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Internet Engineering Task Force (IETF)                    K. Sankar, Ed.Request for Comments: 6208                                         CiscoCategory: Informational                                         A. JonesISSN: 2070-1721                                                     SNIA                                                              April 2011Cloud Data Management Interface (CDMI) Media TypesAbstract   This document describes several Internet media types defined for the   Cloud Data Management Interface (CDMI) by the Storage Networking   Industry Association (SNIA).  The media types are:   o  application/cdmi-object   o  application/cdmi-container   o  application/cdmi-domain   o  application/cdmi-capability   o  application/cdmi-queueStatus of This Memo   This document is not an Internet Standards Track specification; it is   published for informational purposes.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Not all documents   approved by the IESG are a candidate for any level of Internet   Standard; seeSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc6208.Sankar & Jones                Informational                     [Page 1]

RFC 6208                    CDMI Media Types                  April 2011Copyright Notice   Copyright (c) 2011 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (http://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Simplified BSD License text as described in Section 4.e of   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.Table of Contents1. Introduction ....................................................31.1. Requirements Language ......................................32. Cloud Data Management Domain and Its Relevance ..................33. Processing Guidelines ...........................................43.1. Media Type: application/cdmi-object ........................43.2. Media Type: application/cdmi-container .....................43.3. Media Type: application/cdmi-domain ........................53.4. Media Type: application/cdmi-capability ....................53.5. Media Type: application/cdmi-queue .........................54. Transport Considerations ........................................65. IANA Considerations .............................................65.1. Media Type: application/cdmi-object ........................65.2. Media Type: application/cdmi-container .....................75.3. Media Type: application/cdmi-domain ........................85.4. Media Type: application/cdmi-capability ....................95.5. Media Type: application/cdmi-queue ........................106. Security Considerations ........................................116.1. Confidentiality and Integrity .............................116.2. Access Control ............................................116.3. Audit .....................................................126.4. JSON Security Considerations ..............................126.5. Executable/Active Content .................................127. Acknowledgements ...............................................128. References .....................................................128.1. Normative References ......................................128.2. Informative References ....................................13Sankar & Jones                Informational                     [Page 2]

RFC 6208                    CDMI Media Types                  April 20111.  Introduction   The Cloud Data Management Interface (CDMI) [CDMI-1], developed by the   Storage Networking Industry Association (SNIA), is the functional   interface that applications will use to create, retrieve, update, and   delete data elements from the cloud.  As part of this interface, the   client will be able to discover the capabilities of the cloud storage   offering and use this interface to manage containers and the data   that is placed in them.  In addition, metadata can be set on   containers and their contained data elements through this interface.1.1.  Requirements Language   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described inRFC 2119 [RFC2119].2.  Cloud Data Management Domain and Its Relevance   A storage cloud is a storage service hosted either on premise or off   premise, across a network.  An important part of the cloud model, in   general, is the concept of a pool of resources that are drawn from,   on demand, in small increments (smaller than what one would typically   purchase by buying equipment).  By abstracting data storage behind a   set of service interfaces and delivering it on demand, a wide range   of actual offerings and implementations are possible.  The only type   of storage that is excluded from this definition is that which is   delivered based on fixed capacity increments rather than on demand.   The CDMI defines a set of functional interfaces (data paths) and   management interfaces (control paths) to create, retrieve, update,   and delete data elements from a storage cloud.  Another important   concept in this standard is that of metadata.  When managing large   amounts of data with differing requirements, metadata is a convenient   mechanism to express those requirements in such a way that underlying   data services can differentiate their treatment of the data to meet   those requirements.  CDMI also defines an extensible metadata system   for storage clouds.   As part of the CDMI interface, the client will be able to discover   the capabilities of the cloud storage offering and to use this   interface to manage containers and the data that is placed in them.   In addition, system metadata can be added to containers and their   contained data elements through this interface.Sankar & Jones                Informational                     [Page 3]

RFC 6208                    CDMI Media Types                  April 2011   The hierarchy that CDMI defines is as follows:   o  The basic element of storage is an object.   o  Objects are stored in a container hierarchy.   o  CDMI also defines an object, called a queue, which has special      properties for in-order, first-in, first-out creation and fetching      of queue objects, similar to a container of data objects.   o  A cloud offering can also support domains, which allow      administrative ownership to be associated with stored objects.      Domains can also be hierarchical, allowing for corporate domains      with multiple children domains for departments or individuals.      The domain concept is also used to map Access Control Lists (ACLs)      to principals as well as to aggregate usage data that is used to      bill, meter, and monitor cloud usage.  (Note: The CDMI "domain"      defined here is not a DNS domain name as specified in [RFC1076]      and [RFC1024]).   o  Finally, a capabilities resource and associated URI [RFC3986]      allows a client to discover the capabilities of the offering and      its implementation of CDMI.3.  Processing Guidelines   This section summarizes the processing of each media type.  This   document provides only the essential information.  The CDMI   specification [CDMI-1], which has more details and appropriate   examples, is the final authority on the processing aspects.3.1.  Media Type: application/cdmi-object   A CDMI object is the basic storage element in a CDMI system and is   analogous to a file within a filesystem.  The object is represented   in the CDMI interface in JavaScript Object Notation (JSON) format   [RFC4627].  (See the JSON web site at [JSON-1] for general   information about JSON).  Each data object has a set of well-defined   fields that includes a single value and optional metadata.  The   implementations are free to store the data in any form they choose,   but the application/cdmi-object SHOULD be represented in the CDMI   interface as defined inSection 8 of the CDMI specification [CDMI-1].3.2.  Media Type: application/cdmi-container   A container object is the fundamental grouping of stored data within   CDMI and is analogous to a directory within a filesystem.  Each   container has zero or more child objects and a set of well-definedSankar & Jones                Informational                     [Page 4]

RFC 6208                    CDMI Media Types                  April 2011   fields that includes standardized and custom metadata.  A container   can include other containers similar to sub-directories in a   filesystem.  The implementations are free to represent the container   in any form they choose, but the application/cdmi-container SHOULD be   represented in the CDMI interface as defined inSection 9 of the CDMI   specification [CDMI-1].3.3.  Media Type: application/cdmi-domain   Domain objects represent the concept of administrative ownership of   stored data within a CDMI storage system.  A CDMI offering may   include a hierarchy of domains that provide access to domain-related   information within a CDMI context.  This domain hierarchy is a series   of CDMI objects that correspond to parent and child domains, with   each domain corresponding to logical groupings of objects that are to   be managed together.Section 10 of the CDMI specification [CDMI-1]   details the information content, representation, and processing of   domain objects.3.4.  Media Type: application/cdmi-capability   Capability objects form a special class of container objects that   allows a CDMI client to discover what subset of the CDMI standard is   implemented by a CDMI provider.  For each URI in a CDMI system, the   set of interactions that the system is capable of performing against   that URI is described by the presence of named "capabilities".  Each   capability present for a given URI indicates what functionality the   cloud storage system will allow against that URI.  Capabilities are   always static.Section 12 of the CDMI specification [CDMI-1] details   the representation and processing of capability objects.3.5.  Media Type: application/cdmi-queue   Queues are a special class of container object and are used to   provide first-in, first-out access when storing and retrieving data.   A queue writer PUTs objects in the queue, and a queue reader GETs   objects from the queue, acknowledging the receipt of the last object   that it received.  Queuing provides a simple mechanism for one or   more writers to send data to a single reader in a reliable way.  If   queues are supported by the cloud storage system, cloud clients   create the queue objects by using the same mechanism used to create   data objects.Section 11 of the CDMI specification [CDMI-1] details   the operations and processing of queue objects.Sankar & Jones                Informational                     [Page 5]

RFC 6208                    CDMI Media Types                  April 20114.  Transport Considerations   The CDMI operates over HTTP [RFC2616] and does not make sense outside   the HTTP realm.  We do not expect the CDMI to operate over other   protocols nor to use a transport protocol, such as TCP [RFC793],   directly.5.  IANA Considerations   IANA has registered the following media types:   o  application/cdmi-object   o  application/cdmi-container   o  application/cdmi-domain   o  application/cdmi-capability   o  application/cdmi-queue5.1.  Media Type: application/cdmi-object   Type name: application   Subtype name: cdmi-object   Required parameters: none   Optional parameters: none   Encoding considerations: Assumes that the representation is always   UTF-8 as defined in [RFC3629] and 8bit as defined in [RFC4288]   Security considerations: SeeSection 6 of RFC 6208   Interoperability considerations: none   Published specification:RFC 6208   Applications that use this media type: Implementations of the Cloud   Data Management Interface (CDMI) defined by the Storage Networking   Industry Association (SNIA)Sankar & Jones                Informational                     [Page 6]

RFC 6208                    CDMI Media Types                  April 2011   Additional information:      Magic number(s): n/a      File extension(s): .cdmio      Macintosh file type code(s): TEXT   Person and email address to contact for further information:   Arnold Jones, arnold.jones@snia.org   Intended usage: COMMON   Restrictions on usage: none   Author: SNIA Cloud Storage Initiative, cloudtwg@snia.org   Change controller: SNIA Cloud Storage Initiative, cloudtwg@snia.org5.2.  Media Type: application/cdmi-container   Type name: application   Subtype name: cdmi-container   Required parameters: none   Optional parameters: none   Encoding considerations: Assumes that the representation is always   UTF-8 as defined in [RFC3629] and 8bit as defined in [RFC4288]   Security considerations: SeeSection 6 of RFC 6208   Interoperability considerations: none   Published specification:RFC 6208   Applications that use this media type: Implementations of the Cloud   Data Management Interface (CDMI) defined by the Storage Networking   Industry Association (SNIA)Sankar & Jones                Informational                     [Page 7]

RFC 6208                    CDMI Media Types                  April 2011   Additional information:      Magic number(s): n/a      File extension(s): .cdmic      Macintosh file type code(s): TEXT   Person and email address to contact for further information:   Arnold Jones, arnold.jones@snia.org   Intended usage: COMMON   Restrictions on usage: none   Author: SNIA Cloud Storage Initiative, cloudtwg@snia.org   Change controller: SNIA Cloud Storage Initiative, cloudtwg@snia.org5.3.  Media Type: application/cdmi-domain   Type name: application   Subtype name: cdmi-domain   Required parameters: none   Optional parameters: none   Encoding considerations: Assumes that the representation is always   UTF-8 as defined in [RFC3629] and 8bit as defined in [RFC4288]   Security considerations: SeeSection 6 of RFC 6208   Interoperability considerations: none   Published specification:RFC 6208   Applications that use this media type: Implementations of the Cloud   Data Management Interface (CDMI) defined by the Storage Networking   Industry Association (SNIA)Sankar & Jones                Informational                     [Page 8]

RFC 6208                    CDMI Media Types                  April 2011   Additional information:      Magic number(s): n/a      File extension(s): .cdmid      Macintosh file type code(s): TEXT   Person and email address to contact for further information:   Arnold Jones, arnold.jones@snia.org   Intended usage: COMMON   Restrictions on usage: none   Author: SNIA Cloud Storage Initiative, cloudtwg@snia.org   Change controller: SNIA Cloud Storage Initiative, cloudtwg@snia.org5.4.  Media Type: application/cdmi-capability   Type name: application   Subtype name: cdmi-capability   Required parameters: none   Optional parameters: none   Encoding considerations: Assumes that the representation is always   UTF-8 as defined in [RFC3629] and 8bit as defined in [RFC4288]   Security considerations: SeeSection 6 of RFC 6208   Interoperability considerations: none   Published specification:RFC 6208   Applications that use this media type: Implementations of the Cloud   Data Management Interface (CDMI) defined by the Storage Networking   Industry Association (SNIA)Sankar & Jones                Informational                     [Page 9]

RFC 6208                    CDMI Media Types                  April 2011   Additional information:      Magic number(s): n/a      File extension(s): .cdmia      Macintosh file type code(s): TEXT   Person and email address to contact for further information:   Arnold Jones, arnold.jones@snia.org   Intended usage: COMMON   Restrictions on usage: none   Author: SNIA Cloud Storage Initiative, cloudtwg@snia.org   Change controller: SNIA Cloud Storage Initiative, cloudtwg@snia.org5.5.  Media Type: application/cdmi-queue   Type name: application   Subtype name: cdmi-queue   Required parameters: none   Optional parameters: none   Encoding considerations: Assumes that the representation is always   UTF-8 as defined in [RFC3629] and 8bit as defined in [RFC4288]   Security considerations: SeeSection 6 of RFC 6208   Interoperability considerations: none   Published specification:RFC 6208   Applications that use this media type: Implementations of the Cloud   Data Management Interface (CDMI) defined by the Storage Networking   Industry Association (SNIA)Sankar & Jones                Informational                    [Page 10]

RFC 6208                    CDMI Media Types                  April 2011   Additional information:   Magic number(s): n/a      File extension(s): .cdmiq      Macintosh file type code(s): TEXT   Person and email address to contact for further information:   Arnold Jones, arnold.jones@snia.org   Intended usage: COMMON   Restrictions on usage: none   Author: SNIA Cloud Storage Initiative, cloudtwg@snia.org   Change controller: SNIA Cloud Storage Initiative, cloudtwg@snia.org6.  Security Considerations   This section was developed withRFC 3552 [RFC3552] as a guide.  CDMI   is an application interface and the relevant security considerations   include confidentiality, integrity, access control, and audit.   Transport and endpoint security artifacts like Distributed Denial of   Service (DDoS) are orthogonal, and domains like non-repudiation are   left to the application that employs this interface.6.1.  Confidentiality and Integrity   The confidentiality and integrity of the CDMI exchanges are   determined by the application that uses the interface.  CDMI does not   contain any specific mechanisms and relies on transport mechanisms   such as Transport Layer Security (TLS) (see [RFC2818]) for   confidentiality and integrity of the messages across the network.6.2.  Access Control   The access control of the CDMI endpoint URLs are beyond this   specification.  If required, applications should use appropriate URL   authentication and authorization techniques, such as URI routers for   different classes of users and restrict access based on URI origin.   For fine-grained control of the CDMI objects, the CDMI specification   [CDMI-1] contains the Access Control Lists (ACLs) and Access Control   Entries (ACEs).  These are described fully inSection 16.1 of the   CDMI specification [CDMI-1].Sankar & Jones                Informational                    [Page 11]

RFC 6208                    CDMI Media Types                  April 20116.3.  Audit   The CDMI specification [CDMI-1] has defined a set of metadata fields,   as explained inSection 16.3, to facilitate the incorporation of   access and other audit markers.  The CDMI metadata system is   extensible, and the implementations can add more metadata as required   by the security posture of the domain.6.4.  JSON Security Considerations   JSON-related security considerations, described inRFC 4627   [RFC4627], apply.6.5.  Executable/Active Content   The CDMI interface does not include any directives for active   content.7.  Acknowledgements   The authors wish to acknowledge the guidance and wisdom of Mark   Carlson and Peter Saint-Andre, comments from Patrick Faltstrom, and   all the insightful discussions and ideas of the SNIA CDMI Cloud   Technical Work Group.8.  References8.1.  Normative References   [CDMI-1]   SNIA, "Cloud Data Management Interface Version 1.0", 2010,              <http://www.snia.org/tech_activities/standards/curr_standards/cdmi>.   [JSON-1]   JSON, "Introducing JSON", 2006, <http://www.json.org>.   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext              Transfer Protocol -- HTTP/1.1",RFC 2616, June 1999.   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO              10646", STD 63,RFC 3629, November 2003.   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform              Resource Identifier (URI): Generic Syntax", STD 66,RFC3986, January 2005.Sankar & Jones                Informational                    [Page 12]

RFC 6208                    CDMI Media Types                  April 2011   [RFC4288]  Freed, N. and J. Klensin, "Media Type Specifications and              Registration Procedures",BCP 13,RFC 4288, December 2005.   [RFC4627]  Crockford, D., "The application/json Media Type for              JavaScript Object Notation (JSON)",RFC 4627, July 2006.8.2.  Informative References   [RFC793]   Postel, J., "Transmission Control Protocol", STD 7,RFC793, September 1981.   [RFC1024]  Partridge, C. and G. Trewitt, "HEMS variable definitions",RFC 1024, October 1987.   [RFC1076]  Trewitt, G. and C. Partridge, "HEMS monitoring and control              language",RFC 1076, November 1988.   [RFC2818]  Rescorla, E., "HTTP Over TLS",RFC 2818, May 2000.   [RFC3552]  Rescorla, E. and B. Korver, "Guidelines for Writing RFC              Text on Security Considerations",BCP 72,RFC 3552, July              2003.Authors' Addresses   Krishna Sankar (editor)   Cisco   170 W. Tasman Drive   San Jose, CA  95134   USA   Phone: (408) 853 8475   EMail: ksankar@cisco.com   Arnold Jones   SNIA   4410 ArrowsWest Drive   Colorado Springs, CO  80907   USA   Phone: (407) 574 7273   EMail: arnold.jones@snia.orgSankar & Jones                Informational                    [Page 13]