Re: RFC: Ubuntu Touch, MMS, and Provisioning

[Tony Espy <espy@canonical.com>]

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On 03/05/2014 12:57 PM, Marcel Holtmann wrote:
> Hi Tony,
>
>> We've been working on MMS support for Ubuntu Touch recently and have run into a couple of stumbling blocks, so I have a few questions about the current MMS logic in oFono ( we're still 1.12 based ), and in particular the provisioning/management of gprs-contexts.
>>
>> As part of this work, we're planning to switch from using the builtin gprs 'provision' plugin, to the new android-provision/apndb plugin ( originally written by Simon Busch ) which uses the file apns-conf.xml instead of mbpi's serviceproviders.xml.
>>
>> There are a couple of issues we ran into...
>>
>> 1. How to represent APNs that support multiple usages types?
>>
>> The "type" attribute in apns-conf.xml is a list vs. the single type defined by a gprs_context.
>>
>> The android-apndb plugin uses TYPE_INTERNET for APNs which support multiple types.  In order to properly support MMS, the core code needed to be modified to allow the MMS properties to be additionally be set on a TYPE_INTERNET context.  Thus if an APN supports both Internet and MMS, our DownloadManager can grab the additional MMS properties from the context and handle MMS traffic.
>>
>> Now perhaps I missed something and there is a way to represent a combined usage APN ( maybe using TYPE_ANY? ), but I couldn't see how to accomplish without changes to the core gprs code.
>>
>> 2. No way to disable core ofono TYPE_MMS network config.
>>
>> The core gprs_context code has special logic for TYPE_MMS contexts which configures the HTTP proxy using networking ioctl requests.  We have an external download manager that handles the actual download of content from the message center.  As it has logic to handle HTTP proxies already, if we use TYPE_MMS, we'd need a way to disable ofono's builtin logic.
>
> you do realize that these are not actually standard HTTP proxies. You are suppose to talk to the MMS Proxy to reach the MMSC. That is how this works. You always go through the MMS Proxy.

I haven't actually worked directly on the proxy support myself, and had 
assumed this was a standard HTTP proxy.  I will make sure my co-worker 
handling the support in our download manager realizes this, and point 
him at mmsd/connman's GWeb code for reference.

> If you are mixing Internet proxies with MMS proxies, you end up in a really awkward configuration later down the road.

Sorry, no intentions of mixing them.

> As Denis mentioned we have been using this successfully within mmsd that we wrote.

I saw that, we originally did a bunch of work with mmsd, however we 
decided instead to add MMS capability to our ubuntu-download-manager 
used in Touch.

 > The current design of oFono works just fine by activating the
 > MMS context and then talking to the MMS proxy to reach the MMSC.

Sure, although as I mentioned orginally, if we already have an active 
data connection and the apn happens to also support MMS, it seems odd 
not being able to share.

Thanks for jumping in, it's been awhile.  ;)

Regards,
/tony