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Re: [osgi-wg] [platform-dev] How to document OSGi extensibility?

As its about to document a service interface is intended to be consumed by the (OSGi) Whiteboard pattern why should it be a bad name? :-)

The context is the following:

There is a service interface that is consumed by some other component using the Whiteboardpattern.

The question was: How can we clearly document that it is supposed to be consumed and what service properties are meant to be present.

Thats similar to what the MetaDataService tries to provide for component configurations.

My very simple first proposal was to have an


annotation on the service interface that documents the possible service properties as strings that map to final static fields. I attached an example here


public interface IAdapterFactory {

* Service property to use when registering a factory as OSGi-service to declare the adaptable class type, this is a multi-string-property, if more than one is given the factory will be register multiple times
	 * @since 3.14
static final String SERVICE_PROPERTY_ADAPTABLE_CLASS = "adaptableClass"; //$NON-NLS-1$

* Optional service property to use when registering a factory as OSGi-service to declare the possible adapter types. If the property is given, the service is only queried when actually required, this is a multi-string-property.
	 * @since 3.14
static final String SERVICE_PROPERTY_ADAPTER_NAMES = "adapterNames"; //$NON-NLS-1$


Am 22.01.21 um 16:39 schrieb Jürgen Albert:
Providing some kind of Service and/or annotation to provide documentation aether at runtime or at development time crossed my mind as well and could be a good Idea.

It seems that I miss a bit of context here however. What are you actually proposing?

BTW: With the little context I have, @Whiteboard would be a bad name choice, because the Whiteboard concept is a bit loaded in the OSGi Context.



Am 22/01/2021 um 16:04 schrieb Christoph Läubrich:
OSGi Alliance was moved to Eclipse last year... :-)

OSGi already defines some annotations for the package level see , OSGi DS makes heavy use with great success of annotations.

The problem is more that the Eclipse way of thinking is sometimes incompatible with standard OSGi ;-)

But I think if a draft for a @Whiteboard annotation could be provided in Eclipse it might become the reference-implementation of an official Eclipse specification later on :-)


Am 22.01.21 um 15:56 schrieb Mickael Istria:

On Fri, Jan 22, 2021 at 3:42 PM Christoph Läubrich <laeubi@xxxxxxxxxxxxxx <mailto:laeubi@xxxxxxxxxxxxxx>> wrote:

    Good point! I'd like to enhance my annotation idea in the following way:

    @Whiteboard(extensions = {
       properties = {"xyz"}

    that way it would be possible to automatically read the meta-data and
    transform them into help or whatever...

Eclipse Platform should avoid the funk of building and relying on Eclipse-specific documentation annotations for OSGi. It looks like in this case, it's more interesting to just bring the idea to the OSGi Alliance so it can become specified or shared with other OSGi projects to identify the best solution in a standard-ish way; and then Eclipse Platform could start using them. Concretely, generating documentation is a difficult task, see how javadoc or PDE extension point doc-gen are complex; we don't want to start dealing with such extra complex new problem in Platform.

Note that 1 issue introduced by the idea of documenting on the interface is that it kinds of break the layers: the IContentAssistProcessor interface is not aware of Generic Editor, so it looks like we'd suddenly have to make it kind of aware of it, at least in the doc, creating a (very soft, not technically binding) dependency cycle. That seems undesired to me.

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