Hi Harsha,
I just tried to hard code a string message, then convert the message to byte
array, but no lucky...
The following is how my program works:
Create a hardcode key, which is String, then convert to byte array, iterate a
network message, send the message one by one:
networkelements foreach {
case networkelement =>
val bytes = Injection(networkelement)
logger.info(s"Synchronously sending Tweet $networkelement to topic
${producerApp.defaultTopic}")
val hardKey = "2"
val parkey = hardKey.getBytes("UTF8")
val topic = producerApp.defaultTopic
producerApp.send(parkey, bytes, topic)
}
Here is how the networkelements created, where NetworkElement is a class that
created by avro, I think you can ignore it:
val networkelements = fixture.messages
val fixture = {
val BeginningOfEpoch = 0.seconds
val AnyTimestamp = 1234.seconds
val now = System.currentTimeMillis().millis
new {
val t1 = new NetworkElement("ANY_USER_1", "ANY_TEXT_1", now.toSeconds)
val t2 = new NetworkElement("ANY_USER_2", "ANY_TEXT_2",
BeginningOfEpoch.toSeconds)
val t3 = new NetworkElement("ANY_USER_3", "ANY_TEXT_3",
AnyTimestamp.toSeconds)
val messages = Seq(t1, t2, t3)
}
}
BTW, I defined the Key and Val types as following:
type Key = Array[Byte]
type Val = Array[Byte]
Thanks,
Haoming
> From: [email protected]
> To: [email protected]
> Subject: Re: Partition Key Cannot be Send Out by Producer
> Date: Thu, 20 Nov 2014 16:59:19 -0800
>
> also the (key: Key, value: Val, topic: Option[String]) "value" should be
> a string converted to a byte array.
> Can you send a example of your key and value data.
>
>
> On Thu, Nov 20, 2014, at 04:53 PM, Haoming Zhang wrote:
> > Hi Harsha,
> >
> > Thanks for suggestion!
> >
> > I have checked this link before, and I tried to create the partition key
> > like the following:
> > val hardKey = "2"
> > val parkey = hardKey.getBytes("UTF8")
> >
> > But I still get the same exception. I also tried set "UTF8" as "UTF-8",
> > but no luck...
> >
> > Regards,
> > Haoming
> >
> > > From: [email protected]
> > > To: [email protected]
> > > Subject: Re: Partition Key Cannot be Send Out by Producer
> > > Date: Thu, 20 Nov 2014 16:43:11 -0800
> > >
> > > Hi Haoming,
> > > Take a look at the code here
> > >
> > > https://github.com/stealthly/scala-kafka/blob/master/src/main/scala/KafkaProducer.scala
> > > for your partKey it should be string and when you converting it into
> > > byte array you can use partKey.getBytes("UTF8")
> > > -Harsha
> > >
> > > On Thu, Nov 20, 2014, at 03:57 PM, Haoming Zhang wrote:
> > > > Hi all,
> > > >
> > > > I'm a beginner of Kafka, currently I'm stuck by how to send out a
> > > > KeyedMessage by producer. I would like to design a partition
> > > > function to route the message based on the key, but the producer cannot
> > > > send the KeyedMessage and I got this exception:
> > > > java.lang.ClassCastException: [B cannot be cast to java.lang.String
> > > >
> > > > What I tried is hardcode a partition key ( I tried String and Integer,
> > > > currently it is Integer ), then convert the partition key to Byte Array:
> > > > val converter = new DataTypeConvertion
> > > > val hardKey = 2
> > > > val partkey = converter.intToByteArray(hardKey)
> > > >
> > > > Then create a KeyedMessage by the following function:
> > > >
> > > > private def toMessage(value: Val, key: Option[Key] = None, topic:
> > > > Option[String] = None): KeyedMessage[Key, Val] = {
> > > > val t = topic.get
> > > > require(!t.isEmpty, "Topic must not be empty")
> > > > key match {
> > > > case Some(key) => new KeyedMessage(t, key, value)
> > > > case _ => new KeyedMessage(t, value)
> > > > }
> > > > }
> > > >
> > > > Then try to send the KeyedMessage by a Kafka producer:
> > > >
> > > > def send(key: Key, value: Val, topic: Option[String] = None) {
> > > > val msg = toMessage(value, Option(key), topic)
> > > > print(msg + "\n")
> > > > print("msg.key" + msg.key + "\n")
> > > > print("msg.message" + msg.message + "\n")
> > > > print("msg.partKey" + msg.partKey + "\n")
> > > > print("msg.topic" + msg.topic + "\n")
> > > > try {
> > > > p.send(msg) //P is an instance of producer, exception happens in
> > > > this line
> > > > } catch {
> > > > case e: Exception =>
> > > > e.printStackTrace()
> > > > System.exit(1)
> > > > }
> > > > }
> > > >
> > > > As you can see, I added many print statement in the above function, and
> > > > the following is the output of above function:
> > > > KeyedMessage(testingInput,[B@7ad40950,[B@7ad40950,[B@7ce18764)
> > > > msg.key: [B@7ad40950
> > > > msg.message: [B@7ce18764
> > > > msg.partKey: [B@7ad40950
> > > > msg.topic: testingInput
> > > >
> > > > The key of KeyedMessage is displayed as [B@7ad40950 , I think it is a
> > > > memory address and the exception (java.lang.ClassCastException: [B
> > > > cannot
> > > > be cast to java.lang.String) happens when "send" function try to convert
> > > > the Byte Array to String.
> > > >
> > > > Am I wrong on creating a key in Byte Array type?
> > > > Some examples of how to use KeyedMessage will be great!
> > > >
> > > > Regards,
> > > > Haoming
> > > >
> > > >
> >
