CSEQ checking for SUBSCRIBE/NOTIFY messages

Hi-

I have this scenario (requests only shown, OK responses are sent but not 
shown here):

CSeq: 1 SUBSCRIBE ----------->
                               <------------CSeq: 1 NOTIFY
                               <------------CSeq: 2 NOTIFY
                               <------------CSeq: 3 NOTIFY
CSeq: 2 SUBSCRIBE------------>

In this scenario, the second SUBSCRIBE (refresh) gets dropped by the 
stack on the receive side:

DEBUG - 
gov.nist.javax.sip.NistSipMessageHandlerImpl.processRequest(NistSipMessageHandlerImpl.java:75) 
[PROCESSING INCOMING REQUEST SUBSCRIBE 
sip:[email protected]:5060;transport=udp SIP/2.0
 transactionChannel = 
gov.nist.javax.sip.stack.SIPServerTransaction@987cd413]
DEBUG - 
gov.nist.javax.sip.stack.SIPTransactionStack.getDialog(SIPTransactionStack.java:465) 
[getDialog([email protected]:[email protected]:1147615033389:[email protected]:1901773286) 
: returning gov.nist.javax.sip.stack.SIPDialog@1b8d6f7]
DEBUG - 
gov.nist.javax.sip.NistSipMessageHandlerImpl.processRequest(NistSipMessageHandlerImpl.java:103) 
[dialogId = 
[email protected]:[email protected]:1147615033389:[email protected]:1901773286]
DEBUG - 
gov.nist.javax.sip.NistSipMessageHandlerImpl.processRequest(NistSipMessageHandlerImpl.java:104) 
[dialog = gov.nist.javax.sip.stack.SIPDialog@1b8d6f7]
DEBUG - 
gov.nist.javax.sip.NistSipMessageHandlerImpl.processRequest(NistSipMessageHandlerImpl.java:423) 
[
#######
Dropping out of sequence in dialog Request
######]
DEBUG - 
gov.nist.javax.sip.stack.UDPMessageChannel.run(UDPMessageChannel.java:392) 
[Done processing SUBSCRIBE sip:[email protected]:5060;transport=udp 
SIP/2.0
/gov.nist.javax.sip.stack.SIPServerTransaction@987cd413]


The reason is because of the final check in this method (ie, 4 is not <= 2):

public boolean isRequestConsumable(SIPRequest dialogRequest) {
        // have not yet set remote seqno - this is a fresh
        if (dialogRequest.getMethod().equals(Request.ACK))
            throw new RuntimeException("Illegal method");
        if (this.getRemoteSequenceNumber() == -1)
            return true;
        else if (this.nextSeqno == null) {
            // sipStack.getLogWriter().logDebug( "nextSeqno == null => 
refusing
            // request" );
            return false;
        } else
            return this.nextSeqno.intValue() <= dialogRequest.getCSeq()
                    .getSequenceNumber();
    }

If I modify isRequestConsumable() to ignore a received SUBSCRIBE, 
everything works fine:

public boolean isRequestConsumable(SIPRequest dialogRequest) {
       
        if (dialogRequest.getMethod().equals(Request.SUBSCRIBE)) {
            return true;
        }
       
        // have not yet set remote seqno - this is a fresh
        if (dialogRequest.getMethod().equals(Request.ACK))
            throw new RuntimeException("Illegal method");
        if (this.getRemoteSequenceNumber() == -1)
            return true;
        else if (this.nextSeqno == null) {
            // sipStack.getLogWriter().logDebug( "nextSeqno == null => 
refusing
            // request" );
            return false;
        } else
            return this.nextSeqno.intValue() <= dialogRequest.getCSeq()
                    .getSequenceNumber();
    }

So, for SUBSCRIBE/NOTIFY (or at least for the notifier side) - it looks 
like there can't be an assumed relationship between the number of 
SUBSCRIBEs and NOTIFYs sent/received, and the rules need to be a little 
different. Would this be the correct fix for this? (Or have I missed 
something altogether...).

Thanks,
Becky