họ có một ngưỡng cao, trần nhà thấp, và không thể tiên đoán. Ngưỡng cao có nghĩa là bộ công cụ này thường đòi hỏi các nhà phát triển để tìm hiểu ngôn ngữ chuyên ngành để sử dụng nó. Một trần nhà thấp chỉ ra rằng bộ công cụ này chỉ làm việc cho | 100 MIR FAROOQ ALI MANUEL A. PEREZ-QUINONES AND MARC ABRAMS they have a high threshold a low ceiling and unpredictability. A high threshold means that the toolkit often requires the developer to learn specialized languages in order to use it. A low ceiling indicates that the toolkit only works for a small class of UI applications . a Web-based UI tool that will not work with other interface styles . Developers quickly run into the toolkit s limitations. Finally a toolkit s unpredictability is due in large part to its approach. Most unpredictable tools apply sophisticated artificial intelligence algorithms to generate their interface. As a result it is difficult for the developer to know what to modify in the high-level model in order to produce a desired change in the UI. UIML while similar in nature to some of the other model-based tools has a few new design twists that make it interesting from a UI research and development point of view. First the language is designed for multiple platforms and families of devices. This is done without attempting to define a lowest common denominator of device functionality. Instead UIML uses a generic vocabulary and other techniques to produce interfaces for the different platforms. The advantage of this approach is that while developers will still need to learn a new language namely UIML this language is all they will need to know to develop UIs for multiple platforms. This helps lower the threshold of using UIML. Secondly UIML provides mapping to a platform s toolkit. Thus UIML in and of itself does not restrict the types of applications that can be developed for different platforms. Therefore UIML has a high ceiling. Finally predictability is not an issue because UIML does not use sophisticated artificial intelligence algorithms to generate UIs. Instead it relies on a set of simple transformations taking advantage of XML s capabilities that produce the resulting interface. From the developer s point of view it is clear .
