-The context aware systems are often designed and implemented based on a specific scenario with predefined resources. In this paper, we describe a ubiquitous interactin space that supports rapid context-aware applications reflecting the smart interaction space with dynamic resources and provides a programmable interface in integrated development environment (IDE) in .NET framework.
Otext-aware application is that the application is aware of its ne of the most distinguishing characteristics of a condynamic operating environment in physical space as well as the user. The physical space consists of many physical devices embedded with computing and internetworking capabilities that may be involved or released dynamically for contnext-aware applications. Here, we distinguish system context from user context as all those device states available for a context-aware application.
In order to develop context-aware application efficiently, we
need a middleware support that collects and controls the system
context efficiently. That is, the system provides the direct
programming interface of its own pervasive system resources that
are changing dynamically with user’s interacting environment.
Context-aware interaction manager (CAIM) [
architecture manner, each service provider has the description
which represents its own capability. It is a strong point for
supporting the dynamic discovery of resources and the
reconfiguration of the system. Therefore, we have assumed every
physical object in the environment has the self-description.
Actually, we use the Universal Plug and Play (UPnP) [
The key features of CAIM are the following: • Dynamic resource discovery: CAIM reflects the dynamic changes of system resources which are comparable with Universal Plug and Play devices. It discovers and binds whole upnp devices in domain. If the user wants to add a new system resource, it can be added simply as a upnp device. •
Maintaining the system context: When a new resource involves, CAIM monitors and caches each states of resource continuously. The contents of system context that CAIM has are which resources are available, what services that the resource has are, how the services can be invoked are, and what the states of the devices are.
Application programming interface: CAIM uses the Web Service to provide the unified application programming interface. To support Web Services, it describes the WSDL (Web Service Description Language) [] definition according to the type of resource. When a new resource is discovered or removed, it updates the definitions dynamically. If, the user connects to CAIM through the general IDE which supports Web Service such as Microsoft Visual Studio .NET, it publishes the current available resource definitions. Then, the user can build context-aware applications alike the general software programming.
Integrated Web Server and UDDI registry: CAIM communicates with other components (UPnP for resources and Web Service for applications) over http. It contains the simple web server. It is not required other web server or UDDI for using Web Service. The user can bind the resources by searching the UUID (Universal Unique IDentifier) or device type.
We have developed CAIM based on Java. It is composed of three major components; Device Adapter, Interaction Manager and Web Service Interface. Device adapter detects and binds the UPnP compatible devices. When the devices are bound, it subscribes the events of devices. Finally, it also executes the actions from the applications. Interaction Manager stores the system context to repository, transfers the messages between Device Adapter and Web Service Interface, and schedules the tasks. Web Service Interface is a communication interface for applications. It generates the WSDL definitions for the registered devices. And it processes the input/output messages to interact with applications. UDDI Registry provides the search and binding mechanisms for the WSDL definitions.
The smart interaction space consists of UPnP-based smart floor,
media wall, and smart ceiling. UPnP smart floor is
implemented using FSR (Force Sensing Resistor) array and can
provide context of user activity as well as tracking of users
without attaching sensor to the body. Ubiquitous media wall is
a modified implementation of CAVE-like environment [
The FSR (Force Sensing Resistor) is made of PTF
(Polymer Thick Film) device, and exhibits decreasing resistance
value while increasing the applied force to the active surface.
Smart floor systems have been implemented in numerous
research efforts [
Fig. 2 shows the conceptual view of the media wall. The media wall displays the media space that can be controlled by smart interaction devices in the room.. Display Wall Projection. The 4 side of the room are display wall. Since the aspect ratio of the wall is different from the video of the projector, 2 projectors are used for each wall side. Software edge-blending and image warping technology are used for this purpose.
Floor Projection: The surface of the smart floor can be used as screen and may mark the floor with interaction cues in Fig 3. The center of the ceiling is equipped with active Pan-tilt-zoom projector with UPnP video render capability. This can be used for various user interaction markings.
Active video camera array 8 active cameras array with pan-tilt-zoom capability video cameras are connected through USB2.0. It can be used for the various multi-view vision systems, and currently used mainly for the real-time visual hull with dynamic view frustum.
Single board computers with PXA255 CPU are used for the UPnP device implementation. The CPU is based on the Intel XScale micro-architecture, and provides 85 GPIO pins for generating and capturing of application-specific input and output signals. Each pin can be programmed as either an input or output using the GPIO Pin Direction Register (GPDR). When programmed as an output, the pin can be set high by writing to the GPIO Pin Output Set Register (GPSR) and cleared low by writing to the GPIO Pin Output Clear Register (GPCR). The set and clear registers can be written to regardless of whether the pin is configured as an input or an output. Fig. 4 shows the implementation of the smart floor using this board.
We believe an infrastructure support by CAIM provides adequate support for resource awareness and unified application programming interface to facilitate rapid context-aware application development. Currently, .NET framework is supported as an integrated development environment for CAIM. We have made the CAIM kernel available for download at http://caim.kist.re.kr for those interested in context-aware application prototyping in UPnP device environment.. The room size smart interaction space is being extended to a connected corridor and a number of office and meeting rooms with UPnP cameras, displays and crickets. With the extended interaction space with location tracking and media display and input devices, the user may develop novel applications that are unique to ubiquitous interaction space that bridges the gap between virtual and physical space..