Can you give some examples for Stream based portals?

Streaming-based portals directly stream portlet content from data sources
In streaming-based portals, portlet rendering is divided into two different phases,
represented by the RENDER_HEADER and RENDER_MARKUP constants. In such portals, a
request attribute whose name is the value of the RENDER_PART constant is set by the
portal server, and this value identifies the rendering phase (RENDER_HEADER or
RENDER_MARKUP)

• Jetspeed, Liferay Portal, and GateIn Portal are buffering portals