Web applications are used for most client/server interactions using the internet. In web applications, some or all of the application is downloaded from the Web each time it is run, typically using web browsers and Java applets. More recently, dynamic web applications, such as those found in many Web 2.0 applications, have brought new kinds of dynamic and interactive elements to a user's web experience. These applications generally involve the use of client-side scripting in a standard language such as JavaScript.
There has also recently been a proliferation of electronic devices having improved functionality, such as mobile phones, person digital assistants (PDAs), television set-top boxes, and others. However, these kinds of devices are often not able to take full advantage of dynamic web applications for various reasons, such as limited screen real-estate, format compatibility, limited computing capabilities, or an inability to support JavaScript. Hence, there is a need for ways to adapt existing dynamic web applications for use on such devices.
In addition, there is a need to be able to customize dynamic web applications for particular users, groups of users, or particular tasks. Proxy server-based technologies have been discussed as possible solutions to provide these types of customizations on the web. However, proxy server technologies generally do work well with Web 2.0 applications. This is because either 1) the JavaScript code implementing the dynamic functionality of a Web 2.0 application is not passed through the proxy server or 2) some elements of the web page's Document Object Model (DOM) that the script expects may be removed by the proxy server.
One approach to add additional functionality to devices is to employ proxy servers to translate client requests and/or server responses. U.S. Pat. No. 5,727,159 describes a proxy server for translating content into a form that is usable by low power portable computers. U.S. Pat. Nos. 5,918,013 and 6,829,746 describe technologies for transcoding documents from an existing format to another format more suitable for the specific situation, such as into another language for a foreign speaker, onto a mobile device with different display requirements, or into a format with larger buttons that might be more accessible for an impaired user. Unfortunately, these technologies also have the problem described above in that they cannot appropriately deal with dynamic content. This is primarily because these technologies cannot execute client-side scripts and maintain sufficient state information about each client.
The use remote desktop technology is another existing technology that might be used to permit devices with limited functionality to use dynamic web applications. Examples of remote desktop technology include Microsoft's Remote Desktop, XWindows, or AT&T's VNC, which can be used to view the output of a web browser from a server machine on a client device. Although these technologies are limited to showing the exact pixels from the server machine, there has been some work on customization. Examples include Wincuts or User Interface Facades. These customizations could, for example, display a subset of buttons from the original interface in the remotely viewed interface. Unlike other proxy server approaches, this approach can deal with client-side JavaScript because a real web browser is being used on the server machine. However, these technologies are still limited by their reliance on images of the server machine. For example, it is difficult, if not impossible, to change the labels on buttons. The input and output capabilities of the server machine and the client machine must also be similar, because the user on the client machine must be able to provide inputs that the server machine would expect, such as pointing and clicking at buttons or dragging a scrollbar.
Accordingly, there is a need for a way to enable devices with limited capabilities to appropriately deal with dynamic web applications. There is also a need for proxy servers that can execute client-side scripts and maintain sufficient state information about each client.