4 Replies Latest reply on Jan 3, 2012 7:34 AM by sarikan

Custom serializer for Hot Rod and server marshaller

sarikan Dec 27, 2011 6:23 AM

Greetings,

I have a domain specific object model, with a custom marshaller/unmarshaller library optimized for this model. It is all in Java.

I will be keeping instances of the domain model in a distributed grid, and I'll be accessing it via Hot Rod client. So far so good.

However, these are complex objects, and I'd like to be able to use my existing marshaller library with Hot Rod. The documentation says that I should be able to plug my own Marshaller implementation, but the documentation always mentions the client. See https://docs.jboss.org/author/display/ISPN/Java+Hot+Rod+client#JavaHotRodclient-Marshallingdata

The documentation even says that there is no need to change server marshaller if one chooses Avro for the Hot Rod client. See bottom of: https://docs.jboss.org/author/display/ISPN/Portable+Serialization+For+Hot+Rod+With+Apache+Avro

I don't understand how this is possible. If I plug my own marshaller to the client, when Hot Rod server receives a byte array, how can it put that into the grid, if it does not unmarshall it? How can Lucene and everything else work if the object does not end up deserialized in the grid?

1. Re: Custom serializer for Hot Rod and server marshaller

galder.zamarreno Jan 2, 2012 3:46 AM (in response to sarikan)

The Hot Rod server does not unmarshall data, it keeps it in binary format. That's precisely one of the challenges of indexing it which is currently not supported. Querying and indexing of data in Hot Rod servers is currently being designed: http://community.jboss.org/wiki/QueryingOverHotRod
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2. Re: Custom serializer for Hot Rod and server marshaller

sarikan Jan 2, 2012 4:12 AM (in response to galder.zamarreno)

Thanks,
In this case, I think I have not fully understood the relationship between Infinispan and Hot Rod server. I was under the impression that it stood between Infinispan and client just to improve options when acessing Infinispan, but it seems to do more. Is there a doc that explains the details of how Hot Rod server uses Infinispan?
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3. Re: Custom serializer for Hot Rod and server marshaller

galder.zamarreno Jan 2, 2012 10:53 AM (in response to sarikan)

Hot Rod is the client/server binary protocol that is used to communicate both sides. The Hot Rod server is basically the server side implementation protocol that talks to Infinispan. For further details on how Hot Rod server uses Infinispan, the actual source code is your best guide: http://github.com/infinispan/infinispan

The protocol details can be found https://docs.jboss.org/author/display/ISPN/Hot+Rod+Protocol+-+Version+1.1 and you can find a comparison between the different server modules in https://docs.jboss.org/author/display/ISPN/Infinispan+Server+Modules

The big difference with Infinispan instances communicated via Hot Rod is that it stores data in binary format in order to enable clients written in any language to access the backend. This poses some challenges with things like querying, or remote notifications, or remote map/reduce functions, but we're working on those. If you're talking to an embedded Infinispan instance, objects are stored as pojos.
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4. Re: Custom serializer for Hot Rod and server marshaller

sarikan Jan 3, 2012 7:34 AM (in response to galder.zamarreno)

Thanks, this helps. My use cases at the moment require a very large heap, Lucene indexing, and finally parallel processing. I will take a look at the source code. The smart aspects of Hot Rod is really attractive. I'll try to see if I can use it rather than inventing a short cut more specific to my current goals.

Thanks for the clarification.
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