Boost Subgraph Implementation and exporting using Graphml

[mayurnarkhede]

I am using boost 1.53.0, I have implemented a small demo using boost for subgraph.
I need to export the subgraph information in the graphml file, while exporting it will create all the nodes in the parent graph but not able to hold the information about it's subraphs.
so please help me if there is any way to hold information about subgraph?.
My implementation is exporting as follows:

<?xml version="1.0" encoding="UTF-8"?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd">
<graph id="G" edgedefault="undirected" parse.nodeids="free" parse.edgeids="canonical" parse.order="nodesfirst">
<node id="n0">
</node>
<node id="n1">
</node>
<node id="n2">
</node>
<node id="n3">
</node>
<node id="n4">
</node>
<node id="n5">
</node>
<edge id="e0" source="n0" target="n1">
</edge>
<edge id="e1" source="n1" target="n2">
</edge>
<edge id="e2" source="n1" target="n3">
</edge>
<edge id="e3" source="n4" target="n1">
</edge>
<edge id="e4" source="n4" target="n5">
</edge>
<edge id="e5" source="n5" target="n3">
</edge>
<edge id="e6" source="n2" target="n5">
</edge>
</graph>
</graphml>


Actully the nodes n0,n1,n2 are members of subgraph G1 and n4,n5 are members of subgrph G2.
G0 is main parent graph.