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https://issues.apache.org/jira/browse/MAHOUT-650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13015497#comment-13015497
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Sean Owen commented on MAHOUT-650:
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Yes, EJB remote interfaces have always needed to deal with Serializable
objects. That's why most of the value classes in the older CF code are
Serializable. While Mahout doesn't make use of Serializable directly, there's
some non-zero audience for needing them marked as Serializable. I buy all that.
DataModel itself is not intended to be wrapped and exposed as a remote service.
You could try to wrap it up as a session bean. In that case, I'd advise you to
not tie the API of your bean directly to the DataModel API. That is, just
because getUserIDs() returns an iterator, doesn't mean your remote bean needs
exactly this method.
And in fact, getUserIDs() returns an iterator instead of an array to allow for
implementations that return an iterator backed not by an array, but by, for
example, a JDBC ResultSet. That's not Serializable, so this will fail anyway if
the DataModel isn't returning an array-backed implementation.
I'd say that the service should expose a method returning long[], which reads
longs from the underlying DataModel's LongPrimitiveIterator. This, to me, is
the most conceptually correct approach on all counts and will work.
> java.io.Serializable should be implemented by
> org.apache.mahout.cf.taste.impl.common.LongPrimitiveArrayIterator
> ---------------------------------------------------------------------------------------------------------------
>
> Key: MAHOUT-650
> URL: https://issues.apache.org/jira/browse/MAHOUT-650
> Project: Mahout
> Issue Type: Improvement
> Components: Collaborative Filtering
> Affects Versions: 0.4
> Environment: Mac OS X 10.6, Java EE 6, EJB 3.1, Glassfish 3.0.1
> Reporter: Manuel Blechschmidt
> Assignee: Sean Owen
> Priority: Minor
> Labels: datamodel, ejb, taste
> Attachments: PatchLongPrimitiveArrayIteratorSerializable.patch,
> RecommenderServices.png, SemRecSysDataModelBean.java,
> SemRecSysDataModelTest.java, SemanticRecommenderDataModel.pdf
>
>
> I am using Mahout in a Java EE 6 application. I implemented a DataModel as an
> EJB 3.1 Singelton Service Bean. I wanted to write some test cases but
> unfortunately some of the classes of Taste are not serializable.
> At the moment LongPrimitiveArrayIterator stops my test cases from working.
> See attached patch, files and images for details
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