Hi,
Returning an empty input stream is not a good idea, as users wouldn't
have feedback about why that stream is empty. Probably an empty blob,
probably a blob that does not exist... An empty input stream does not
provide the right semantics so that the calling code knows what is
going on and what to do.
The same applies to a null return value. It makes sense for a standard
"get" method to return null to indicate a resource does not exist, but
when it comes to "get the resource contents" (which is what you do
when getting its InputStream), returning a null value does not provide
the right semantics. The calling code doesn't know if the resource
does not exist, if the resource exists but has no content, etc, and
will have to do the same existence checks anyway.
I think failing is the right thing to do there, although an NPE is not
the best exception to propagate. We should be propagating a
ResourceNotFoundException there.
>From a calling code perspective, a getBlog or blobExists call before
calling streamBlob looks like the right thing to do.
Regards,
I.
On Wed, 22 Aug 2018 at 11:34, Jean Helou <s...@byjean.eu> wrote:
>
> Hello,
>
> I am currently working on integrating JClouds to create a blobstore storage
> for apache james. I noticed that using
>
> blobStore.streamBlob("container", "wrongid");
>
> yields a NullPointerException when trying to access a blob which doesn't
> exist. The NPE is raised in RegionScopedSwiftBlobStore when the streamBlob
> method tries to read the blob metadata.
>
> I think it should null check and return null or an empty inputstream but not
> raise an NPE
>
> see
> https://github.com/jclouds/jclouds/blob/46759f8bda00f86ef934345846e22e2bd2b0d7ae/apis/openstack-swift/src/main/java/org/jclouds/openstack/swift/v1/blobstore/RegionScopedSwiftBlobStore.java#L691
>
> for now I work around by using
>
> blobStore.getBlob("container","id");
>
> doing the nullcheck myself and then getting the inputstream from the blob's
> payload.
>
> best regards,
> jean
>
