SLD Dynamic Graphic Size

Does anybody know that is possible to make the value of tag to dynamic in SLD?

I'm using geoserver to define a style, but I need more different size objects.

I mean like this:

      <Graphic>
        <Mark>
          <WellKnownName>square</WellKnownName>
          <Fill>
            <CssParameter name="fill">#FF0000</CssParameter>
          </Fill>
  开发者_C百科      </Mark>
        <Size>${poi_size}</Size>
      </Graphic> 

If anybody knows that how can I have to do this, please answer.

Much appreciated for the answers.

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Finally, I found the answer for my question here: http://docs.geoserver.org/stable/en/user/styling/sld-cookbook/points.html#attribute-based-point