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: 6 July 2024 JHU/APL
3 January 2024
DTNMA Application Resource Identifier (ARI)
draft-birrane-dtn-ari-04
Abstract
This document defines the structure, format, and features of the
naming scheme for the objects defined in the Delay-Tolerant
Networking Management Architecture (DTNMA) Application Management
Model (AMM), in support of challenged network management solutions
described in the DTNMA document.
This document defines the DTNMA Application Resource Identifier
(ARI), using a text-form based on the common Uniform Resource
Identifier (URI) and a binary-form based on Concise Binary Object
Representation (CBOR). These meet the needs for a concise, typed,
parameterized, and hierarchically organized set of managed 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-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 6 July 2024.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Provisions Relating to IETF Documents (https://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
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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 . . . . . . . . . . . . . . . . . . . . 8
3.2. Literals . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3. Object References . . . . . . . . . . . . . . . . . . . . 11
3.3.1. Namespace ID . . . . . . . . . . . . . . . . . . . . 12
3.3.2. Object Type . . . . . . . . . . . . . . . . . . . . . 13
3.3.3. Object ID . . . . . . . . . . . . . . . . . . . . . . 13
3.3.4. Parameters . . . . . . . . . . . . . . . . . . . . . 13
4. ARI Text Form . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1. URIs and Percent Encoding . . . . . . . . . . . . . . . . 15
4.2. Literals . . . . . . . . . . . . . . . . . . . . . . . . 16
4.2.1. Typed Literal Values . . . . . . . . . . . . . . . . 17
4.2.2. Untyped Literal Values . . . . . . . . . . . . . . . 21
4.2.3. Preferred Encodings . . . . . . . . . . . . . . . . . 22
4.3. Object References . . . . . . . . . . . . . . . . . . . . 23
4.4. URI References . . . . . . . . . . . . . . . . . . . . . 24
5. ARI Binary Form . . . . . . . . . . . . . . . . . . . . . . . 24
5.1. Intermediate CBOR . . . . . . . . . . . . . . . . . . . . 25
5.2. Literals . . . . . . . . . . . . . . . . . . . . . . . . 25
5.3. Object References . . . . . . . . . . . . . . . . . . . . 28
5.4. URI References . . . . . . . . . . . . . . . . . . . . . 29
6. ARI Patterns . . . . . . . . . . . . . . . . . . . . . . . . 30
6.1. ARI Matching . . . . . . . . . . . . . . . . . . . . . . 30
7. Transcoding Considerations . . . . . . . . . . . . . . . . . 31
8. Interoperability Considerations . . . . . . . . . . . . . . . 32
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9. Security Considerations . . . . . . . . . . . . . . . . . . . 32
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32
10.1. URI Schemes Registry . . . . . . . . . . . . . . . . . . 32
10.2. CBOR Tags Registry . . . . . . . . . . . . . . . . . . . 33
10.3. DTN Management Architecture Parameters . . . . . . . . . 33
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 37
11.1. Normative References . . . . . . . . . . . . . . . . . . 37
11.2. Informative References . . . . . . . . . . . . . . . . . 39
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 40
A.1. Primitive-Typed Literal . . . . . . . . . . . . . . . . . 41
A.2. Timestamp Literal . . . . . . . . . . . . . . . . . . . . 42
A.3. Semantic-Typed Literal . . . . . . . . . . . . . . . . . 42
A.4. Complex CBOR Literal . . . . . . . . . . . . . . . . . . 42
A.5. Non-parameterized Object Reference . . . . . . . . . . . 43
A.6. Parameterized Object Reference . . . . . . . . . . . . . 43
A.7. Recursive Structure with Percent Encodings . . . . . . . 44
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 44
1. Introduction
The unique limitations of Delay-Tolerant Networking (DTN) 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 Management Architecture (DTNMA) [I-D.ietf-dtn-dtnma] 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 DTNMA Application Management Model (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
AMM further describes a physical data model, called the Application
Data Model (ADM), that can be defined in the context of applications
to create resources in accordance with the AMM schema. These named
resources can be predefined in moderated publications or custom-
defined as part of the Operational Data Model (ODM) of an agent.
Every AMM resource must be uniquely identifiable. To accomplish
this, an expressive naming scheme is required. The Application
Resource Identifier (ARI) provides this naming scheme. This document
defines the ARI, based on the structure of a Uniform Resource
Identifier (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
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 scheme 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 DTNMA 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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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,
unreserved, pct-encoded, path-absolute, and path-noscheme. From the
document [RFC3339] the definitions are taken for date-time, full-
date, and duration. From the document [RFC5234] the definitions are
taken for bit, hexdig, digit, and char-val.
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 AMM 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 DTNMA as defined in
[I-D.ietf-dtn-dtnma]. It is expected to be accessible by its
Managers over a DTN.
Manager: An entity managing others in the DTNMA as defined in
[I-D.ietf-dtn-dtnma]. 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.
Application 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 DTNMA 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 7); the data model of both forms of the
ARI allows for either.
2.2.2. Relative Paths
// Relative object paths and resolving are TBD. A simple method is
// to always use the object-containing namespace as a base URI for
// resolving URI References.
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.
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 7).
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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 6 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 literal 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.
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 AMM data type. The CBOR
primitive types are named CDDL symbols as defined in Section 3.3 of
[RFC8610].
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When converting from AMM literal types, the chosen CBOR type SHALL be
determined by the mapping in Table 1. Additionally, when handling
typed literal ARIs any combination of AMM literal 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 AMM type CBOR the well-
formed-ness of the CBOR contained SHOULD be verified before the
literal is treated as valid.
+==================+================+
| AMM Literal Type | Used CBOR Type |
+==================+================+
| NULL | null |
+------------------+----------------+
| BOOL | bool |
+------------------+----------------+
| BYTE | uint |
+------------------+----------------+
| INT | int |
+------------------+----------------+
| UINT | uint |
+------------------+----------------+
| VAST | int |
+------------------+----------------+
| UVAST | uint |
+------------------+----------------+
| REAL32 | float |
+------------------+----------------+
| REAL64 | float |
+------------------+----------------+
| TEXTSTR | tstr |
+------------------+----------------+
| BYTESTR | bstr |
+==================+================+
| Non-primitive types |
+==================+================+
| TP | lit-time |
+------------------+----------------+
| TD | lit-time |
+------------------+----------------+
| LABEL | lit-label |
+------------------+----------------+
| CBOR | lit-cbor |
+==================+================+
| Containers |
+==================+================+
| AC | ari-collection |
+------------------+----------------+
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| AM | ari-map |
+------------------+----------------+
| TBL | ari-tbl |
+------------------+----------------+
| EXECSET | exec-set |
+------------------+----------------+
| RPTSET | rpt-set |
+------------------+----------------+
Table 1: AMM Literal Types to
CBOR Types
When interpreting an untyped literal ARI, the implied AMM literal
type SHALL be determined by the mapping in Table 2.
+=====================+============================+
| CBOR Primitive Type | Implied AMM Literal Type |
+=====================+============================+
| undefined | _no type_ |
+---------------------+----------------------------+
| null | NULL |
+---------------------+----------------------------+
| bool | BOOL |
+---------------------+----------------------------+
| uint | Smallest of BYTE, UINT, or |
| | UVAST to hold the value |
+---------------------+----------------------------+
| nint | Smallest of INT, or VAST |
| | to hold the value |
+---------------------+----------------------------+
| float16, float32 | FLOAT32 |
+---------------------+----------------------------+
| float64 | FLOAT64 |
+---------------------+----------------------------+
| bstr | BYTESTR |
+---------------------+----------------------------+
| tstr | TEXTSTR |
+---------------------+----------------------------+
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.
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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 ID
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:
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 representing valid UTF-8 text in
accordance with [RFC3629].
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 6).
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.
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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 7).
The following subsection explains the form of those object
identifiers.
3.3.3. Object ID
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
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. A text form object name SHALL contain
only URI path segment characters representing valid UTF-8 text in
accordance with [RFC3629].
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 specialized uses for the term
"parameter" to disambiguate each purpose, as defined below.
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Formal Parameters:
Formal parameters define the type, name, and order of the
information that customizes an ARI. They represent the unchanging
"signature" of the parameterized object. Because ARIs represent a
_use_ of an object and not its definition, formal parameters are
not present in an ARI and instead are part of an object model.
Given Parameters:
Given parameters represent the data values used to distinguish
different instances of a parameterized object. A given parameter
is an AMM value and is represented by an ARI within the context of
a parameter list (AC) or parameter map (AM). Because of necessary
normalizing (of type and default value) based on formal
parameters, multiple given parameters can correspond with the same
meaning (see Actual Parameters below).
Additionally, there are two ways in which the value of a given
parameter can be specified: parameter-by-value and parameter-by-
name.
Parameter-By-Value: This method involves directly supplying the
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 an
other parameter and using that other parameter's value as a
substitute for the value of this parameter. This method is
useful when a parameterized ARI is produced by an AMM object
which itself is parameterized. The original ARI parameters
contain literal ARIs with LABEL type, and when the value is
produced based on input parameters the substitution is made.
In this way, an actual parameter can be "flowed down" to
produced values at runtime.
Actual Parameters:
Actual parameters represent a normalized set of values taken from
a set of given parameters and normalized using a set of
corresponding formal parameters. An actual parameter is an AMM
value and is represented by an ARI.
Because normalizing can cause a given parameter to change type (in
order to conform to a formal parameter type) or take on a default
value (when not present in the given parameters), a single set of
actual parameters can correspond with multiple options for given
parameters.
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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 = [ARIPREFIX] ari-ssp
ari-ssp = lit-ssp-struct / objref-ssp-struct
; restricted to only literals as a subset of "ari" symbol
lit-ari = [ARIPREFIX] lit-ssp-struct
ARIPREFIX = "ari:"
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,
literal and object type names, and object names have a limited
character set all within the symbol val-seg. For literals and nested
parameters though, the percent encoding of Section 2.4 of [RFC3986]
is needed.
The following symbol val-seg is an allowed superset of all
identifiers
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; A subset of RFC 3986 segment-nz and pchar symbols which matches all
; identifiers, primitive values, and typed-literal values
val-seg = 1*( unreserved / pct-encoded / val-delims)
val-delims = "!" / "'" / "*" / "+" / ":" / "@"
; A text name must start with an alphabetic character or underscore
id-text = (ALPHA / "_") *(ALPHA / DIGIT / "_" / "-" / ".")
; An integer enumeration must contain only digits
id-num = 1*DIGIT
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 AMM literal 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
AMM literal 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 is elided.
The text form of literal ARI has two layers of coding: the URI path
structure and the type-specific value coding. These are
distinguished below in the ABNF by the lit-ssp-struct symbol being
for the general path structure and type-specific coding defined in
Section 4.2.1.
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lit-ssp-struct = lit-container / lit-typeval-struct / lit-notype-struct
; More complex text (still in the "val-seg" character set) for
; non-primitive values
lit-typeval-struct = "/" lit-type "/" val-seg
; Type is restricted to valid AMM literal types
lit-type = id-text / id-num
; These use different symbols than lit-typeval-struct because of recursion
lit-container = lit-ac / lit-am / lit-tbl / lit-execset / lit-rptset
lit-ac = "/" ("AC" / "17") "/" ari-collection
lit-am = "/" ("AM" / "18") "/" ari-map
lit-tbl = "/" ("TBL" / "19") "/" ari-tbl
lit-execset = "/" ("EXECSET" / "20") "/" exec-set
lit-rptset = "/" ("RPTSET" / "21") "/" rpt-set
; The untyped value is a subset of the "lit-notype" symbol
lit-notype-struct = val-seg
4.2.1. Typed Literal Values
The definition in this section is a specialization of the lit-
typeval-struct structure for specific literal types.
An ARI encoder or decoder SHALL handle both text name and integer
enumeration forms of the lit-type symbol. When present and able to
be looked up, the literal type SHOULD be a text name.
The text form of typed values SHALL be one of the following, based on
the associated lit-type value in the ARI:
NULL:
This type contains only the single the fixed value "null".
null = "null"
BOOL:
This type contains the two fixed values "true" and "false".
bool = "true" / "false"
BYTE, INT, UINT, VAST, or UVAST:
The integer types, signed or unsigned, match the following integer
ABNF symbol:
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integer = int-dec / int-bin / int-hex
int-dec = optsign 1*DIGIT
int-bin = optsign "0b" 1*BIT
int-hex = optsign "0x" 1*(HEXDIG HEXDIG)
optsign = ["+" / "-"]
REAL32 or REAL64:
The floating-point types match the following float ABNF symbol,
which includes a specialized text form that avoids decimal or
exponential conversion of the underlying value. The raw floating
point text form SHALL be the prefix "0fx" followed by the
hexadecimal encoding of the network-byte-order binary encoding in
accordance with [IEEE.754-2019] for binary16, binary32, or
binary64 values.
float = float-exp / float-dec / float-raw
float-exp = optsign 1*DIGIT ["." 1*DIGIT] "e" optsign 1*DIGIT
float-dec = optsign 1*DIGIT "." 1*DIGIT
; Custom encoding of IEEE-754 binary content
; The hex data will really only be 2, 4, or 8 bytes
float-raw = optsign "0fx" *(HEXDIG HEXDIG)
TEXTSTR:
The text string type matches the following tstr ABNF symbol after
percent-decoding, which is consistent with the CBOR Diagnostic
Notation definition. As an alternative, if the text value matches
the id-text character set it can be encoded directly without
quoting.
; double-quoted and escaped text
tstr = tstr-quoted / id-text
tstr-quoted = DQUOTE *(%x20-21 / %x23-7E) DQUOTE
BYTESTR:
The byte string type matches the following bstr ABNF symbol after
percent-decoding, which is consistent with the CBOR Diagnostic
Notation definition. All non-raw byte strings are encoded in
accordance with [RFC4648].
bstr = bstr-raw / bstr-b16 / bstr-b64
bstr-raw = SQUOTE *(%x20-21 / %x23-7E) SQUOTE
bstr-b16 = "h" SQUOTE 1*(HEXDIG HEXDIG) SQUOTE
bstr-b32 = "b32" SQUOTE 1*(ALPHA / %x32-37) *EQ SQUOTE
bstr-b64 = "b64" SQUOTE 1*(ALPHA / DIGIT / "+" / "/") *EQ SQUOTE
SQUOTE = "'"
EQ = "="
TP:
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This type uses either the date-time ABNF symbol of Appendix A of
[RFC3339] always in the "Z" time-offset, or as a numeric
representation of the relative time from the DTN epoch. This text
is unquoted and, to avoid percent encoding, this text form MAY
omit the separator characters "-" and ":".
tp-val = date-time / float / integer
TD:
This type uses either the duration ABNF symbol of Appendix A of
[RFC3339] with a positive or negative sign prefix, or as a numeric
representation of the relative time value. This text is unquoted
and due to the constraints on the value need not be percent
encoded.
td-val = duration / float / integer
LABEL:
This type uses the id-text ABNF symbol from this document. This
text is unquoted and due to the constraints on the value need not
be percent encoded.
CBOR:
This type uses the following emb-cbor ABNF symbol for its value.
The first encoding choice uses the percent encoded form of CBOR
extended diagnostic notation of Appendix G of [RFC8610]. The
second encoding is the raw byte string of the embedded CBOR.
emb-cbor = cbor-diag / bstr
cbor-diag = "<<" *(%x20-3B / %x3D / %x3F-7E) ">>"
AC:
This type uses the following ari-collection ABNF symbol for its
value. Each item of the collection is an already-percent-encoded
text-form ARI.
; A comma-separated list of any form of ARI with enclosure
ari-collection = "(" ari *("," ari) ")"
AM:
This type uses the following ari-map ABNF symbol for its value.
Each key of the map is an already-percent-encoded text-form
literal-value ARI. Each value of the map is an already-percent-
encoded text-form ARI.
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; A comma-separate list of pairs, each delimited by equal-sign
; with literal-only keys
ari-map = "(" ari-map-pair *("," ari-map-pair) ")"
ari-map-pair = lit-notype "=" ari
TBL:
This type uses the following ari-tbl ABNF symbol for its value.
The value is prefixed by the number of columns in the table,
followed by an AC representing each separate row in the table.
Each item of the table is an already-percent-encoded text-form
ARI.
ari-tbl = "c=" *DIGIT ";" *ari-collection
| Note that although the TBL uses the same syntax as AC for
| encoding each row, the value itself is not necessarily
| internally represented by a sequence of AC values.
EXECSET:
This type uses the following exec-set ABNF symbol for its value.
The value is prefixed by the optional nonce value for the
associated execution(s), followed by an AC representing each item
to be executed (either a CTRL reference, MAC-producing reference,
or MAC value). Each item of the targets is an already-percent-
encoded text-form ARI.
exec-set = "n=" exec-nonce ";" exec-targets
exec-nonce = null / integer / bstr
exec-targets = ari-collection
| Note that although the EXECSET uses the same syntax as AC
| for encoding each row, the value itself is not necessarily
| internally represented by an AC.
RPTSET:
This type uses the following rpt-set ABNF symbol for its value.
The value consists of the optional nonce value for the associated
execution(s), a reference absolute time for all contained reports,
and the list of contained reports. Each contained report consists
of a relative creation time for the report (relative to the RPTSET
reference time), a reference to the source of the report, and an
AC representing each item in the report. Each item of a report is
an already-percent-encoded text-form ARI, as is the source
reference. The nonce and timestamps are untyped values.
rpt-set = "n=" exec-nonce ";r=" tp-val ";" *rpt-container
rpt-container = "(t=" td-val ";s=" ari ";" rpt-items ")"
rpt-items = ari-collection
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| Note that although the report container uses the same syntax
| as AC for encoding each row, the items itself is not
| necessarily internally represented by an AC.
Some examples of typed literal values are below. The represented
values for TP, TD, and CBOR types are the same just with different
text representations.
ari:/BOOL/true
ari:/UINT/10
ari:/VAST/10
ari:/LABEL/name
ari:/TP/20230102T030405Z
ari:/TP/2023-01-02T03:04:05Z
ari:/TP/725943845
ari:/TD/+PT1H
ari:/TD/3600
ari:/CBOR/h'0a'
ari:/CBOR/%3C%3C10%3E%3E
These are typed container values with text form for AC and AM lists,
here not percent-encoded:
ari:/AC/(1,2,3)
ari:/AM/(1=2,2=4,3=9)
ari:/TBL/c=3;(1,true,%22A%22)(2,false,%22B%22)
4.2.2. Untyped Literal Values
The definition in this section is a specialization of the lit-notype-
struct structure for specific primitive types.
When untyped, the literal value SHALL be one of the primitive types
named by the lit-notype ABNF symbol below. The separate value
encodings use symbols from Section 4.2.1.
| The order of this symbol sequence is significant because the
| unquoted tstr must be matched after the enumerated types of
| undefined, null, and bool.
lit-notype = undefined / null / bool / float / integer / tstr / bstr
; the undefined value is only valid as an untyped literal
undefined = "undefined"
Some example of the forms for a literals are below. These first are
untyped literal values:
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ari:undefined
ari:true
ari:10
ari:%27bytes%27
ari:h%276869%27
ari:%22text%22
4.2.3. Preferred Encodings
Several of the literal types defined in Section 4.2.1 allow the same
AMM value to be represented by multiple logically equivalent
encodings. Because these encodings are not equivalent in represented
text size or processing needs it is useful for an ARI processor to
allow a user to determine preferred encodings when processing text-
form ARIs.
Integer values: These options correspond to the BYTE, INT, UINT,
VAST, and UVAST types and untyped int values. These values can be
encoded as either base-2, base-10, or base-16. In uses which are
more resource constrained and less human-facing a processor MAY
encode integers only in base-16.
Floating point values: These options correspond to the REAL32 and
REAL64 types and untyped float values. These values can be
encoded as either dotted-decimal, exponential, or hex-encoded raw
bytes. In uses which are more resource constrained and less
human-facing a processor MAY encode floats only as raw bytes.
Byte string values: These options correspond to the BYTESTR type and
untyped bstr values. These values can be encoded as either raw
bytes, base-16, base-32, or base-64. In uses which are more
resource constrained and less human-facing a processor MAY encode
byte strings only as base-16.
Time values: These options correspond to the TP and TD types. These
values can be encoded as either delimited text, non-delimited
text, or decimal numbers. In uses which are more resource
constrained and less human-facing a processor MAY encode time
values only as decimal numbers.
Embedded CBOR values: These options correspond to the CBOR type.
These values can be encoded as either CBOR Diagnostic Notation or
as a byte string. In uses which are more resource constrained and
less human-facing a processor MAY encode CBOR values only as byte
strings.
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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 contents of the parameters SHALL be interpreted as a
literal AC or AM in accordance with Section 4.2.
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(%22a%20param%22,/UINT/10)
ari:/41/-1/0
The object-reference ARI has a corresponding ABNF definition of:
objref-ssp-struct = (obj-ident / obj-ident) [paramlist]
; The object identity can be used separately than parameters
obj-ident = ("/" ns-id / ".") "/" obj-type "/" obj-id
; Parameters are either AC or AM
paramlist = ari-collection / ari-map
ns-id = ns-adm / ns-odm
ns-adm = id-text ["@" full-date] / id-num
ns-odm = ("!" id-text) / ("-" id-num)
; Type is restricted to valid AMM object types
obj-type = id-text / ("-" id-num)
obj-id = id-text / id-num
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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
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.
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.
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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 / objref-ari
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 AMM literal type
identifier. 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 literal type SHALL be an integer enumeration. When
typed, the decoded literal value SHALL be a valid CBOR item
conforming to the AMM literal type definition of the $lit-typeval
CDDL socket. When untyped, the decoded literal value SHALL be one of
the primitive types named by the lit-notype CDDL symbol.
lit-ari = lit-typeval / lit-notype
; undefined value is only allowed as non-typed literal
lit-notype = undefined / null / bool / int / float / tstr / bstr
lit-typeval = $lit-typeval .within lit-typeval-struct
lit-typeval-struct = [
lit-type: lit-type-id,
lit-value: any
]
lit-type-id = (int32 .ge 0)
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; IANA-assigned literal types
$lit-typeval /= [0, null]
$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, int64] ; 8-byte
$lit-typeval /= [7, uint64] ; 8-byte
$lit-typeval /= [8, float16 / float32]
$lit-typeval /= [9, float16 / float32 / float64]
$lit-typeval /= [10, tstr]
$lit-typeval /= [11, bstr]
; Absolute timestamp as seconds from DTN Time epoch
$lit-typeval /= [12, lit-time]
; Relative time interval as seconds
$lit-typeval /= [13, lit-time]
lit-time = int / time-fraction
; Same structure as tag #4 "decimal fraction" but limited in domain
time-fraction = [
exp: (-9 .. 9) .within int,
mantissa: int,
]
; Parameter label
$lit-typeval /= [14, lit-label]
lit-label = tstr .regexp "[A-Za-z].*"
; Embedded CBOR item
$lit-typeval /= [15, lit-cbor]
lit-cbor = bstr .cbor any
; Literal type ID value
$lit-typeval /= [16, lit-type-id]
; Ordered list of ARIs
$lit-typeval /= [17, ari-collection]
ari-collection = [*ari-notag]
; Map from untyped literal to ARI
$lit-typeval /= [18, ari-map]
ari-map-key = lit-notype
ari-map = {*ari-map-key => ari-notag}
; Table of ARIs
$lit-typeval /= [19, ari-tbl]
ari-tbl = [
ncol: uint, ; Number of columns in the table
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*tbl-row ; All rows are concatenated in the single array
]
tbl-row = (*ari-notag)
; Execution-Set
$lit-typeval /= [19, exec-set]
exec-set = [
nonce,
exec-targets,
]
nonce = bstr / uint / null
exec-targets = (*objref-ari)
; Reporting-Set
$lit-typeval /= [20, rpt-set]
rpt-set = [
nonce,
ref-time: lit-time, ; Interpreted as a TP absolute time
*rpt-container
]
rpt-container = [
rel-time: lit-time ; Interpreted as a TD relative to ref-time
source: objref-ari,
rpt-items
]
rpt-items = (*ari-notag)
Some example of the forms for a literal are below. These first are
untyped primitive values:
true
"text"
10
And these are typed values:
[4, 10]
[15, <<10>>]
The literal-value ARI has a corresponding CDDL definition of:
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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.
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 parameters SHALL be either the ari-collection or
ari-map structure. In other words, just the value-portion of the AC
or AM typed literal because no other disambiguation needs to be made
for the parameter type.
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:
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; Type-agnostic structure of object-reference
objref-ari = $objref-ari .within objref-ari-struct
objref-ari-struct = [
obj-ident<obj-type-id>,
?params: ari-collection / ari-map
]
; Identity of a single object
obj-ident<obj-type> = (
ns-id,
obj-type,
obj-id,
)
; The null-value namespace means relative to a context ADM/ODM
ns-id = int64 / null
obj-type-id = (int32 .lt 0)
obj-id = (int32 .ge 0) / tstr
; Generic usable for restricting objref-ari by type
objref-type<obj-type> = [
obj-ident<obj-type>,
?params: ari-collection / ari-map
]
; IANA-assigned object types
CONST = -2
$objref-ari /= objref-type<CONST>
CTRL = -3
$objref-ari /= objref-type<CTRL>
EDD = -4
$objref-ari /= objref-type<EDD>
OPER = -6
$objref-ari /= objref-type<OPER>
SBR = -8
$objref-ari /= objref-type<SBR>
TBR = -10
$objref-ari /= objref-type<TBR>
VAR = -11
$objref-ari /= objref-type<VAR>
TYPEDEF = -12
$objref-ari /= objref-type<TYPEDEF>
5.4. URI References
The binary form of ARI does not provide the ability to encode a URI
Reference. When a text-form ARI contains a relative path, it must be
fully resolved before it can be translated to a binary-form ARI.
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6. ARI Patterns
Because the ARI logical structure (Section 3) uses path segments to
delimit the components of the absolute path, 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.
While an ARI is used to dereference to a specific managed object and
invoke behavior on that object, an ARI Pattern is used solely to
perform matching logic against text-form ARIs. 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. Because an ARI Pattern
is just used to match text-form ARIs it has no specific restrictions
on enumerated segment text the way a valid ARI does.
The ABNF for the ARI Pattern is given here:
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 = "*"
6.1. ARI Matching
An ARI Pattern SHALL be considered to match an ARI when, after
removing the ARI's parameters, each component of the ARI Pattern
matches the corresponding ARI path component. Each pattern component
SHALL be considered to match according to the following rules:
Specific value: The pattern component SHALL be compared with the ARI
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component after both are percent-decoded in accordance with
Section 2.1 of [RFC3986] and UTF-8 decoded in accordance with
[RFC3629].
Single-segment wildcard: The pattern component SHALL be considered
to match with any ARI component, if present, including an empty
component.
7. Transcoding Considerations
When translating literal types into text form and code point lookup
tables are available, the literal type SHOULD be converted to its
text name. When translating literal types from text form and code
point lookup tables are available, the literal type SHOULD be
converted from its text name. The conversion between AMM literal
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 AMM literal 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 AMM
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.
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8. 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.
| 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.
9. 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.
10. IANA Considerations
This section provides guidance to the Internet Assigned Numbers
Authority (IANA) regarding registration of schema and namespaces
related to ARIs, in accordance with BCP 26 [RFC1155].
10.1. 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 DTNMA Managers and Agents to identify
managed objects.
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Contact:
IETF Chair <chair@ietf.org>
Change controller:
IESG <iesg@ietf.org>
Reference:
Section 4 of [This document].
10.2. 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 DTNMA ARI
Reference:
Section 5 of [This document].
10.3. DTN Management Architecture Parameters
This document defines several new sub-registries within a new "DTN
Management Architecture Parameters" registry.
This document defines a new sub-registry "Literal Types" within the
"DTN Management Architecture Parameters" registry [IANA-DTNMA]
containing initial entries from Table 3. Enumerations in this sub-
registry SHALL be non-negative integers representable as CBOR uint
type with an argument shorter than 4-bytes. Names in this sub-
registry SHALL be unique among all entries in this and the "Managed
Object Types" sub-registry. The registration procedure for this sub-
registry is Specification Required.
+=============+=========+==============================+===========+
| Enumeration | Name | Description | Reference |
+=============+=========+==============================+===========+
| _255_ | LITERAL | A reserved type name for the | [This |
| | | union of all possible | document] |
| | | literal types. | |
+-------------+---------+------------------------------+-----------+
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| _0_ | NULL | The singleton null value. | [This |
| | | | document] |
+-------------+---------+------------------------------+-----------+
| _1_ | BOOL | A native boolean true or | [This |
| | | false value. | document] |
+-------------+---------+------------------------------+-----------+
| _2_ | BYTE | An 8-bit unsigned integer. | [This |
| | | | document] |
+-------------+---------+------------------------------+-----------+
| _4_ | INT | A 32-bit signed integer. | [This |
| | | | document] |
+-------------+---------+------------------------------+-----------+
| _5_ | UINT | A 32-bit unsigned integer. | [This |
| | | | document] |
+-------------+---------+------------------------------+-----------+
| _6_ | VAST | A 64-bit signed integer. | [This |
| | | | document] |
+-------------+---------+------------------------------+-----------+
| _7_ | UVAST | A 64-bit unsigned integer. | [This |
| | | | document] |
+-------------+---------+------------------------------+-----------+
| _8_ | REAL32 | A 32-bit [IEEE.754-2019] | [This |
| | | floating point number. | document] |
+-------------+---------+------------------------------+-----------+
| _9_ | REAL64 | A 64-bit [IEEE.754-2019] | [This |
| | | floating point number. | document] |
+-------------+---------+------------------------------+-----------+
| _10_ | TEXTSTR | A text string composed of | [This |
| | | (unicode) characters. | document] |
+-------------+---------+------------------------------+-----------+
| _11_ | BYTESTR | A byte string composed of | [This |
| | | 8-bit values. | document] |
+-------------+---------+------------------------------+-----------+
| _12_ | TP | An absolute time point (TP). | [This |
| | | | document] |
+-------------+---------+------------------------------+-----------+
| _13_ | TD | A relative time difference | [This |
| | | (TD) with a sign. | document] |
+-------------+---------+------------------------------+-----------+
| _14_ | LABEL | A text label of a parent | [This |
| | | object parameter. This is | document] |
| | | only valid in a nested | |
| | | parameterized ARI. | |
+-------------+---------+------------------------------+-----------+
| _15_ | CBOR | A byte string containing an | [This |
| | | encoded CBOR item. The | document] |
| | | structure is opaque to the | |
| | | Agent but guaranteed well- | |
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| | | formed for the ADM using it. | |
+-------------+---------+------------------------------+-----------+
| _16_ | ARITYPE | An integer value | [This |
| | | representing one of the code | document] |
| | | points in this Literal Types | |
| | | table or the Object Types | |
| | | table. | |
+-------------+---------+------------------------------+-----------+
| _17_ | AC | An array containing an | [This |
| | | ordered list of ARIs. | document] |
+-------------+---------+------------------------------+-----------+
| _18_ | AM | A map containing keys of | [This |
| | | primitive ARIs and values of | document] |
| | | ARIs. | |
+-------------+---------+------------------------------+-----------+
| _19_ | TBL | A two-dimensional table | [This |
| | | containing cells of ARIs. | document] |
+-------------+---------+------------------------------+-----------+
| _20_ | EXECSET | A structure containing | [This |
| | | values to be executed by an | document] |
| | | Agent. | |
+-------------+---------+------------------------------+-----------+
| _21_ | RPTSET | A structure containing | [This |
| | | reports of values sampled | document] |
| | | from an Agent. | |
+-------------+---------+------------------------------+-----------+
| 22 to 254, | | _Unassigned_ | |
| | | | |
| 256 to | | | |
| 65279 | | | |
+-------------+---------+------------------------------+-----------+
| 65280 to | | Enumerations that are | [This |
| 2147483647 | | 2**16-2**8 and larger are | document] |
| | | reserved for private or | |
| | | experimental use. | |
+-------------+---------+------------------------------+-----------+
Table 3: Literal Types
This document defines a new sub-registry "Managed Object Types"
within the "DTN Management Architecture Parameters" registry
[IANA-DTNMA] containing initial entries from Table 4. Enumerations
in this sub-registry SHALL be negative integers representable as CBOR
nint type with an argument shorter than 4-bytes. Names in this sub-
registry SHALL be unique among all entries in this and the "Literal
Types" sub-registry. The registration procedure for this sub-
registry is Specification Required.
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+================+=========+============================+===========+
| Enumeration | Name | Description | Reference |
+================+=========+============================+===========+
| _-256_ | OBJECT | A reserved type name for | [This |
| | | the union of all possible | document] |
| | | object types. | |
+----------------+---------+----------------------------+-----------+
| _-2_ | CONST | Constant | [This |
| | | | document] |
+----------------+---------+----------------------------+-----------+
| _-3_ | CTRL | Control | [This |
| | | | document] |
+----------------+---------+----------------------------+-----------+
| _-4_ | EDD | Externally Defined Data | [This |
| | | | document] |
+----------------+---------+----------------------------+-----------+
| _-6_ | OPER | Operator | [This |
| | | | document] |
+----------------+---------+----------------------------+-----------+
| _-8_ | SBR | State-Based Rule | [This |
| | | | document] |
+----------------+---------+----------------------------+-----------+
| _-10_ | TBR | Time-Based Rule | [This |
| | | | document] |
+----------------+---------+----------------------------+-----------+
| _-11_ | VAR | Variable | [This |
| | | | document] |
+----------------+---------+----------------------------+-----------+
| _-12_ | TYPEDEF | ADM-defined type | [This |
| | | | document] |
+----------------+---------+----------------------------+-----------+
| -13 to -255, | | _Unassigned_ | |
| | | | |
| -257 to | | | |
| -65280 | | | |
+----------------+---------+----------------------------+-----------+
| -65281 to | | Enumerations that are | [This |
| -2147483648 | | -1-(2**16-2**8) and larger | document] |
| | | 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 Architecture Parameters" registry
[IANA-DTNMA] containing initial entries from Table 6. Enumerations
in this sub-registry are non-negative integers representable as CBOR
uint type with an argument shorter than 8-bytes. The registration
procedures for this sub-registry are indicated in Table 5.
+===================+=====================================+
| Enumeration Range | Registration Procedure |
+===================+=====================================+
| 1 to 24 | Standards Action With Expert Review |
+-------------------+-------------------------------------+
| 25 to 255 | Private Use |
+-------------------+-------------------------------------+
| 256 to 4294967296 | Specification Required |
+-------------------+-------------------------------------+
Table 5: Application Data Models Registration Procedures
+=============+======+===========+==============================+
| Enumeration | Name | Reference | Notes |
+=============+======+===========+==============================+
| 0 | | [This | Value zero is reserved. |
| | | document] | |
+-------------+------+-----------+------------------------------+
| 1 to 24 | | | _Unassigned_ |
+-------------+------+-----------+------------------------------+
| 25 to 255 | | [This | Enumerations with 8-bit size |
| | | document] | are reserved for Private Use |
+-------------+------+-----------+------------------------------+
| 256 to | | | _Unassigned_ |
| 4294967296 | | | |
+-------------+------+-----------+------------------------------+
| 4294967296 | | [This | Enumerations that are larger |
| and larger | | document] | than 32-bit are reserved for |
| | | | private or experimental use. |
+-------------+------+-----------+------------------------------+
Table 6: Application Data Models
11. References
11.1. Normative References
[IANA-CBOR]
IANA, "Concise Binary Object Representation (CBOR) Tags",
<https://www.iana.org/assignments/cbor-tags/>.
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[IANA-DTNMA]
IANA, "Delay-Tolerant Networking Management Architecture
(DTNMA) Parameters",
<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>.
[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>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>.
[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>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[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>.
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[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>.
11.2. 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>.
[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-dtnma]
Birrane, E. J., Heiner, S., and E. Annis, "DTN Management
Architecture", Work in Progress, Internet-Draft, draft-
ietf-dtn-dtnma-08, 10 December 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-dtn-
dtnma-08>.
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[I-D.birrane-dtn-adm]
III, E. J. B., Sipos, B., and J. Ethier, "DTNMA
Application Management Model (AMM) and Data Models", Work
in Progress, Internet-Draft, draft-birrane-dtn-adm-06, 3
January 2024,
<https://datatracker.ietf.org/api/v1/doc/document/draft-
birrane-dtn-adm/>.
Appendix A. Examples
The examples in this section rely on the ADM and ODM definitions in
Table 7 and Table 8 respectively.
+=============+=======+
| Enumeration | Name |
+=============+=======+
| 10 | adm10 |
+-------------+-------+
| 20 | adm20 |
+-------------+-------+
Table 7: Example ADMs
+=============+=======+
| Enumeration | Name |
+=============+=======+
| -10 | odm10 |
+-------------+-------+
Table 8: Example ODMs
Given those namespaces, the example types are listed in Table 10 and
objects are listed in Table 9 where the Namespace column uses the ARI
text form convention.
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+===========+========+=============+================+===============+
| Namespace | Object | Enumeration | Name | Signature |
| | Type | | | |
+===========+========+=============+================+===============+
| adm10 | EDD | 3 | num_bytes | () |
+-----------+--------+-------------+----------------+---------------+
| adm10 | CTRL | 2 | do_thing | (AC targets, |
| | | | | UINT count) |
+-----------+--------+-------------+----------------+---------------+
| adm10 | CONST | 1 | rpt_with_param | (ARI var, |
| | | | | TEXTSTR |
| | | | | text) |
+-----------+--------+-------------+----------------+---------------+
| !odm10 | VAR | 1 | my_counter | () |
+-----------+--------+-------------+----------------+---------------+
Table 9: Example Objects
+===========+==========+=============+========================+
| Namespace | Type | Enumeration | Summary |
| | Name | | |
+===========+==========+=============+========================+
| adm10 | distance | 1 | A specialization of |
| | | | uint with scale of 1.0 |
| | | | and unit of meter. |
+-----------+----------+-------------+------------------------+
Table 10: Example ADM Types
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. Primitive-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]
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and finally to the binary string of:
0x820504
A.2. Timestamp Literal
This is the timestamp "2000-01-01T00:16:40Z" which is DTN Time epoch
plus 1000 seconds. The ARI text (which is identical to its percent-
encoded form) is:
ari:/TP/20000101T001640Z
which is translated to enumerated form:
ari:/12/1000
and converted to CBOR item:
[12, 1000]
and finally to the binary string of:
0x820c1a000f4240
A.3. Semantic-Typed Literal
This is the literal value 20 interpreted as a semantic type distance
from adm10. The ARI text (which is identical to its percent-encoded
form) is:
ari:/adm10/TYPEDEF/distance(20)
which is translated to enumerated form:
ari:/10/-12/1(20)
and converted to CBOR item:
[10, -12, 1, [20]]
and finally to the binary string of:
0x840a2b018114
A.4. 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 can be directly percent encoded as
ari:/CBOR/%3C%3C%7B%22test%22%3A%5B3%2C4.5%5D%7D%3E%3E
The embedded item can further be CBOR-encoded to a byte string and
percent-encoded, along with a translated type enumeration of:
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.5. 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.6. 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(/AC/(./edd/num_bytes,/!odm10/var/my_counter),3)
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which is translated to enumerated and resolved form:
ari:/10/-3/2(/17/(/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:
0x840A220282D82982830A230383292A0103
A.7. 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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