và cung cấp các khối xây dựng tái sử dụng. Tương tự như thế, các vật dụng bối cảnh cung cấp các lợi ích sau: • Họ một sự tách biệt của mối quan tâm bởi ẩn sự phức tạp của các cảm biến thực tế được sử dụng từ các ứng dụng Cho dù vị trí của người dùng được cảm nhận bằng cách sử dụng phù hiệu hoạt động, | 310 SIMON LOCK AND HARRY BRIGNULL Finally the SMS gloss used in the creation of new messages which cannot be illustrated visually is basically an SMS parser which checks incoming SMS looks for new message requests creates new message bubbles and initiates distribution as required. . IMPLEMENTATION OF INFRASTRUCTURE AND DEVELOPMENT FRAMEWORK The infrastructure described in this chapter has been designed to support the construction of distributed heterogeneous multi-device multi-user interactive applications. A prototype version of the infrastructure is currently available and has to this date been used to construct and test a number of different multi-user interactive applications. The infrastructure is built on top of Jini and RMI technologies from Sun Microsystems. Jini provides all of the basic facilities for the description registration and discovery of device services. This is based around one or more centralised lookup services which store details of all currently available services. A lookup service is first identified by multicast communication once identified new services can be added to the registry or it can be queried to identify a suitable device for a particular purpose. The infrastructure also provides a programmer s API and set of common device services to aid in application development. The infrastructure takes on many of the important and common tasks required to build such applications. In addition to this the infrastructure gives programmers access to a selection of varied and diverse input and output devices through a high-level serviceconsumer architecture. Services execute on hardware to which devices are directly or indirectly . through a proxy attached. Code level adapters called Consumers give programmers simple and easy access to the features of remote services. In this way heterogeneous remote devices are presented to the programmer as a consistent set of local consumer classes. RMI is used by the bubbles infrastructure to achieve
