With so many sophisticated applications on the Web, the key/value HTML form seems overly simplistic for today's Web applications. The browser is increasingly being used to manipulate complex resources and an increasingly popular technique for encoding sophisticated data in HTML is RDFa.
RDFa defines a method of encoding data within the DOM of an HTML page using attributes. This allows complex data resources to be connected to the visual aspects that are used to represent them. RDFa provides a standard way to convert an HTML DOM structure into RDF data for further processing.
Instead of encoding your data in a key/value form, encode your data in RDFa and use DHTML and AJAX to manipulate the DOM structure and in turn manipulate the data. The conversion from HTML to data can be done on the server or client using existing libraries.
There are a few ways that RDFa can help with communication to the server. The simplest would be to send back the entire HTML DOM for RDFa parsing on the server. However, an HTML page might contain an excessive amount of bulk and therefore this would not be appropriate as a general solution. Instead, using an RDFa parser on the client, the resulting RDF data can be sent to the server, ensuring only the data is transmitted back. This would reduce excessive network traffic and move some of the processing to the client.
RDFa on the client and submitting change-sets can help streamline data processing and manipulation and avoid much of the boilerplate code associated with mapping data from one format to another.