【文章內(nèi)容簡(jiǎn)介】 ailor, Configuration Manager, and Mobile Proxy. The purpose and functions of each ponent will be introduced separately. System design details are presented in Section 3.. Page TailorPage Tailor in the form of mobile code can be downloaded and executed in a user39。s browser when he/she is about to personalize a Web page. It provides some visual manipulations for users to help them specify their preferences about a Web page. The preferences here include: blocks of a Web page that should be retained and their final arrangement. All the preferences about this page would be saved in a remote database that is managed by Configuration Manager. Fig. 4 is a snapshot when executing Page Tailor in a Firefox Web browser.Fig. 4. Page Tailor in Firefox Web browser.. Execution and initializationWhen browsing Web pages, a user can click on the installed bookmarklet to download and execute Page Tailor. From the other perspective of users, it seems that the Web page itself provides the personalizing functions.After the Page Tailor window is launched in the user39。s browser, some actions are performed in the background automatically. First, Page Tailor will connect with Configuration Manager to retrieve the user preferences about this current visited page. If the user has personalized this page before, Page Tailor would retrieve the old preferences, and then use the data retrieved to reconstruct the past, such as blocks that had been selected and their order.On the contrary, if there are no preferences about this page, nothing will happen, of course. The purpose of this action is to help users accelerate the setting time。 particularly when he/she only wants to perform a slight modification.. Visual manipulationsIn order to help a user specify his/her preferences about a Web page, Page Tailor provides some visual manipulations. Fig. 5 demonstrates the feature that a user can select a block in a Web page at different granularity. For example, in the top half of this picture, a block containing more information than that in the bottom is selected. A selected block is highlighted in yellow.Fig. 5. Select blocks at different granularity.Fig. 6 illustrates another feature — drag and drop. In this picture, three views are shown from left to right. In the beginning, three blocks have already been selected (left). Next, we switch the last two blocks (middle), and then the final result es out (right). The sequence of blocks in the Page Tailor window would be the same as that in the browsers on mobile devices.Fig. 6. Rearrange the selected blocks.. User preferencesXPath [9] is a language that describes how to locate specific elements in a document. This is the standard we adopted to store the user preference. In our Web Page Tailoring system, the user preferences stored are posed of XPath expressions. In other words, when a user adds a block to the Page Tailor window, Page Tailor would internally generate an XPath expression for that block. By using XPath expressions, we can uniquely identify this block in the future provided that if the layout of this page does not change too frequently.As for the sequence of selected blocks, the XPath expressions of selected blocks are concatenated together according to their order in the Page Tailor window (separated by mas) to form the user preferences about this page. Fig. 7 is a practical example.Fig. 7. Internal expression of user preferences about a Web page.. Configuration ManagerThe preferences specified by a user will be stored in a database. Configuration Manager serves as a gatekeeper to control the access to the backend database. It provides a Web based interface) for a user to manage his/her preferences base on the HTTP Web protocol. Two Web services are also exported to allow other ponents in this system to access the preferences programmatically. One is used for querying the database and the other for updating.The reason why we adopted the Web service approach ultimately is because of its language and platformspecific nature. Hence, other ponents utilizing the services in our system could be implemented in different programming languages that are more appropriate for specific tasks.. Mobile ProxyMobile Proxy is a specially made proxy that is responsible for the final step in pleting the personalizing process. It would monitor every HTTP request and makes Web service calls (query service) with the request URL as the parameter to Configuration Manager. The returned user preferences, if any, could then be employed to filter out the unwanted Web page content and rearrange the remaining blocks.Fig. 8 summarizes the munication between these three major ponents. Page Tailor is first downloaded and executed in a user39。s browser. Then the Web services exported