Can't make metadata working on OpenStack

[shortcut1337]

Hi, we are facing an issue we can't overcome.

We are developping a web app in php which has a document storage/management part using Node.js & OpenStack with pkgcloud library.

We've done the create/delete/copy.

What's left to do is to create a rename function and play with metadata.

For the renaming part, we are going to copy data with a new name (including children) and then deleting them. Our main concern is about using a transaction-like operation giving the fact we can't allow the operation to not run completly. All of them need to be copied & deleted or none of them.
Are transactions possible in PKGcloud ?

Concerning the metadata, how can we set metadata when we create the record for the first time ?
And for the update metadata afterwards, we are using the UpdateFileMetadata function which is returning the file with the metadata set in the callback function (function(err, file)) but it doesn't seems to store it in OpenStack.
When we query the file after we've set the metadata, metadata is still empty. The only moment we can see the file's metadata is in the callback file object from UpdateFileMetadata.
It looks like it does indeed modify the file's metadata the moment the script is running but doesn't store it correctly in OpenStack.

You will find part of our code attached to this message.
openstackUpdateMetaData.txt