How does one stream files, html or custom AJAX responses from web parts?
Our current quick-and-very-dirty solution is to make the web part call the current page with certain query parameters, which the web part checks and instead of performing normal load it writes the required things to output and calls response end.
This sounds bad since SharePoint might load other web parts and execute their code before reaching our web part.
The web part is configured with data source settings which means the streaming context must be specific to the web part so it can acquire the correct data source settings.