Hi, Sam
Thanks for your response. I used 'deliberate' to express my frustration.
From the wiki pages, I assume that the collaboration wrapper is
supported in 0.106 although activities that use it must port to sugar3.
The current version of
chat is using this and can act as a tutorial example.
I have some activities that need this capability so I'll try to give it
a try.
Thanks
Tony
On 12/24/2015 09:36 AM, Sam P. wrote:
Hi Tony,
On Thu, Dec 24, 2015 at 5:35 PM, Tony Anderson <tony_ander...@usa.net
<mailto:tony_ander...@usa.net>> wrote:
Hi,
It would really be helpful for us to get an explanation when
working activities are deliberately broken ('deprecated') as in
this case. What is the new means to implement collaboration? What
advantage does it offer to the 'tubes' method we have been using
from the beginning? Is this another example of Fedora run amok?
Ok, so there is a feature page which gives some background on all of
this: http://wiki.sugarlabs.org/go/Features/Fixing_Collab_(Tubes)
<http://wiki.sugarlabs.org/go/Features/Fixing_Collab_%28Tubes%29>
Activities were not deliberately broken, that is quite strong language
to be using about telepathy apis anyway.
Telepathy has channels, which activities can use to communicate.
There are text channels, file transfer channels, and even tubes
channels. However tubes had an interesting (read, bad) design that it
re-invented the channel negotiation (requesting a new channel, etc.)
inside a channel! What a crazy design. The telepathy developers
manual also says that it was deprecated because it lacked extendibility.
Either way, upstream (telepathy in this case) deprecated the api.
This happened around 7 years ago. (At least, there are 7 year old or
so tickets in BSLO noting the deprecation). Anyway, for 7 years the
api remained in telepathy and nobody was too bothered. But recently
(whatever telepathy version made it into fedora 22) the api was
removed, which breaks sugar and sugar activities ability to
collaborate. This is a very reasonable deprecation timeframe in my
opinion, and telepathy had all right to remove the api. Importantly,
this is not fedora running amok.
As you say, the traditional way to handle this particular case
would be to re-write the 'tubes' api using whatever the new method
is so that the existing
applications do not have to be modified. This, after all, was the
purpose of 'object programming'.
Well, that would be very painful. The 'tubes' api is not an api
provided by sugar, it is provided by telepathy.
Some of the tubes api concepts (eg. multiple tubes within 1 channel),
don't map very well at all to the modern telepathy ideas. It would be
pretty messy.
Every activity that uses tubes also has 160 lines of code dedicated to
negotiating the tubes, all of which are subtly different in annoying
ways (like copy, paste, change code reuse). It would be a testing
nightmare to get this crazy tubes wrapper to work on all the activities.
It is really frustrating when one is trying to provide new
capabilities for the XO to have to spend almost all of the time
re-implementing activities that have stopped working in the newer
releases.
Well, this won't effect XOs unless somebody gets fedora 22+ running on
them (most run f18, there is alpha image of f20 for XO4). As Martin
proposed, we can keep the old behaviour and the old activities will
still run, on older systems.
While it is annoying to have to port activities to a new, simple
abstraction, in the end it makes it easier for you to provide new
capabilities for XOs. Adding collaboration will not require
copy-and-pray coding with 100s of lines of boilerplate. Instead you
can use a simple, document api:
http://people.sugarlabs.org/sam/docs-collab-wrapper-try2/sugar3.presence.wrapper.html
Thanks,
Sam
Tony
On 12/24/2015 12:34 AM, Sam P. wrote:
Hi Martin,
On Thu, Dec 24, 2015 at 6:52 AM, Martin Abente
<martin.abente.lah...@gmail.com
<mailto:martin.abente.lah...@gmail.com>> wrote:
Hello everyone,
I have been reviewing the current state of the collaboration
proposals and I am afraid it is still too early for merging
it. We need to explore more use cases, and this will only
happens when we start porting more Activities that actually
use TUBES. Therefore, i want to share some thoughts on this.
*Opinions:*
1. There haven't been enough changes in the Activities
regarding Tubes deprecation.
2. Dropping the Tubes support from Sugar without changing
all the activities that depend on Tubes means that we
will break collaboration for those activities anyway, and
there wont be much gain by just doing that.
3. Making changes in the Sugar API without proper testing
with more activities (and scenarios) is simply not a good
idea.
4. But, making changes in the Activities can be easily
handled since they are self contained.
5. Most of our users still use Fedora 18 through OLPC
deployments, where Tubes is available.
*Suggestions:*
1. Lets make Sugar handle the Tubes deprecation better so it
doesn't break, but lets not remove the support for TUBES yet.
2. Instead, we can start changing the activities using the
Wrapper that Walter and Sam prepared, but using it
locally on each Activity for now.
3. Once and if, we have most of our activities ported to the
new telepathy API (which will be based on the Wrapper),
then we can include the Wrapper into sugar-toolkit-gtk3,
in a next release and remove it from Activities.
*Pros:*
1. We avoid breaking collaboration for *(a)* Activities that
use TUBES and run on older systems where TUBES is
available, and *(b)* Activities that does not use TUBES
on newer systems where TUBES is no longer available. This
_is_ an improvement versus the current situation where is
completely broken on newer systems.
2. We do this whole re-work incrementally, without having to
change the API (sort of) blindly.
3. There will be more flexibility to explore ideas in
Activities land.
*Cons:*
1. There will be repeated code in Activities, but that can
be changed easily later.
*What would be needed:*
1. To detect if there is TUBES support, as Sam mentioned in
his first PR [1]. *Can someone look into this?*
I looked into this a while ago, and it didn't seem that it would
be easy. Maybe we could add a gsetting that defaults to off (for
new distros) and then OLPC OS Builder can turn it on to say give
activities tubes?
1.
2. Do not create TUBES channel when there is not support.
This [2] is just a hack and the logic works fine, but it
depends on whether or not we can detect support.
1. Cleanup the Wrapper and make sure that it is possible to
use it locally in activities.
Yep, the wrapper can already be used locally in activities, see
Bibliography activity [1] and physics activity [2].
However, I do believe that the fact that activities are using a
wrapper doesn't stop up from also having it in sugar3. As you
noted, it is repeated code in activities. It is easier to change
the sugar3 code later as needed than to change the wrapper code
in every activity. Therefore, I believe that we should have a
try/except clause to preference the sugar3 wrapper, but fallback
to the local one.
*Other improvements that we could land now:*
1. Give more flexibility to activities to use file transfer
channels without having the shell messing with them. [3]
As a note, the wrapper makes heavy use of file transfers (eg. for
init) currently. This does result in shell notifications on
older Sugars, although the activities can still collaborate.
Good write up by the way.
Thanks,
Sam
[1]
https://github.com/samdroid-apps/bibliography-activity/tree/collab
[2] https://github.com/walterbender/physics/pull/10
*Conclusions:*
If we don't do something about this, next Sugar releases will
still be broken for collaboration, for more scenarios than
necessary.
Let me know what you guys think,
Martin.
*Refs:*
[1] https://github.com/sugarlabs/sugar-toolkit-gtk3/pull/270
[2]
https://github.com/tchx84/sugar-toolkit-gtk3/commit/bed0ac5f4259ff1669323db26acb27f5d9c8ed1f
[3] https://github.com/sugarlabs/sugar/pull/621
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