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From Dmitriy Setrakyan <dsetrak...@apache.org>
Subject Re: OSGi migration may require a special marshaller
Date Tue, 03 Nov 2015 19:05:07 GMT
Romain,

Can you comment on the ClassLoaderResolver suggestion that I proposed
earlier? Will it solve your problem?

D.

On Tue, Nov 3, 2015 at 2:38 AM, Romain Gilles <romain.gilles@gmail.com>
wrote:

> Hi Raul,
>  - Do you plan to use the TCCL when marshalling in OSGi env? If yes how?
>  - I like the point 2. Maybe for a graph of object that come from different
> packages / bundles you may have to recursively capture the package version
> of the individual element of your graph.
>  - For the point 3 I wonder if it will not over-complexify the solution. As
> a developer you will have to think about it. And it is not obvious in the
> code where things are serialized or not. You may use lambda in your
> application code therefore the current package become what you call a DTO
> package. The current state of ignite does not enforce you to specify it for
> "classical" classloading application. If you introduce this extra step for
> OSGi ready application you will maybe discourage people to use OSGi.
>
> To comeback to our solution. We start we a strong assumption: our cluster
> is homogeneous in term of code so, of course, it simplify our life :).
>
> BTW if you can introduce an extension point in the class resolution
> mechanism it can be interesting for end user in order to allow them to
> optimize it based on there specific use cases.
>
> Romain.
>
> Le mar. 3 nov. 2015 à 00:21, Raul Kripalani <raul@evosent.com> a écrit :
>
> > Hi Andrey,
> >
> > Thanks for the participation in this topic.
> >
> > I don't like the solution to incorporate the bundle symbolic name in the
> > serialised form. Nothing guarantees that the classdef will be located
> under
> > the same bundle in both source and target machines. We also have to take
> > into account that OSGi allows for multiple versions of the same
> > bundle/packages to co-exist in the same  container. So it becomes more
> > complex.
> >
> > Using the TCCL should work when serialising, but it'll probably be of no
> > use when deserialising on the other end.
> >
> > I need to enhance Ignite to:
> >
> > 1. Use the TCCL when marshalling on one end.
> > 2. Incorporate the package version of the class in the serialised form if
> > Ignite is running in an OSGi environment.
> > 3. On the receiver end, discover cache entities / DTOs in all bundles
> > through a custom OSGi manifest header or the like, as I explained before.
> > Package version must be taken into account.
> >
> > What do you think?
> >
> > Raúl.
> > On 2 Nov 2015 17:25, "Andrey Kornev" <andrewkornev@hotmail.com> wrote:
> >
> > > Raul,
> > >
> > > The fundamental hurdle we need to jump over to make Ignite OSGi-enabled
> > is
> > > the marshalling. More specifically the issue is with deserialization of
> > the
> > > classes that are provided by the bundles other than the Ignite bundle
> > > itself.
> > >
> > > When the Ignite transport layer receives a message it needs to figure
> out
> > > how to deserialize the bytes and for that it needs to know the bundle
> > that
> > > provides the class to be deserailized. At this point TCCL is of no use.
> > To
> > > make things more complex, the class may contain other classes that come
> > > from other bundles, and so on recursively. This means that each object
> in
> > > the hierarchy must be serialized with its bundle name (or bundle id),
> so
> > > that the deserializer will then be able to correctly resolve the class
> > > while traversing the object hierarchy during deserialization.
> > >
> > > Unfortunately, Ignite's OptimizedMarshaller is lacking the ability to
> > plug
> > > in a custom class resolver. Romain's solution was to use Kryo that does
> > > provide a way to customize class resolution. It has solved the problem
> of
> > > capturing the bundle info and he was able to successfully run Ignite
> as a
> > > bundle in an OSGi container (after some repackaging and inclusion of
> the
> > > manifest). But Kryo-based marshalling introduced a lot of complexity to
> > the
> > > code and incorrect use of Kryo's numerous serializers caused some weird
> > > hard-to-debug issues in the Ignite core (like duplicate cache entries
> due
> > > to incorrect marshalling of the GridDhtPArtitonFullMap class -- go
> > > figure!). Overall the Kryo-based solution is brittle and hard to
> > maintain.
> > >
> > > I feel the correct solution to OSGi problem would be to
> > > 1) enhance the OptimizedMarshaller to allow custom class resolution.
> > > 2) provide an OSGi-enabled OptimizedMarshaller (in addition to the
> > > original one) to be used in OSGi environment.
> > >
> > > Regards
> > > Andrey
> > >
> > > > From: raulk@apache.org
> > > > Date: Mon, 2 Nov 2015 12:41:47 +0000
> > > > Subject: Re: OSGi migration may require a special marshaller
> > > > To: dev@ignite.apache.org
> > > >
> > > > Hi Romain,
> > > >
> > > > I'm working on the OSGi compatibility of Ignite. I appreciate your
> > input.
> > > >
> > > > I'm thinking about the situation you describe and I wonder if you're
> > > > exporting Ignite as an OSGi service which is then consumed from other
> > > > bundles. Under this situation, it would be quite easy to reproduce
> the
> > > > behaviour you describe if Ignite is not resolving classes via the
> TCCL.
> > > > Need to dig deeper into that.
> > > >
> > > > Off the top of my head, there are two alternatives to solve it:
> > > >
> > > > 1. Use the TCCL for marshalling/unmarshalling (if not already used) –
> > we
> > > > gotta be wary of possible regressions.
> > > > 2. Create a special OSGi header Ignite-Export-Package so that bundles
> > > > containing DTOs can expose packages to Ignite's marshallers.
> > > >
> > > > Regards,
> > > >
> > > > *Raúl Kripalani*
> > > > PMC & Committer @ Apache Ignite, Apache Camel | Integration, Big Data
> > and
> > > > Messaging Engineer
> > > > http://about.me/raulkripalani |
> > http://www.linkedin.com/in/raulkripalani
> > > > http://blog.raulkr.net | twitter: @raulvk
> > > >
> > > > On Mon, Nov 2, 2015 at 9:56 AM, Gilles, Romain <
> > romain.gilles@misys.com>
> > > > wrote:
> > > >
> > > > > Hi all,
> > > > >
> > > > > I'm really interested in this issue:
> > > > > https://issues.apache.org/jira/browse/IGNITE-1270 . We some stuff
> to
> > > make
> > > > > it work in our osgi environment. The main issue for us now is the
> > > > > serialization. I think it you will have to rework the
> > > OptimizedMarshaller
> > > > > or any other marshaller that works with object that come from
> outside
> > > your
> > > > > class space.
> > > > >
> > > > > We have try kryo that works. Kryo provide an extension point in
> order
> > > to
> > > > > resolve the classes:
> > > > >
> > >
> >
> https://github.com/EsotericSoftware/kryo/blob/master/src/com/esotericsoftware/kryo/ClassResolver.java
> > > > > . With this extension we are able to solve the problem of external
> > > classes.
> > > > > The only issue with kryo is that some classes need a certain care
> in
> > > the
> > > > > serialization process and therefore a specialized serializer.
> > > > >
> > > > > So I would like to know from the community what do think of
> changing
> > > the
> > > > > way the optimized marshaller works or introducing the support of
> yet
> > > > > another marshaller based on a kryo like technology?
> > > > >
> > > > >
> > > > > Thanks in advance,
> > > > >
> > > > >
> > > > > Best regards,
> > > > >
> > > > >
> > > > > Romain.
> > > > >
> > > > >
> > > > > PS: I'm ready to help in the both cases.
> > > > > "Misys" is the trade name of the Misys group of companies. This
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