Reliable SMS receive

Reliable SMS receive

[Pavel Machek]

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Hi!

I see that great care is taken not to lose outgoing message: "
Persisting of outgoing SMS messages.  Whenever oFono is asked to send
an SMS message, it adds it to an internal queue and persists it on
disk.  The queue is persistent across reboots of oFono and allows to
queue SMS messages even while the modem is offline."

Is there something similar possible for incoming messages? I really
hate losing those... Best think would be if

a) SMS comes from the modem

b) ofono sends the SMS over the dbus

c) application writes it to stable storage, and confirms that back on
dbus

d) ofono confirms reception of SMS to the modem.

e) modem confirms it to the network.

If something goes wrong, network will retransmit message and it will
be delivered on the next boot.

(Other schemes would work for me, too...)

Ideas?
								Pavel



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Re: Reliable SMS receive

[Denis Kenzior]

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Hi Pavel,

On 02/01/2019 04:05 PM, Pavel Machek wrote:
> Hi!
> 
> I see that great care is taken not to lose outgoing message: "
> Persisting of outgoing SMS messages.  Whenever oFono is asked to send
> an SMS message, it adds it to an internal queue and persists it on
> disk.  The queue is persistent across reboots of oFono and allows to
> queue SMS messages even while the modem is offline."
> 
> Is there something similar possible for incoming messages? I really
> hate losing those... Best think would be if

So fundamentally oFono is only responsible for messages 'in-transit'. 
So it takes great care to ensure it doesn't lose these, as you already 
pointed out.  This goes for outgoing messages as well as incoming ones 
while they're being de-fragmented & reassembled.

Once a message has been fully received and handed off to the history 
plugin, oFono's responsibility ends.

> 
> a) SMS comes from the modem
> 
> b) ofono sends the SMS over the dbus
> 
> c) application writes it to stable storage, and confirms that back on
> dbus
> 
> d) ofono confirms reception of SMS to the modem.
> 
> e) modem confirms it to the network.

That is not how this works.  oFono performs full reassembly of all SMS 
fragments.  The application receives the message only once it has been 
fully reassembled.  It has no control over acks, oFono does this 
automatically.  Besides, most modems don't really support this properly 
anyway.

> 
> If something goes wrong, network will retransmit message and it will
> be delivered on the next boot.
> 
> (Other schemes would work for me, too...)
> 
> Ideas?

Write a history plugin that persists your messages in permanent storage 
if you're worried about losing them over D-Bus.

Regards,
-Denis