[Sugar-devel] Chromium integration inside the sugar shell (was Re: Kicking off HTML5 activities work)

[lionel at olpc-france.org]

Hi Daniel,

 

Impressive idea with a cool architecture. BTW, to be honest I think it’s

too complex.

Why not just create a standard Python activity template that call the WebKit
WebView? Like we do today.

 

But maybe I miss something or maybe we don’t speak of the same thing?

When I wrote the GSoC proposal, I think to a two steps process.

 

What I call the “first step” is just to create an activity template with a
full screen WebView control and a Sugar to JavaScript.

So it’s like my work on Enyo today but:

-          With a better way than “console-message” to communicate between
JavaScript & Sugar,

-          With a JavaScript/CSS framework to reproduce in HTML5 the Sugar
Look&Feel and sugar.graphics stuff,

-          With a JavaScript framework that allow calling all Sugar features
(telepathy, data store, l10n, drag&drop, 
).

We could probably do all these things without lot of change on current Sugar
implementation and current Sugar activity way of working. In my mind, this
could work even on Sugar 0.96-0.98 without any change!

 

Except if I’m wrong, what you’re currently describe is the “second step”:
upgrading Sugar to support directly HTML5 activities.

In this second step we could imagine that Sugar will be very different than
today (may be an Android layer or a Chromium layer) and that no current
Python activities will work on it. BTW HTML5 activities built with the
“first step framework” should be very easy to adapt: just need to change the
JavaScript framework implementation to use natives features instead of Sugar
Python features (for example: call HTML5 storage instead of Datastore
storage) and remove the XO Manifest/Package. I do like your architecture
proposal for this second step but it’s difficult to me to think to this
second step without we’ve got a more precise view of the first step.

 

                Lionel.

 

 

 

De : Daniel Narvaez [mailto:dwnarvaez at gmail.com] 
Envoyé : jeudi 11 avril 2013 21:52
À : sugar-devel at lists.sugarlabs.org
Cc : Lionel Laské
Objet : Chromium integration inside the sugar shell (was Re: Kicking off
HTML5 activities work)

 

Hello,

I spent some time today thinking and experimenting with Chromium integration
and I have a more detailed plan to propose now.

There is an important premise to be made. In both Chromium and Firefox OS,
application's installation is very much in the hands of the web browser. It
happens as the result of a user clicking on a button, inside a web store.
Chromium is a bit more flexible but the other possibilities are basically
just developer tools.
I think this limits our possibilities a lot. We need to use the browser
applications management, rather then installing applications ourselves and
then launching them with some command line option. Of course Chromium is
open source and we could develop the stuff which is missing. But, in my
opinion it's just too much work and it's going to be a pain to maintain in
the future, core developers are not going to care about it, given it's not
important for their products.

That said, I think I mostly figured out a plan to integrate with Chromium
web apps management, without having to write a lot of code.

* Chromium is started up with the sugar session, using the
--no-startup-window, to make it invisible. The sugar extension has a
"background" permission, which will keep it running even with no windows.
* The extension runs a python script, using chrome.runtime.connectNative.
Communication uses json-rpc wrapped in the message protocol supported by the
extension. The python script fetches the list of installed activities (as
exposed by chrome.management.getAll) and listen to changes.
* The python script exposes a dbus service, allowing the sugar shell to get
the list of installed applications and to display icons for them in the
home. We use GIOChannel to read stdin, so that we don't block and integrate
with the glib mainloop.
* When the user click on an icon, a LaunchApplication is called on the dbus
service, which proxies it to the extension, which launches the application.
We will probably need a trivial patch to chromium to start it without UI.
There is already a define for chromeos, but it's a compile time thing (in
extension_prefs.cc, GetLaunchContainer).
* The shell notices that a new window has been opened and associates it with
the application information. This allows to activate and close the activity
as necessary.
* Uninstalling an activity works in the same way as launching. Shell ->
python script -> extension.
* Implementation of collaboration and datastore libraries could also be
based on the python script messaging.

I implemented (badly) a good part of this and I didn't find fundamental
problems with it. Except for one, which is not specific to this plan. Sugar
supports multiple instances of the same activity, web application frameworks
doesn't. How are we going to deal with that? I haven't thought much about it
yet, but it seems something we want to be very clear about.

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