SensBase - Winter term 2004/2005
DescriptionThe key objective of the Sens-ation research project series is to develop a client-server platform for providing sensor information from sensor boards to various clients. A proxy module provides on the server side a common interface for sensor without a detailed description of hardware. It’s necessary to protect the sensor hardware from simultaneous access by multiple clients. Direct access to the hardware interface of a sensor module can be challenging. If the hardware interface can’t be used by multiple clients. The solution of this problem is to use a proxy module as virtual interface. The proxy module is a kind of buffer between the server and used sensor modules, which accumulate and stores sensor information in a database that are most often requested by clients. A major feature of the proxy module is providing simultaneous access to sensor information and a common interface for all registered sensor modules. The common interface encapsulates and hides all specific implementation details of the hardware (cf. Figure 1).
Figure 1. The architecture of the server and planned interfaces
All sensor information collected by the proxy module will be stored in a relational database and can be accessed via a separate application. This form of storage makes it easy to calculate a variety of heuristics from current and saved sensor information. The heuristically calculated values will we available through our public service interface. If a client requests sensor values, the server will transmit not only the current value but also the prospective values for the next hours.
Figure 2. The architecture of a mobile client
Another approach is to route the request of a mobile client over a proxy service, to provide an easier access without the overhead of SOAP/XML messages (cf. Figure 2). Because mobile internet connections are mostly expensive and have low bandwidth, these smaller messages give an improvement (and would save time and money).
Our goal is to evaluate these interfaces and compare the usability, transmitting time and the capabilities to represent the data.
Furthermore we will implement different clients, especially for mobile devices. There is an objective to reduce the wireless connection time. The client proxy method will save history values in a local database and can also decide if new online connections are necessary. Another advantage is the option to use the prospective values for the response in case of failed connection to the server.
Starting from the left: Matthias Pfaff, Tareg Egla (Supervisor),
Christian Semisch, Andrea Lahn, Nicolai Marquardt.
(Missing: Tom Gross (Supervisor))