Reference Guide

NOTE
At this point AbstractModel (which Model extends) and Transportable
are used just to denote that
Switch
follows the data transfer object pattern [31]. AbstractModel
is a convenient partial
implementation because it properly overrides equals() and hashCode() methods. However, if the
HP
VAN SDN Controller’s persistence framework is used to persist
data, then data transfer objects take an
explicit role and they must follow certain
hierarchical constraints. At the time this document was written,
the HP VAN SDN Controller
made use of two different persistence frameworks: Relational (JPA) and
Non-Relational (Cassandra). These frameworks will be unified in the f
uture, but at this phase two
different interfaces
for transfer objects are defined: one to use in relational models and one to use in
non-relational. See Introduction
In a network managed by a controller, the controlle
r itself stands out to be a single point of
failure. Controller failures can disrupt the entire network functionality. HP VAN SDN
Controller Distributed Coordination
infrastructure provides various mechanisms that
controller applications can make use of in achieving active-active, active-
standby
Distributed Coordination paradigms and internode communication.
The Distributed
Coordination infrastructure provides 2 services for the applications to develop
Distributed
Coordination aware controller modules.
•
Controller Teaming
•
Distributed Coordination Service
Following figure describes the communication between the controller applications and the
HP VAN SDN Controller Distributed Coordination sub-systems. “App1 –
1” indicates
instance of application 1 on con
troller instance 1. Distributed services, ensures the data
synchronization across the controller cluster nodes.
Figure 44 Application view of Coordination Services
152