Re: SV: Ericsson Support for SMS receive

[Dan Williams <dcbw redhat com>]

On Wed, 2011-03-23 at 12:07 +0100, Marcel Holtmann wrote:
> Hi Torgny,
> 
> > > > CCing NetworkManager mailing list. I'm sorry that the thread below is not
> > > > formatted the way you like it but I'm keeping it below for reference.
> > > > 
> > > > The discussion is about sms support in ModemManager. I've started
> > > > implementing it a bit but ran into issues.
> > > > 
> > > > I think that a SetStorageLocation method as suggested by Eric would be
> > > > sane to add. And have that mirror the CPMS command as Jason suggested.
> > > > 
> > > > Should I still include the mem-type in SmsReceived signal? Or should we
> > > > assume that the caller takes care of setting the storage correctly? The
> > > > same question is valid for the SmsGet method (and delete).
> > > > 
> > > > About the SmsReceived vs Completed signals, I interpreted it as the
> > > > SmsReceived signal is emitted for all sms and for the final sms _both_
> > > > the SmsReceived and Completed signals are emitted. I don't have the code
> > > > available right now though, so I'll have to look at it again later.
> > > > 
> > > > Another issue is how to handle the completed flag in the SmsReceived
> > > > signal and the Completed signals. I suppose one have to parse the pdu to
> > > > be able to tell?
> > > 
> > > using the SIM card as storage for SMS is a pretty much bad idea. It will
> > > work sort of nice at first, but in the long run it will give you a lot
> > > of problems. It is limited in storage space and vulnerable to denial of
> > > service attacks with multipart SMS.
> > 
> > So do you suggest defaulting to ME without even offering the option to the 
> > caller? In that case, I guess having the memory type in the SmsReceived signal 
> > is kind of redundant...
> 
> if you are serious with SMS support effort, then that is what I would
> propose. SIM storage has never been a good idea in the first place.
> 
> > > Another problem is trying to make text mode for SMS on an AT modem work.
> > > That will fail since every single modem makes a mistake with text mode
> > > handling. Once you enter the cases with non-English character sets, you
> > > will be fighting wind mills. You need to use PDU mode.
> > 
> > Agreed, and we don't even have the option to use text mode with Ericsson 
> > modems. Only pdus are supported. But as the dbus interface is specified now, we 
> > need to parse the pdu in ModemManager. Or do you mean that that should be left 
> > to the caller as well?
> 
> You need to handle all PDU related efforts inside ModemManager. Giving
> this kind of detail to the caller is going fail. Handling the PDUs
> correctly is actually highly complicated.
> 
> Once you enter the area of concatenated and binary SMS this all becomes
> pretty much tricky. You need a damn good handling on this.

I tend to agree, I think sending this stuff up to callers isn't the
right approach.  There's enough detail to handle that we probably do
need to handle it and provide the abstraction in MM.

Dan