A direct CDD search with rpsblast through the BLAST server is not part of the BLAST URLAPI system. It returns results instantaneously without generating an RID. BLAST server, however, does issue an RID for a CDD search performed simultaneously for a protein BLAST request with 'CDD_SEARCH=true'. This CDD specific RID is different from that of the protein BLAST and can be used to retrieve the CDD search result.
To get the RID and the retrieval link, we can take a look at this section in the returned HTML page after the successful 'Put' step:
<input name="CDD_RID" value="ACT784U2015" type="hidden" />
To retrieve the CDD result, use the example URL:
http://www.ncbi.nlm.nih.gov/Structure/cdd/wrpsb.cgi?RID=ACT784U2015
Please note that this is NOT part of the official BLAST URLAPI, and may change without notice.
An alternative to this is to perform CDD searches through the BLAST URLAPI using a URL with the following parameters:
&DATABASE=cdd&QUERY=P12345&SERVICE=rpsblast&PROGRAM=blastp&CMD=Put
The CDD search result obtained in this way will be in different presentation format than the direct CDD search through rpsblast.