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Re: [iot-wg] Why use concierge?
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HI Jens,
Sorry for the late reply. Find below more details
On 29/04/2014 3:58 AM, Jens Reimann wrote:
Hello Pascal,
Thanks for your answers.
We already start Eclipse without the native launcher in most cases.
Wrapped by a Python script to find the correct jar. However you
sometimes get some native bundles in there. I am not sure if this is
Equinox or the Eclipse Runtime though.
The eclipse.exe companion jar comes to mind (e.g.
equinox.launcher_win32.win32) and it may be brought in by some features
you depend on but equinox itself has no native dependencies.
For P2 I find it rather hard to find god starting points for alternative
solutions. I think it does what it is intended to do, and it does it
good. But you pretty soon get lost when it comes to alternative
launching and provisioning ways (beside the Eclipse IDE). I don't blame
anyone, I know how hard it is to write documentation ;-)
Some of these other starting points are not documented because they
never got beyond the prototype stage a few years ago because nobody
ended up need them.
Also is the whole Eclipse way a bit more powerful than plain OSGi. As
far as I know OSGi proposes OBR for provisioning. However I did find no
support for that in Equinox or P2. I think it was Felix that allowed
installing bundles directly from Maven repositories, which would also be
an alternative way.
If you are talking about OBR as found in Felix, know that it is
not more standard than p2 is.... What has been standardized a couple
years ago is a repository format, a service to access repositories and
an API to perform dependency resolution. This is far from solving the
problem of downloading bundles and then installing them in a
transactional way in your runtime.
I also have to admit that I am not sure what the best way actually is
for small devices. On the one hand you want to be flexible and only
install the bundles that you need. It may be nice to do this manually
("clicking" together your system with dependencies). On the other hand
if you have 100s of devices and every device is special you don't want
to maintain this manually.
For small devices, you most likely don't want p2 dependency
resolution (or any other) to run on the device because it will likely be
too much computation. However if you still want a transactional
installation you could go by using the p2 engine to perform the download
and the installation in the runtime. Then how the engine gets the list
of IU to install / uninstall / update is an implementation detail :) For
example you could use the OMA DM from OSGi (not sure how it would work
with the LWM2M server), or implement something custom where the device
contacts a server, the server does the resolution and returns the list
of things to install, or use remote service, ... I'm sure there are many
other ways to do this and these are just things that I know could be
made to work.
HTH
Pascal
But I guess all this should be subject to a different post :)
And yes "more independence from Equinox in your application" correct.
Jens
On 04/27/2014 04:17 AM, Pascal Rapicault wrote:
Hi Jens
Answer embedded.
On 24/04/2014 4:52 AM, Jens Reimann wrote:
Hello Pascal,
I don't want to sound negative, but from the viewpoint of Eclipse SCADA
we are pretty happy with Equinox ;-)
But we also learned, the hard way, that Equinox seems to make a lot of
"special things". That might be easier at first, but creates problems
when other OSGi containers become a topic. At the moment we are not able
to deploy to other OSGi containers since we need P2 and EMF
For EMF we really do need EMF. But for P2, we only require a some sort
of build -> provision toolchain. Which is Maven Tycho (p2) -> P2
Director at the moment.
Our long term goal is to also have other, more pure, OSGi containers.
Also not needing any native code in order to launch the framework. And
for this we would like to use technology coming from the Eclipse
eco-system.
The framework can be started w/o the native launcher. For example
you can start the Eclipse IDE by running java -jar
plugins/org.eclipse.equinox.launcher_....jar and you can also directly
start equinox itself in a similar way (java -jar
org.eclipse.osgi_...jar). You can also see code embedding Equinox in
Tycho.
For this we would need Declarative Services (DS) and some sort of
provision mechanism. P2 is a bit bulky, but works fine for our case. We
do use the P2 director to assemble our applications (depending from the
System Configuration the user created). This done on either the
configuration machine or the target machine. There is no "online
update". So if we have a system configuration with 10 servers and each
server has 2 different applications, all applications are provisioned
using the P2 director from the initial set of P2 repositories.
It is true that p2 is a bit bulky and is currently known to only
run on Equinox. However p2 has been designed to run and provision
other frameworks. In fact back when we started we were able to
provision Felix. At this point I don't know exactly what it would take
to make that work again, but I think this is in the real of
possibilities.
The other thing you may be interested in is in knowing that there
has been designs and prototypes done in p2 to make it work "after the
fact". Meaning that you would not need to have the p2 folder and all
that in your application. Instead p2 would be able to reason about the
currently installed bundle and take it from there to perform the
installation (still bringing transactionality and dependency resolution).
However we also see a shift at the moment from this deployment scheme,
to a more distributed scheme. In the the past we had two big servers,
and that's it. At the moment systems go up to 20 different nodes which
are (compared to then) less powerful. And we now start to have ARM based
devices which will have even less performance and greater numbers.
So in the end the three most important reasons for us to move to a
different OSGi container are:
-) Better provisioning
Maybe a topic of the p2-dev mailing list, but I would be
interested in knowing what are the criteria for a better provisioning.
-) Less (or better no) native dependencies (launcher)
See note above.
-) Better compatibility with OSGi
I m assume you mean more independence from Equinox in your
application, or do you have something else in mind
Thanks
Pascal
Jens
On 04/23/2014 06:19 PM, Pascal Rapicault wrote:
Hi,
Since Concierge has been released, I noticed a lot of interest from
the variou IoT projects to move to concierge from Equinox and I would
like to understand the motivation of such a move? I can obviously get
the size argument, but is there more to it?
Thanks
Pascal
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