Re: Namespaces - questions

[Stefan Guggisberg <st...@gmail.com>]

On 2/28/07, Wolf Benz <eu...@gmail.com> wrote:
> Hi Stefan,
>
> 1/ It seems though, that the JR impl takes the spec a bit loosely...

since jackrabbit shares its code base with the official jsr 170 TCK
you may rest assured that jackrabbit doesn't 'take the spec a bit loosely'...

if you read the relevant sections of the specification carefully you'll
relalize that jackrabbit's implementation is absolutely compliant
with spec.

> if you read source like these 2 snippets:
> (snippet from Jackrabbit 1.2.2 -
> org.apache.jackrabbit.core.NamespaceRegistryImpl)
>
> Code: (you can't unregister a NS)
> ---------
> /**
>       * {@inheritDoc}
>       */
>      public void unregisterNamespace(String prefix)
>              throws NamespaceException,
> UnsupportedRepositoryOperationException,
>              AccessDeniedException, RepositoryException {
> ...
>          /**
>           * as we can't guarantee that there are no references to the
> specified
>           * namespace (in names of nodes/properties/node types etc.)
> we simply
>           * don't allow it.
>           */
>          throw new NamespaceException("unregistering namespaces is
> not supported.");
> ---------
>
> & The same goes for remapping: (presented as functionality that
> actually works...)
>
> Code: (you can't remap a NS)
> ---------
>   public void registerNamespace(String prefix, String uri) {
> ...
>
>       if (prefixToURI.containsKey(prefix)) {
>              /**
>               * prevent remapping of existing prefixes because this
> would in effect
>               * remove the previously assigned namespace;
>               * as we can't guarantee that there are no references to
> this namespace
>               * (in names of nodes/properties/node types etc.) we
> simply don't allow it.
>               */
>              throw new NamespaceException("failed to register
> namespace "
>                      + prefix + " -> " + uri
>                      + ": remapping existing prefixes is not
> supported.");
>          }
> ---------
>
> So... whhat do I have to think if this? (or do I miss smth?)

you do indeed, see my previous comment.

>
> 2/ Apart from that: what would then be the preferred place to put a
> custom CND file?
> In /workspaces/myworkspace/nodetypes  ?
>
> 3/ In reaction to text below from previous mail: the question was not
> why we had to write
> s.getRootNode().getNode("myapp:someNode"); // i.e. with the inclusion
> of the NS (I do get the concept of NSes :-)
>
> ... but why the prior and explicit need for a second
> "s.setNamespacePrefix("myapp", "http://your.com/ns/1");"
> as it is already registered at that point. (Is it really necessary
> within one app - fail to see why)

so do i. you only need to set your session prefix mappings if you want
to remap an already registered namespace to a different prefix in your
session.

cheers
stefan

>
>
>
> >
> > 2/ Why do you explicitely (again) do the
> > "s.setNamespacePrefix("myapp", "http://your.com/ns/1");" as you not
> > only registered the NS, but also provide the NS (myapp) in your call
> > on the next line: "s.getRootNode().getNode("myapp:someNode");"
> > Is it necessary?
>
> namespaces in JCR are modelled after XML namespaces. for more
> information
> please refer to sections 4.5 and 6.3 in the jsr 170 specification.
>
> cheers
> stefan
>
>