Return-Path: Date: Fri, 7 May 2010 16:57:04 -0300 From: "Gustavo F. Padovan" To: =?iso-8859-1?Q?Jo=E3o?= Paulo Rechi Vita Cc: =?iso-8859-1?Q?Jos=E9?= Antonio Santos Cadenas , "linux-bluetooth@vger.kernel.org" Subject: Re: Data transmission and reconnections in HDP Message-ID: <20100507195704.GC4857@vigoh> References: <201005071302.36198.jcaden@libresoft.es> <20100507120859.GD12461@vigoh> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi all, * Jo?o Paulo Rechi Vita [2010-05-07 15:25:17 -0300]: > Hello Jose! > > On Fri, May 7, 2010 at 09:08, Gustavo F. Padovan wrote: > > Hi Jos?, > > > > * Jos? Antonio Santos Cadenas [2010-05-07 13:02:36 +0200]: > > > >> Hi all, > >> > >> I start this thread to discuss the alternatives to move the data from the > >> application to the l2cap socket in HDP. Till now we have the following > >> alternatives (please, add more if we missed something) > >> > >> Reconnections options: > >> > >> ?Option 1: Implicit reconnections: The application is not concern about the > >> disconnections or reconnections of the data channel until it is deleted. > >> > >> ? ? ? We prefer this option because fixes more with a manager philosophy. A > >> 20601 manager sould not perceive temporal disconnections because this way can > >> hold it state if it perceives a disconnection, next time it reconnects it will > >> need to exchange again apdus for association. > >> > >> ?Option 2: Reconnections by the application. The applications are notified when > >> a data channel is disconnected and should perform a reconnection before using > >> it again. > >> > > The HDP Implementation Guidance Whitepaper clearly states that > transport (HDP) disconnection / reconnection should be transparent for > the data layer (IEEE 11073-20601), so I guess option 2 here would > break the spec. > > >> Data transmission options: > >> > >> ?Option 1: Fd_passing the l2cap socket of the data channel to the client. The > >> problem with this is that some data can be lost by d-bus if the channel is > >> disconnected. (We have to check how fd-passing works). > > > > DBus just pass the fd and then don't touch the fd anymore, data can't be > > lost by DBus. > > > > I guess the problem Jose tried to address here is the case that HDP > had temporarily disconnected the data channel and then the application > try to write to the FD (which will be closed). Some data may be lost > by the application on this process. If you are using Streming Mode you really don't care, if ERTM an error will be reported and the application will get notified. ;) -- Gustavo F. Padovan http://padovan.org