Please look at PipedInputStream/PipedOutputStream which should address
this use case.
On Mon, Aug 04, 2014 at 08:10:49PM -0400, Steve Kingsland wrote:
> My use case is:
>
> 1. the calling code is generating content in memory, and wants an
> OutputStream to write it to (currently it's going to disk);
>
> 2. the putBlob() method wants a btye[], InputStream, etc. that it can read
> from.
>
> My problem is that *both* parties want to control the transaction. Here is
> what my calling code looks like:
>
> OutputStream documentOutputStream = null;
> try {
> documentOutputStream = this.
> *documentResourceFactory.getDocumentOutputStream(documentPath);*
>
> renderAndWriteDocument(renderContext, documentOutputStream);
> }
> catch (IOException e) {
> ...
> }
> finally {
> Closeables.closeQuietly(documentOutputStream);
> }
>
> I'm trying to create an implementation of DocumentResourceFactory that
> returns an OutputStream for writing the document to an Object Store using
> jclouds, instead of writing it to the local file system. I guess a
> stream-based API isn't really supported for writing to object stores...
>
> In my case, the files are small enough that I'm OK buffering them in
> memory. So what I'm planning to do, if there are no better options, is to
> create an OutputStream implementation that buffers the file contents, and
> uploads it to the blob store when flush()/close() is called. But that
> doesn't sound great, so I'm hoping maybe someone else has a better idea?
>
>
>
> *Steve Kingsland*
>
> Senior Software Engineer
>
> *Opower * <http://www.opower.com/>
>
>
> *We’re hiring! See jobs here <http://www.opower.com/careers> *
>
>
> On Mon, Aug 4, 2014 at 7:53 PM, Andrew Gaul <[email protected]> wrote:
>
> > On Mon, Aug 04, 2014 at 04:39:15PM -0400, Steve Kingsland wrote:
> > > I'm trying to use jclouds to write to an S3-compatible object store
> > (Ceph),
> > > and I'd like to use an OutputStream to write the payload for a Blob. How
> > do
> > > I do this?
> > >
> > > I'm working on an existing system which uses a stream-based abstraction
> > > around all of the file I/O, that looks like this:
> > >
> > > public interface ResourceFactory {
> > > InputStream getInputStream(String resourcePath) throws IOException;
> > >
> > > OutputStream getOutputStream(String resourcePath) throws IOException;
> > > }
> > >
> > > I was able to implement getInputStream() for *reading* a blob from
> > jclouds,
> > > but I'm not sure how to return an OutputStream for *writing* a blob.
> > >
> > > I know this question has already been asked
> > > <https://groups.google.com/forum/#!topic/jclouds/F2pCt9i7TSg>, but it
> > seems
> > > like a common-enough use case that it shouldn't be terribly complicated
> > to
> > > implement. Can anyone provide suggestions for how to accomplish this?
> > >
> > > The best I could find is Payload#writeTo
> > > <
> > http://demobox.github.io/jclouds-maven-site-1.7.2/1.7.2/jclouds/apidocs/org/jclouds/io/WriteTo.html
> > >,
> > > which accepts an OutputStream but is @Deprecated. Thanks in advance!
> >
> > Steve, I am not sure I understand your use case. putBlob consumes an
> > input *source*, e.g., ByteSource or InputStream. Why do you want to
> > provide it an output *sink*, e.g., OutputStream? If you have a special
> > need, could you provide a custom implementation of ByteSource or
> > InputStream, or use PipedInputStream/PipedOutputStream if you really
> > must use an OutputStream?
> >
> > --
> > Andrew Gaul
> > http://gaul.org/
> >
--
Andrew Gaul
http://gaul.org/
