On 10/27/15 13:33 , Balázs Zsoldos wrote:
As an application developer, I don't need to implement the extender
pattern since framework developers have done that for me. It's all about
layers and perspective.
As a technology developer, how would you implement an extender pattern
without the framework packages? You could not. If those packages are not
exported by the system bundle, you cannot implement the extender pattern.
As an application developer, you could not import a bundle that implements
the extender pattern, as the bundle would not resolve.
You mean that the Framework developers should implement technologies like
Declarative Services and include it into the Framework?
I was using the term "framework developers" in the general sense, not as
in OSGi framework. DS provides application developers a framework for
creating OSGi applications without dependencies on OSGi API. But really,
this is just an argument over semantics and is not germane to the real
issue.
From my perspective, you cannot define system.packages as a value that
depends on framework implementation details to know what the value is.
-> richard
On Tue, Oct 27, 2015 at 6:27 PM, Richard S. Hall <he...@ungoverned.org>
wrote:
On 10/27/15 13:14 , Balázs Zsoldos wrote:
That is not my interpretation. System packages are those packages provided
by the system bundle. From a wiring perspective, all of the JRE packages
look like they are coming from the system bundle just like the OSGi core
packages, so your distinction doesn't really make sense to me.
Seems that we are different :). I interpret rules based on use-cases. I
cannot find any use-case where I wanted to handle framework packages like
JDK packages. On the other hand, I see use-cases where I want to handle
them separately.
It is much more consistent to defines system.packages like,
"system.packages represents all packages that will be exported by the
system bundle", instead of something like "system.packages represents all
packages exported by the system bundle plus some additional packages that
will tacked on but may vary by framework implementation".
Wrong. The extender pattern is based almost wholly around such an
approach.
How would you implement the extender pattern without the framework
packages?
As an application developer, I don't need to implement the extender
pattern since framework developers have done that for me. It's all about
layers and perspective.
-> richard
On Tue, Oct 27, 2015 at 6:04 PM, Richard S. Hall <he...@ungoverned.org>
wrote:
On 10/27/15 11:27 , Balázs Zsoldos wrote:
@David:
I know about the *org.osgi.framework.system.**packages.extra* property,
but
that is about another use-case.
*org.osgi.framework.system.**packages.extra *can be used to extend the
list
of system packages.
*org.osgi.framework.system.**packages* can be used to reduce the list of
the system packages.
I want to reduce the list of system packages as some packages are coming
from bundles. More specifically, I want to list only those packages
that I
actually need from the JDK. Reason: Many packages are incomplete or
buggy
in the JDK: javax.transaction.*, javax.xml.*...
@Andy:
The text at
https://osgi.org/javadoc/r5/core/org/osgi/framework/Constants.html#FRAMEWORK_SYSTEMPACKAGES
says:* Framework launching property identifying packages which the
system
bundle must export.*
"Must" does not mean that only those packages should be exported by the
system bundle.
@Everyone:
Questions:
- What is the exact meaning of system packages from the
perspective of
this setting? In my opinion, the list of packages that are coming
outside
the OSGi container.
That is not my interpretation. System packages are those packages
provided
by the system bundle. From a wiring perspective, all of the JRE packages
look like they are coming from the system bundle just like the OSGi core
packages, so your distinction doesn't really make sense to me.
org.osgi.* packages do not come outside from the OSGi
container.
- Could the org.osgi.* packages come from custom bundles? I think,
no.
- Can you write an application that does not need any of the
org.osgi.*
package? I think you cannot.At least one bundle has to implement an
Activator to have any kind of functionality in the system.
Otherwise
the
bundles will be resolved, but they will do nothing (not even a
static
block
will be called).
Wrong. The extender pattern is based almost wholly around such an
approach.
-> richard
- Can you imagine any use-case where exporting org.osgi.* packages
by
the system bundle could cause any issue? I cannot.
- Is it an extra work that org.osgi.* packages have to be appended
if
system.packages are overridden? Yes, always.
If we answer these questions, we will come to the conclusion (at least I
:)
) that org.osgi.* packages should always be exported by the system
bundle.
They are not in the scope of the meaning of system.packages setting.
Kind regards,
*Balázs **Zsoldos*
On Tue, Oct 27, 2015 at 3:21 PM, David Bosschaert <
david.bosscha...@gmail.com> wrote:
Yes, that's precisely what the
org.osgi.framework.system.packages.extra was designed for. That way
you don't need to remember what the framework puts on
org.osgi.framework.system.packages in order to augment it.
Best regards,
David
On 27 October 2015 at 14:18, Andy Lee <thelees.a...@gmail.com> wrote:
If you are trying to extend the set of packages exported by the system
bundle, you should use org.osgi.framework.system.packages.extra. By
specifying org.osgi.framework.system.packages you are overriding the
default value used by the framework, and hence must include the
packaged
that are expected to be supplied by the framework.
See
https://osgi.org/javadoc/r5/core/org/osgi/framework/Constants.html#FRAMEWORK_SYSTEMPACKAGES
--Andy
On Tue, Oct 27, 2015 at 10:00 AM, Balázs Zsoldos <
balazs.zsol...@everit.biz>
wrote:
Hi,
I asked this 1-2 years ago, but I think it is worthy to ask it
again.
Are you sure that the set of system packages should include the OSGi
core
packages?
In my understanding:
- system packages are the ones coming from outside of the OSGi
container
- osgi core packages are offered by the framework bundle, but
they
are
not system packages
In practice:
- If I specify org.osgi.system.packages property for equinox, I
do
not
have to define the packages implemented by the framework
- If I specify the same property for felix, I must copy-paste
the
packages of osgi.core always
Do you think there is a use-case when osgi.core packages offered by
the
framework should be excluded from the exported packages of the system
bundle? I think Equinox has the right behavior here.
Do you see any chance to change this behavior in the future?
Kind regards,
*Balázs **Zsoldos*
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