how does gstreamer drive pipeline by different sink

[koler.andrew]

hi,nice expert
i have a gst pipeline which has two sink element.one is gst-rtsp-server sink,another is filesink.when i access the pipeline by remote rtsp client,the pipeline could run and filesink could save the stream.but when i stop accessing,the pipeline stop and filesink could not save stream.
i think the pipeline was driven by rtsp sink.so,when i stop rtsp access,the pipeline stops.in order to change it,i would like to drive the pipeline by filesink.but i don't know how to do it because i could not understand gstreamer in depth.
so i put my questions on maillist:
first,i want to know why the pipeline be driven by rtsp sink and not be driven by filesink.what is the driver rule about the pipeline which has two sink element.  
second,could i change some parameters such as pipeline sys clock,pipeline playing state etc ,to control the pipeline running by filesink .
any light would be welcome.
thanks
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