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Re: B2B proposal

  • From: "Lewis, Keith" < >
  • To: jsr359-experts < >
  • Subject: Re: B2B proposal
  • Date: Sat, 15 Jun 2013 02:37:29 +0100

Jonas,

thanks for the helpful comments.
Having thought further about the provisional responses I think you are correctthat the API is too complex.
I suggest that we move the method back to SipSession (it was there in v2 of mey proposal). We can deal with the fact that rseq is not sufficiently unique by combining it with other values to make a responseId string. This would mean that we have the following methods

String SipProvisionalResponse.getResponseId() (or this could be on SipServletResponse)
Map<String, SipProvisionalResponse> SipSession.getUnaknowledgedResponses()

The map would use the responseId as the key.

This change would allow a simplified definition of an "active" invite since we could remove the text about unacknowledged provisionals - it would just be active until the ACK was sent or received.

I suggest that for final responses we leave the method on SipInviteRequest but have a version that takes no parameter that can be used for re-invites or when we know that there is no forking.

SipServletResponse getFinalResponse(); SipServletResponse getFinalResponse(SipSession session);

When we use the version taking a session the container must check that the session is one of the derived sessions for the call.

The non-INVITE transactions are retrieved using the getPendingRequests method. This could be split into getPendingIncomingRequests() and getPendingOutgoingRequests() and the UAMode parameter removed.

If these modifications seem OK I will reissue my proposal.

Keith

On Thu, Jun 13, 2013 at 7:16 PM, Jonas Borjesson < " target="_blank"> > wrote:
Good morning,

See my response inline

/Jonas

>> --------- Forwarded message ----------
>> From: Jonas Borjesson < "> >
>> Date: Wed, Jun 12, 2013 at 7:28 PM
>> Subject: Re: B2B proposal
>> To: ">
>>
>>
>> Hi all,
>>
>> I agree with George – i.e., 1A is my preferred solution since as I'm
>> sure you know by now that I like interfaces, things become more
>> explicit. Apart from that, I do have a few other questions/comments:
>>
>> === Consistency ===
>> The suggestion calls for a lot of new very specific methods, such as
>> SipInviteRequest.
>> getUnacknowlegedProvisionalResponse(s),
>> SipFactory.createContinuationRequest and
>> SipSession.getActiveInvites(UAMode).
>>
>> The first two ones are very specific but the third one has two
>> meanings, incoming and outgoing which is defined by the UAMode. Going
>> with the rest of the methods and the overall intent of the proposal
>> should they just be renamed to
>> SipSession.getActiveIncoming/OutgoingInvites? I can go both ways but
>> just wanted to ask. I think consistency is super important in an API.
>> However, from a simplicity point of view I have some other concerns
>> about these every specific methods...
>
>
> I like the idea of having SipSession.getActiveIncoming/OutgoingInvites
>
>> Also, we often returns Collection but sometimes pass in Set. If the
>> intent is indeed to e.g. not allow duplicates then sure, use a Set but
>> then I would ask if that really matters for the proposed changes? So
>> is the useage of Set deliberate?
>
> Yes createContinuationRequest could take a Collection.
>
>> And finally, in 289 Iterators are what is typically returned so if
>> nothing else the return values from these new proposals should
>> probably do the same (even though there are some inconsistencies in
>> 289 as well – SipApplicationSession.getTimers() e.g.) .
>
> But Collections are more useful - I would prefer utility over consistency.
> We can find out what others think.
>

In what way are the more useful? I think the big question here is
whether or not we are returning a streamed response. Iterators
actually give more flexibility for the implementors (even though our
first priority should not be the implementors but rather the users but
I think there is a big difference between the intent of collections vs
iterators). E.g., if you do not have everything in memory, such as
reading from a file, database or perhaps something across the network,
an iterator is what you want. Otherwise you have to suck down
everything first before returning the result. In our case, in a
distributed scenario you may actually have the stuff you are asking
for in your local JVM, which is where iterators excel. Anyway, I can
go either way but I think this aspect is worth considering before
making a final decision.


>>
>> === Simplicity ===
>>
>> In general, we should certainly make the life of the developers easy
>> but I don't always think creating a bunch of different very special
>> purpose methods will actually help. If we end up creating methods such
>> as SipFactory.createContinuationRequest then I believe that the API is
>> broken as it is and patching it is only going to make developers more
>> confused.
>>
>> --- CreateContinuationRequest ---
>>
>> So, createContinuationRequest, apart from making that particular use
>> case just slightly easier, is it a good idea? Perhaps the routing
>> directive should be added to the SipFactory.createRequest methods
>> instead? If we decide to keep the createContinuationRequest, why not a
>> createReverseRequest too?
>>
>>
>> I guess I personally do not like the createContinuationRequest because
>> for consistency sake we should then also add all the other
>> possibilities but the API becomes really cluttered, which is even
>> worse. So, I'm voting for not including this method and if really
>> needed enhance the SipFactory.createRequest ones instead, which I
>> believe is also what Binod suggested.
>
> I included createContinuationRequest as a lightweight version of the
> B2BuaHelper.createRequest() methods which may be deprecated. You are right
> we could just remove it.

Ok, sounds good to me...

>
> If a B2B application is sequenced in by a remote container that used
> ROUTE-BACK it should copy route headers. If the same app is to work well
> with a local app router it should use the CONTINUE directive. I was thinking
> that there may be some merit in doing both in the same method but not much
> would be lost by removing the method and having these two actions performed
> separately.
>
> (I note that it is quite cumbersome to copy route headers in the correct
> order so a pushRoutes() method might be helpful for creating B2B apps).
>
> Also, on a separate note, the javadoc isn't super clear what the
> directive is for the newly created request. I assume is is NEW, which
> makes sense but the only reference I have found regarding this is the
> javadoc on SipServletRequest.setRoutingDirective, which is referring
> to the deprecated SipFactory.createRequest. Perhaps we should improve
> the javadoc here...
>
>
> (side note2: for a beautiful API that gets stuff done, check out the
> Python Requests API (though http is way simpler protocol but this API
> is what I try and strive for)
> http://docs.python-requests.org/en/latest/)
>
>
> --- SipInviteRequest.getUnacknowledgedProvisionalResponse ---
>
> Why do we need to pass in the SipSession? If we do, it seems like this
> method should be on the SipSession as opposed to the request. Since it
> is on the request, I would assume this method would only return
> responses for this particular transaction, correct? And if so, the
> SipSession is not needed since the request you are operating on
> explicitly is associated with a SipSession, or perhaps I'm missing
> something...
>
> Version 2 of my proposal did have this method on the SipSession. I realised
> a problem with that as explained in the email that accompanied version 3.
>
> The rseq value in a reliable provisional is only unique for that dialog. Due
> to forking there can be several dialogs which return provisional responses.
> In order to locate a specific response at a UAC which is downstream of a
> forking proxy we need to pass the session (or derived session) along with
> the rseq to the method on SipInviteRequest.
>
> If we put the method on the SipSession there is still a problem with the
> uniqueness of the rseq value. PRACK can arrive after the corresponding ACK
> by which time a new INVITE transaction can be in progress which also has
> provisional responses. To retrieve the correct response we would need to
> pass it the requestId of the INVITE transaction as well as the rseq.
>
> It seems best to avoid cluttering the SipSession interface with methods such
> as this one.

Ok, I think you lost me but I guess my original question was also that
the request itself is uniquely associated with a particular sip
session (it cannot have two) so if you ask the request, the sip
session is implied. Right?

Anyway, I suck at the prack stuff so I'm going to go with whatever you
want as long as we make sure that the methods are clear, the
documentation is there and we don't run the risk of confusing
container implementors as well as users.

>>
>> --- SipSession.getActiveInvites ---
>>
>> What about getActiveXXX? i.e., what about all the other methods?
>
> Only INVITE transactions require an ACK, other transactions are complete
> once the final response is sent/received. Similarly only INVITES can have
> reliable provisional responses.

Sure, but until you get a final response the "other" type of requests
are still "active". And if you are after only whether or not you have
received an ACK or not, wouldn't a method following the other
getUnacknowledgedXXXX methods be more appropriate?



--
Keith
 
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Re: B2B proposal

(continued)

Re: B2B proposal

Binod 06/13/2013

Message not available

Message not available

Fwd: B2B proposal

Strickland, Tom 06/13/2013

Re: B2B proposal

Jonas Borjesson 06/13/2013

Re: B2B proposal

Strickland, Tom 06/14/2013

Re: B2B proposal

Binod 06/14/2013

Re: B2B proposal

Strickland, Tom 06/14/2013

Re: B2B proposal

Binod 06/17/2013

Re: B2B proposal

Nitzan Nissim 06/17/2013

Re: B2B proposal

Strickland, Tom 06/17/2013

Re: B2B proposal

Jonas Borjesson 06/14/2013

Re: B2B proposal

Lewis, Keith 06/15/2013
 
 
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