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Re: mobile-devel-list Digest, Vol 18, Issue 7
Murry has a good point; simply separating any given application into UI and back-end elements isn't necessarily going to make anything better, and will add some complexity overall. Yet there is value in what Esben is saying. It's clear to me that a "service" for downloading URLs in a system-consistent way has a lot of value. I think the difference here is in composing these system-wide services (finer granularity than applications) in such a way that user applications can utilize them in a consistent and seamless way. There is Art as well as Engineering involved in designing good service-level APIs that offer compelling, flexible composition yet are simple and agnostic enough to be used system-wide. 

my 2 cents,
ken

On Dec 10, 2008, at 7:00 AM, mobile-devel-list-request gnome org wrote:


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Today's Topics:

  1. A New GNOME Order (Esben Stien)
  2. Re: A New GNOME Order (Murray Cumming)
  3. Re: A New GNOME Order (Philip Van Hoof)
  4. Re: A New GNOME Order (Stefan Kost)
  5. Re: A New GNOME Order (Kalle Vahlman)


----------------------------------------------------------------------

Message: 1
Date: Tue, 09 Dec 2008 20:05:17 +0100
From: Esben Stien <b0ef esben-stien name>
Subject: A New GNOME Order
To: mobile-devel-list gnome org
Message-ID: <87vdttjhjm fsf quasar esben-stien name>
Content-Type: text/plain; charset=us-ascii

I fear we are not setting correct guidelines for GNOME applications
and now with GNOME mobile, there are just numerous weaknesses in GNOME
that needs to be addressed at the highest level; a set of policies.

It would be very nice with a policy of separating the core and UI
throughout GNOME. This does not only mean applications using
libraries; this means using daemons as the core of every application.

This is proper engineering and gives a very good and powerful base.

An example is Epiphany; by having a browser client core, you can
connect many different interfaces to the core and browse the same open
URLs'. Manipulating the data from a terminal is also a breeze. There
are numerous use cases to this. Some Epiphany developers are favouring
this idea, as per mailing list request.

With different devices and use cases, we have different
interfaces. This is possible with a separated core communicating with
the client over a protocol. This is relevant for any application and
should be the policy of GNOME.

A system wide download daemon, in the same spirit as f.ex mldonkey
lets every application feed a URL, torrent, etc. to the daemon and you
can get notified when the download completes with the notification
daemon.

A system wide media player daemon, in the same spirit as xmms2/mpd,
but also with video and using gstreamer. Applications like totem, and
really most GNOME applications, should just be clients connecting to
such central services, instead of creating poor engineering efforts
where the core code is intermingled with a user interface.

The list goes on and on when it comes to GNOME applications, making
them extremely limited and non scalable, not able to quickly move to
new targets.

We need to use the UNIX power more and we can should foster different
interfaces to very powerful cores, which would satisfy everybody'. A
user interface should be just that; an interface, but the core should
be able to handle more than simple operations.

I'm all for the cute GNOME applications, but I think we're not using
the power that is available to us.

We need core daemons and good interfaces to talk to them. We need all
user UI and GUI to talk to these daemons. Only then can we adapt to
new targets quickly.

--
Esben Stien is b0ef e     s      a
        http://www. s     t    n m
         irc://irc.  b  -  i  .   e/%23contact
          sip:b0ef@   e     e
          jid:b0ef@    n     n


------------------------------

Message: 2
Date: Tue, 09 Dec 2008 18:38:19 +0100
From: Murray Cumming <murrayc murrayc com>
Subject: Re: A New GNOME Order
To: Esben Stien <b0ef esben-stien name>
Cc: mobile-devel-list gnome org
Message-ID: <1228844299 2545 101 camel murrayc-desktop>
Content-Type: text/plain

On Tue, 2008-12-09 at 20:05 +0100, Esben Stien wrote:

this means using daemons as the core of every application.

This is proper engineering and gives a very good and powerful base.


This is fantasy. Truly useful applications are more than just shallow
facades over data models or command line tools. An application that can have its UI easily replaced by another UI or reimplemented in another UI 
toolkit is not a highly usable application. It's just a form.

--
murrayc murrayc com
www.murrayc.com
www.openismus.com



------------------------------

Message: 3
Date: Tue, 09 Dec 2008 18:55:45 +0100
From: Philip Van Hoof <pvanhoof gnome org>
Subject: Re: A New GNOME Order
To: Esben Stien <b0ef esben-stien name>
Cc: mobile-devel-list gnome org
Message-ID: <1228845345 12200 82 camel tinc>
Content-Type: text/plain

On Tue, 2008-12-09 at 20:05 +0100, Esben Stien wrote:


I fear we are not setting correct guidelines for GNOME applications
and now with GNOME mobile, there are just numerous weaknesses in GNOME 
that needs to be addressed at the highest level; a set of policies.

It would be very nice with a policy of separating the core and UI
throughout GNOME. This does not only mean applications using
libraries; this means using daemons as the core of every application.


This is already happening for various components.

For example Tracker is becoming a RDF triple store. Although these
developments are not for tomorrow (rather for in a few months) a few
good GNOME developers are working on this as we speak.

This however will mean that you can ask Tracker quite a lot of things.

I also know multiple teams are considering to implement "E-mail as a
desktop service". For example the Evolution team has been discussing
this. This wont be easy, though (cursor based data models for the
summary and sorting at the service, and next to that streaming the
contents of MIME parts over the IPC to the UI are quite complex things
to perform over IPC).

IMHO should these team focus on the MIME part handling. As RDF triple
stores will eventually solve their "cursor based data models that are
sorted at the service"-problem.

Just doing camel_folder_get_summary() over IPC is of course not a very
good idea (Evolution's UI wouldn't be as snappy-fast as it is now, it
would instead take ~ 10 seconds to open a normal sized folder). That's
why you want sorting-at-the-service and page-based fetches and/or a
cursor based remote API (like database cursors, remote enumerators or
iterators - or whatever name you fancy for this -).

A recent example of developers moving functionality into services is
Thumbnailing:

http://live.gnome.org/ThumbnailerSpec

We are planning to spec the same thing for media cover and album art
downloading. On the Maemo devices you will have a D-Bus API for this
already. Just checkout the .xml files in this project if you want to
have a sneak preview:

https://stage.maemo.org/svn/maemo/projects/haf/trunk/hildon-thumbnail/

That project also implements the ThumbnailerSpec, by the way.

Today I also started this proposal to allow E-mail clients to spew out
their metadata:

http://live.gnome.org/Evolution/Metadata

This is being proposed on Evolution's Hackers mailing list. You can
certainly join the fun of implementing it, just ping me.
So if you want a lot of your desktop to be Desktop service oriented then that's great. Put on your pointy hat, grow a beard, drink Jolt Cola and 
come join the fun.


This is proper engineering and gives a very good and powerful base.


Sure, great. Come join the fun!

[CUT]


--
Philip Van Hoof, freelance software developer
home: me at pvanhoof dot be
gnome: pvanhoof at gnome dot org
http://pvanhoof.be/blog
http://codeminded.be



------------------------------

Message: 4
Date: Wed, 10 Dec 2008 09:11:08 +0200
From: Stefan Kost <ensonic hora-obscura de>
Subject: Re: A New GNOME Order
To: Esben Stien <b0ef esben-stien name>
Cc: mobile-devel-list gnome org
Message-ID: <493F6B8C 50801 hora-obscura de>
Content-Type: text/plain; charset=ISO-8859-1

Esben Stien schrieb:

...

We need core daemons and good interfaces to talk to them. We need all
user UI and GUI to talk to these daemons. Only then can we adapt to
new targets quickly

We had a media player daemon on Nokia tablets for a while and its not
the solution. Uou need a good highlevel api and then it is easy to write a different UI and reuse the underlying engine. I think a separation is 
good, but it can be at build time, it does not need to be a run time.

Stefan


------------------------------

Message: 5
Date: Wed, 10 Dec 2008 10:43:56 +0200
From: "Kalle Vahlman" <kalle vahlman gmail com>
Subject: Re: A New GNOME Order
To: "Murray Cumming" <murrayc murrayc com>
Cc: mobile-devel-list gnome org
Message-ID:
	<177e83dd0812100043o35cde8a8o65a170364d5487f8 mail gmail com>
Content-Type: text/plain; charset=UTF-8

2008/12/9 Murray Cumming <murrayc murrayc com>:

On Tue, 2008-12-09 at 20:05 +0100, Esben Stien wrote:

this means using daemons as the core of every application.

This is proper engineering and gives a very good and powerful base.


This is fantasy. Truly useful applications are more than just shallow
facades over data models or command line tools. An application that can have its UI easily replaced by another UI or reimplemented in another UI 
toolkit is not a highly usable application. It's just a form.


Not sure which way Esben meant it, but I agree that creating daemons
for the sake of creating daemons is not "proper engineering".

Allowing remote access to application functionality _in addition_ to
the normal UI however is another thing though, and that's where lots
of GNOME software has been headed ever since the dawn of D-Bus.

I think the thing that would be most useful would be a set of standard
D-Bus interfaces that applications could depend on for
interconnecting. Eg. Music players, messaging applications, download
managers etc.. Lots of these exist already, but it would be highly
beneficial to bless some of them as part of the GNOME API.

--
Kalle Vahlman, zuh iki fi
Powered by http://movial.fi
Interesting stuff at http://sandbox.movial.com
See also http://syslog.movial.fi


------------------------------

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