Internet DRAFT - draft-birrane-dtn-ari
draft-birrane-dtn-ari
Delay-Tolerant Networking E.J. Birrane
Internet-Draft E.A. Annis
Intended status: Standards Track B. Sipos
Expires: 13 September 2023 JHU/APL
12 March 2023
Asynchronous Resource Identifier
draft-birrane-dtn-ari-01
Abstract
This document defines the structure, format, and features of the
naming scheme for the objects defined in the Delay-Tolerant
Networking (DTN) Application Data Model (ADM), in support of
challenged network management solutions described in the Delay-
Tolerant Networking Autonomous Management Architecture (AMA).
This document defines a new Asynchronous Resource Identifier (ARI),
based on the structure of a common URI, meeting the needs for a
concise, typed, parameterized, and hierarchically organized set of
data elements.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
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This Internet-Draft will expire on 13 September 2023.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
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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 Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Use of ABNF . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Use of CDDL . . . . . . . . . . . . . . . . . . . . . . . 5
1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
2. ARI Purpose . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Resource Parameterization . . . . . . . . . . . . . . . . 7
2.2. Compressible Structure . . . . . . . . . . . . . . . . . 7
2.2.1. Enumerated Path Segments . . . . . . . . . . . . . . 8
2.2.2. Relative Paths . . . . . . . . . . . . . . . . . . . 8
2.2.3. Patterning . . . . . . . . . . . . . . . . . . . . . 8
3. ARI Logical Structure . . . . . . . . . . . . . . . . . . . . 8
3.1. Names, Enumerations, Comparisons, and
Canonicalizations . . . . . . . . . . . . . . . . . . . . 9
3.2. Literals . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3. Object References . . . . . . . . . . . . . . . . . . . . 11
3.3.1. Namespace . . . . . . . . . . . . . . . . . . . . . . 11
3.3.2. Object Type . . . . . . . . . . . . . . . . . . . . . 12
3.3.3. Object Name . . . . . . . . . . . . . . . . . . . . . 12
3.3.4. Parameters . . . . . . . . . . . . . . . . . . . . . 13
4. ARI Text Form . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1. URIs and Percent Encoding . . . . . . . . . . . . . . . . 14
4.2. Literals . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3. Object References . . . . . . . . . . . . . . . . . . . . 16
4.4. URI References . . . . . . . . . . . . . . . . . . . . . 17
4.5. Patterns . . . . . . . . . . . . . . . . . . . . . . . . 18
5. ARI Binary Form . . . . . . . . . . . . . . . . . . . . . . . 18
5.1. Intermediate CBOR . . . . . . . . . . . . . . . . . . . . 19
5.2. Literals . . . . . . . . . . . . . . . . . . . . . . . . 19
5.3. Object References . . . . . . . . . . . . . . . . . . . . 20
5.4. URI References . . . . . . . . . . . . . . . . . . . . . 21
5.5. Patterns . . . . . . . . . . . . . . . . . . . . . . . . 21
6. Transcoding Considerations . . . . . . . . . . . . . . . . . 22
7. Interoperability Considerations . . . . . . . . . . . . . . . 22
8. Security Considerations . . . . . . . . . . . . . . . . . . . 23
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
9.1. URI Schemes Registry . . . . . . . . . . . . . . . . . . 23
9.2. CBOR Tags Registry . . . . . . . . . . . . . . . . . . . 24
9.3. DTN Management Protocol Registry . . . . . . . . . . . . 24
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 28
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10.1. Normative References . . . . . . . . . . . . . . . . . . 28
10.2. Informative References . . . . . . . . . . . . . . . . . 29
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 30
A.1. Typed Literal . . . . . . . . . . . . . . . . . . . . . . 31
A.2. Complex CBOR Literal . . . . . . . . . . . . . . . . . . 31
A.3. Non-parameterized Object Reference . . . . . . . . . . . 32
A.4. Parameterized Object Reference . . . . . . . . . . . . . 32
A.5. Recursive Structure with Percent Encodings . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction
The unique limitations of Delay-Tolerant Networking transport
capabilities [RFC4838] necessitate increased reliance on individual
node behavior. These limitations are considered part of the expected
operational environment of the system and, thus, contemporaneous end-
to-end data exchange cannot be considered a requirement for
successful communication.
The primary DTN transport mechanism, Bundle Protocol version 7,
(BPv7) [RFC9171], standardizes a store-and-forward behavior required
to communicate effectively between endpoints that may never co-exist
in a single network partition. BPv7 might be deployed in static
environments, but the design and operation of BPv7 cannot presume
that to be the case.
Similarly, the management of any BPv7 protocol agent (BPA) (or any
software reliant upon DTN for its communication) cannot presume to
operate in a resourced, connected network. Just as DTN transport
must be delay-tolerant, DTN network management must also be delay-
tolerant.
The DTN Autonomous Management Architecture (DTN AMA)
[I-D.ietf-dtn-ama] outlines an architecture that achieves this result
through the self-management of a DTN node as configured by one or
more remote managers in an asynchronous and open-loop system. An
important part of this architecture is the definition of a conceptual
data schema for defining resources configured by remote managers and
implemented by the local autonomy of a DTN node.
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The DTN Asynchronous Management Model (DTN AMM) [I-D.birrane-dtn-adm]
defines a logical schema that can be used to represent data types and
structures, autonomous controls, and other kinds of information
expected to be required for the local management of a DTN node. The
DTN AMM further describes a physical data model, called the
Application Data Model, that can be defined in the context of
applications to create resources in accordance with the DTN AMM
logical schema. These named resources can be predefined in moderated
publications or custom-defined as part of the operational management
of a network or a node.
Every AMM resource must be uniquely identifiable. To accomplish
this, an expressive naming scheme is required. The AMM Resource
Identifier (ARI) provides this naming scheme. This document defines
an ARI, based on the structure of a URI, meeting the needs for a
concise, typed, parameterized, and hierarchically organized naming
convention.
1.1. Scope
The ARI scheme is based on the structure of a URI [RFC3986] in
accordance with the practices outlined in [RFC8820].
ARIs are designed to support the identification requirements of the
DTN AMM logical schema. As such, this specification will discuss
these requirements to the extent necessary to explain the structure
and use of the ARI syntax.
This specification does not constrain the syntax or structure of any
existing URI (or part thereof). As such, the ARI scheme does not
impede the ownership of any other URI definition and is therefore
clear of the concerns presented in [RFC7320].
This specification does not discuss the manner in which ARIs might be
generated, populated, and used by applications. The operational
utility and configuration of ARIs in a system are described in other
documents associated with DTN management, to include the AMA and AMM
specifications.
This specification does not describe the way in which path prefixes
associated with an ARI are standardized, moderated, or otherwise
populated. Path suffixes may be specified where they do not lead to
collision or ambiguity.
This specification does not describe the mechanisms for generating
either standardized or custom ARIs in the context of any given
application, protocol, or network.
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This specification does not describe the ways in which an ARI could
be encoded into other formats, to include compressed binary formats.
However, the design of the ARI syntax discusses compressibility to
the extent that the design impacts the ability to create such
encodings.
1.2. Use of ABNF
This document defines text structure using the Augmented Backus-Naur
Form (ABNF) of [RFC5234]. The entire ABNF structure can be extracted
from the XML version of this document using the XPath expression:
'//sourcecode[@type="abnf"]'
The following initial fragment defines the top-level rules of this
document's ABNF.
start = ari
From the document [RFC3986] the definitions are taken for pchar,
path-absolute, and path-noscheme. From the document [RFC5234] the
definition is taken for digit.
1.3. Use of CDDL
This document defines Concise Binary Object Representation (CBOR)
structure using the Concise Data Definition Language (CDDL) of
[RFC8610]. The entire CDDL structure can be extracted from the XML
version of this document using the XPath expression:
'//sourcecode[@type="cddl"]'
The following initial fragment defines the top-level symbols of this
document's CDDL, which includes the example CBOR content.
start = ari
; Limited sizes to fit the AMP data model
int32 = (int .lt 2147483648) .ge -2147483648
uint32 = uint .lt 4294967296
int64 = (int .lt 9223372036854775808) .ge -9223372036854775808
uint64 = uint .lt 18446744073709551616
This document does not rely on any CDDL symbol names from other
documents.
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1.4. Terminology
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 in BCP 14 [RFC2119]
[RFC8174] when, and only when, they appear in all capitals, as shown
here.
Additionally, the following terms are used in this document:
Agent: An entity being managed in the AMA as defined in
[I-D.ietf-dtn-ama]. It is expected to be accessible by its
Managers over a DTN.
Manager: An entity managing others in the AMA as defined in
[I-D.ietf-dtn-ama]. It is expected to be accessible by its Agents
over a DTN.
Application Data Model (ADM): Definitions of pre-planned objects
being managed on remote agents across challenged networks. An ADM
is versioned, but a single version of an ADM cannot change over
time once it is registered. This is similar in function to an SMI
MIB or an YANG module.
Operational Data Model (ODM): The operational configuration of an
Agent, exclusive of the pre-planned objects defined by ADMs.
These objects are dynamic configuration applied at runtime, either
by Managers in the network or by autonomy on the Agent.
Asynchronous Resource Identifier (ARI): An identifier for any ADM or
ODM managed object, as well as ad-hoc managed objects and literal
values. ARIs are syntactically conformant to the Uniform Resource
Identifier (URI) syntax documented in [RFC3986] and using the
scheme name "ari". This is similar in function to an SMI OID or
an YANG XPath expression along with parameters.
Namespace A moderated, hierarchical taxonomy of namespaces that
describe a set of ADM scopes. Specifically, an individual ADM
namespace is a specific sequence of ADM namespaces, from most
general to most specific, that uniquely and unambiguously identify
the namespace of a particular ADM.
2. ARI Purpose
ADM resources are referenced in the context of autonomous
applications on an agent. The naming scheme of these resources must
support certain features to inform AMA processing in accordance with
the ADM logical schema.
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This section defines the set of unique characteristics of the ARI
scheme, the combination of which provides a unique utility for
naming. While certain other naming schemes might incorporate certain
elements, there are no such schemes that both support needed features
and exclude prohibited features.
2.1. Resource Parameterization
The ADM schema allows for the parameterization of resources to both
reduce the overall data volume communicated between DTN nodes and to
remove the need for any round-trip data negotiation.
Parameterization reduces the communicated data volume when parameters
are used as filter criteria. By associating a parameter with a data
source, data characteristic, or other differentiating attribute, DTN
nodes can locally process parameters to construct the minimal set of
information to either process for local autonomy or report to remote
managers in the network.
Parameterization eliminates the need for round-trip negotiation to
identify where information is located or how it should be accessed.
When parameters define the ability to perform an associative lookup
of a value, the index or location of the data at a particular DTN
node can be resolved locally as part of the local autonomy of the
node and not communicated back to a remote manager.
2.2. Compressible Structure
The ability to encode information in very concise formats enables DTN
communications in a variety of ways. Reduced message sizes increase
the likelihood of message delivery, require fewer processing
resources to secure, store, and forward, and require less resources
to transmit.
While the encoding of an ARI is outside of the scope of this
document, the structure of portions of the ARI syntax lend themselves
to better compressibility. For example, DTN ADM encodings support
the ability to identify resources in as few as 3 bytes by exploiting
the compressible structure of the ARI.
The ARI syntax supports three design elements to aid in the creation
of more concise encodings: enumerated forms of path segments,
relative paths, and patterning.
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2.2.1. Enumerated Path Segments
Because the ARI structure includes paths segments with stable
enumerated values, each segment can be represented by either its text
name or its integer enumeration. For human-readability in text form
the text name is preferred, but for binary encoding and for
comparisons the integer form is preferred. It is a translation done
by the entity handling an ARI to switch between preferred
representations (see Section 6); the data model of both forms of the
ARI allows for either.
2.2.2. Relative Paths
Hierarchical structures are well known to support compressible
encodings by strategically enumerating well-known branching points in
a hierarchy. For this reason, the ARI syntax uses the URI path to
implement a naming hierarchy.
Supporting relative paths allow for the ARI namespace to be shortened
relative to a well-known prefix. By eliminating the need to repeat
common path prefixes in ARIs (in any encoding) the size of any given
ARI can be reduced.
This relative prefix might be relative to an existing location, such
as the familiar "../item" or relative to a defined nickname for a
particular path prefix, such as "{root}/item".
2.2.3. Patterning
Patterning in this context refers to the structuring of ARI
information to allow for meaning data selection as a function of
wildcards, regular expressions, and other expressions of a pattern.
Patterns allow for both better compression and fewer ARI
representations by allowing a single ARI pattern to stand-in for a
variety of actual ARIs.
This benefit is best achieved when the structure of the ARI is both
expressive enough to include information that is useful to pattern
match, and regular enough to understand how to create these patterns.
3. ARI Logical Structure
This section describes the components of the ARI scheme to inform the
discussion of the ARI syntax in Section 4. At the top-level, an ARI
is one of two classes: literal or object reference. Each of these
classes is defined in the following subsections.
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3.1. Names, Enumerations, Comparisons, and Canonicalizations
Within the ARI logical model, there are a number of domains in which
items are identified by a combination of text name and integer
enumeration: ADMs, ODMs, literal types, object types, and objects.
In all cases, within a single domain the text name and integer
enumeration SHALL NOT be considered comparable. It is an explicit
activity by any entity processing ARIs to make the translation
between text name and integer enumeration (see Section 6).
Text names SHALL be restricted to begin with an alphabetic character
followed by any number of other characters, as defined in the id-text
ABNF symbol. This excludes a large class of characters, including
non-printing characters. When represented in text form, the text
name for ODMs is prefixed with a "!" character to disambiguate it
from an ADM name (see Section 3.3).
For text names, comparison and uniqueness SHALL be based on case-
insensitive logic. The canonical form of text names SHALL be the
lower case representation.
Integer enumerations for ADMs and ODMs SHALL be restricted to a
magnitude less than 2**63 to allow them to fit within a signed 64-bit
storage. The ADM registration in Table 5 reserves high-valued code
points for private and experimental ADMs, while the entire domain of
ODM code points (negative integers) is considered private use.
Integer enumerations for primitive types and object types SHALL be
restricted to a magnitude less than 2**31 to allow them to fit within
a signed 32-bit storage. The registrations in Table 3 and Table 4
respectively Integer enumerations for objects (within an ADM or ODM)
SHALL be restricted to a magnitude less than 2**31 to allow them to
fit within a signed 32-bit storage, although negative-value object
enumerations are disallowed.
For integer enumerations, comparison and uniqueness SHALL be based on
numeric values not on encoded forms. The canonical form of integer
enumerations in text form SHALL be the shortest length decimal
representation.
3.2. Literals
Literals represent a special class of ARI which are not associated
with any particular ADM or ODM. A literal has no other name other
than its value, but literals may be explicitly typed in order to
force the receiver to handle it in a specific way.
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Because literals will be based on the CBOR data model [RFC8949] and
its extended diagnostic notation, a literal has an intrinsic
representable data type as well as an AMP data type. The CBOR
primitive types are named CDDL symbols as defined in Section 3.3 of
[RFC8610].
When converting from AMP primitive types, the chosen CBOR type SHALL
be determined by the mapping in Table 1. Additionally, when handling
typed literal ARIs any combination of AMP primitive type and CBOR
primitive type not in Table 1 SHALL be considered invalid. This
restriction is enforced by the CDDL defined in Section 5.
Additionally, when handling a literal of AMP type CBOR the well-
formed-ness of the CBOR contained SHOULD be verified before the
literal is treated as valid.
+====================+==========================+
| AMP Primitive Type | Used CBOR Primitive Type |
+====================+==========================+
| BOOL | bool |
+--------------------+--------------------------+
| BYTE | uint |
+--------------------+--------------------------+
| INT | int |
+--------------------+--------------------------+
| UINT | uint |
+--------------------+--------------------------+
| VAST | int |
+--------------------+--------------------------+
| UVAST | uint |
+--------------------+--------------------------+
| REAL32 | float |
+--------------------+--------------------------+
| REAL64 | float |
+--------------------+--------------------------+
| TV | int |
+--------------------+--------------------------+
| TS | int |
+--------------------+--------------------------+
| STR | tstr |
+--------------------+--------------------------+
| LABEL | tstr |
+--------------------+--------------------------+
| BYTESTR | bstr |
+--------------------+--------------------------+
| CBOR | bstr |
+--------------------+--------------------------+
Table 1: Literal Types to CBOR Primitives
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When interpreting an untyped literal ARI, the implied AMP primitive
type SHALL be determined by the mapping in Table 2.
+=====================+============================+
| CBOR Primitive Type | Implied AMP Primitive Type |
+=====================+============================+
| bool | BOOL |
+---------------------+----------------------------+
| uint | UVAST |
+---------------------+----------------------------+
| nint | VAST |
+---------------------+----------------------------+
| float16, float32 | FLOAT32 |
+---------------------+----------------------------+
| float64 | FLOAT64 |
+---------------------+----------------------------+
| bstr | BYTESTR |
+---------------------+----------------------------+
| tstr | STR |
+---------------------+----------------------------+
Table 2: Literal Implied and Allowed Types
3.3. Object References
Object references are composed of two parts: object identity and
optional parameters. The object identity can be dereferenced to a
specific object in the ADM/ODM, while the parameters provide
additional information for certain types of object and only when
allowed by the parameter "signature" from the ADM/ODM.
The object identity itself contains the components, described in the
following subsections: namespace, object type, and object name. When
encoded in text form (see Section 4), the identity components
correspond to the URI path segments.
3.3.1. Namespace
ADM resources exist within namespaces to eliminate the possibility of
a conflicting resource name, aid in the application of patterns, and
improve the compressibility of the ARI. Namespaces SHALL NOT be used
as a security mechanism to manage access. An Agent or Manager SHALL
NOT infer security information or access control based solely on
namespace information in an ARI.
Namespaces have two possible forms; one more human-friendly and one
more compressible:
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Text form: This form corresponds with a human-readable identifier
for either an ADM or a ODM namespace. The text form is not
compressible and needs to be converted to a numeric namespace
based on a local registry. A text form namespace SHALL contain
only URI path segment characters.
Numeric form: This form corresponds with a compressible value
suitable for on-the-wire encoding between Manager and Agent.
Sorting and matching numeric namespaces is also faster than text
form. A numeric form namespaces SHALL be small enough to be
represented as a 64-bit signed integer.
Independent to the form of the namespace is the issuer of the
namespace, which is one of:
ADM namespace: When a namespace is associated with an ADM, its text
form SHALL begin with an alphabetic character and its numeric form
SHALL be a positive integer. All ADM namespaces are universally
unique and, except for private or experimental use, SHOULD be
registered with IANA (see Table 5).
ODM namespace: When a namespace is not associated with an ADM, its
text form SHALL begin with a bang character "!" and its numeric
form SHALL be a negative integer. These namespaces do not have
universal registration and SHALL be considered to be private use.
It is expected that runtime ODM namespaces will be allocated and
managed per-user and per-mission.
3.3.2. Object Type
Due to the flat structure of an ADM, as defined in
[I-D.birrane-dtn-adm], all managed objects are of a specific and
unchanging type from a set of available managed object types. The
preferred form for object types in text ARIs is the text name, while
in binary form it is the integer enumeration (see Section 6).
The following subsection explains the form of those object
identifiers.
3.3.3. Object Name
An object is any one of a number of data elements defined for the
management of a given application or protocol that conforms to the
ADM logical schema.
Within a single ADM or runtime namespace and a single object type,
all managed objects have similar characteristics and all objects are
identified by a single text name or integer enumeration. The
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preferred form for object names in text ARIs is the text name, while
in binary form it is the integer enumeration. Any ADM-defined object
will have both name and enumeration, while a runtime-defined object
can have either but not both. Conversion between the two forms
requires access to the original ADM, and its specific revision, in
which the object was defined.
3.3.4. Parameters
The ADM logical schema allows many object types to be parameterized
when defined in the context of an application or a protocol.
If two instances of an ADM resource have the same namespace and same
object type and object name but have different parameter values, then
those instances are unique and the ARIs for those instances MUST also
be unique. Therefore, parameters are considered part of the ARI
syntax.
The ADM logical schema defines two types of parameters: Formal and
Actual. The terms formal parameter and actual parameter follow
common computer programming vernacular for discussing function
declarations and function calls, respectively.
Formal Parameters:
Formal parameters define the type, name, and order of the
information that customizes an ARI. They represent the unchanging
"definition" of the parameterized object. Because ARIs represent
a _use_ of an object and not its definition, formal parameters are
not present in an ARI.
Actual Parameters:
Actual parameters represent the data values used to distinguish
different instances of a parameterized object.
An actual parameter MUST specify a value and MAY specify a type.
If a type is provided it MUST match the type provided by the
formal parameter. An actual parameter MUST NOT include NAME
information.
Including type information in an actual parameters allows for
explicit type checking of a value, which might otherwise be
implicitly cast.
There are two ways in which the value of an actual parameter can
be specified: parameter-by-value and parameter-by-name.
Parameter-By-Value: This method involves directly supplying the
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value as part of the actual parameter. It is the default
method for supplying values.
Parameter-By-Name: This method involves specifying the name of
some other parameter and using that other parameter's value for
the value of this parameter. This method is useful when a
parameterized ARI contains another parameterized ARI. The
contained object's actual parameter can be given as the name of
the containing ARI's parameter. In that way, a containing
ARI's parameters can be "flowed down" to all of the objects it
contains.
4. ARI Text Form
This section defines how the data model explained in Section 3 is
encoded as text conforming to the URI syntax of [RFC3986]. The most
straightforward text form of ARI uses an explicit scheme and an
absolute path (starting with an initial slash "/"), which requires no
additional context to interpret its structure.
When used within the context of a base ARI, the URI Reference form of
Section 4.4 can be used. In all other cases an ARI must be an
absolute-path form and contain a scheme.
While this text description is normative, the ABNF schema in this
section provides a more explicit and machine-parsable text schema.
The scheme name of the ARI is "ari" and the scheme-specific part of
the ARI follows one of the two forms corresponding to the literal-
value ARI and the object-reference ARI.
ari = absolute-ari / relative-ari
absolute-ari = "ari:" ari-ssp
ari-ssp = ari-ssp-literal / ari-ssp-objref
; A text name must start with an alphabetic character
id-text = ALPHA *pchar
; An integer enumeration must contain only digits
id-num = 1*DIGIT
4.1. URIs and Percent Encoding
Due to the intrinsic structure of the URI, on which the text form of
ARI is based, there are limitations on the syntax available to the
scheme-specific-part [RFC7595]. One of these limitations is that
each path segment can contain only characters in the pchar ABNF
symbol defined in [RFC3986]. For most parts of the ARI this
restriction is upheld by the values themselves: ADM/ODM names, type
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names, and object names have a limited character set as well. For
literals and nested parameters though, the percent encoding of
Section 2.4 of [RFC3986] is needed.
In the ARI text examples in this document the URIs have been percent-
decoded for clarity, as might be done in an ARI display and editing
tool. But the actual encoded form of the human-friendly ARI
ari:"text" is ari:%22text%22. Outside of literals, the safe
characters which are not be percent-encoded are the structural
delimiters /()[], used for parameters and ARI collections.
One other aspect of convenience for human editing of text-form ARIs
is linear white space. The current ABNF pattern, staying within the
URI pattern, do not allow for whitespace to separate list items or
otherwise. A human editing an ARI could find it convenient to
include whitespace following commas between list items, or to
separate large lists across lines. Any tool that allows this kind of
convenience of editing SHALL collapse any white space within a single
ARI before encoding its contents.
4.2. Literals
Based on the structure of Section 3.2, the text form of the literal
ARI contains only a URI path with an optional AMP primitive type. A
literal has no concept of a namespace or context, so the path is
always absolute. When the path has two segments, the first is the
AMP primitive type and the second is the encoded literal value. When
the path has a single segment it is the encoded literal value. As a
shortcut, an ARI with only a single path segment is necessarily an
untyped literal so the leading slash can be elided.
An ARI encoder or decoder SHALL handle both text name and integer
enumeration forms of the primitive type. When present and able to be
looked up, the primitive type SHOULD be a text name.
The literal value SHALL be the percent encoded form of the CBOR
extended diagnostic notation text of Appendix G of [RFC8610]. When
untyped, the decoded literal value SHALL be one of the primitive
types named by the lit-notype CDDL symbol of Section 5.2. When
typed, the decoded literal value MAY be any valid CBOR item
conforming to the AMP primitive type definition.
Some example of the forms for a literals are below. These first are
untyped primitive values:
ari:true
ari:"text"
ari:10
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And these are typed values:
ari:/UINT/10
ari:/LABEL/"name"
ari:/CBOR/<<10>>
The literal-value ARI has a corresponding ABNF definition of:
; The primitive type name is optional
ari-ssp-literal = ["/" lit-type] ["/"] lit-value
; Type is restricted to valid AMP primitive types
lit-type = id-text / id-num
; The value is percent-encoded CBOR Diagnostic syntax
lit-value = *pchar
4.3. Object References
Based on the structure of Section 3.3, the text form of the object
reference ARI contains a URI with three path segments corresponding
to the namespace-id, object-type, and object-id. Those three
segments (excluding parameters as defined below) are referred to as
the object identity.
An ARI encoder or decoder SHALL handle both text name and integer
enumeration forms of the namespace-id, object-type, and object-id.
The final segment containing the object-id MAY contain parameters
enclosed by parentheses "(" and ")". There is no semantic
distinction between the absence of parameters and the empty parameter
list. The parameter list SHALL be separated by comma characters ",".
Each parameter item SHALL be either an ARI or an ARI collection.
Within a parameter item, ARI collections SHALL be indicated by
enclosing square brackets "[" and "]". The ARI collection list SHALL
be separated by comma characters ",". Each parameter item is handled
recursively as the text form of ARI.
The parameters as a whole SHALL be the percent encoded form of the
constituent ARIs, excluding the structural delimiters /()[],.
Implementations are advised to be careful about the percent encoded
vs. decoded cases of each of the nested ARIs within parameters to
avoid duplicate encoding or decoding. It is recommended to dissect
the parameters and ARI collections in their encoded form first, and
then to dissect and percent decode each separately and recursively.
ari:/adm-a/EDD/someobj
ari:/adm-a/CTRL/otherobj(true,3)
ari:/adm-a/CTRL/otherobj("a param",/UINT/10)
ari:/41/-1/0
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The object-reference ARI has a corresponding ABNF definition of:
ari-ssp-objref = obj-ident [paramlist]
; The object identity can be used separately than parameters
obj-ident = "/" ns-id "/" obj-type "/" obj-id
; A comma-separated list of parameters with enclosure
paramlist = "(" param *("," param) ")"
param = ari / ac
ns-id = ns-adm / ns-odm
ns-adm = id-text / id-num
ns-odm = ("!" id-text) / ("-" id-num)
; Type is restricted to valid AMP primitive types
obj-type = id-text / ("-" id-num)
obj-id = id-text / id-num
; A comma-separated list of any form of ARI with enclosure
ac = "[" ari *("," ari) "]"
4.4. URI References
The text form of ARI can contain a URI Reference, as defined in
Section 3 of [RFC3986], which can only be resolved using a base URI
using the algorithm defined in Section 5 of [RFC3986]. When
resolving nested ARI content, the base URI of any interior resolution
is the next-outer ARI in the nested structure. The outermost ARI
SHALL NOT be a URI Reference because it will have no base URI to
resolve with.
Because a relative-path ARI with no path separators is considered to
be an untyped literal, an ARI reference SHALL contain at least one
path separator. For the case where the ARI reference is to a sibling
object from the base URI the relative path SHOULD be of the form "./"
to include the path separator.
When resolving nested ARI content, the parameters of the URI
reference SHALL be preserved in the resolved ARI. This behavior is
equivalent to the query parameter portion when resolving a generic
URI reference.
; Relative ARI must be resolved before interpreting
relative-ari = path-nonempty [paramlist]
; Non-empty absolute or relative path
path-nonempty = path-absolute / path-noscheme
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4.5. Patterns
Because each of the text form use path segments to delimit the
components of the absolute ARI, and due to the restrictions of the
ARI path segment content, it is possible for URI reserved characters
to be able to provide wildcard-type patterns. Although the form is
similar, an ARI Pattern is not itself an ARI and they cannot be used
interchangeably. The context used to interpret and match an ARI
Pattern SHALL be explicit and separate from that used to interpret
and dereference an ARI.
The ARI Pattern SHALL NOT ever take the form of a URI Reference; only
as an absolute URI. An ARI Pattern SHALL NOT ever contain
parameters, only identity.
An ARI Pattern has no optional path segments. When used as a literal
ARI pattern the path SHALL have two segments. When used as an
object-reference ARI pattern the path SHALL have three segments.
The single-wildcard is the only defined segment pattern and a segment
can either be a real ID or a single wildcard.
ari-pat = "ari:" ari-pat-ssp
ari-pat-ssp = ari-pat-literal / ari-pat-objref
ari-pat-literal = "/" id-pat "/" id-pat
ari-pat-objref = "/" id-pat "/" id-pat "/" id-pat
; The non-wildcard symbol is the same as ARI syntax
id-pat = wildcard / (*pchar)
wildcard = "*"
5. ARI Binary Form
This section defines how the data model explained in Section 3 is
encoded as a binary sequence conforming to the CBOR syntax of
[RFC8949]. Within this section the term "item" is used to mean the
CBOR-decoded data item which follows the logical model of CDDL
[RFC8610].
The binary form of the URI is intended to be used for machine-to-
machine interchange so it is missing some of the human-friendly
shortcut features of the ARI text form from Section 4. It still
follows the same logical data model so it has a one-for-one
representation of all of the styles of text-form ARI.
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A new CBOR tag TBD999999 has been registered to indicate that an
outer CBOR item is a binary-form ARI. This is similar in both syntax
and semantics to the "ari" URI scheme in that for a nested ARI
structure, only the outer-most ARI need be tagged. The inner ARIs
are necessarily interpreted as such based on the nested ARI schema of
this section.
While this text description is normative, the CDDL schema in this
section provides a more explicit and machine-parsable binary schema.
; An ARI can be tagged if helpful
ari = ari-notag / #6.999999(ari-notag)
ari-notag = lit-ari / ari-objref
5.1. Intermediate CBOR
The CBOR item form is used as an intermediate encoding between the
ARI data and the ultimate binary encoding. When decoding a binary
form ARI, the CBOR must be both "well-formed" according to [RFC8949]
and "valid" according to the CDDL model of this specification.
Implementations are encouraged, but not required, to use a streaming
form of CBOR encoder/decoder to reduce memory consumption of an ARI
handler. For simple implementations or diagnostic purposes, a two
stage conversion between ARI--CBOR and CBOR--binary can be more
easily understood and tested.
5.2. Literals
Based on the structure of Section 3.2, the binary form of the literal
ARI contains a data item along with an optional AMP primitive type.
In order to keep the encoding as short as possible, the untyped
literal is encoded as the simple value itself. Because the typed
literal and the object-reference forms uses CBOR array framing, this
framing is used to disambiguate from the pure-value encoding of the
lit-notype CDDL symbol.
When present, the primitive type SHALL be an integer enumeration.
When untyped, the decoded literal value SHALL be one of the primitive
types named by the lit-notype CDDL symbol. When typed, the decoded
literal value MAY be any valid CBOR item conforming to the AMP
primitive type definition.
Some example of the forms for a literal are below. These first are
untyped primitive values:
true
"text"
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10
And these are typed values:
[4, 10]
[15, <<10>>]
The literal-value ARI has a corresponding CDDL definition of:
lit-ari = lit-typeval / lit-notype
lit-notype = bool / int / float / tstr / bstr
lit-typeval = $lit-typeval .within lit-typeval-struct
lit-typeval-struct = [
lit-type: (int32 .ge 0),
lit-value: any
]
; FIXME: will expand with assigned types
$lit-typeval /= [1, bool]
$lit-typeval /= [2, uint .size 1] ; 1-byte
$lit-typeval /= [4, int32] ; 4-byte
$lit-typeval /= [5, uint32] ; 4-byte
$lit-typeval /= [6, uint64] ; 8-byte
$lit-typeval /= [7, int64] ; 8-byte
$lit-typeval /= [8, float16 / float32]
$lit-typeval /= [9, float64]
$lit-typeval /= [10, tstr]
$lit-typeval /= [11, bstr]
$lit-typeval /= [12, int]
$lit-typeval /= [13, int]
$lit-typeval /= [14, tstr .regexp "[A-Za-z].*"]
$lit-typeval /= [15, bstr .cbor any]
5.3. Object References
Based on the structure of Section 3.3, the binary form of the object
reference ARI is a CBOR-encoded item. An ARI SHALL be encoded as a
CBOR array with at least three items corresponding to the namespace-
id, object-type, and object-id. Those three items are referred to as
the object identity. The optional fourth item of the array is the
parameter list.
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The namespace-id SHALL be present only as an integer enumeration.
The object-type SHALL be present only as an integer enumeration. The
object-id SHALL be present as either a text name or an integer
enumeration. The processing of text name object identity components
by an Agent is optional and SHALL be communicated to any associated
Manager prior to encoding any ARIs for that Agent.
When present, the parameter list SHALL be a CBOR array containing
either ARI or ARI collection items. The CBOR tag 41 (meaning a
homogeneous array per [IANA-CBOR]) SHALL be used to indicate that a
parameter item is an ARI collection. All other, untagged parameter
items SHALL be handled as an ARI.
An example object reference without parameters is:
[41, -1, 0]
Another example object reference with parameters is:
[41, -2, 3, ["a param", [4, 10]]]
The object-reference ARI has a corresponding CDDL definition of:
ari-objref = [obj-ident, ?params]
obj-ident = (
ns-id,
obj-type,
obj-id,
)
ns-id = int64
obj-type = $obj-type-reg .within (int32 .lt 0)
obj-id = (int32 .ge 0) / tstr
params = [*ari-or-ac]
ari-or-ac = ari / ac
ac = #6.41([*ari])
; FIXME: will expand with assigned types
$obj-type-reg = nint
5.4. URI References
TBD
5.5. Patterns
TBD
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6. Transcoding Considerations
When translating literal types into text form and code point lookup
tables are available, the primitive type SHOULD be converted to its
text name. When translating literal types from text form and code
point lookup tables are available, the primitive type SHOULD be
converted from its text name. The conversion between AMP primitive
type name and enumeration requires a lookup table based on the
registrations in Table 3.
When translating literal values into text form, it is necessary to
canonicalize the CBOR extended diagnostic notation of the item. The
following applies to generating text form from CBOR items:
* The canonical text form of CBOR bool values SHALL be the forms
identified in Section 8 of [RFC8949].
* The canonical text form of CBOR int and float values SHALL be the
decimal form defined in Section 8 of [RFC8949].
* The canonical text form of CBOR tstr values SHALL be the definite-
length, non-concatenated form defined in Section 8 of [RFC8949].
* The canonical text form of CBOR bstr values SHALL be the definite-
length, base16 ("h" prefix), non-concatenated form defined in
Section 8 of [RFC8949].
* When presenting the AMP primitive type of CBOR the values SHALL be
the embedded CBOR form defined in Appendix G.3 of [RFC8610].
When translating object references into text form and code point
lookup tables are available, any enumerated item SHOULD be converted
to its text name. When translating object references from text form
and code point lookup tables are available, any enumerated item
SHOULD be converted from its text name. The conversion between AMP
object-type name and enumeration requires a lookup table based on the
registrations in Table 4. The conversion between name and
enumeration for either namespace-id or object-id require lookup
tables based on ADMs and ODMs known to the processing entity.
7. Interoperability Considerations
DTN challenged networks might interface with better resourced
networks that are managed using non-DTN management protocols. When
this occurs, the federated network architecture might need to define
management gateways that translate between DTN and non-DTN management
approaches.
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| NOTE: It is also possible for DTN management be used end-to-end
| because this approach can also operate in less challenged
| networks. The opposite is not true; non-DTN management
| approaches should not be assumed to work in DTN challenged
| networks.
Where possible, ARIs should be translatable to other, non-DTN
management naming schemes. This translation might not be 1-1, as the
features of the ADM may differ from features in other management
naming schemes. Therefore, it is unlikely that a single naming
scheme can be used for both DTN and non-DTN management.
8. Security Considerations
Because ADM and ODM namespaces are defined by any entity, no security
or permission meaning can be inferred simply from the expression of
namespace.
9. IANA Considerations
This section provides guidance to the Internet Assigned Numbers
Authority (IANA) regarding registration of schema and namespaces
related to the ADM Resource Identifier (ARI), in accordance with BCP
26 [RFC1155].
9.1. URI Schemes Registry
This document defines a new URI scheme "ari" in Section 4. A new
entry has been added to the "URI Schemes" registry [IANA-URI] with
the following parameters.
Scheme name:
ari
Status:
Permanent
Applications/protocols that use this scheme name:
The scheme is used by AMP Managers and Agents to identify managed
objects.
Contact:
IETF Chair <chair@ietf.org>
Change controller:
IESG <iesg@ietf.org>
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Reference:
Section 4 of [This document].
9.2. CBOR Tags Registry
This document defines a new CBOR tag TBD999999 in Section 5. A new
entry has been added to the "CBOR Tags" registry [IANA-CBOR] with the
following parameters.
Tag:
TBD999999
Data Item:
multiple
Semantics:
Used to tag a binary-form DTNMP ARI
Reference:
Section 5 of [This document].
9.3. DTN Management Protocol Registry
This document defines a new sub-registry "Primitive Types" within the
"DTN Management Protocol" registry [IANA-DTNMP] containing the
following initial entries. Enumerations in this sub-registry are
non-negative integers representable as CBOR uint type with an
argument shorter than 4-bytes. The registration procedure for this
sub-registry is Specification Required.
+=============+=========+===========+==============================+
| Enumeration | Name | Reference | Description |
+=============+=========+===========+==============================+
| _TBD1_ | BOOL | [This | A native boolean value. |
| | | document] | |
+-------------+---------+-----------+------------------------------+
| _TBD2_ | BYTE | [This | An 8-bit unsigned integer. |
| | | document] | |
+-------------+---------+-----------+------------------------------+
| _TBD4_ | INT | [This | A 32-bit signed integer. |
| | | document] | |
+-------------+---------+-----------+------------------------------+
| _TBD5_ | UINT | [This | A 32-bit unsigned integer. |
| | | document] | |
+-------------+---------+-----------+------------------------------+
| _TBD6_ | VAST | [This | A 64-bit signed integer. |
| | | document] | |
+-------------+---------+-----------+------------------------------+
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| _TBD7_ | UVAST | [This | A 64-bit unsigned integer. |
| | | document] | |
+-------------+---------+-----------+------------------------------+
| _TBD8_ | REAL32 | [This | A 32-bit [IEEE.754-2019] |
| | | document] | floating point number. |
+-------------+---------+-----------+------------------------------+
| _TBD9_ | REAL64 | [This | A 64-bit [IEEE.754-2019] |
| | | document] | floating point number. |
+-------------+---------+-----------+------------------------------+
| _TBD10_ | STR | [This | A text string composed of |
| | | document] | characters. |
+-------------+---------+-----------+------------------------------+
| _TBD11_ | BYTESTR | [This | A byte string composed of |
| | | document] | 8-bit values. |
+-------------+---------+-----------+------------------------------+
| _TBD12_ | TV | [This | |
| | | document] | |
+-------------+---------+-----------+------------------------------+
| _TBD13_ | TS | [This | |
| | | document] | |
+-------------+---------+-----------+------------------------------+
| _TBD14_ | LABEL | [This | A text label of a parent |
| | | document] | object parameter. This is |
| | | | only valid in a nested |
| | | | parameterized ARI. |
+-------------+---------+-----------+------------------------------+
| _TBD15_ | CBOR | [This | A byte string containing an |
| | | document] | encoded CBOR item. The |
| | | | structure is opaque to the |
| | | | Agent but guaranteed well- |
| | | | formed for the ADM using it. |
+-------------+---------+-----------+------------------------------+
| TBD16 to | | | _Unassigned_ |
| 65279 | | | |
+-------------+---------+-----------+------------------------------+
| 65280 to | | [This | Enumerations that are |
| 2147483647 | | document] | 2**16-2**8 and larger are |
| | | | reserved for private or |
| | | | experimental use. |
+-------------+---------+-----------+------------------------------+
Table 3: Primitive Types
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This document defines a new sub-registry "Managed Object Types"
within the "DTN Management Protocol" registry [IANA-DTNMP] containing
the following initial entries. Enumerations in this sub-registry are
negative integers representable as CBOR nint type with an argument
shorter than 4-bytes. The registration procedure for this sub-
registry is Specification Required.
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+=============+=======+===========+==========================+
| Enumeration | Name | Reference | Description |
+=============+=======+===========+==========================+
| _-TBD1_ | MDAT | [This | ADM Metadata |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD2_ | CONST | [This | Constant |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD3_ | CTRL | [This | Control |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD4_ | EDD | [This | Externally Defined Data |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD5_ | MAC | [This | Macro |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD6_ | OPER | [This | Operator |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD7_ | RPTT | [This | Report Template |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD8_ | SBR | [This | State-Based Rule |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD9_ | TBLT | [This | Table Template |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD10_ | TBR | [This | Time-Based Rule |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| _-TBD11_ | VAR | [This | Variable |
| | | document] | |
+-------------+-------+-----------+--------------------------+
| TBD12 to | | | _Unassigned_ |
| 65279 | | | |
+-------------+-------+-----------+--------------------------+
| 65280 to | | [This | Enumerations that are |
| 2147483647 | | document] | 2**16-2**8 and larger |
| | | | are reserved for private |
| | | | or experimental use. |
+-------------+-------+-----------+--------------------------+
Table 4: Managed Object Types
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This document defines a new sub-registry "Application Data Models"
within the "DTN Management Protocol" registry [IANA-DTNMP] containing
the following initial entries. Enumerations in this sub-registry are
non-negative integers representable as CBOR uint type with an
argument shorter than 8-bytes. The registration procedure for this
sub-registry is Specification Required.
+=============+======+===========+==============================+
| Enumeration | Name | Reference | Notes |
+=============+======+===========+==============================+
| 0 | | [This | Value zero is reserved. |
| | | document] | |
+-------------+------+-----------+------------------------------+
| 1 to | | | _Unassigned_ |
| 4294967296 | | | |
+-------------+------+-----------+------------------------------+
| 4294967296 | | [This | Enumerations that are larger |
| and larger | | document] | than 32-bit are reserved for |
| | | | private or experimental use. |
+-------------+------+-----------+------------------------------+
Table 5: Application Data Models
The Operational Data Models code points are all private use, so do
not need to have an IANA registry defined.
10. References
10.1. Normative References
[IANA-CBOR]
IANA, "Concise Binary Object Representation (CBOR) Tags",
<https://www.iana.org/assignments/cbor-tags/>.
[IANA-DTNMP]
IANA, "Delay-Tolerant Networking (DTN) Management
Protocol", <https://www.iana.org/assignments/TBD/>.
[IANA-URI] IANA, "Uniform Resource Identifier (URI) Schemes",
<https://www.iana.org/assignments/uri-schemes/>.
[IEEE.754-2019]
IEEE, "IEEE Standard for Floating-Point Arithmetic",
IEEE IEEE 754-2019, DOI 10.1109/IEEESTD.2019.8766229, 18
July 2019, <https://ieeexplore.ieee.org/document/8766229>.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[RFC7595] Thaler, D., Ed., Hansen, T., and T. Hardie, "Guidelines
and Registration Procedures for URI Schemes", BCP 35,
RFC 7595, DOI 10.17487/RFC7595, June 2015,
<https://www.rfc-editor.org/info/rfc7595>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/info/rfc8949>.
[RFC9171] Burleigh, S., Fall, K., and E. Birrane, III, "Bundle
Protocol Version 7", RFC 9171, DOI 10.17487/RFC9171,
January 2022, <https://www.rfc-editor.org/info/rfc9171>.
10.2. Informative References
[RFC1155] Rose, M. and K. McCloghrie, "Structure and identification
of management information for TCP/IP-based internets",
STD 16, RFC 1155, DOI 10.17487/RFC1155, May 1990,
<https://www.rfc-editor.org/info/rfc1155>.
[RFC4838] Cerf, V., Burleigh, S., Hooke, A., Torgerson, L., Durst,
R., Scott, K., Fall, K., and H. Weiss, "Delay-Tolerant
Networking Architecture", RFC 4838, DOI 10.17487/RFC4838,
April 2007, <https://www.rfc-editor.org/info/rfc4838>.
[RFC7320] Nottingham, M., "URI Design and Ownership", RFC 7320,
DOI 10.17487/RFC7320, July 2014,
<https://www.rfc-editor.org/info/rfc7320>.
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[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC8820] Nottingham, M., "URI Design and Ownership", BCP 190,
RFC 8820, DOI 10.17487/RFC8820, June 2020,
<https://www.rfc-editor.org/info/rfc8820>.
[I-D.ietf-dtn-ama]
Birrane, E. J., Annis, E., and S. Heiner, "Asynchronous
Management Architecture", Work in Progress, Internet-
Draft, draft-ietf-dtn-ama-03, 25 October 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-dtn-ama-
03>.
[I-D.birrane-dtn-adm]
Birrane, E. J., DiPietro, E., and D. Linko, "AMA
Application Data Model", Work in Progress, Internet-Draft,
draft-birrane-dtn-adm-03, 2 July 2018,
<https://datatracker.ietf.org/doc/html/draft-birrane-dtn-
adm-03>.
Appendix A. Examples
The examples in this section rely on the ADM and ODM definitions in
Table 6 and Table 7 respectively.
+=============+=======+
| Enumeration | Name |
+=============+=======+
| 10 | adm10 |
+-------------+-------+
| 20 | adm20 |
+-------------+-------+
Table 6: Example ADMs
+=============+=======+
| Enumeration | Name |
+=============+=======+
| -10 | odm10 |
+-------------+-------+
Table 7: Example ODMs
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Given those namespaces, the example objects are listed in Table 6
where the Namespace column uses the ARI text form convention.
+===========+========+=============+================+==============+
| Namespace | Object | Enumeration | Name | Signature |
| | Type | | | |
+===========+========+=============+================+==============+
| adm10 | EDD | 3 | num_bytes | () |
+-----------+--------+-------------+----------------+--------------+
| adm10 | CTRL | 2 | do_thing | (AC targets, |
| | | | | UINT count) |
+-----------+--------+-------------+----------------+--------------+
| adm10 | RPTT | 1 | rpt_with_param | (ARI var, |
| | | | | STR text) |
+-----------+--------+-------------+----------------+--------------+
| !odm10 | VAR | 1 | my_counter | () |
+-----------+--------+-------------+----------------+--------------+
Table 8: Example Objects
Each of the following examples illustrate the comparison of ARI forms
in different situations, covering the gamut of what can be expressed
by an ARI.
A.1. Typed Literal
This is the literal value 4 interpreted as a 32-bit unsigned integer.
The ARI text (which is identical to its percent-encoded form) is:
ari:/UINT/4
which is translated to enumerated form:
ari:/5/4
and converted to CBOR item:
[5, 4]
and finally to the binary string of:
0x820504
A.2. Complex CBOR Literal
This is a literal value embedding a complex CBOR structure. The CBOR
diagnostic expression being encoded is
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{"test": [3, 4.5]}
which is CBOR-encoded to a byte string and percent-encoded to the URL
path:
ari:/CBOR/h%27A164746573748203F94480%27
which is translated to enumerated form:
ari:/15/h%27A164746573748203F94480%27
and converted to CBOR item (note the byte string is no longer text-
encoded):
[15, h'A164746573748203F94480']
and finally to the binary string of:
0x820F4BA164746573748203F94480
A.3. Non-parameterized Object Reference
This is a non-parameterized num_bytes object in the ADM namespace.
The ARI text (which is identical to its percent-encoded form) is:
ari:/adm10/edd/num_bytes
which is translated to enumerated form:
ari:/10/-4/3
and converted to CBOR item:
[10, -4, 3]
and finally to the binary string of:
0x830A2303
A.4. Parameterized Object Reference
This is an parameterized do_thing object in the ADM namespace.
Additionally, the parameters include two relative-path ARI References
to other objects in the same ADM, which are resolved after text-
decoding. The ARI text (which is identical to its percent-encoded
form) is:
ari:/adm10/ctrl/do_thing([../edd/num_bytes,/!odm10/var/my_counter],3)
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which is translated to enumerated and resolved form:
ari:/10/-3/2([/10/-4/3,/-10/-11/1],3)
and converted to CBOR item:
[10, -3, 2, [
41([
[10, -4, 3],
[10, -11, 1]
]),
3
]]
and finally to the binary string of:
0x840A220282D82982830A2303830A2A0103
A.5. Recursive Structure with Percent Encodings
This is a complex example having nested ARIs, some with percent-
encoding needed. The human-friendly (but not valid URI) text for
this case is:
ari:/adm10/rptt/rpt_with_param("text")
which is percent encoded to the real URI:
ari:/adm10/rptt/rpt_with_param(%22text%22)
which is translated to enumerated form:
ari:/10/-7/1(%22text%22)
and converted to CBOR item:
[10, -7, 1, ["text"]]
and finally to the binary string of:
0x840A2601816474657874
Authors' Addresses
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Edward J. Birrane, III
The Johns Hopkins University Applied Physics Laboratory
11100 Johns Hopkins Rd.
Laurel, MD 20723
United States of America
Phone: +1 443 778 7423
Email: Edward.Birrane@jhuapl.edu
Emery Annis
The Johns Hopkins University Applied Physics Laboratory
Email: Emery.Annis@jhuapl.edu
Brian Sipos
The Johns Hopkins University Applied Physics Laboratory
Email: brian.sipos+ietf@gmail.com
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