Hi Salvatore, On 04/11/13 13:58, Salvatore Pinto wrote:
The first proposed draft is attached. We would really appreciate your comments and maybe to add a point for discussion in the next WG meeting.
Thanks for posting the document. I haven't really gone through it in detail, so these are just some initial observations. First, it looks like you have inserted the word "Cloud" as a prefix to every class in the document. This isn't an extension, but a complete rewrite! Second, GLUE 2 contains extension points to allow communities to gain experience with new information without requiring the change of LDAP (or other) schemas on deployment machines. If you haven't already got operational experience of the cloud extensions then you really should consider using these extension points first. Third, some of the objects show no additional information beyond the existing GLUE 2.0 definitions; for example, the CloudStorageAccessProtocol seems identical (from memory) to the StorageAccessProtocol. Fourth, the inheritance model seems broken. Many classes show considerable overlap with their non-Cloud equivalents: CloudStorageServiceCapacity has TotalSize, FreeSize, etc, but also StoredObjects. As the cloud versions do not extend from the non-Cloud classes, a publishing system would have to publish twice as many objects (the Cloud ones and the non-Cloud ones). NB that inheritance isn't the solution to this problem; rather, you should have non-overlapping attributes. Fifth, have you considered what is current state-of-art within the cloud ecosystem? Talking specifically about storage, you should look at what already exists. In particular, CDMI provides a standards-based interface for interacting with cloud storage. It includes specific metadata about a storage system. I suggest you look at this metadata as a source of inspiration. NB. I'm NOT suggesting you copy all the metadata from CDMI into GLUE 2! Finally, please be careful that any additional publishing fits in with existing storage systems. Grid and cloud are not two mutually exclusive worlds; with dCache, for example, we have software where a single storage instance can provide both grid- and cloud-like storage. It should be possible for such systems to publish themselves without doubling the number of objects. HTH, Paul.