Streaming SAX Parser

So, I need a SAX parser. There are lots of those - so, no big deal there. But I also need a *streaming* SAX parser. That is, I need to be able to feed the parser data as I receive it. The platform in question has slow network access with high latency. It takes a while for the XML to start being received by the device, and it takes a while to receive all of the XML. In the mean time, the user interface should be updated based on the XML that has been received - even if all of the XML hasn't yet been received. Thus, I need a streaming SAX parser. And I can't find any. I guess I should write my own? Uggh. I thought this sort of thing had been standardized years ago.