Yancho

$source = "select give_source('POINT(".$sp.")',1000,200)";
$target = "select give_target('POINT(".$ep.")',1000,200)" ;
$sql = "

        SELECT gid, astext(the_geom) as wkt, length(the_geom) AS length
        FROM shootingstar_sp
        ('streets',
          (
          select gid from streets where
          source = ( $source )
          limit 1
          )
        ,

          (
          select gid from streets where
          target = ( $target )
          limit 1

          )
        ,
        5000,
        'length',
        true,
        true
        );
 ";