Accessing service description from UpnpDevice

[rytilahti]

Hi Steven,

it would be nice if there would be a way to access the XML tree of the parsed device description. In my case I would like to access some custom elements (see https://github.com/rytilahti/python-songpal/blob/master/songpal/main.py#L180). Do you think it'd be feasible to pass the parsed tree onwards to UPnpDevice?

[StevenLooman]

Certainly. Also, I'll store it on to the UpnpService and other relevant parts (UpnpActions/UpnpStateVariables).

I think you want to parse the additional properties. I'm thinking if we shouldn't (also) parse these in async_upnp_client and store these. What do you think, and how would you like to see this?

[rytilahti]

I think one way would be to store the encountered, non-standard elements into a parsed extras (better-naming-wanted(tm)) dictionary of the corresponding class (UPnPDevice, UPnPService, ..).

So on songpal's end the call would look something like:

info = device.extras["av:X_ScalarWebAPI_DeviceInfo"]
endpoint = info["av:X_ScalarWebAPI_BaseURL"]

for

  <device>
  ....
    <av:X_ScalarWebAPI_DeviceInfo>
      <av:X_ScalarWebAPI_Version>1.0</av:X_ScalarWebAPI_Version>
      <av:X_ScalarWebAPI_BaseURL>http://192.168.xx:10000/sony</av:X_ScalarWebAPI_BaseURL>
      <av:X_ScalarWebAPI_ServiceList>
        <av:X_ScalarWebAPI_ServiceType>guide</av:X_ScalarWebAPI_ServiceType>
        <av:X_ScalarWebAPI_ServiceType>system</av:X_ScalarWebAPI_ServiceType>
        <av:X_ScalarWebAPI_ServiceType>audio</av:X_ScalarWebAPI_ServiceType>
        <av:X_ScalarWebAPI_ServiceType>avContent</av:X_ScalarWebAPI_ServiceType>
      </av:X_ScalarWebAPI_ServiceList>
    </av:X_ScalarWebAPI_DeviceInfo>
  ....
  </device>

Or would it even make sense to store the whole parse-tree as such (and provide those existing shortcuts based on that)? device.parsed["friendlyName"], device.data["UDN"] etc?

I think it's your call what's the most sane way to do this, I'd be perfectly happy with any solution that lets me read that data out without reparsing it myself :-)

[StevenLooman]

Not sure how far we should take this, so for now I'll just store an attribute called xml at the relevant objects. Please check 4e490f0 and let me know if this is usable to you.

If so, do you want me to release 0.13.5?

[rytilahti]

Ok, that's fine, too. I experimented with it a bit (rytilahti/python-songpal#35) and stumbled upon a couple of things:

• modelNumber is not currently exposed.
• xml.etree is a pita compared to lxml ;-) looks like there's no sane way for a debug xml output (not from Element at least, wrapping it inside an ElementTree would have allowed combining StringIO + write() to accomplish that)

Anyway, a new release including the exposed xml would be great!

[StevenLooman]

Are you looking for this, with regard to point two?

xmlstr = ElementTree.tostring(xml, encoding='utf8', method='xml')

[rytilahti]

Oops, yes, that's what I was using already (the pretty-printing part was caused by printing out bytes instead of a string). It does seem to mangle the namespaces (uses ns[0-9] instead of the original ones), but it's just debug info so that's fine.

[StevenLooman]

Released 0.13.5.

modelNumber is not included though... next release.

[StevenLooman]

Released 0.13.6.

modelNumber and some friends are now exposed.

[StevenLooman]

Closing the issue. If there is anything else please let me know.

[rytilahti]

Thanks, that'll clean up my parsing code a bit (no need to define the 'device' namespace nor parse it separately)!

[StevenLooman]

Thank you for the review.