Hi Teles,
delicate issue :-) Basically, what the specification is telling us
is that you are not expected to answer a CANCEL request in the
doCancel method. The container manages the CANCEL and INVITE
transactions for you generating the appropiate responses and
cancelling branches if needed according to UAS or proxy roles played
by the application. You receive the CANCEL request in the doCancel
method for sake of notification to the application only.
Since you are not doing proxy, but B2BUA, from the point of view of
the container, the upstream leg (which is a UAS) and the downstream
(which is a UAC) are completely separated and only linked at an
application level, that means that is up to the application to manage
the upstream CANCEL. You have to proceed in three different ways
depending on the transaction state:
A) You have answered to the upstream INVITE request with a final
positive final response:
- The container will automatically send a 200OK to the CANCEL
- You don't receive the CANCEL request in the doCANCEL since the
transaction is not cancelled
- The upstream sends a BYE request when it receives the 200OK
(since it realizes that the transaction couldn't be cancelled)
- You manage the BYE request as usual
B) You have answered to the upstream INVITE request with a non
positive final response (i.e. 4XX):
- The container will automatically send a 200OK to the CANCEL
- You don't receive the CANCEL request in the doCANCEL since the
transaction is not cancelled
- The downstream dialog is not supposed to be stablished (if it
was you application wouldn't have sent an error response to the
upstream, would it? ) so no need to care about it
C) You have not answered to the upstream INVITE with a final response
- The container will automatically send a 200OK to the CANCEL
- The container will automatically send a 487 response to the INVITE
- The application will receive the CANCEL request in the doCancel
method
- The application sends a CANCEL to the downstream dialog if
it is not completed
- The application sends a BYE to the downstream dialog if it
is completed
- Any attempt to answer (or proxy) the incoming INVITE will cause
an IllegalStateException to be thrown
Hope I was of some help
Regards
Gines
El 08/03/2007, a las 12:31, tele escribió:
Hi,
I'm so closer to complete the basic b2bua but i need last
clarification
about the CANCEL.
The specification of servlet API said:
Receiving CANCEL
When a CANCEL is received for a request which has been passed to an
application, and the appli-
cation has not responded yet or proxied the original request, the
container responds to the original
request with a 487 (Request Terminated) and to the CANCEL with a
200 OK
final response, and it
notifies the application by passing it a SipServletRequest object
representing the CANCEL
request. The application should not attempt to respond to a request
after receiving a CANCEL for
it. Neither should it respond to the CANCEL notification.
Clearly, there is a race condition between the container generating
the
487 response and the SIP
servlet generating its own response. This should be handled using
standard Java mechanisms for
resolving race conditions. If the application wins, it will not be
notified that a CANCEL request
was received. If the container wins and the servlet tries to send a
response before (or for that matter
after) being notified of the CANCEL, the container throws an
IllegalStateException.
I should not override the method onCancel?
it's not clear to me what to do.
anyway the CANCEL didn't go to the other 'leg'.
thanks!
:tele
On Wed, 2007-03-07 at 16:36 +0100, tele wrote:
I've solve my stupid problem.
The problem was in my change of Call-ID that i need for my
requirements.
In the code with problem i did the custom change after create the new
Request.
SipServletRequest downstreamReq =
sf.createRequest(req,false);
//Retrieve SipApplicationSession and SipSessions
SipApplicationSession sas =
req.getSession().getApplicationSession();
// change call-id
String oldcid = downstreamReq.getCallId();
downstreamReq.removeHeader("Call-ID");
downstreamReq.addHeader("Call-ID","1111" + oldcid);
do my change before create the downstreamReq solve my problem.
:tele
On Mon, 2007-03-05 at 22:50 +0100, tele wrote:
Hi gines,
You have been very clear! now i've understand the "dialog
marking" but i
cannot get my b2bua test working.
i'll add more debug to see why the BYE generated is incorrect in
case of
hangup from the caller.
hem... another question:
how can i get the Logger reference of the Servlet for adding
more debug?
or i need to create a new logger with log4j and write log to a
new file.
anyway attached there is the full source code for now.
thank you very much :)
regards,
:tele
Ginés Gómez wrote:
Hi ,
I understand. I'll try to explain myself clearer. Let's go back to
your original code. This is extracted from the doInvite method.
Here
you save both call legs in the application session
.....
//Save reference to SipSessions in the SipApplication
sas.setAttribute("upstreamLeg",upstreamLeg);
sas.setAttribute("downstreamLeg",downstreamLeg);
.....
what I suggest is that you do the following (after saving in
ApplicationSession)
upstreamLeg.setAttribute("COUNTERPART_LEG",downstreamLeg);
downstreamLeg.setAttribute("COUNTERPART_LEG",upstreamLeg);
this way, at any time, you can always get a reference to the
counterpart dialog doing
req.getSession().getAttribute("COUNTERPART_LEG");
then, when receiving the BYE
protected void doBye(SipServletRequest req) throws
ServletException,IOException{
//Answer positively
request.createResponse(200,"Have a nice day").send();
//Mark my dialog as finished
request.getSession().setAttribute("FINISHED","OK");
//Get the other leg and finish it in case it is not finished
//Note how useful is to have in both SipSessions (that is,
both
legs) an attribute which refers the
//other leg involved in the B2BUA transaction.
SipSession counterPartLeg= (SipSession)
request.getSession.getAttribute("COUNTERPART_LEG");
if (counterPartLeg.getAttribute("FINISHED")==null){
counterPartLeg.createRequest("BYE").send();
}
}
as you'll see what I do is sending BYE to the 'other' leg. I don't
care wether I'm processing upstream or downstream because the
COUNTERPART_LEG attribute in the SipSession will always return a
reference to the counterpart SipSession. Since the processing
(answer
OK, send BYE the other leg) is simetrical regardless the BYE was
received from the upstream or the downstream the method will work
:-)
Regards
Gines
protected void doBye(SipServletRequest req) throws
ServletException,
IOException {
req.createResponse(200,"OK").send();
SipSession downstreamLeg =
(SipSession)req.getSession().getApplicationSession
().getAttribute("downstreamLeg");
SipServletRequest byeRequest =
downstreamLeg.createRequest("BYE");
byeRequest.send();
}
this works only when the BYE come from called.
maybe i can get the Id of session of the current request
arrived in
doBye with getId() and do a check for the other id in the
upstreamLeg
and downstreamLeg then if equals to any of this, generate the BYE
request in the other call-leg.
pseudo code:
String sessionId (SipSession)req.getSession().getId();
SipSession upSession =
(SipSession)req.getSession().getApplicationSession
().getAttribute("upstreamLeg");
SipSession downSession =
(SipSession)req.getSession().getApplicationSession
().getAttribute("downstreamLeg");
if (sessionId == upSession.getId())
{
// create and send BYE request in the upstreamLeg
....
} else {
// create and send BYE request in the downstreamLeg
....
};
regards,
:tele
On Mon, 2007-03-05 at 15:27 +0100, Ginés Gómez wrote:
Anyway.... when doing B2BUA you tipically don't need to wait for
200OK to generate BYE response. You can simply send a 200OK to
any
incoming BYE request (since there is no SDP involved in the BYE
handshake) then finish the other leg. The idea would be doing
something like this (not 100% real code, some pseudocode here)
protected void doBye(SipServletRequest req) throws
ServletException,IOException{
//Answer positively
request.createResponse(200,"Have a nice day").send();
//Mark my dialog as finished
request.getSession().setAttribute("FINISHED","OK");
//Get the other leg and finish it in case it is not finished
//Note how useful is to have in both SipSessions (that is,
both
legs) an attribute which refers the
//other leg involved in the B2BUA transaction.
SipSession counterPartLeg= (SipSession)
request.getSession.getAttribute("COUNTERPART_LEG");
if (counterPartLeg.getAttribute("FINISHED")==null){
counterPartLeg.createRequest("BYE").send();
}
}
Regards
Gines
El 05/03/2007, a las 14:36, tele escribió:
Hi Gines!
It's almost clear to me how to do, this what i have done and
it works.
now i need last clarification how forward the 200 OK from BYE
request, i
cannot get it working.
for forwarding the 200 ok from the BYE in the doBye request i
save
downstreamLeg.setAttribute("byereq", req) and then in the
doResponse i
get the bye request and create the response from it,
something like this but i'm wrong.
if (resp.getStatus() == 200 && resp.getMethod().equalsIgnoreCase
("BYE"))
{
SipServletRequest upstreamRequest =
(SipServletRequest)upstreamLeg.getAttribute("byereq");
SipServletResponse upstreamResponse =
upstreamRequest.createResponse(resp.getStatus
(),resp.getReasonPhrase
());
//Copy the content from the downstream
response
to the upstream response
if (resp.getContentType() != null) {
upstreamResponse.setContent(resp.getRawContent(),
resp.getContentType());
}
upstreamResponse.send();
}
this is what i have done for working ACK.
protected void doAck(SipServletRequest req) throws
ServletException,
IOException {
//Retrieve the upstream request to respond it
SipSession downstreamLeg =
(SipSession)req.getSession().getApplicationSession
().getAttribute
("downstreamLeg");
SipServletResponse downstreamResponse =
(SipServletResponse)
downstreamLeg.getAttribute("200ok");
SipServletRequest ackRequest =
downstreamResponse.createAck();
//Copy the content from the downstream response to the
upstream
response
if (req.getContentType() != null) {
ackRequest.setContent(req.getRawContent(),
req.getContentType());
}
ackRequest.send();
}
protected void doBye(SipServletRequest req) throws
ServletException,
IOException {
SipSession downstreamLeg =
(SipSession)req.getSession().getApplicationSession
().getAttribute
("downstreamLeg");
SipServletRequest byeRequest =
downstreamLeg.createRequest("BYE");
// Copy the content from the downstream response to the
upstream
response
if (req.getContentType() != null) {
byeRequest.setContent(req.getRawContent(),
req.getContentType());
}
byeRequest.send();
}
protected void doResponse(SipServletResponse resp) throws
ServletException, IOException {
if (resp.getStatus() == 200 &&
resp.getMethod().equalsIgnoreCase("INVITE")) {
SipSession downstreamLeg = (SipSession)
resp.getSession().getApplicationSession().getAttribute
("downstreamLeg");
downstreamLeg.setAttribute
("200ok",resp);
}
//Retrieve the upstream request to respond it
SipSession upstreamLeg =
(SipSession)resp.getSession().getApplicationSession
().getAttribute
("upstreamLeg");
}
On Mon, 2007-03-05 at 00:29 +0100, Ginés Gómez wrote:
The problem is that you didn't implement the doACK method.
Implement
it following a similar technique as the one used in
doResponse. Save
the 200OK response in the downstream session so you can
retrieve it
when the ACK arrives from the upstream then generate ACK using
response.createACK() and copy the content using getContentType/
setContentType geContent/setContent if required
Hope it helps
Gines
Attached there is a .zip with all the log, trace and
configuration.
thanks for the support,
:tele
<wesip_test.zip>
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