## 4 QoSSDSBS System Model  
Our system model, QoSSDSBS, consists of an environment where mobile nodes use services to publish and bind with another node. Each mobile node provides services and acts as a service provider, and the service requester communicates using MANET protocols. Each node will have specific services, power, and battery life. Service composition is a process to integrating all the services, according to the user requirement from multiple mobile nodes. In our proposed system architecture, the QoSSDSB broker acts as a service, which can incorporate these composite services from numerous mobile nodes, as depicted in Figure 1.  
Each N mobile node from N1 to N7 will have specific or the same services, with different QoS metrics for each service. Consider the nodes N2 and N6 in Figure 1, which provide the same service S2 as the other QoS metrics. In Figure 1, seven nodes offer six different and standard services. In Figure 2, the broker will group the mobile nodes based on their services. The services offered by each node are depicted, and the broker that acts as a composer will combine and integrate these services based on the user's requirements.  
Different nodes offer the same services. In this process, the broker utilizes QoS metrics such as such as delay, bandwidth, throughput, etc., to select the best service from the distinct nodes. The service registration takes place at the broker, whenever the mobile nodes within the cluster initiate a service. So, a broker's responsibility is to find adequate services by applying the QoS metrics. The broker will match the service and lists the node offering atomic services inside the cluster. According to Figures 1 and 2, we list the nodes services as follows.  
N1 = [Service 1, Service 2]  
N2 = [Service 2, Service 3]  
N3 = [Service 1, Service 4]  
N4 = [Service 4, Service 5]  
N5 = [Service 2, Service 3]  
N6 = [Service 2, Service 4, Service 6]  
N7 = [Service 5, Service 6]  
Figure 3 describes the overall architecture of QoSBS for service composition in MANET, with nodes functions in different layers of service. The service-composition layer can cope with other protocols; the communication layer provides wireless connectivity with nodes in their region. The connectivity for such a network includes ad hoc 802.11 standards, Bluetooth, etc. The communication with other networks is done with the help of IEEE 802.11. In the network layer, it provides general routing between the mobile nodes. For MANET, many traditional routing protocols are available such as the AODV [30], DSDV  
Figure 1: Composite services of mobile nodes.  
Figure 2: Selection of broker based on its services.  
(Destination-Sequenced Distance Vector) [31], etc. For the proposed QoSDSBS architecture, the AODV acts as a routing protocol because it outperforms with the QoS metrics for mobile nodes. The service-discovery layer provides the protocol to discover the services available in the mobile nodes.  
The protocol used for service discovery is GSD (Group-based Service Discovery) and any cluster-based broker selection for service discovery [32; 33]. In the service composition layer, broker-based integration of services based on the QoS metrics from the QoS management is used. This protocol is used to discover the service with different QoS metrics and integrate those services that provide a composite service to the requester node, with the help of a broker node. In the application layer, it gives a different platform for service composition. The services offered include either real-time service or non-real-time service.