Idoc Acknowledgements and BPM.

Question

All,
My current requirement is to post an Idoc from my BPM, and get back the Idoc Acknowledgement. On the basis of the status field in the ALEAUDIT Idoc I need to determine the further course in my BPM.
<u><b>Option 1:</b></u>
1. In the Send Step of my BPM , I can request for Application Acknowledgement. I have done this and am able to receive the Acknowledgement and see the same against the Acknowledgement Msg ID in MONI. I am able to see the ALEAUDIT idoc triggered for my Send Step back to my BPM .
The question in case we are to use this Option is , how do I access this AleAudit Idoc message in my BPM. As I want to have a switch, I need this to be populated in a container element of my BPM. Is this possible? Is this approach a correct one? Any Ideas?
<u><b>Option 2</b></u>
I can have a Send Step in my BPM to send the Idoc from XI to R3. this will be a normal Send Step with no Acknowledgements. I can also use a Receive Step in the BPM to receive the ALEAUDIT Idoc back to the BPM.
This I guess can be done with a Receive determination where R3 is the sender and the AleAudit Idoc is the receive etc.
Issues with this approach, I need to use a Correlation against the Send and Receive Step to send the Idoc and receive the AleAudit.
1. What is the Correaltion that can be used?  Is there a standard correaltion. for such cases?I looked into the Idoc and the AleAudit but could' nt find a suitable Correlation Field.
Do both these solutuons make sense? has anyone got a better approach?
Any comments are appreciated.
Regards
Bhavesh
PS: Have gone through the How to guide on Idoc Ack's and the blogs on SDN as well. But if still someone feels that there is a blog that is relevant to this issue, please do let me know if I have missed anything.

Answer 1

Ha, now that was interesting question. Brains were rusty, relooked into that lookup and these are the fields of the IDXRRCVPOR we use,
Used the RFC - RFC read table
XI's Idoc Number is in Field IDOCNUMBER
Original SAP IDoc Number is in Field SNDLAD.
Code excerpt attached below.
@ Henrique : Work's been crazy past few months. The blog is on my to do list, hopefully someday soon it should be out. My Apologies guys!
Channel rfcChannel =     LookupService.getChannel(BusinessService, CommChannel);
//As the call is being made to RFC, RFCAccessor is obtained.
rfcAccessor = LookupService.getSystemAccessor(rfcChannel);
rfcXML =
                    "<?xml version=\"1.0\" encoding=\"UTF-8\"?><ns0:RFC_READ_TABLE xmlns:ns0=\"urn:sap-com:document:sap:rfc:functions\"><DELIMITER/><NO_DATA/><QUERY_TABLE>IDXRCVPOR</QUERY_TABLE><ROWCOUNT/><ROWSKIPS/><DATA><item><WA/></item></DATA><FIELDS><item><FIELDNAME>SNDLAD</FIELDNAME><OFFSET/><LENGTH/><TYPE/><FIELDTEXT/></item></FIELDS><OPTIONS><item><TEXT>IDOCNUMBER EQ &apos;"
                         + SourceDocNum
                         + "&apos;</TEXT></item></OPTIONS></ns0:RFC_READ_TABLE>";
inputStream = new ByteArrayInputStream(rfcXML.getBytes());
XmlPayload inPayload = LookupService.getXmlPayload(inputStream);
Payload outPayload = rfcAccessor.call(inPayload);
responseStream = outPayload.getContent();
DocumentBuilderFactory factory =DocumentBuilderFactory.newInstance();
/* Create DOM structure from input XML */
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(responseStream);
NodeList list = document.getElementsByTagName("WA");
for (int k = 0; k < list.getLength(); k++) {
    Node node = list.item(k);
   if (node != null) {
     node = node.getFirstChild();
                if (node != null) {
          if (!node.getNodeValue().equals("")) {
               OutputDocNum = node.getNodeValue();
Regards
Bhavesh