Hello

czw., 29 paź 2020 o 19:17 'paul stanley' via OPS4J <[email protected]>
napisał(a):

>
> Thanks Grzegorz.  I know what you mean about doing my "normal job", I also
> have be careful as to what can be shared to the community.
>
> I realise that the ServiceLoader is a bit of a problem and I've already
> had to alter other standard services to be bundle-aware.  Which is why I
> think implementing a Bundle Listener could be a better approach for the
> SCI's.
>
> I'm out of the office for a couple of weeks so I'm going to look
> prototyping a solution when I get back.
>

It'd be great! I'm planning to get back to Pax Web 8 in ~2-3 weeks, but
definitely won't spend >50% of my working time on it... I'm going to
describe the undefined aspects in some place, so we know how it works by
default and what could potentially be configurable.

regards
Grzegorz Grzybek


> Cheers
> Paul
> On 29 Oct 2020, at 13:28, Grzegorz Grzybek <[email protected]> wrote:
>>
>> Hello
>>
>> You're generally right. I'm working on Pax Web 8 improvements (actual,
>> full implementation of OSGi CMPN R6+ Whiteboard specification + HttpService
>> specification + Web Applications Specification) and I tackled the problem
>> of ServletContainerInitializers.
>>
>> The problem is that OSGi CMPN spec doesn't mention SCIs at all, only Web
>> Applications Specification generally assumes that "web bundle" should be
>> processed ("extended") by the implementation which involves web.xml parsing
>> + fragments parsing + (possibly) "classpath scanning". See for example:
>>
>> A WAB can optionally contain a web.xml resource to specify additional
>>> configuration. This web.xml must be found with the Bundle *findEntries*
>>> method at the path WEB-INF/web.xml. The findEntries method includes
>>> fragments, allowing the web.xml to be provided by a fragment.
>>>
>>
>> So here there's nothing about "scanning other bundles" not referred
>> through "fragment" relationship.
>>
>> Also:
>>
>> Unlike a WAR, a WAB is not constrained to package classes and code
>>> resources in the WEB-INF/classes directory or dependent JARs in
>>> WEB-INF/lib/ only. These entries can be packaged in any way that's valid
>>> for an OSGi bundle as long as such directories and JARs are part of bundle
>>> class path as set with the Bundle-ClassPath header and any attached
>>> fragments. JARs that are specified in the Bundle-ClassPath header are
>>> treated like JARs in the WEB-INF/lib/ directory of the Servlet
>>> specification. Similarly, any directory that is part of the
>>> Bundle-ClassPath header is treated like WEB-INF/classes directory of the
>>> Servlet specification.
>>>
>>
>> So again - you can "bring" additional libraries to your "bundle
>> classpath" by referring them in "Bundle-ClassPath" header. No scanning of
>> everything (that's for example tracked by BundleListener).
>>
>> And about java.util.ServiceLoader (which should in theory be a suggestion
>> to how ServletContainerInitializer "services" are found),
>> "java.util.ServiceLoader#load(java.lang.Class<S>, java.lang.ClassLoader)"
>> method simply uses the passed classLoader and the other "load()" version
>> uses TCCL. Neither of these methods scan ALL classloaders (all bundles in
>> OSGi).
>>
>> In Pax Web 8 I'm definitely going to solve this problem - for now, a
>> bundle that registered "a context"
>> (org.osgi.service.http.context.ServletContextHelper) is an "entry point" to
>> classLoader "mesh" where all are checked for SCIs.
>>
>> My Pax Web 8 refactoring is taking its shape at
>> https://github.com/ops4j/org.ops4j.pax.web/tree/master-improvements
>> branch, but I have to do my normal job a bit ;) So please be patient.
>>
>> regards
>> Grzegorz Grzybek
>>
>>
>> czw., 29 paź 2020 o 14:13 'paul stanley' via OPS4J <
>> [email protected]> napisał(a):
>>
>>> Hello.
>>>
>>> I'm tracing this through to try and understand why Jersey Servlet
>>> Initializer is not invoked for a pure Jaxrs applications running in Karaf
>>> 4.3.0.
>>>
>>> It appears the way that the ServletContainerInitializerScanner in the
>>> pax-web-api  has a fundamental design flaw when it searches bundles for
>>> instances of the /META-INF/services/ ServletContainerInitializerScanner
>>> file.  Namely that it only searches dependent bundles of the one that is
>>> being initialised.  As the implementation of any service is meant to be
>>> hidden by the API, it means that you will never be able to initialise any
>>> web servlet.  As such the pax-jetty-web adds the bodge of wiring-in itself
>>> to all web-context so its contextInitializer code can be discovered, but no
>>> other implementations.
>>>
>>> Rather than performing a bundle scan each time, surely jetty should be
>>> implementing the bundle listener pattern and have the set of servlet
>>> initializers that are available in the platform?  Or am I missing something?
>>>
>>> Cheers,
>>>
>>> Paul
>>>
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