• Cloud Comments Off on Why not pick one of the “open” APIs instead of CDMI?

    There is a post by Jerry Huang , CEO of Gladinet on the problems with trying to be compatible with Amazon’s S3 API. Jerry suggest you look at OpenStack or a common library instead.
    Amazon’s API (as with any cloud vendor’s API) is a moving target for sure, but the main issue is that these APIs are under the change control of a single vendor. Doesn’t matter how “open” the API is (in terms of copyright license) because the vendor can change it to disadvantage a competitor. So if you are a competitor, you would be foolish to use that API as the only interface into your cloud. So what happens? Each cloud vendor releases their own “open” API – similar but slightly different (enough to get around copyright), almost always RESTful and pretty much they all do the same thing.
    So, you get the situation we have today with rapid proliferation of many different interfaces all pretty much the same. But that doesn’t help the poor clients. They have to code to N different interfaces to work with N different clouds. And since they are rapidly evolving, they have to keep up with all these API changes over time.
    The Cloud Storage standard CDMI does not have this problem. CDMI is under the change control of a standards body (SNIA) and accommodates requirements from all the cloud storage players in it’s standardization process. More importantly, it was developed under the SNIA IP policy to help prevent any of the specification author companies from gaming the spec with their Intellectual Property. Thus cloud vendors can pick up the CDMI specification and implement it with confidence. They don’t need to come up with their own API. CDMI also has a standard way to extend the specification for vendor specific functions that still allows for core compatibility with other vendors. Want to do versioning? There is an example vendor extension in CDMI that shows you how.
    From a client side point of view, Jerry also mentions common libraries. Jclouds is a good example of this (for Java). There also common libraries for other languages. While that can insulate a client from the many proliferating APIs, it’s a tough task to keep that library up to date with these APIs (just ask Adrian). The sooner the various cloud providers can implement the CDMI standard (even along-side of their existing ones), the sooner common libraries like Jclouds can just maintain a single adapter to a standard API.

  • Cloud Comments Off on Draft 1.0 Cloud Storage Specification Available

    The SNIA has released a final working draft of the Cloud Data Management Interface (CDMI) version 1.0. The folks that have put this specification together in record time include:

    Company – Individual
    Bycast Inc. – David Slik
    Cisco Systems – Mike Siefer
    Hitachi Data Systems – Eric Hibbard
    Iron Mountain – Chris Schwarzer
    NetApp Inc. – Alan Yoder
    NetApp Inc. – Lakshmi N. Bairavasundaram
    Olocity – Scott Baker
    Oracle – Mark Carlson
    QLogic – Hue Nguyen
    Individual – Rich Ramos

    Thanks as well for the comments from lots of folks outside of the SNIA. These have all been incorporated into this latest public review draft.

    The specification is now in front of the SNIA membership for a vote to become a SNIA Architecture industry standard. It will also become both a National (ANSI) and International (ISO) standard down the road.

    I have heard lots of FUD around standardization of cloud interfaces, including the notion that standards take “too long” and that they cannot evolve quickly enough to accommodate the rapid evolution of this new industry. The SNIA Cloud Storage TWG that created this specification was formed last April and has produced a robust 1.0 version of a cloud standard in less than a year – record time for a standards body.

    The CDMI standard is extensible by vendors to cover the complete functionality of their cloud and can also be “shrink to fit” for clouds that don’t have all the bells and whistles of the full specification. These extensions are expected to be candidates for future version of the specification as multiple vendors implement them.

    Storage and Cloud vendors who have putting off implementing CDMI until 1.0 was available, now no longer have an excuse! Customers of public and private clouds can now start asking their vendors to show adoption of the standard in their roadmaps. Tools and common API libraries can now proceed to add support for a standard cloud storage interface.

    To get the Draft 1.0 CDMI specification, go here:


  • Cloud Comments Off on SNIA Release new draft of Cloud Storage Standard

    The SNIA announced that version 0.9 of the Cloud Data Management Interface (CDMI) is available for download.

    This version incorporates comments received from the initial public review back in September, as well as some new features. One feature is the ability to access specific byte ranges of a data object. Another important feature is the ability to access specific metadata elements individually. These features will help reduce the bandwidth required to perform certain operations.

    We have also incorporated feedback suggesting better conformance to HTTP and the principles of REST. The document is easier to read and better explains the concept behind the interface. One of those is the notion of tagging the containers and data objects with Data System Metadata. Table 14 in chapter 16 now goes into much more detail on the various metadata tags that are standardized:


    By tagging a data object or container of data objects with this metadata, specific data requirements are expressed to the cloud. If the cloud provider can deploy data services to meet these requirements, they can charge more as a result, leading to cloud storage that is better than the typical “best effort” services offered today.

    For each of these elements, there is a corresponding “billed” value that the cloud provider supplies indicating how well the data requirement has been met. The better the service provided, the more they can charge as a result. This metadata is preserved in the serialized data format that is also standardized by CDMI so that as you move data from one cloud to another (Public<->Public, or Private<->Public), the data requirements can be interpreted interoperably by the new cloud.

    There are many other new features in this version of CDMI, including a new security writeup. Please download and review this version and provide feedback over the next month so we can have a robust version 1.0 early next year.


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