[jruby-user] Serialization Problem when using HashMap

[Ian Bentley]

I'm using JRuby in a Rails application, which is supported by a Java backend.  One of the Java Interface functions requires a hashmap be passed from the JRuby to the Ruby code, and I'm running into an unexpected RuntimeException in this case.

The Hashmap construction is very straightforward:

def java_map

    hash_map = ::Java::JavaUtil::HashMap.new

    hash_map[:original_document_uri] = "".to_s

end

This construction causes no errors in JRuby, and I can nicely access the map as expected.

The trouble comes when I attempt to pass this map into Java:

NativeException (java.lang.RuntimeException: org.jcodings.specific.ASCIIEncoding):

  org/apache/activemq/command/ActiveMQObjectMessage.java:111:in `storeContent'

  org/apache/activemq/command/ActiveMQObjectMessage.java:162:in `setObject'

  org/apache/activemq/ActiveMQSession.java:380:in `createObjectMessage'

  org/logicblaze/lingo/jms/marshall/DefaultMarshaller.java:60:in `createRequestMessage'

  org/logicblaze/lingo/jms/JmsClientInterceptor.java:131:in `invoke'

  net/zerofootprint/jms/JmsProxyFactoryBean.java:58:in `invoke'

  org/springframework/aop/framework/ReflectiveMethodInvocation.java:172:in `proceed'

  org/springframework/aop/framework/JdkDynamicAopProxy.java:202:in `invoke'

  $Proxy15:-1:in ...(I've removed my application specific details here, as they seem unimportant)

That is the stacktrace that I get on my rails log, and in my java log I get:

java.lang.RuntimeException: org.jcodings.specific.ASCIIEncoding

          ... (similar trace to above)

Caused by: java.io.NotSerializableException: org.jcodings.specific.ASCIIEncoding

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1164)

at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)

at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)

at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)

at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)

at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)

at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)

at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)

at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:330)

at java.util.HashMap.writeObject(HashMap.java:1000)

        ... (far too long for inclusion)

As you can see, I am using ActiveMQ as my broker, and have the java running in a Tomcat instance, while the JRuby is running inside Trinidad.

I'm not sure if the HashMap here is a red herring, but it seems that whatever I put into the hashmap causes this exception.

Finally, I tried using an empty hashmap, and that seemed to work ok.

I hope someone can lend me a bright Idea.

--
Ian Bentley

[Paweł Wielgus]

Hi Ian,
something You put into the hashmap is using org.jcodings.specific.ASCIIEncoding
so while serializing your map You get:
Caused by: java.io.NotSerializableException: org.jcodings.specific.ASCIIEncoding
and that's why empty map works.

Best greetings,
Paweł Wielgus.

2011/1/25 Ian Bentley <ian.b...@gmail.com>:

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[Ian Bentley]

Pawel,

Thanks for getting back.  That was my belief, but I couldn't understand why 

    hash_map[:original_document_uri] = "".to_s

would be causing that error.  It turns out that it's the symbol on the lhs which causes the problem.

Thanks,

Ian

2011/1/25 Paweł Wielgus <poul...@gmail.com>

--
Ian Bentley