OSLC category link in RTC

Hi,

 I am trying to create a workitem in rtc using oslc 2.0. But i am not able to set the "Filed Agiainst" .
My category name is "Category1". But how to get the corresponding link for that?
Lets say my Xml is:

rdf:Description rdf:about="https://localhost:9443/ccm/resource/itemOid/com.ibm.team.workitem.Category/_nTskMOGwEeSnDqhiDVbyjw"></rdf:Description>
<rdf:Description rdf:about="https://localhost:9443/ccm/oslc/iterations/_ktRUhuGwEeSnDqhiDVbyjw">
</rdf:Description>

But as input , I have the category name i.e. "category1" not the link.

Thanks,
Sud