## 2 Service-oriented and Self-managed Optical Networks
### Service-oriented Optical Network Architectures  
Figure 1 depicts the service plane (highlighted in gray) introduced by the SOON project in [7], and relates it with the elements and interfaces of the ASTN planes of management, control and transport, described in [8]. The figure also shows the two main building blocks of the service plane:  
* Service virtualization, which allows client applications to refer network resources in abstract terms, such as session or topology.
* Service (connectivity) adaptation, which translates connectivity requests into a set of messages that the control plane can understand. The format and contents of these messages depend both on the nature of connectivity requests and on the technology in which the control plane is implemented.  
This service plane concept can be implemented in many ways. For example, [PERSON] _et al._ propose and evaluate a service platform for optical transport networks based on the session initiation protocol (SIP) that enables applications to exchange messages with the network to generate service requests for the reservation of the resources they need. The proposed service platform subsequently translates such requests into technology-dependent directives for the IP/optical network nodes [9]. The service platform is composed of three functional layers:  
* An application-oriented network layer, which manages application signaling and generates the service requests. This layer handles the communication among end hosts and maps generic communication instances into network service sessions that are managed using the SIP protocol.
* A service plane, which manages the mapping between service requests and technology-specific directives. This plane follows the architecture depicted in Figure 1.
* A GMPLS-enabled transport network infrastructure, which performs data forwarding. Note that this infrastructure includes the control and transport planes depicted in Figure 1.  
Another implementation example is the European PHOSPHOROUS project, in which Harmony is used as the basis for a service-oriented IP/optical network [10]. Harmony is a multi-domain path provisioning system where users and grid applications can reserve end-to-end paths in advance. In other words, Harmony is a network resource brokering system that allows heterogeneous domain interoperability by performing an inter-domain resource brokering over network resource provisioning systems (NRPS) such as GMPLS. Harmony is based on a web service architecture and contains a network service plane (NSP). In PHOSPHOROUS, the communication interfaces of the NSP and the NRPS adapters implement common web service operations for topology and reservation management. The optical network domains publish only their border endpoints (interfaces) to the NSP. Intra-domain connections are hidden to the NSP and maintained by the corresponding NRPS.  
More recently, [PERSON] _et al._[11] have proposed a thin layer for seamless interconnection of multi-technology transport networks, which implicitly involves a service-oriented optical network. The rationale for this proposal is as follows: the evolution from voice- to data-oriented networks results in multi-technology transport networks, which shall be interconnected seamlessly to provide end-to-end services. In this context, the thin layer is an enabling technology to achieve this goal through providing point-to-point links between endpoints with the required QoS. To do so, the thin layer encompasses the necessary control and management functionalities.