Atom feed thumbnails

[maiki interi]

Not entirely on topic with `#658 </issues/658>`_ or
`#659 </issues/659>`_, but related.

My expectation was for the atom feed to contain the thumbnail of
the image (or equivalent of other media types). This is important
to me, as I want to widgetize/aggregate the feed on other sites.

I found two places where feeds are generated,
``mediagoblin/user_pages/views.py`` and
``mediagoblin/listings/views.py``:

::

        for entry in cursor:
            feed.add(entry.get('title'),
                entry.get('description_html'),
                content_type='html',
                author=request.matchdict['user'],
                updated=entry.get('created'),
                url=entry.url_for_self(request.urlgen))

I am not sure what the thumbnail is, but I am betting it is a
**summary** or maybe **content** (see the
`werkzeug atom docs <http://werkzeug.pocoo.org/docs/contrib/atom/>`_).
I think this is important, even if we are moving to make it a full
ActivityStream, since the federation I have in mind is something
akin to a dashboard view of new photos posted on my friends'
sites.

So, can we get a thumbnail in there? =]

[Christopher Allan Webber]

Yes we certainly need a way to share this...

[Inconexo ø]

I have done a try. Not very happy because I had to:


1) Write html code inside python code. I don't feel that very
   orthodox.
2) Img comes inside html content. I don't know if there is a better
   way to include this, but I haven't found it inside the atom library
   documentation.

Please, tell me any comment that would improve my implementation.

git:
[https://gitorious.org/\ :sub:`inconexo/mediagoblin/inconexos-mediagoblin](https://gitorious.org/`\ inconexo/mediagoblin/inconexos-mediagoblin)
branch: 676\_feed\_thumbs

[Christopher Allan Webber]

Hey Inconexo, thanks for the work on this. :)

I think the best route would be to actually shift over the work to
making our own atom feed generator... I think we'll need to for
`#659 </issues/659>`_ anyway. And this would avoid such grossness
as we're extending that code.

Inconexo: if you're interested in pushing us toward a beautiful
federated future, a good way to start might be to help write an
atom feed generator using lxml :)
`http://lxml.de/tutorial.html <http://lxml.de/tutorial.html>`_

If you're interested in this, let me know! If you are interested
but have no experience with lxml, read that tutorial and ping me on
irc... you'll find it's pretty easy though, I think.

[Inconexo ø]

Well, finally, feed library is written. Please notice I am a
beginner with Python. Please comment any problem and I will fix
it.

I have kept two goals:


1) Same interface as Werkzeurg's. This way, changing one feed
   generator to other is changing the import.
2) Extensibility. I have made a generator class. If we wanted to
   generate RSS or other feed systems, we could write another
   generator, reusing a lot of code.

I have also added thumbnails capabilities. First, I added
media:thumbnails elements, but it doesn't seem to work with
firefox' and other's agregators. Any help with that is appreciated.
So, I used the same old trick: including the thumbnail inside the
content.

Anyway, you can take a look:

git:
[https://gitorious.org/\ :sub:`inconexo/mediagoblin/inconexos-mediagoblin](https://gitorious.org/`\ inconexo/mediagoblin/inconexos-mediagoblin)
branch: feed\_library

[Elrond]

Okay, this one diverged somewhat into "we need a feed library". And
one was created.
This is actually bug `#711 </issues/711>`_.
So made this one block'd by 711.

When 711 is done, we should revisit this one.

[Will Kahn-Greene]

The original url for this bug was ​http://bugs.foocorp.net/issues/676 .
Relations:
#310: related, #311: related, #358: blocked

[spaetz]

To post media in the atom feed, we'll need to add something like:

<link rel="enclosure" type="image/jpeg" href="​http://farm9.staticflickr.com/8343/8187137313_2e211c431f_b.jpg" />

to the atom feed. At least this is what the flickr atom feed does.

[spaetz]

I pushed a Work-In-Progess branch 328_media_in_atom_feed to my repo at ​git://gitorious.org/~spaetz/mediagoblin/spaetz-mediagoblin.git

It does not implement a new Atom feed generator, but at least it embeds the posted media as a
<link href="....jpg" rel="enclosure"/> which is what the flickr atom feed also does to convey the posted media.

I stumbled upon 2 roadblocks while implementing: mg_globals.public_store.file_url(media_entry) returns a relativ URL without HOST and we need a real fully external URL there. How can we achieve that?

Second, how can I determine the media type of the media so that browsers detect it correctly? Right now I hardcoded 'type': 'image/jpeg' which is obviously bad.

[Will Kahn-Greene]

Given that this is about thumbnails and not enclosing the actual media item, it's not corrrect to use <link href="..." rel="enclosure"/>. That's for enclosing media items like for podcasts, picturecasts, etc. Flickr encloses the entire media item.

To have thumbnails, you should use the MRSS module:

​http://www.feedforall.com/mediarss.htm

Firefox feed preview shows enclosures, but not thumbnails (weirdly, I helped write that).

What YouTube does is create an HTML thingy with the thumbnail in that and put that in the description. I suggest you do something like that. That's very common with podcast-like feeds.