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Versions: 03 04 05                                                      
Network Working Group                                            S. Hole
Internet Draft: ACAP                                         A. Melnikov
                                                    MessagingDirect Ltd.
Document: draft-ietf-acap-option-03.txt                       April 2000
                                                     Expires in 6 months

                 ACAP Application Options Dataset Class

Status of this memo

     This document is an Internet-Draft and is in full conformance with
     all provisions of Section 10 of RFC2026.

     Internet-Drafts are working documents of the Internet Engineering
     Task Force (IETF), its areas, and its working groups.  Note that
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     A version of this draft document is intended for submission to the
     RFC editor as a Proposed Standard for the Internet Community.
     Discussion and suggestions for improvement are requested. This
     document will expire six months after publication.  Distribution of
     this draft is unlimited.

     Copyright Notice

         Copyright (C) The Internet Society 2000.  All Rights Reserved.

1. Introduction

     The Application Configuration Access Protocol (ACAP) is designed to
     support remote storage and access of application option,

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     configuration and preference information.  The generalized form of
     this runtime configuration is called "options".  Options consist of
     any type of structured or unstructured data that an application
     requires to operate in a user specific manner.

     Storage of application options in an ACAP server substantially
     solves the "kiosk user" problem for applications -- serial use of a
     single machine by multiple users.  It also solves the "nomadic
     user" problem -- use of more than one machine on a regular basis by
     a single user.

     The specification defines the "option" dataset class for use with

2. Conventions used in this document

     The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
     in this document are to be interpreted as described in [KEYWORDS].

     The attribute syntax specifications use the Augmented Backus-Naur
     Form (ABNF) notation as specified in [ABNF].

3. ACAP personal options

3.1. ACAP option representation

     Individual options are represented as ACAP entries in option
     datasets.  The name of the entry, as defined by the "entry"
     attribute for the entry, is the name of option.

3.2. Scalar options

     Scalar options are ACAP entries that contain simple (unstructured)
     data.  The "option.value" attribute of the entry contains the data
     for the option.  The value can be single or multivalued.

     Following is an example of a single and multivalued scalar option:

      entry = "color.preferred"
         option.value = "blue"
      entry = "color.list"
      option.value = ("red" "green" "blue" "cyan" "black")

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     Scalar options that are intended to be used by multiple applica-
     tions should be registered as defined in section 4.4.

3.3. Structured options

     Structured options are ACAP entries that contain multiple related
     items of data in a single option.  Data for the option is contained
     in multiple named attributes collectively called "field
     attributes".  Each field attribute can be single or multivalued.

     Following is an example of a structured option:

      entry = "color.definition"
      option.color.definition.name  = "blue"
      option.color.definition.rgb   = ("blue=255" "red=0" "green=0")
      option.color.definition.index = "66"

     By definition, structured options are application specific.  While
     the content of the field attributes can be obtained by any applica-
     tion, it's intended use is open to interpretation by the applica-

3.4. ACAP option hierarchy

     Option sets MAY be represented using ACAP hierarchy.  Any entry in
     an option dataset can also be a hierarchy node by setting the "sub-
     dataset" attribute.  Applications can model arbitrarily structured
     configuration information using hierarchical datasets containing
     scalar or structured options.  An option subdataset of scalar
     options models an associative list.  An option subdataset of struc-
     tured options models an array of structures.

3.5. ACAP option attribute formal syntax

     The naming conventions for option entry attributes is defined by
     the following ABNF.

   option-value-attr         = scalar-option-attr / structured-option-attr

   scalar-option-attr        = "option.value"

   structured-option-attr    = "option." name-component
                               1*("." name-component)

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4. ACAP option namespace

     The general ACAP namespace is organized to promote inheritance
     between site, host, group, and user specific configuration informa-
     tion, as defined in [ACAP].  It defines a "site", "group", "host",
     and "user" second level hierarchy.   The option dataset defines a
     third level of hierarchy that promotes inheritance from second
     level datasets, and isolates user and application specific
     instances of configuration information.

4.1. ACAP "/option" dataset class

     The dataset class whose name is "/option" is assumed to contain
     option datasets as defined in this specification.

4.2. Third level option datasets

     Third level option datasets break the option namespace into generic
     and application specific option sets.   This serves two purposes:
     to promote the creation and inheritance of common options between
     applications, and isolation of application specific configuration
     from other applications.

4.2.1. The "vendor" option namespace

     The "vendor" option namespace is a set of datasets, each named in
     the form "vendor.<vendor-name>", where "<vendor-name>" is the name
     of a specific application or application vendor.

     The entries in the vendor namespace enumerate the applications that
     make use of ACAP option storage at that level.  Each vendor dataset
     contains option entries and/or subdatasets for a specific vendor
     applications.  All options not in the "standard" namespace MUST be
     in one of the "vendor" option namespaces.

     The "vendor-name" for an application or vendor MUST be registered
     with IANA according to the rules in section 5.1.  The "ven-
     dor.x-<vendor-name>" namespace is reserved for temporary use by
     vendors during product development, or for local applications that
     are not generally distributed.

     Vendors are free to suballocate their namespace as they see fit.
     For example, a vendor may chose to store options for the various
     applications that it produces in subdatasets underneath their ven-
     dor namespace.  For example, the CoolStuff software company may

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     chose to organize the option namespace for their software products


     rather than try to register their application names as a vendor-
     name in the vendor namespace.

4.2.2. The "standard" option namespace

     The "standard" option namespace is a dataset named "standard" that
     contains option entries that are generally applicable to a number
     of applications. The namespace is reserved for shared options that
     do not meet the requirements for a separate ACAP dataset class.

     The standard option namespace is further partitioned into "standard
     option classes" where option names are of the form "<standard-
     option-class-prefix>.<option-name>". Standard option classes are
     associated with a class of applications, e.g. mail user agents. The
     "<standard-option-class-prefix>" is a registered string that
     uniquely identifies the option class, e.g. "mua".

     This document defines two standard option class prefixes - "common"
     and "X".  The "common" standard option class contains options that
     are generally applicable to a large number of application classes.
     For example, a default font or window background color.  The "X"
     namespace is reserved for temporary use by software developers dur-
     ing product development.

     Following are some examples of the standard option namespace:


     Option classes and names in the "standard" option namespace MUST be
     registered with IANA according to the rules in section 5.2.  Ven-
     dors MUST NOT use the temporary namespace in products that are gen-
     erally distributed.

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4.3. Example option namespace

     The following example demonstrates how the "standard" and "vendor"
     namespaces isolate application specific and standard configuration
     within the standard ACAP dataset namespace hierarchy.


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4.4.  Formal Syntax for the Option Dataset Namespace

     The naming conventions for the option dataset are defined by the
     standard ABNF in [ACAP] for dataset namespaces, constrained and/or
     extended by the following ABNF.

   dname-component  = 1*UTF8-CHAR
                     ;; MUST NOT begin with "." or contain "/"

   name-component   = 1*UTF8-CHAR
                     ;; MUST NOT contain ".", "/", "%", or "*"

   option-dataset   = "/option/" owner

   option-component = standard-component / vendor-component

   owner            = owner-site / owner-host / owner-group /
                      owner-user / "~/" option-component

   owner-group      = "group/" dname-component "/" option-component

   owner-host       = "host/" dname-component "/" option-component

   owner-site       = "site/" option-component

   owner-user       = "user/" dname-component "/" option-component

   standard-component = "standard/" standard-option-class "."
                      ;; The name-component MUST BE an IANA registered
                      ;; option name under the option class.

   standard-option-class = "common" / "X" / name-component
                      ;; The name-component MUST BE an IANA registered
                      ;; option class prefix.

   vendor-component = vendor-name "/" dname-component

   vendor-name      = vendor-token *("." name-component)

   vendor-token     = "vendor." name-component
                      ;; The name-component is the name of the
                      ;; application or vendor organization to which
                      ;; the options belong.

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5.  Namespace registration procedures

     Some portions of the ACAP option namespace are designed to be
     extensible within the standard.  The goals for extensibility
     include: (1) minimal process to extend the namespace within the
     standard, (2) promote interoperability within the namespace, and
     (3) support experimentation and development within the namespace.

     To support these requirements, the ACAP Option dataset draws on the
     recommendations for registration policies and procedures outlined

5.1.  Registering vendor names

     The "vendor" option namespace is specifically designed to support
     delegation of authority to individual organizations.  The goal is
     to provide a completely independent namespace for each application
     vendor.  The requirement is that each vendor namespace be uniquely
     associated with one and only one vendor or product.

     The "vendor" option namespace uses the identical registry as the
     "vendor" dataset class defined in [ACAP].  Organizations that wish
     to register a vendor name for the option namespace MUST follow the
     procedures outlined in [ACAP].

5.2.  Registering standard options

     The "standard" option namespace requires standardization procedures
     for two different types of object: standard option class prefixes
     and standard option names.

     Standard option class prefixes MUST be registered with IANA.  New
     option class proposals MUST be confirmed using IETF Consensus, pri-
     marily through consultation on the ACAP implementors mailing list.
     Registration of an option class MUST include a review contact that
     is responsible for approving registrations for option names regis-
     tered in the option class.  Registrations MUST provide the follow-
     ing information when requesting a new standard option class prefix.

       To: iana@iana.org
       Subject: Registration of ACAP standard option class

       Requested standard option class name: <option-class-name>
       Requested standard option class prefix: <option-class-prefix>
       Requested standard option class short description:

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       Approval contact: name, address, e-mail address, phone number
       # as many contacts as appropriate - must be at least one

     Standard option names MUST be registered with IANA using the Hier-
     archical Allocation model described in [IANA-CONSIDERATIONS].  All
     proposals MUST be reviewed and passed by the IANA registered con-
     tact for the option class prior to submission.  Discussion on new
     option name proposals on the ACAP implementors mailing list is
     strongly encouraged.  Registrations MUST provide the following
     information when requesting a new standard option name.

       To: iana@iana.org
       Subject: Registration of ACAP standard option

       Containing option class: <option-class-name>
       Requested option name: <option-class-prefix>.<option-name>
       Option short description:
       Value semantics: # any specific semantic restrictions placed
                          on the value of the option, e.g. URL,
                          integer, ...
       Value default: # a recommended default value for the option

6. Recommendations for standardization

     There are no absolute rules for when to register a set of standard
     options vs. defining a new dataset class.  In general, one can
     always register a standard option class and a set of option names
     under that class.  In some cases, it MAY be appropriate to define a
     new dataset class instead of registering a set of standard options.

     The key distinguishing feature of a dataset class definition is its
     documentation requirements.   Dataset class definitions specify the
     semantic relationships in the dataset class.   The semantic rela-
     tionships between subdatasets, entries and attributes are fully
     defined and part of the standard.

     If a set of standard options has any of the following characteris-
     tics, then it should be considered a candidate for a new dataset

     1. The option set consists of a list (array) of identically struc-
     tured options.  Proper representation of option sets of this type
     require a subdataset.  This is not prohibited by the standard
     option namespace, but the list relationship of the options needs to
     be documented.   This makes it appropriate for a new dataset class.

     2. Many or all of the options are semantically related or dependent
     on one another.   Individual options are incomplete, or not useful

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     unless evaluated in the context of the other options in the class.
     The relationship or dependencies cannot be documented by individual
     option registrations.

     3. The set of options are interpreted by applications with addi-
     tional semantic rules that apply to the set of options, and cannot
     be documented in the registration information for individual stan-
     dard options.

     In summary, any standard option set that has semantic relationships
     beyond a single option value is a candidate for a new dataset class
     definition.  Standard option sets SHOULD NOT be defined that have
     additional semantic rules outside those of the individual options.
     Standard option sets that acquire additional semantics over a
     period of time, SHOULD be redefined as a dataset class using the
     procedures and format outlined in [ACAP].

     Note that these considerations apply only to options in the "stan-
     dard" option namespace.  Semantic relationships in the vendor
     namespace are at the discretion of the vendor and are not consid-
     ered part of the extended standardization content of the ACAP
     option namespace.

7. Security Considerations

     It is important to make sure that access controls are set correctly
     on personal options.   Sensitive configuration information, includ-
     ing application security information, should not be exposed to
     other users without an explicit request by the user.

     This specification does not address storing private certificates
     and other security information in the option namespace.  This may
     be added to a future version of this specification when more exper-
     imentation has been done.

8. Acknowledgments

     Many thanks to the following people who have contributed to devel-
     opment of the option dataset class specification: Jack DeWinter,
     Rob Earhart, Ned Freed, Randy Gellens, John Meyers, Chris Newman,
     Lyndon Nerenberg, John-Paul Sicotte, Matt Wall and other partici-
     pants of the IETF ACAP working group.

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9. References

     [ABNF] Crocker, D., Overell, P., "Augmented BNF for Syntax Specifi-
     cations: ABNF", RFC 2234, November 1997


     [ACAP] Newman, C., Myers, J. G., "Application Configuration Access
     Protocol", RFC 2244, November 1997.


     [IANA-CONSIDERATIONS] Thomas Narten, Harald Tveit Alvestrand,
     "Guidelines for Writing an IANA Considerations Section in RFCs",
     RFC 2434, October 1998.


     [KEYWORDS] Bradner, S., "Key words for use in RFC to Indicate
     Requirement Levels", RFC 2119, March 1997.


10. Authors' Addresses

     Steve Hole

     Alexey Melnikov

     MessagingDirect Ltd.
     900 10117 - Jasper Ave.
     Edmonton, Alberta, T5J 1W8, CANADA

11. Full Copyright Statement

     Copyright (C) The Internet Society 2000.  All Rights Reserved.

     This document and translations of it may be copied and furnished to
     others, and derivative works that comment on or otherwise explain
     it or assist in its implementation may be prepared, copied, pub-
     lished and distributed, in whole or in part, without restriction of
     any kind, provided that the above copyright notice and this para-
     graph are included on all such copies and derivative works.  How-
     ever, this document itself may not be modified in any way, such as

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     by removing the copyright notice or references to the Internet
     Society or other Internet organizations, except as needed for the
     purpose of developing Internet standards in which case the proce-
     dures for copyrights defined in the Internet Standards process must
     be followed, or as required to translate it into languages other
     than English.

     The limited permissions granted above are perpetual and will not be
     revoked by the Internet Society or its successors or assigns.

     This document and the information contained herein is provided on

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