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From Jun Rao <jun...@gmail.com>
Subject Re: Consumer exception
Date Wed, 06 Jun 2012 18:48:42 GMT
MessageAndMetadata contains a Message and the metadata associated with it
(e.g., topic, partition, offset).

Thanks,

Jun

On Wed, Jun 6, 2012 at 10:59 AM, navneet sharma <navneetsharma0505@gmail.com
> wrote:

> Thanks Jun, i got it.
> Somehow i overlooked "iter.next().message()" .
>
> What confused me more is that when iterator is ConsumerIterator<Message> ,
> how its returning MessageAndMetadata<Message>.
> Whats the relation between Message and MessageAndMetadata?
>
> Regards,
> Navneet Sharma
>
>
> On Wed, Jun 6, 2012 at 8:28 PM, Jun Rao <junrao@gmail.com> wrote:
>
> > Navneet,
> >
> > KafkaStream<Message> returns an iterator of MessageAndMetadata<Message>.
> > The java example simply calls iter.next().message() to get the message
> from
> > MessageAndMetadata.
> >
> > Thanks,
> >
> > Jun
> >
> > On Tue, Jun 5, 2012 at 11:13 PM, navneet sharma <
> > navneetsharma0505@gmail.com
> > > wrote:
> >
> > > Hi Jun,
> > >
> > > Just to make sure that i have updated code, i updated source code just
> > now
> > > from this location:
> > > http://svn.apache.org/repos/asf/incubator/kafka/trunk
> > >
> > > but i am not seeing  kafka.examples.Consumer with MessageAndMetadata
> > > implementation.
> > > Any help will be appreciated. Meanwhile, I will try something on my
> own.
> > >
> > > Thanks,
> > > Navneet Sharma
> > >
> > > On Wed, Jun 6, 2012 at 9:49 AM, Jun Rao <junrao@gmail.com> wrote:
> > >
> > > > Java example in trunk is modified to use MessageAndMetadata. This
> > > happened
> > > > probably 2-3 weeks ago.
> > > >
> > > > Thanks,
> > > >
> > > > Jun
> > > >
> > > > On Tue, Jun 5, 2012 at 8:49 PM, navneet sharma
> > > > <navneetsharma0505@gmail.com>wrote:
> > > >
> > > > > yes of course, the code snippet which i posted is from the
> > > > > kafka.examples.Consumer
> > > > > only.
> > > > >
> > > > > Its not modified to use MessageAndMetadata.
> > > > >
> > > > > Has it been changed in last week?
> > > > >
> > > > > Thanks,
> > > > > Navneet Sharma
> > > > >
> > > > > On Tue, Jun 5, 2012 at 8:12 PM, Jun Rao <junrao@gmail.com>
wrote:
> > > > >
> > > > > > In trunk, the iterator api has changed to
> > > > > KafkaStream<MessageAndMetadata>.
> > > > > > Take a look at kafka.examples.Consumer in java-examples.
> > > > > >
> > > > > > Thanks,
> > > > > >
> > > > > > Jun
> > > > > >
> > > > > > On Tue, Jun 5, 2012 at 6:33 AM, navneet sharma
> > > > > > <navneetsharma0505@gmail.com>wrote:
> > > > > >
> > > > > > > Hi,
> > > > > > >
> > > > > > > I downloaded the latest code from trunk last week and i
was
> > trying
> > > > this
> > > > > > > snippet as given in examples.
> > > > > > >
> > > > > > >
> > > > > > > Map<String, Integer> topicCountMap = new HashMap<String,
> > > Integer>();
> > > > > > >    topicCountMap.put(topic, new Integer(1));
> > > > > > >    Map<String, List<KafkaStream<Message>>>
consumerMap =
> > > > > > > consumer.createMessageStreams(topicCountMap);
> > > > > > >    KafkaStream<Message> stream =
>  consumerMap.get(topic).get(0);
> > > > > > >    ConsumerIterator<Message> it = stream.iterator();
> > > > > > >    while(it.hasNext())
> > > > > > >
> > > >  System.out.println(ExampleUtils.getMessage(it.next().message()));
> > > > > > >  }
> > > > > > >
> > > > > > > But its giving following error:
> > > > > > > Type mismatch: cannot convert from
> > KafkaStream<MessageAndMetadata>
> > > to
> > > > > > > KafkaStream<Message> at
> > > > > > > ConsumerIterator<Message> it = stream.iterator();
> > > > > > >
> > > > > > > Can you please tell how to run the above snippet with
> > > > > MessageAndMetadata?
> > > > > > > And also please tell whether it requires any code changes
in
> > > producer
> > > > > as
> > > > > > > well?
> > > > > > >
> > > > > > > Thanks,
> > > > > > > Navneet Sharma
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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