Messing around with a ruby Well-Known-Binary converter.

wkb.rb

module WellKnownBinary
    
    require 'bindata'    
    
    TYPE_ID = { 
        :point              => 1,
        :linestring         => 2,
        :polygon            => 3,
        :multipoint         => 4,
        :multilinestring    => 5,
        :multipolygon       => 6,
        :geometrycollection => 7,
        :circularstring     => 8,
        :compoundcurve      => 9,
        :curvepolygon       => 10,
        :multicurve         => 11,
        :multisurface       => 12,
        :curve              => 13,
        :surface            => 14,
        :polyhedralsurface  => 15,
        :tin                => 16,
        :triangle           => 17
    }.freeze
    
    BYTE_ORDER = {
        :big_endian    => 0,
        :xdr           => 0,
        :little_endian => 1,
        :ndr           => 1
    }.freeze
    
    class DefineByteOrder < BinData::Record
    
        uint8   :byte_order, :initial_value => BYTE_ORDER[:little_endian]
        
        def big_endian?
            byte_order == 0
        end
        
        def little_endian?
            byte_order != 0
        end
    end
    
    class PointBE < BinData::Record
        double_be :x
        double_be :y        
    end
    
    class PointLE < BinData::Record
        double_le :x
        double_le :y        
    end

    class PointArrayBE < DefineByteOrder
        uint32be   :num_points
        array       :points, :initial_length => :num_points, :type => :PointBE
    end
    
    class PointArrayLE < DefineByteOrder
        uint32le   :num_points
        array       :points, :initial_length => :num_points, :type => :PointLE
    end
    
    class WKBPoint < DefineByteOrder
    
        # uint32  :wkb_type, :value => WKB_TYPE_ID[:wkb_point]
        choice :wkb_type, :copy_on_change => true, :selection => lambda { big_endian? } do
            uint32be true,  :value => TYPE_ID[:point]
            uint32le false, :value => TYPE_ID[:point]
        end
        
        #Point   :point
        choice :point, :copy_on_change => true, :selection => lambda { big_endian? } do
            PointBE true
            PointLE false
        end
    end
    
    class WKBLineString < DefineByteOrder        
        #uint32      :wkb_type, :value => WKB_TYPE_ID[:wkb_linestring]
        choice  :wkb_type, 
                :copy_on_change => true, 
                :selection => lambda { big_endian? } do
                    uint32be true,  :value => TYPE_ID[:linestring]
                    uint32le false, :value => TYPE_ID[:linestring]
                end
                
        #PointArray  :points
        choice :point, 
               :copy_on_change => true,
               :selection => lambda { big_endian? } do
                    PointArrayBE true
                    PointArrayLE false
               end
    end

end

include WellKnownBinary

# converts a byte array to a hex string
def bin_to_hex(s)
    s.unpack('H*').first
end

#
# converts a hex string to a byte array
#   s = hex string
def hex_to_bin(s)
  s.scan(/../).map { |x| x.hex }.pack('c*')
end

# create a WKB point
foo = WKBPoint.new( :point => { :x => 47.0001, :y => 89.0011 } )

# inspect the point
# p    foo

# get the byte array (WKB)
foo_bin   = foo.to_binary_s

# get the hex string for the byte array
foo_hex   = bin_to_hex( foo_bin )

# display the hex string
# puts "    foo hex: #{foo_hex}"

# convert from hex string back to a byte array
re_foo = WKBPoint.read( hex_to_bin('01010000008D976E1283C0F33F16FBCBEEC9C30240') )
p re_foo
puts "created from string"
puts "created: #{ bin_to_hex(re_foo.to_binary_s) }"
puts ""

re_foo.byte_order = 0
puts "changed byte order to big endian"
puts 
puts " big-endian: #{ bin_to_hex(re_foo.to_binary_s) }"
puts
p re_foo

re_foo.byte_order = 1
puts "changed byte order to little endian"
puts 
puts " little-endian: #{ bin_to_hex(re_foo.to_binary_s) }"
puts
p re_foo

# Creating from WKB hex string: 01010000008D976E1283C0F33F16FBCBEEC9C30240
# 
# {"byte_order"=>1, "wkb_type"=>1, "point"=>{"x"=>1.2345, "y"=>2.3456}}
# created from string
# created: 01010000008d976e1283c0f33f16fbcbeec9c30240
# 
# changed byte order to big endian
# 
# big-endian: 00000000013ff3c083126e978d4002c3c9eecbfb16
# 
# {"byte_order"=>0, "wkb_type"=>1, "point"=>{"x"=>1.2345, "y"=>2.3456}}
# changed byte order to little endian
# 
# little-endian: 01010000008d976e1283c0f33f16fbcbeec9c30240
# 
# {"byte_order"=>1, "wkb_type"=>1, "point"=>{"x"=>1.2345, "y"=>2.3456}}
# 
# > Process Exit Code: 0