Side_1_360

trail assigned to it (OBLIGATION noServer-
Trail). An eventual successful output of the
action is indicated to the caller (OBLIGATION
successTopologicalLinkDeleted).

5.2 Information Viewpoint

The information viewpoint defines the informa-
tion object types involved in the delete topologi-
cal linkaction and the relationships that exist
between object instances.

The information object types affected by the said
action are iptomLayerNetworkDomain, iptom-
TopologicalLink, iptomServerTrail, and iptom-
ServerLayerNetworkDomain. Figure 11 presents
the inheritance diagram for these information
object types.

All types inherit from the [G.853.1] networkIn-
formationTop information object type. All infor-
mation objects inherit the resourceIdattribute
from networkInformationTop. This attribute rep-
resents the unique identification of a resource,
and the resourceIdassociated with an informa-
tion object must be unique for its associated
class.

[G.853.1] object types topologicalLink, trans-
portConnection, and layerNetworkDomain are
supertypes from which the relevant specialisa-
tions are made. A topologicalLink information
object represents a link provided by one and
only one server trail, in a client layer. The formal
definition of the topologicalLink information
object type is presented in section 3.2.2. A trans-
portConnection information object represents a
[G.805] connection, or a [G.805] trail. The trans-
portConnection subtype trail, from which the
iptomServerTrail is derived, represents a [G.805]
trail. Finally, a layerNetworkDomain informa-
tion object represents an administrative domain
in which all resources pertain to the same
[G.805] layer.

All involved subtypes inherit the signalidentifi-
cationattribute from their respective supertypes.
This attribute represents the specific format of
signal that a resource carries. The specific for-
mats are technology-specific, and are defined in
technology-specific extensions. IP-specific for-
mats have not been defined.

Additionally, iptomTopologicalLink inherits the
linkDirectionalityattribute. This attribute char-
acterises the ability of the topological link to
carry traffic in one, two or undefined direction.
The formal definition of the linkDirectionality
attribute is presented in section 3.2.2.The stan-
dard userLabelattribute, representing a user-
friendly label given to a resource by a user, is
also present in iptomTopologicalLink informa-
tion objects.

Figure 12 presents the relationship diagram for

the same information object types. The diagram

is restricted to the relationship types of relevance

to the delete topological link action.

The topologicalLinkIsSupportedByTrailrelation-

ship between the iptomTopologicalLink and

iptomServerTrail information objects is of spe-

cial interest to the delete topological linkaction.

If the topological link specified in a delete topo-

logical linkaction participates in such a relation-

ship, it cannot be deleted, and the action request

is rejected. The formal definition of the topologi-

calLinkIsSupportedByTrailrelationship type is

presented in section 3.2.2.

A layer network domain has a container-element

sort of relationship with the network resource

objects that compose it, formally represented by

the layerNetworkDomainIsMadeOfrelationship

type. A layerNetworkDomainIsMadeOfrelation-

ship instance may include several element role

instances, but it may include one and only one

container LND role instance.

While the topologicalLinkIsSupportedByTrail

relationship type represents a relationship

between a server layer trail and one or more

client layer topological links, the iptomLnd-

CanServeLndsrelationship type represents the

corresponding relationship between server and

client layer network domains.

Figure 11 Inheritance

diagram for topological link

and related entities

G.853.1 transportConnection

signalidentification

directionality

G.853.1 networkInformationTop

recourceId

G.853.1 topologicalLink

signalidentification

linkDirectionality

G.853.1 trail iptomTopologicalLink

userLabel

iptomServerTrail G.853.1 layerNetworkDomain

signalidentification

iptomServerLayer

NetworkDomain iptomLayerNetworkDomain