There is an interesting Ajax-related proposal in Apache incubator, named XAP (eXtensible Ajax Platform). It is a project donated by Nexaweb Technologies Inc and represents XML-based declarative framework for building rich internet applications based on Ajax. You can find more information about this project on Nexaweb site
In the proposal there is the following paragraph:
Although these toolkits ease development of Ajax-powered web applications, there are still significant development and maintenance challenges, mainly associated with writing, debugging and maintaining JavaScript code. In particular, some developers would prefer not to use JavaScript.
I’m not sure whether XML is easier to debug and maintain than JavaScript and also whether any XML-declarative framework can have the same flexibility for writing GUIs as scripting language? Also, why we need another XML dialect when there is XUL which is mature and proven in practice. Do you think that JavaScript is the weak point of Ajax and how would you overcome it?