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From "Robinet, Etienne" <43...@etu.he2b.be>
Subject Re: SPI Module - OSGi Bundle
Date Thu, 07 May 2020 07:59:15 GMT
Hi guys,
As I am really not an expert, which approach should we use?

Etienne

Le mer. 6 mai 2020 à 15:57, Łukasz Dywicki <luke@code-house.org> a écrit :

> Hey Niclas,
> While this code seems straight I don't think it is needed, and valid in
> our case.
> Main benefit of extender and extender based patterns is centralized
> processing of drivers.
> I am keen to keep only interfaces in the API packages and bundles and
> move active parts of code (such base classes) to another place. It is
> necessary to avoid creation of implementation dependency. And that's
> what is in fact, promoted by shared activator class.
>
> Best,
> Łukasz
>
>
> On 06.05.2020 13:47, Niclas Hedhman wrote:
> > My suggestion was;
> > 1. Don't do the BundleTracker classes, and instead change to a bundle
> > activator for each.
> > 2. Add the "Bundle-Activator: org.apache.plc4x.java.osgi.DriverActivator"
> > to the driver META/MANIFEST.MF
> > 3. Do the equivalent for the Transports.
> >
> > public class DriverActivator implements BundleActivator {
> >
> >     private ServiceRegistration<PlcDriver> reg;
> >
> >     @Override
> >     public void start( BundleContext context ) throws Exception {
> >         Hashtable<String, String> props = new Hashtable<>();
> >         props.put( OsgiDriverManager.PROTOCOL_CODE,
> driver.getProtocolCode() );
> >         props.put( OsgiDriverManager.PROTOCOL_NAME,
> driver.getProtocolName() );
> >         reg = context.registerService( PlcDriver.class, driver, props );
> >     }
> >
> >     @Override
> >     public void stop( BundleContext context ) {
> >         context.unregisterService( reg );
> >     }
> > }
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > On Wed, May 6, 2020 at 2:33 PM Etienne Robinet <erobinet@apache.org>
> wrote:
> >
> >> Hi all,
> >> So concretely what changes should be done so that a Driver/Transport
> >> declares itself his service? Beside the changes in the manifest?
> >> Etienne
> >> On 2020/05/06 01:26:42, Niclas Hedhman <niclas@hedhman.org> wrote:
> >>> Łukasz,
> >>>
> >>> the reason I say it is not very OSGi-y, is that the principle of OSGi
> is
> >>> that the bundle handles its own service registrations. In the case of
> >> JDBC
> >>> (I initiated that spec, and I am the founder of OPS4J as well as Pax
> >>> subproject, 2005), it needed to address the problem that JDBC drivers
> >>> existed and changing their build and/or manifests was decided to be
> "not
> >>> viable". The approach there is a work-around for legacy code, which I
> and
> >>> Stuart McCulloch basically invented. IIRC, this happened in 2007.
> >>>
> >>> I didn't suggest that bundles require Declarative Services. I suggested
> >>> that the "inside of the loop" in Etienne's code is put into an
> Activator,
> >>> the code residing in the API and SPI bundles respectively, and that
> each
> >>> driver/transport has a "Bundle-Activator: ....." in the manifest
> >>> referencing respective activator. It is not more intrusive than the
> >>> Export-Package, Import-Package that will be required anyway.
> >>>
> >>> Advantages; It is more in the spirit of OSGi. But importantly, the
> >>> driver/transport is now an active bundle, rather than a library bundle,
> >> and
> >>> in theory the start/stop of a bundle could (there might be other
> reasons
> >>> why not) turn it on/off in runtime. If special needs pop up, maybe to
> >>> deploy for the OpenHAB project, it is possible to override the
> >>> driver/transport with hacking the API/SPI bundles.
> >>>
> >>> And I can't see any disadvantages other than "need to rework a bit of
> >> code".
> >>>
> >>> But I don't have skin in the game. Not in OSGi, not here, so take my
> >>> recommendations into consideration or throw them away. I just got the
> >>> impression that you didn't really get what I suggested.
> >>>
> >>>
> >>> // Niclas
> >>>
> >>>
> >>>
> >>> On Wed, May 6, 2020 at 4:57 AM Łukasz Dywicki <luke@code-house.org>
> >> wrote:
> >>>
> >>>> Hey Etienne, that's awesome piece of work. I can test it! :-)
> >>>>
> >>>> I believe that's what Etienne code does it in a valid OSGi way. And I
> >> do
> >>>> believe not because he mentioned me by name, but due to below
> >>>> argumentation.
> >>>>
> >>>> Proposed code uses extender pattern to grab specific META-INF/services
> >>>> entries and register them in OSGi service registry. If you will take a
> >>>> look on following line:
> >>>>
> >>>>
> >>
> https://github.com/apache/plc4x/blob/feature/osgi/plc4j/api/src/main/java/org/apache/plc4x/java/osgi/ApiActivator.java#L63
> >>>> you will find that bundle is an jar which changes state to ACTIVE.
> >>>> Additionally that bundle classloader is used to find services and that
> >>>> bundle context is used to register services. In the end service which
> >>>> appears looks like one registered by driver/transport module.
> >>>>
> >>>> The main point for above implementation is basic - getting the
> standard
> >>>> PLC4X driver JAR working in OSGi without forcing it to knowing too
> much
> >>>> about OSGi. Driver needs to ship manifest with import/export
> statements
> >>>> and that's it. Additionally driver does not have to have a XML
> >>>> descriptor which registers service. Quite many third parties might be
> >>>> supplying drivers without any or with limited knowledge of OSGi.
> >>>> Do drivers have to be a service? Well, it they can still be a valid
> >> OSGi
> >>>> service, registered using any other way! OSGi aware driver manager
> uses
> >>>> OSGi services instead of static list own classloader to find
> >>>> META-INF/services entries:
> >>>>
> >>>>
> >>
> https://github.com/apache/plc4x/blob/feature/osgi/plc4j/api/src/main/java/org/apache/plc4x/java/osgi/OsgiDriverManager.java#L62
> >>>>
> >>>> JDBC JARs are handled in such a way already in pax-jdbc. Take a look
> >> here:
> >>>>
> >>>>
> >>
> https://github.com/ops4j/org.ops4j.pax.jdbc/blob/master/pax-jdbc/src/main/java/org/ops4j/pax/jdbc/impl/Activator.java#L72
> >>>> Same or very similar code can be found in apache-camel, which brought
> >>>> hundreds of components to OSGi, so I believe their way can be seen as
> >>>> high level guide.
> >>>> What Etienne did is a pattern implementation.
> >>>>
> >>>> With regard to capabilities/requirements - this is a resolver puzzle.
> >> It
> >>>> relies on additional information. As an unbaptized, non-religious osgi
> >>>> guy (I take it as a tool and not act of faith), I often do skip it. I
> >> do
> >>>> find it useful, however quite often problematic and hard to understand
> >>>> (yet another non-trivial syntax in manifest to follow). On older
> >>>> runtimes capabilities are not even considered. For never ones there
> are
> >>>> already existing namespaces:
> >>>> https://www.osgi.org/capability-namespaces-reference/
> >>>> including, one for services:
> >>>>
> >>
> https://docs.osgi.org/specification/osgi.cmpn/7.0.0/service.namespaces.html
> >>>> My point is that capabilities are used to attest that runtime will
> >>>> consist all necessary things in place after provisioning operation. It
> >>>> does not say HOW given capabilities should be made, cause resolver is
> >>>> hit before bundle gets active. It is a safety check. I'm fine with
> >>>> having one, however we need to make it right to do not narrow use of
> >>>> driver bundles only with our own extender.
> >>>>
> >>>> Beside the point, I am not sure if plc4x-api is a best place for osgi
> >>>> specific logic. That is a standard dilema to address in how we want to
> >>>> treat osgi and non-osgi users. :-)
> >>>>
> >>>> Cheers!
> >>>> Łukasz
> >>>>
> >>>> On 05.05.2020 12:34, Julian Feinauer wrote:
> >>>>> Hi Etienne and Niclas,
> >>>>>
> >>>>> indeed we could orient (again) on how JDBC does that in OSGi.
> >>>>> They really focus on "late binding" so that you resolve the driver
> >>>> directly when you need it.
> >>>>> In theory, there is no such thing as a DriverManager in OSGi but
> >> only a
> >>>> PlcDriver with the capability ("plc4x-protocol": "s7") or something.
> >>>>>
> >>>>> I did it witht he driver maanger mostly fort he ease as first
> >> approach.
> >>>>>
> >>>>> Julian
> >>>>>
> >>>>> Am 05.05.20, 12:30 schrieb "Niclas Hedhman" <niclas@hedhman.org>:
> >>>>>
> >>>>>     Also, just in case, a custom activator is ever required, it can
> >> be
> >>>>>     overridden easily without breaking the over all design
> >>>>>
> >>>>>     On Tue, May 5, 2020 at 6:27 PM Niclas Hedhman <
> >> niclas@hedhman.org>
> >>>> wrote:
> >>>>>
> >>>>>     > Yes, that's what I mean, because that is what you have inside
> >> the
> >>>> loop, so
> >>>>>     > it should work.
> >>>>>     >
> >>>>>     > On Tue, May 5, 2020 at 11:50 AM Robinet, Etienne <
> >>>> 43823@etu.he2b.be>
> >>>>>     > wrote:
> >>>>>     >
> >>>>>     >> Hi Niclas,
> >>>>>     >> thanks for the feedback. So you mean to make the Activator in
> >>>> API/SPI
> >>>>>     >> generic so every Driver would call it and declare the service
> >>>> itself?
> >>>>>     >>
> >>>>>     >> Le mar. 5 mai 2020 à 05:25, Niclas Hedhman <
> >> niclas@hedhman.org>
> >>>> a écrit :
> >>>>>     >>
> >>>>>     >> > What you are doing is not particularly OSGi-y... The
> >> expected
> >>>> way to do
> >>>>>     >> > this is to have each bundle register their PlcDriver or
> >>>> Transport to the
> >>>>>     >> > OSGi service registry.
> >>>>>     >> >
> >>>>>     >> > That said, what you have done is otherwise fine, as you
> >>>> basically
> >>>>>     >> trying to
> >>>>>     >> > centralize the BundleActivators away from respective
> >>>> Driver/Transport.
> >>>>>     >> And
> >>>>>     >> > I assume you do so to limit code in the drivers/transports.
> >>>>>     >> >
> >>>>>     >> > Another way would be to make two generic BundleActivator in
> >>>> this bundle
> >>>>>     >> and
> >>>>>     >> > have each driver/transport just declare them in the
> >> manifest.
> >>>> That
> >>>>>     >> would be
> >>>>>     >> > a bit more conventional.
> >>>>>     >> >
> >>>>>     >> > // Niclas
> >>>>>     >> >
> >>>>>     >> > On Tue, May 5, 2020 at 11:06 AM Robinet, Etienne <
> >>>> 43823@etu.he2b.be>
> >>>>>     >> > wrote:
> >>>>>     >> >
> >>>>>     >> > > Hi all,
> >>>>>     >> > > With the change of Christofer this problem got solved.
> >>>> Nonetheless, I
> >>>>>     >> > kept
> >>>>>     >> > > the work I did (inspired by the work of Lukasz) to make an
> >>>> Activator
> >>>>>     >> for
> >>>>>     >> > > API (Driver Services) and SPI (Transport Services). I also
> >>>> tested it,
> >>>>>     >> but
> >>>>>     >> > > as I am pretty new to this, if anyone could just give me a
> >>>> feedback on
> >>>>>     >> > the
> >>>>>     >> > > code:
> >>>>>     >> > >
> >>>>>     >> > > API Activator:
> >>>>>     >> > >
> >>>>>     >> > >
> >>>>>     >> >
> >>>>>     >>
> >>>>
> >>
> https://github.com/apache/plc4x/blob/feature/osgi/plc4j/api/src/main/java/org/apache/plc4x/java/osgi/ApiActivator.java
> >>>>>     >> > > SPI Activator:
> >>>>>     >> > >
> >>>>>     >> > >
> >>>>>     >> >
> >>>>>     >>
> >>>>
> >>
> https://github.com/apache/plc4x/blob/feature/osgi/plc4j/spi/src/main/java/org/apache/plc4x/java/osgi/SpiActivator.java
> >>>>>     >> > >
> >>>>>     >> > > If everything is alright, I could merge this today.
> >>>>>     >> > >
> >>>>>     >> > > Etienne
> >>>>>     >> > >
> >>>>>     >> > > Le mar. 7 avr. 2020 à 17:52, Christofer Dutz <
> >>>>>     >> christofer.dutz@c-ware.de>
> >>>>>     >> > a
> >>>>>     >> > > écrit :
> >>>>>     >> > >
> >>>>>     >> > > > Hi folks,
> >>>>>     >> > > >
> >>>>>     >> > > > I just pushed a change that might get rid of this error.
> >>>>>     >> > > >
> >>>>>     >> > > > I added the Plc4xBootstrap in an attempt to get the
> >>>> TestTransport
> >>>>>     >> > > working.
> >>>>>     >> > > > For some reasons the netty folks created the
> >> EmbeddedChannel
> >>>>>     >> > differently
> >>>>>     >> > > > than the rest.
> >>>>>     >> > > > However as the TestTransport is the only one needing
> >> this
> >>>> change, I
> >>>>>     >> > moved
> >>>>>     >> > > > these classes to the test-transport module
> >>>>>     >> > > > and extended NettyChannelFactory with a createBootstrap
> >>>> method
> >>>>>     >> which is
> >>>>>     >> > > > simply overridden in TestTransport.
> >>>>>     >> > > >
> >>>>>     >> > > > So please give everything a try if it now works as
> >> planned.
> >>>>>     >> > > >
> >>>>>     >> > > > Chris
> >>>>>     >> > > >
> >>>>>     >> > > >
> >>>>>     >> > > >
> >>>>>     >> > > > Am 07.04.20, 17:36 schrieb "Etienne Robinet" <
> >>>> 43823@etu.he2b.be>:
> >>>>>     >> > > >
> >>>>>     >> > > >     Hi all,
> >>>>>     >> > > >     I’ve checked the Manifest. If I put the
> >>>> Embed-Dependency to the
> >>>>>     >> > > > plc4j-spi artifact  it does not find the Transport
> >> Service.
> >>>> And if I
> >>>>>     >> > dont
> >>>>>     >> > > > it does not find the Plc4xBootstrap.
> >>>>>     >> > > >
> >>>>>     >> > > >     Etienne ROBINET
> >>>>>     >> > > >
> >>>>>     >> > > >     > Le 7 avr. 2020 à 16:48, Łukasz Dywicki <
> >>>> luke@code-house.org>
> >>>>>     >> a
> >>>>>     >> > > > écrit :
> >>>>>     >> > > >     >
> >>>>>     >> > > >     > I was updating my local checkout yesterday. Can't
> >>>> promise if I
> >>>>>     >> > will
> >>>>>     >> > > > be
> >>>>>     >> > > >     > able to help, but will give a try with 0.7
> >> snapshot.
> >>>>>     >> > > >     >
> >>>>>     >> > > >     > Best,
> >>>>>     >> > > >     > Łukasz
> >>>>>     >> > > >     >
> >>>>>     >> > > >     >
> >>>>>     >> > > >     >> On 07.04.2020 15:39, Etienne Robinet wrote:
> >>>>>     >> > > >     >> Hi again,
> >>>>>     >> > > >     >> I've been looking at this issue all day, and I am
> >>>> back to the
> >>>>>     >> > > > initial error:
> >>>>>     >> > > >     >> https://i.imgur.com/LLfan8H.png
> >>>>>     >> > > >     >>
> >>>>>     >> > > >     >> The difference is I used and Activator for API
> >> and
> >>>> SPI to
> >>>>>     >> > register
> >>>>>     >> > > > the driver and transports Service, which are then
> >> loaded by
> >>>> the
> >>>>>     >> custom
> >>>>>     >> > > > blueprint. The error now is caused again because this
> >> class
> >>>> is not
> >>>>>     >> > > exported
> >>>>>     >> > > > (I think?) by the SPI, but is used by one of the
> >> dependency
> >>>>>     >> (io.netty).
> >>>>>     >> > > >     >> Any ideas on how to solve this?
> >>>>>     >> > > >     >>
> >>>>>     >> > > >     >> Etienne
> >>>>>     >> > > >     >>
> >>>>>     >> > > >     >>> On 2020/04/07 06:53:54, Etienne Robinet <
> >>>>>     >> erobinet@apache.org>
> >>>>>     >> > > > wrote:
> >>>>>     >> > > >     >>> Hi all,
> >>>>>     >> > > >     >>> the faulty ClassLoader is the
> >>>>>     >> > > > BundleDelegatingClassLoader(plc4x-test [191]). Which
> >> means
> >>>> that the
> >>>>>     >> > > custom
> >>>>>     >> > > > bundle can not find the class right?
> >>>>>     >> > > >     >>>
> >>>>>     >> > > >     >>> I'm sorry if it's a silly question but I am
> >> pretty
> >>>> new to
> >>>>>     >> this.
> >>>>>     >> > > >     >>>
> >>>>>     >> > > >     >>> Etienne
> >>>>>     >> > > >     >>>
> >>>>>     >> > > >     >>> On 2020/04/06 20:28:17, Łukasz Dywicki <
> >>>> luke@code-house.org
> >>>>>     >> >
> >>>>>     >> > > > wrote:
> >>>>>     >> > > >     >>>> I haven't used Camel for a while, but to me it
> >>>> seems to be
> >>>>>     >> a
> >>>>>     >> > > > problem
> >>>>>     >> > > >     >>>> caused by caller's classloader.
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >     >>>> See that in stack trace you have a thread
> >> which is
> >>>> started
> >>>>>     >> by
> >>>>>     >> > > > camel, so
> >>>>>     >> > > >     >>>> there are 3 or even 4 classloaders to be
> >>>> considered:
> >>>>>     >> > > >     >>>> - plc4x, definitely not a faulty one
> >>>>>     >> > > >     >>>> - netty, could be troublesome but unlikely to
> >> be
> >>>> used
> >>>>>     >> > > >     >>>> - camel-core, or component itself
> >>>>>     >> > > >     >>>> - custom bundle which started the route
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >     >>>> Anything beside last one which knows all the
> >>>> dependencies
> >>>>>     >> will
> >>>>>     >> > > > blow up
> >>>>>     >> > > >     >>>> whole universe. Here is why - only the custom
> >>>> bundle knows
> >>>>>     >> all
> >>>>>     >> > > the
> >>>>>     >> > > >     >>>> dependencies necessary to run logic and can be
> >>>> used to fix
> >>>>>     >> > > messed
> >>>>>     >> > > > up
> >>>>>     >> > > >     >>>> classpath. In most of the cases, that's the
> >>>> "trick" you
> >>>>>     >> have
> >>>>>     >> > to
> >>>>>     >> > > > make in
> >>>>>     >> > > >     >>>> order to get OSGi happy.
> >>>>>     >> > > >     >>>> Camel component may not, and should not depend
> >> on
> >>>> specific
> >>>>>     >> > > driver,
> >>>>>     >> > > >     >>>> however in your case it does. Possibly due to
> >> new
> >>>> APIs in
> >>>>>     >> > > > transport
> >>>>>     >> > > >     >>>> layer its shouldn't be used for adhoc fixes.
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >     >>>> We can try to turn drivers into services (see
> >> here
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >
> >>>>>     >> > >
> >>>>>     >> >
> >>>>>     >>
> >>>>
> >>
> https://github.com/splatch/plc4x/commit/5ce379cf8d2f5dc91fdfb6d8a8e2c0531906e69f
> >>>>>     >> > > > )
> >>>>>     >> > > >     >>>> in order to cut concrete class dependency and
> >> rely
> >>>> on
> >>>>>     >> isolated
> >>>>>     >> > > > APIs.
> >>>>>     >> > > >     >>>> This code was done before new abstractions over
> >>>> netty were
> >>>>>     >> > > > introduced,
> >>>>>     >> > > >     >>>> but it should cut in half API and caller side
> >> (not
> >>>> sure if
> >>>>>     >> > we're
> >>>>>     >> > > > on
> >>>>>     >> > > >     >>>> declarative services).
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >     >>>> My tip to you Etienne - please verify which
> >> class
> >>>> loader is
> >>>>>     >> > used
> >>>>>     >> > > > in your
> >>>>>     >> > > >     >>>> polling cycle. You can do that by making
> >>>> breakpoint in
> >>>>>     >> faulty
> >>>>>     >> > > > method of
> >>>>>     >> > > >     >>>> S7Driver and evaluating expression
> >>>>>     >> > > >     >>>>
> >> "Thread.currentThread().getContextClassLoader()".
> >>>>>     >> > > >     >>>> Once you know that you can either fix
> >> classloading
> >>>> in the
> >>>>>     >> > > calling
> >>>>>     >> > > > class
> >>>>>     >> > > >     >>>> loader or override classloader for thread to
> >>>> proper one.
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >     >>>> Best,
> >>>>>     >> > > >     >>>> Łukasz
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >     >>>> On 03.04.2020 10:27, Etienne Robinet wrote:
> >>>>>     >> > > >     >>>>> Hi Christian,
> >>>>>     >> > > >     >>>>> you mean the code used in the Camel route? It
> >> is
> >>>> an
> >>>>>     >> > blueprint:
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>> <?xml version="1.0" encoding="UTF-8"?>
> >>>>>     >> > > >     >>>>> <blueprint xmlns="
> >>>>>     >> http://www.osgi.org/xmlns/blueprint/v1.0.0
> >>>>>     >> > "
> >>>>>     >> > > >     >>>>>           xmlns:xsi="
> >>>>>     >> > http://www.w3.org/2001/XMLSchema-instance
> >>>>>     >> > > "
> >>>>>     >> > > >     >>>>>           xsi:schemaLocation= "
> >>>>>     >> > > > http://www.osgi.org/xmlns/blueprint/v1.0.0
> >>>>>     >> > > >
> >> https://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
> >>>>>     >> > > >     >>>>>
> >>>> http://camel.apache.org/schema/blueprint
> >>>>>     >> > > >
> >>>> http://camel.apache.org/schema/blueprint/camel-blueprint-2.24.2.xsd
> >>>>>     >> ">
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>>    <camelContext id="PLC-IoTDB" xmlns="
> >>>>>     >> > > > http://camel.apache.org/schema/blueprint"
> >>>> streamCache="true" >
> >>>>>     >> > > >     >>>>>        <route id="plc-route" >
> >>>>>     >> > > >     >>>>>            <from
> >>>>>     >> > > > uri="timer://plcFetch?fixedRate=true&period=1000"/>
> >>>>>     >> > > >     >>>>>            <pollEnrich>
> >>>>>     >> > > >     >>>>>                <simple>plc4x:s7:tcp://
> >>>>>     >> > > > 192.168.178.10?address=#fields</simple>
> >>>>>     >> > > >     >>>>>            </pollEnrich>
> >>>>>     >> > > >     >>>>>            <log message="${body}"/>
> >>>>>     >> > > >     >>>>>            <to uri="mock:test?retainLast=10"/>
> >>>>>     >> > > >     >>>>>        </route>
> >>>>>     >> > > >     >>>>>    </camelContext>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>>    <bean id="fields"
> >> class="java.util.ArrayList">
> >>>>>     >> > > >     >>>>>        <argument>
> >>>>>     >> > > >     >>>>>            <list>
> >>>>>     >> > > >     >>>>>               <bean
> >>>>>     >> class="org.apache.plc4x.camel.TagData">
> >>>>>     >> > > >     >>>>>                   <argument index="0"
> >>>> value="IntTest"/>
> >>>>>     >> > > >     >>>>>                   <argument index="1"
> >>>>>     >> > value="%DB1.DBW254:INT"/>
> >>>>>     >> > > >     >>>>>               </bean>
> >>>>>     >> > > >     >>>>>               <bean
> >>>>>     >> class="org.apache.plc4x.camel.TagData">
> >>>>>     >> > > >     >>>>>                   <argument index="0"
> >>>> value="StringTest"/>
> >>>>>     >> > > >     >>>>>                   <argument index="1"
> >>>>>     >> > > value="%DB1.DBX0:STRING"/>
> >>>>>     >> > > >     >>>>>               </bean>
> >>>>>     >> > > >     >>>>>            </list>
> >>>>>     >> > > >     >>>>>        </argument>
> >>>>>     >> > > >     >>>>>    </bean>
> >>>>>     >> > > >     >>>>> </blueprint>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>> This code used to wrok actually, I just
> >> wanted to
> >>>> test the
> >>>>>     >> > new
> >>>>>     >> > > > TagData of the integration. This is the bundling in the
> >>>> pom, these
> >>>>>     >> > > imports
> >>>>>     >> > > > had to be there before too
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>> <plugin>
> >>>>>     >> > > >     >>>>>
> >> <groupId>org.apache.felix</groupId>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> <artifactId>maven-bundle-plugin</artifactId>
> >>>>>     >> > > >     >>>>>                <version>4.2.1</version>
> >>>>>     >> > > >     >>>>>                <extensions>true</extensions>
> >>>>>     >> > > >     >>>>>                <configuration>
> >>>>>     >> > > >     >>>>>                    <instructions>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >
> >>>> <Bundle-SymbolicName>${project.artifactId}</Bundle-SymbolicName>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > > <Bundle-Version>${project.version}</Bundle-Version>
> >>>>>     >> > > >     >>>>>                        <Export-Package>
> >>>>>     >> > > >     >>>>>
> >>>>  *;version=${project.version}
> >>>>>     >> > > >     >>>>>                        </Export-Package>
> >>>>>     >> > > >     >>>>>                        <Import-Package>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > org.apache.plc4x.java.spi.transport,
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > org.apache.plc4x.java.s7.readwrite,
> >>>>>     >> > > >     >>>>>                            *
> >>>>>     >> > > >     >>>>>                        </Import-Package>
> >>>>>     >> > > >     >>>>>                    </instructions>
> >>>>>     >> > > >     >>>>>                </configuration>
> >>>>>     >> > > >     >>>>>            </plugin>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>> Etienne
> >>>>>     >> > > >     >>>>>
> >>>>>     >> > > >     >>>>> On 2020/04/03 08:17:45, Christian Schneider <
> >>>>>     >> > > > chris@die-schneider.net> wrote:
> >>>>>     >> > > >     >>>>>> The code in plc4x directly uses the class
> >> (not a
> >>>> String
> >>>>>     >> of
> >>>>>     >> > the
> >>>>>     >> > > > name). This
> >>>>>     >> > > >     >>>>>> is good. Normally such a class reference
> >> should
> >>>> work
> >>>>>     >> fine.
> >>>>>     >> > > >     >>>>>>
> >>>>>     >> > > >     >>>>>> Can you show your code as a complete example?
> >>>>>     >> > > >     >>>>>>
> >>>>>     >> > > >     >>>>>> Christian
> >>>>>     >> > > >     >>>>>>
> >>>>>     >> > > >     >>>>>>
> >>>>>     >> > > >     >>>>>> Am Fr., 3. Apr. 2020 um 09:58 Uhr schrieb
> >> Julian
> >>>>>     >> Feinauer <
> >>>>>     >> > > >     >>>>>> j.feinauer@pragmaticminds.de>:
> >>>>>     >> > > >     >>>>>>
> >>>>>     >> > > >     >>>>>>> I am off with my knowledge.
> >>>>>     >> > > >     >>>>>>> You could ask the Karaf friends (#karaf in
> >>>> Slack). They
> >>>>>     >> are
> >>>>>     >> > > > all OSGi
> >>>>>     >> > > >     >>>>>>> experts and very friendly and helpful.
> >>>>>     >> > > >     >>>>>>> Or perhaps Christian has an idea here?
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>> Best
> >>>>>     >> > > >     >>>>>>> Julian
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>> Am 03.04.20, 09:50 schrieb "Etienne
> >> Robinet" <
> >>>>>     >> > > > erobinet@apache.org>:
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>>    Hi again,
> >>>>>     >> > > >     >>>>>>>    I've been struggling with this issue for
> >> 2
> >>>> days
> >>>>>     >> now... I
> >>>>>     >> > > > still don't
> >>>>>     >> > > >     >>>>>>> get it why it can not find classes. here is
> >> the
> >>>> current
> >>>>>     >> > > > problem:
> >>>>>     >> > > >     >>>>>>>    https://i.imgur.com/LtZMdsu.png
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>>    We can see that the classes are
> >> available and
> >>>>>     >> exported,
> >>>>>     >> > I
> >>>>>     >> > > > don't know
> >>>>>     >> > > >     >>>>>>> why the Camel Context can't find it. I even
> >>>> tried to
> >>>>>     >> add an
> >>>>>     >> > > > Activator to my
> >>>>>     >> > > >     >>>>>>> bundle, and load these classes there and it
> >>>> works! But
> >>>>>     >> not
> >>>>>     >> > in
> >>>>>     >> > > > the
> >>>>>     >> > > >     >>>>>>> blueprint. If anyone had any idea on where
> >> the
> >>>> problem
> >>>>>     >> > is...
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>>    Etienne
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>>    On 2020/04/01 01:31:15, Niclas Hedhman <
> >>>>>     >> > > niclas@hedhman.org>
> >>>>>     >> > > > wrote:
> >>>>>     >> > > >     >>>>>>>> It happens that OSGi classloading result in
> >>>> the wrong
> >>>>>     >> > NCDFE
> >>>>>     >> > > > and that
> >>>>>     >> > > >     >>>>>>> one of
> >>>>>     >> > > >     >>>>>>>> the classes "used" (i.e. return type,
> >>>> parameter,
> >>>>>     >> throws,
> >>>>>     >> > > > extends,
> >>>>>     >> > > >     >>>>>>>> implements) in the reported class is not
> >>>> visible by the
> >>>>>     >> > > > classloader.
> >>>>>     >> > > >     >>>>>>> And
> >>>>>     >> > > >     >>>>>>>> occasionally, it is a "diamond problem",
> >> i.e.
> >>>> that the
> >>>>>     >> > > > Constraints
> >>>>>     >> > > >     >>>>>>> (IIRC,
> >>>>>     >> > > >     >>>>>>>> see chapter 3.8 in OSGi spec) can't be
> >>>> satisfied.
> >>>>>     >> > > >     >>>>>>>>
> >>>>>     >> > > >     >>>>>>>> Sorry that I don't have time to dig into
> >> the
> >>>> actual
> >>>>>     >> > > situation
> >>>>>     >> > > > here,
> >>>>>     >> > > >     >>>>>>> but I
> >>>>>     >> > > >     >>>>>>>> thought I could share some of my past
> >> (dark)
> >>>>>     >> history....
> >>>>>     >> > ;-)
> >>>>>     >> > > >     >>>>>>>>
> >>>>>     >> > > >     >>>>>>>> Cheers
> >>>>>     >> > > >     >>>>>>>> Niclas
> >>>>>     >> > > >     >>>>>>>>
> >>>>>     >> > > >     >>>>>>>> On Wed, Apr 1, 2020 at 12:43 AM Christofer
> >>>> Dutz <
> >>>>>     >> > > >     >>>>>>> christofer.dutz@c-ware.de>
> >>>>>     >> > > >     >>>>>>>> wrote:
> >>>>>     >> > > >     >>>>>>>>
> >>>>>     >> > > >     >>>>>>>>> Hi all,
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>> But If I search for uses of that class,
> >> it's
> >>>> only in
> >>>>>     >> the
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> org.apache.plc4x.java.spi.connection.NettyChannelFactory
> >>>>>     >> > > > which is
> >>>>>     >> > > >     >>>>>>> in the
> >>>>>     >> > > >     >>>>>>>>> SPI module.
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>> So I am not sure where this is accessed
> >>>> directly from
> >>>>>     >> the
> >>>>>     >> > > > outside.
> >>>>>     >> > > >     >>>>>>> I know
> >>>>>     >> > > >     >>>>>>>>> every driver would use the
> >>>> NettyChannelFactory, but
> >>>>>     >> that
> >>>>>     >> > > > shouldn't
> >>>>>     >> > > >     >>>>>>> be an
> >>>>>     >> > > >     >>>>>>>>> OSGi type problem as the SPI classes
> >> should
> >>>> be able to
> >>>>>     >> > > access
> >>>>>     >> > > >     >>>>>>> their own
> >>>>>     >> > > >     >>>>>>>>> classes.
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>> Chris
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>> Am 31.03.20, 16:07 schrieb "Etienne
> >> Robinet" <
> >>>>>     >> > > > 43823@etu.he2b.be>:
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>    Hi,
> >>>>>     >> > > >     >>>>>>>>>    From the log the class is called
> >> outside
> >>>> the SPI by
> >>>>>     >> > the
> >>>>>     >> > > >     >>>>>>> transport
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>    Etienne
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>> Le 31 mars 2020 à 15:24, Julian Feinauer
> >> <
> >>>>>     >> > > >     >>>>>>>>> j.feinauer@pragmaticminds.de> a écrit :
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>> Hi,
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>> yes, if ist only needed internally its
> >>>> fine.But why
> >>>>>     >> does
> >>>>>     >> > > >     >>>>>>> someone
> >>>>>     >> > > >     >>>>>>>>> then get a Class Not Found Exception?
> >>>>>     >> > > >     >>>>>>>>>> This is usually a hint to some class
> >> loader
> >>>> issue in
> >>>>>     >> > OSGi
> >>>>>     >> > > >     >>>>>>> which is
> >>>>>     >> > > >     >>>>>>>>> related to exports/ imports.
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>> J
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>> Am 31.03.20, 15:23 schrieb "Christofer
> >> Dutz"
> >>>> <
> >>>>>     >> > > >     >>>>>>>>> christofer.dutz@c-ware.de>:
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>   As this package is only referenced from
> >>>> within SPI,
> >>>>>     >> > > >     >>>>>>> couldn't we
> >>>>>     >> > > >     >>>>>>>>> just exclude it from the package exports?
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>   Chris
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>   Am 31.03.20, 15:17 schrieb "Julian
> >>>> Feinauer" <
> >>>>>     >> > > >     >>>>>>>>> j.feinauer@pragmaticminds.de>:
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>       Hi,
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>       the issue is that if we export it,
> >>>> then we
> >>>>>     >> break
> >>>>>     >> > > >     >>>>>>> Nettys OSGi
> >>>>>     >> > > >     >>>>>>>>> integration as we get a split package
> >>>> situation (two
> >>>>>     >> > > bundles
> >>>>>     >> > > >     >>>>>>> exporting the
> >>>>>     >> > > >     >>>>>>>>> same package, which is forbidden in OSGi).
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>       So I see no easy solution (but had
> >> to
> >>>> do the
> >>>>>     >> same
> >>>>>     >> > > >     >>>>>>> once as
> >>>>>     >> > > >     >>>>>>>>> Netty is pretty... private).
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>       J
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>       Am 31.03.20, 15:15 schrieb
> >> "Christofer
> >>>> Dutz" <
> >>>>>     >> > > >     >>>>>>>>> christofer.dutz@c-ware.de>:
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>           Hi all,
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>           I just discussed this issue
> >> with
> >>>> Etienne
> >>>>>     >> and I
> >>>>>     >> > > >     >>>>>>> thought it
> >>>>>     >> > > >     >>>>>>>>> was important for all, so I asked him to
> >>>> bring it
> >>>>>     >> here.
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>           In my effort to get the
> >>>> EmbeddedChannel
> >>>>>     >> > working
> >>>>>     >> > > >     >>>>>>> as a full
> >>>>>     >> > > >     >>>>>>>>> "transport" module, I had to override the
> >>>> Netty
> >>>>>     >> Bootstrap
> >>>>>     >> > > >     >>>>>>> mechanism.
> >>>>>     >> > > >     >>>>>>>>>>           Unfortunately in order to do
> >> so, I
> >>>> need to
> >>>>>     >> > call
> >>>>>     >> > > >     >>>>>>> "init"
> >>>>>     >> > > >     >>>>>>>>> from the derived class. Unfortunately
> >> this is
> >>>> package
> >>>>>     >> > > > private in
> >>>>>     >> > > >     >>>>>>> Netty so I
> >>>>>     >> > > >     >>>>>>>>> had
> >>>>>     >> > > >     >>>>>>>>>>           To add it to the same package.
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>           Would it help to just not
> >> export
> >>>> these
> >>>>>     >> > packages
> >>>>>     >> > > >     >>>>>>> to OSGi?
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>           But I'm also open for
> >> alternatives
> >>>> (Please
> >>>>>     >> > none
> >>>>>     >> > > >     >>>>>>> involving
> >>>>>     >> > > >     >>>>>>>>> mega-evil reflection hackery).
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>           Chris
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>           Am 31.03.20, 15:10 schrieb
> >> "Etienne
> >>>>>     >> Robinet" <
> >>>>>     >> > > >     >>>>>>>>> erobinet@apache.org>:
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>               Hi all,
> >>>>>     >> > > >     >>>>>>>>>>               I've been working on the
> >> Camel
> >>>>>     >> Component
> >>>>>     >> > and
> >>>>>     >> > > >     >>>>>>> decided
> >>>>>     >> > > >     >>>>>>>>> to test it inside Karaf, but I noticed
> >> that
> >>>> I've got
> >>>>>     >> this
> >>>>>     >> > > > error
> >>>>>     >> > > >     >>>>>>> now:
> >>>>>     >> > > >     >>>>>>>>>>
> >>>> https://i.imgur.com/kUZPwZ5.png
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>               Seems like this class is
> >> not
> >>>> exported
> >>>>>     >> by
> >>>>>     >> > the
> >>>>>     >> > > >     >>>>>>> bundle
> >>>>>     >> > > >     >>>>>>>>> so it can not be found. Anyone has an
> >> idea on
> >>>> how we
> >>>>>     >> > could
> >>>>>     >> > > > solve
> >>>>>     >> > > >     >>>>>>> this?
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>               Etienne
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>>
> >>>>>     >> > > >     >>>>>>>>
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>>
> >>>>>     >> > > >     >>>>>>
> >>>>>     >> > > >     >>>>>> --
> >>>>>     >> > > >     >>>>>> --
> >>>>>     >> > > >     >>>>>> Christian Schneider
> >>>>>     >> > > >     >>>>>> http://www.liquid-reality.de
> >>>>>     >> > > >     >>>>>>
> >>>>>     >> > > >     >>>>>> Computer Scientist
> >>>>>     >> > > >     >>>>>> http://www.adobe.com
> >>>>>     >> > > >     >>>>>>
> >>>>>     >> > > >     >>>>
> >>>>>     >> > > >     >>>
> >>>>>     >> > > >
> >>>>>     >> > > >
> >>>>>     >> > > >
> >>>>>     >> > >
> >>>>>     >> >
> >>>>>     >>
> >>>>>     >
> >>>>>
> >>>>
> >>>
> >>
> >
>

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