Re: [reSIProcate] RFC Question...
Please see Inline comments too.
kaiduan
--- John Draper <lists@xxxxxxxxxxxxxxxx> wrote:
> kaiduan xie wrote:
>
> >John,
> >
> >Please see the inline comments.
> >
> >kaiduan
> >--- John Draper <lists@xxxxxxxxxxxxxxxx> wrote:
> >
> >
> >
> >>Hi,
> >>
> >>I have a question about the interpretation of the
> >>RFC 3261. Cam someone
> >>explain a few
> >>things for me? It is part of my feeble effort to
> >>understand what A
> >>dialog is,
> >>and how it relates to requests, when they are
> >>created, and what they
> >>contain.
> >>
> >>The RFC says....
> >>
> >>12.2.1.1 Generating the Request
> >>
> >> A request within a dialog is constructed by
> >>using many of the
> >> components of the state stored as part of the
> >>dialog.
> >>
> >>Ok - what do they mean by a request within a
> dialog?
> >> Does this mean
> >>I instantiate a "dialog" object at the same time I
> >>send the INVITE?
> >>
> >>
> >
> >The request in a dialog may be re-INVITE, BYE
> message
> >if the dialog is created by INVITE message. For
> >SUBSCRIBE created dialog, the in-dialog request may
> be
> >SUBSCRIBE which is used to refresh the
> subscription.
> >
> >
> So - you say a SUBSCRIBE would be a request within a
> dialog?
The first SUBSCRIBE creates a dialog, the re-freshing
SUBSCRIBE is a in-dialog request.
> >"12.1 Creation of a Dialog
> >
> > Dialogs are created through the generation of
> >non-failure responses to requests with specific
> >methods. Within this specification, only 2xx and
> >101-199 responses with a To tag, where the request
> was
> > INVITE, will establish a dialog."
> >
> >
> I just got to this section last night. But I'm
> still trying understand it.
> For instance "Within this specification, only 2xx
> and 101-199 responses
> with
> a To tag...." was it implying that responses will
> have a "To" tag in it?
Yes.
> >>and a request that is NOT in the dialog, would be
> >>like the REGISTER?
> >>is that right?
> >>
> >>
> >
> >REGISTER message does not create dialog, now only
> >INVITE and SUBSCRIBE message creates dialog.
> >
> >
> This answered my question I had above this.
>
> >
> >
> >>The RFC goes on to say.... "using many of the
> >>components of the state".
> >>What is the meaning of the word "components" in
> this
> >>context? and
> >>it states that the state is stored as part of the
> >>dialog. If that's the
> >>case, then why is it part of SipSession? Do all
> >>dialogs have SipSessions?
> >>
> >>But the word "components" really confuses me when
> >>used in this context.
> >>
> >>
> >
> >The components of the state means: dialog ID, a
> local
> >sequence number, a remote sequence number, a local
> >URI, a remote URI, remote target, ...
> >
> >
> Oh, so a Component is like a "header field" or
> related to them. Right?
>
> >Please see Page 70 of RFC 3261.
> >
> >"A dialog contains certain pieces of state needed
> for
> >further message transmissions within the dialog.
> This
> >state consists of the dialog ID, a local sequence
> >number (used to order requests from the UA to
> > its peer), a remote sequence number (used to
> order
> >requests from its peer to the UA), a local URI, a
> >remote URI, remote target, a boolean flag called
> >"secure", and a route set, which is an ordered list
> of
> >URIs. The route set is the list of servers that
> need
> >to be traversed to send a request to the peer."
> >
> >
> I had trouble associating a "Piece of state" with a
> header field.
> But interpreting what you said, this is what I
> understand.
>
> John
>
>
___________________________________________________
Post your free ad now! http://personals.yahoo.ca