How do I make an (abstract) superclass for factories?

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Arvid

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Nov 16, 2020, 2:56:17 AM11/16/20
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Hello OSGI enthusiasts,

I have a question (again): I have several factories whose configuration is provided by JSON files. 
Now, to make it more modular, I have split the factories over a few different projects. 
Apart from their project and configuration, the factories are the same. So that I don't get a boiler plate code, I would like to write an abstract super class for the factories. 
But unfortunately I have no success with it, because then the factories can no longer be found. 
Even if I keep the @References in every derivation. The abstract super class would then have to be in the API.

How can I do that, or even do it better in a different way? 
Does anyone have an example?

Best regards 
Arvid


Jürgen Albert

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Nov 16, 2020, 3:04:46 AM11/16/20
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Hi Arvid,

I had the same Problem at a certain point.

-dsannotations-options: inherit

This Should solve your issue.

see: https://bnd.bndtools.org/instructions/dsannotations-options.html

Hope this helps,

Jürgen.

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Stefan Feilmeier

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Nov 16, 2020, 3:08:32 AM11/16/20
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Hi Arvid,

this is how I usually solve similar problems in OpenEMS (https://openems.io):

(The example is a "driver" component for Modbus connections - either via serial RS485 line or Ethernet):


I had not know about Jürgens tip. Sounds interesting and will have a look.

Regars,
Stefan

Jürgen Albert

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Nov 16, 2020, 3:16:28 AM11/16/20
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@Stefan:

Speaking of tips: Did you know that you can use the EventTopics Annotation to get rid of the error prone properties. See -> https://docs.osgi.org/specification/osgi.cmpn/7.0.0/service.event.html#org.osgi.service.event.propertytypes.EventTopics

Regards,

Jürgen.

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David Jencks

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Nov 16, 2020, 4:34:13 AM11/16/20
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When I argued for and implemented this option, BJ and Peter pointed out that it tends to make your bundle dramatically more fragile, as it depends on a superclass that by default isn’t in the bundle, and may change incompatibly.  I advise using bnd to pull the superclass (in a private package) into each of the bundles extending it.

David Jencks

BJ Hargrave

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Nov 16, 2020, 9:18:18 AM11/16/20
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See also https://stackoverflow.com/questions/37681829/why-arent-osgi-declarative-services-ds-annotations-inherited-from-super-class for more information behind the reason component inheritance is not supported by the DS spec.

To view this discussion on the web visit https://groups.google.com/d/msgid/bndtools-users/100342BD-C0B0-4782-9B7A-4482D552987D%40gmail.com.


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