Encoding rules of YANG 'instance-identifier' in the Concise Binary Object Representation (CBOR)

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Table of Contents

1. Introduction

The RFC 9254 Encoding Rules of Data Modeled with YANG in the Concise Binary Object Representation (CBOR) does not define encoding rules for 'instance-identifier' pointing to list without keys entry instances and instances of leaf-list entries. The goal of this document is to define the missing rules and make clarifications in the used terminology.¶

2. Terminology and Notation

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "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.¶

The following terms are defiend in [RFC7950]:¶

• list¶

• leaf-list¶

• leaf¶

• container¶

• instance-identifier¶

The following term is defined in [RFC8949]:¶

• data item¶

The following terms are defined in [RFC9254]:¶

• delta (of YANG SIDs)¶

• absolute SID¶

The following terms are defined in [RFC9595]:¶

• item¶

• YANG Schema Item iDentifier (or "YANG SID" or simply "SID")¶

Note that the [RFC9254] also define term YANG Schema Item iDentifier but the definition describe the same term.¶

TODO: use the "The following terms are used within this document:" header?¶

Keyless list:

Is config false YANG list without any keys.¶

Keyed list:

Is YANG list that is not a keyless list. It is either a config true list or config false list with at least one key.¶

Single instance node:

Is a instance node with at most one possible instantiation. Instantiations of top-level containers are single instance nodes, instantiations of leafs of toplevel containers are single instance nodes. Container and leaf instantiations of single instance node are also single instance nodes. No list or leaf-list entries are single instance nodes, even if they have max-elements equal to one. If instance is a child of list entry it is not a single instance node. Note that this term is defined so that set of instance nodes that are uniquely identified by only YANG Schema Item iDentifier and set of single instance nodes are the same set.¶

3. Representing YANG 'instance-identifier' Type in CBOR

container system {
  ...
  leaf reporting-entity {
    type instance-identifier;
  }
}

container auth {
  leaf-list foreign-user {
    type string;
  }
}

// in module isis
container adjacencies {
  config false;
  list adjacency {
    leaf neighbor-sysid {
      type string;
    }
    leaf more-data {
      type binary;
    }
  }
}

list user-group {
  config true;
  key "group-name"

  leaf group-name {
    type string;
  }

  leaf-list user {
    type string;
  }
}

list working-group {
  leaf name {
    type string;
  }

  leaf-list chair {
    type instance-identifier;
  }
}

list device {
  key "id";

  leaf id {
    type string;
  }

  list security {
    config false;

    list user {
      key "name";
      leaf name;

      list access-token {
        leaf type {
          type identityref { base token; }
        }
        leaf token-data {
          type binary;
        }
      }
    }
  }
}

identity token;

4. Content-Types

TODO Is it possible to reuse the Content-types define in the [RFC9254]? It would be wasteful to assign new MIME content-type basically the same format.¶

5. Security Considerations

The security considerations of [RFC8949], [RFC7950], [RFC9254] and [RFC9595] apply.¶

TODO Security¶

6. IANA Considerations

This document has no IANA actions.¶

TODO Is it possible to keep the same IANA allocations of th [RFC9254]? This draft wants to be more of a bugfix document than new encoding scheme.¶

7. References

Acknowledgments

TODO acknowledge. thank Andy Bierman for his friendly responses on mailing list.¶

Author's Address