PSS Platform high level architecture
The PSS architecture is presented in the following figure:
Action : Micheal to add the relevant architecture diagram.
The architecture consists of five different layers, each addressing a well defined part of the PSS functionality. The names and purpose of these layers are presented hereafter for completeness.
Layer 1 - Devices
The PSS definition suggests that a single PSS can span across many different devices. Depending on their processing and networking capabilities, these devices may either implement the PSS stack or part of it, or simply interact with the rest of the PSS framework. The device classification that follows aims to identify the devices that may be part of a PSS and is based on a survey of current market-leading technologies grouped by functional/technical commonalities.
- Server: An independent computer dedicated to provide one or more services over a computer network. Examples are: Windows Media Center, Apple Itheatre, PCs.
- Laptop: A small portable computer. Examples are: Mac Book, Sony Vaio, Tablet PC.
- Mobile phone: A pocket-sized handheld computing device. Examples are: iPhone, HTC Tytan, Nokia N90, PDA.
- Sensors: A group of devices that can measure a physical quantity and convert it into a signal, which in turn can be read by an observer or an instrument. They can be embedded into other devices. Examples are: RFID readers, GPS location estimators, accelerometers, thermometers, altimeter, barometer, air speed indicator, signal strength measurer, etc.
- Smart objects: A resource-constrained device which can be connected to the Internet or a LAN via a wifi connection, ethernet, GPRS, 3G etc., usually intended for displaying multimedia content such as a combination of text, audio, still images, animation and video. Examples are WiFi? photoframes, Chumby, Nabaztag, home eAppliances and surveillance cameras.
- Interactive entertainment electronic device: An Interactive entertainment electronic device produces a video display signal, which can be used with a display device (a television, monitor, etc.) to display a video game or an external source of signal (e.g. ipTV). Examples are: set-top box, gaming console.
Layer 2 - System Run-Time Environment
The System Run-Time layer serves as an abstraction layer between the underlying device operating system and the PSS software in order to achieve as much platform independence as possible. Essentially, this layer is what makes a device PSS-capable. Hence, employing an "off-the-shelf" implementation of a virtual machine run-time will offer PSS portability over a wide range of software and hardware platforms.
Layer 3 - Overlay Network Management
The Overlay Network Management layer provides the PSS architecture with a Peer-to-Peer (P2P) management and communication layer. The services within this layer will provide functionality for PSS peer group management, peer discovery and message routing between peer networks. It is assumed the lower level adhoc networking functionality will be managed by other 3rd party components and therefore it is considered outside the scope of the Persist Project.
Layer 4 - Service Run-Time Environment
The Service Run-Time Environment layer provides a container for the PSS services. It supports service life cycle management features and provides a service registry, as well as, a device registry. Moreover, it allows for service management in a distributed fashion among multiple devices within the same PSS. In this context, it delivers fault tolerance, as well as, device resource management. The Service Run-Time Environment also provides advanced information management features for achieving high data availability and addressing storage requirements of PSS services
Layer 5 - PSS Framework
The PSS Framework layer is the core of the PSS architecture. Its functions include discovering and composing PSS and 3rd party services, as well as, managing context data and user preferences. Moreover, the PSS Framework layer supports automatic learning of preferences and inference of user intentions. This information, together with data from recommender systems, enables the proactive behaviour of the PSS platform. Grouping of context data and preferences, as well as, conflict resolution are also provided by the PSS Framework layer.
Introduction - Installation - Architecture Overview - Architecture Structural View - Running the example service - Writing your own service - Networking And Service Communication - Using Context management - Using Security and Privacy management features - Determining user intent - Accessing the service recommender - Accessing proactivity features