PS4PCSim: A Proactive Simulator for Pervasive Computing using WSFD

2. From Web Service-Oriented Architecture To Device Infrastructure

We have seen the major evolutions of classical SOA, as shown in Figure 1.

2.2. Service Oriented Architecture for Device

Decentralized discovery and appearance/disappearance mechanisms allow discovering services in mobile environment that are not known a priori (ws4d.org). Evented communications introduce some dynamic interactions between consumers and providers. Moreover, it adds a loose coupling between services. WSOAD (Web Service Oriented Architecture for Device) is born of the combination of these evolutions. They benefit from all the advantages of SOAD, on which is added interoperability from WSOA. Currently there are two implementations of WSOAD: UPnP (2003) and DPWS (Driscoll et al., 2009). WSOAD provides the properties needed for software infrastructures of ubiquitous systems. For many years, service oriented architectures (SOA) have been used in home automation, mobile and ubiquitous computing to represent as services the sets of functionalities offered by devices (Rouached et al., 2010). They offer lots of features such as encapsulation, dynamicity, discoverability and interoperability. They evolved from standard SOA to SOA for device (SOAD) by adding two main features: decentralized proactive discovery and asynchronous communications. Services advertise their presence and clients create search requests using multicast or broadcasted messages. Asynchronous communications used by SOAD like Jini are events notifications, providing proactivity to devices often interacting with humans or the environment. Evolutions of WSOAD allow creating proactive dynamic distributed applications, suitable for ubiquitous computing environments. Using services for devices, any modification occurring in the software infrastructure can be integrated at runtime into the model of the software infrastructure.

Figure 1.

From services to web-services for device