Resumen de Context-aware negotiation: the basis for ubiquitous service provisioning
This PhD Thesis reports the author's research done in the field of Ubiquitous and Pervasive Computing (UPC). On previous work we worked on device characterization and content adaptation strategies in client-server architectures. Building on top of this experience, our first approach was to work on proxies as the means to break away from e-2-e and perform all the characterization, negotiation and adaptation at the application level, as mobile and Ubiquitous Computing initiatives promoted. We worked on how to take advantage of synergies among context acquisition, content negotiation, device capability expression, delivery context characterization, content adaptation and application layer protocol optimization, and demonstrated how to build a collaborative system to improve performance, self-adaptability, ubiquity and the QoE of web applications in links with restrictions.
During this work, we found faults in using TCP/IP as the underlying network architecture for UPC -i.e. problems of identification, lack of protocol adaptation, context-awareness, lack of information flow between layers, no service discovery, restricted negotiation, etc. Thankfully, we were not alone in this and the Post-IP and Future Internet trends were starting, encouraging us to develop a new network architecture from scratch with UPC and constrained networks and devices in mind. This focus on ubiquity implies designing an architecture that suits the requirements of sensor/actuators and object networks. Steadily, WSN and other edge networks are becoming a majority in the Internet and they require solutions that fit their needs and restricted capabilities. Furthermore, it is easier to implement innovations in the edges than in the core of the network.
Therefore, learning from previous work, we proposed a solution based on context awareness, device-independence and constrained networks design principles. Extending the concept of delivery context, we proposed a modular context-aware architecture with an integrated semantic discovery and negotiation protocol, plus some context exchange mechanisms. Hence, this architecture does not follow the e-2-e principles but involves every intermediate node in the discovery, adaptation and negotiation of telematic services. Likewise it does break with the traditional layered model, proposing a modular framework based on Role-Based Architectures(RBA)/Service-Oriented Architectures (SOA) principles. Further deviations from current networking model is the infrastructure-agnosticism and autonomic nature of the architecture, designed to work in pure ad hoc mode, infrastructure-assisted mode or in-between hybrid modes.
Some lessons learnt from these experiences are that, when designing a new network architecture, it is necessary to bear in mind that it should be flexible and adaptable enough to perform reasonably well in all kinds of environments, without making assumptions about execution environment, infrastructure support or a minimum set of device capabilities. Network architectures should be truly ubiquitous, providing tools for consuming network services anytime, anywhere, and anyhow (that is, on any device, on any platform), thus integrating all kinds of edge networks, platforms and devices. This is of great importance, since most advances in the networking field come from the edges. Hence, we need a shift from strict end-to-end arguments, building a network architecture that provides more intelligence to the network side whilst still leaving decision-making processes to the end-points. Such a shift is required in order to deal with increasing network heterogeneity, both in terms of services, devices and physical technologies. We need to cope with different conditions throughout the delivery chain, and thus the intermediate nodes must be aware of the environment and be able to adapt to any change in the network.
