// Asynchronous response from Message Hub / Kafka.
kafkaProducer.send(record,
new Callback() {
   public void onCompletion(RecordMetadata m, Exception e) {
       if(e != null) {
       e.printStackTrace();
       } else { 
    log.debug("****Message sent, offset: " + m.offset() + 
    " @ partition " + m.partition());
    log.debug(" <<<< " +
    " document_id " + key +
    " @ " + account.getActivityId());
    }
   }
});

当尝试使用上述代码将消息发布到消息中心时，我们总是会遇到以下错误。
2016-06-21 18:38:22-[info]com.ibm.cloudant.streaming.messagehub.client.send（476）：>>>>发送文档\u id julia30@my\u database 2016-06-21 18:38:22-[debug]org.apache.kafka.clients.networkclient$defaultmetadataupdater.maybeupdate（623）：初始化到节点-1的连接以发送元数据请求2016-06-21 18:38:22-[debug]org.apache.kafka.clients.networkclient.initiateconnect（487）：启动到kafka01-prod01.messagehub.services.us-south.bluemix节点-1的连接。net:9093. 2016-06-21 18:38:22-[调试]org.apache.kafka.common.security.authenticator.saslclientauthenticator$1.运行（105）：创建saslclient:client=multiuser-adapter@multiuser.messagehub.ibm.com;服务=Kafka；serviceostname=kafka01-prod01.messagehub.services.us-south.bluemix.net；mechs=[gssapi]2016-06-21 18:38:22-[debug]com.ibm.cloudant.streaming.messagehub.accountmanager.（53）：进程id:15825 2016-06-21 18:38:22-[info]org.apache.kafka.common.network.saslchannelbuilder.buildchannel（92）：由于org.apache.kafka.common.kafkaexception:未能在上配置saslclientauthenticatororg.apache.kafka.common.security.authenticator.saslclientauthenticator.configure（saslclientauthenticator。java:96)在org.apache.kafka.common.network.saslchannelbuilder.buildchannel（saslchannelbuilder。java:89)在org.apache.kafka.common.network.selector.connect（selector。java:162)在org.apache.kafka.clients.networkclient.initiateconnect（网络客户端。java:489)在org.apache.kafka.clients.networkclient.access$400（networkclient。java:47)在org.apache.kafka.clients.networkclient$defaultmetadataupdater.maybeupdate（networkclient。java:624)在org.apache.kafka.clients.networkclient$defaultmetadataupdater.maybeupdate（networkclient。java:543)在org.apache.kafka.clients.networkclient.poll（networkclient。java:254)在org.apache.kafka.clients.producer.internals.sender.run（sender。java:216)在org.apache.kafka.clients.producer.internals.sender.run（sender。java:128)在java.lang.thread.run（线程。java:745)原因：org.apache.kafka.common.kafkaexception:未能在org.apache.kafka.common.security.authenticator.saslclientauthenticator.createsaslclient（saslclientauthenticator）上创建saslclient。java:112)在org.apache.kafka.common.security.authenticator.saslclientauthenticator.configure（saslclientauthenticator。java:94) ... 还有10个原因：javax.security.sasl.saslexception:plain:必须在com.sun.security.sasl.plainclient.（plainclient）中指定授权id和密码。java:58)在com.sun.security.sasl.clientfactoryimpl.createsaslclient（clientfactoryimpl。java:97)在javax.security.sasl.sasl.createsaslclient（sasl。java:384)在com.ibm.messagehub.login.messagehubsalslclientfactory.createsaslclient（messagehubsalslclientfactory）。java:77)在javax.security.sasl.sasl.createsaslclient（sasl。java:384)在org.apache.kafka.common.security.authenticator.saslclientauthenticator$1.run（saslclientauthenticator。java:107)在org.apache.kafka.common.security.authenticator.saslclientauthenticator$1.run（saslclientauthenticator。java:102)位于javax.security.auth.subject.doas（subject）的java.security.accesscontroller.doprivileged（本机方法）。java:422)在org.apache.kafka.common.security.authenticator.saslclientauthenticator.createsaslclient（saslclientauthenticator。java:102) ... 11更多2016-06-21 18:38:22-[错误]org.apache.kafka.clients.producer.internals.sender.run（130）：kafka producer i/o线程中未捕获的错误：org.apache.kafka.common.kafkaexception:org.apache.kafka.common.kafkaexception:未能在上配置saslclientauthenticatororg.apache.kafka.common.network.saslchannelbuilder.buildchannel（saslchannelbuilder）。java:93)在org.apache.kafka.common.network.selector.connect（selector。java:162)在org.apache.kafka.clients.networkclient.initiateconnect（networkclient。java:489)在org.apache.kafka.clients.networkclient.access$400（networkclient。java:47)在org.apache.kafka.clients.networkclient$defaultmetadataupdater.maybeupdate（networkclient。java:624)在org.apache.kafka.clients.networkclient$defaultmetadataupdater.maybeupdate（networkclient。java:543)在org.apache.kafka.clients.networkclient.poll（networkclient。java:254)在org.apache.kafka.clients.producer.internals.sender.run（sender。java:216)在org.apache.kafka.clients.producer.internals.sender.run（sender。java:128)在java.lang.thread.run（线程。java:745)原因：org.apache.kafka.common.kafkaexception:未能在org.apache.kafka.common.security.authenticator.saslclientauthenticator.configure（saslclientauthenticator）中配置saslclientauthenticator。java:96)在org.apache.kafka.common.network.saslchannelbuilder.buildchannel（saslchannelbuilder）。java:89) ... 9其他原因：org.apache.kafka.common.kafkaexception:未能在org.apache.kafka.common.security.authenticator.saslclientauthenticator.createsaslclient（saslclientauthenticator）上创建saslclient。java:112)在org.apache.kafka.common.security.authenticator.saslclientauthenticator.configure（saslclientauthenticator。java:94) ... 还有10个原因：javax.security.sasl.saslexception:plain:必须在com.sun.security.sasl.plainclient.（plainclient）中指定授权id和密码。java:58)在com.sun.security.sasl.clientfactoryimpl.createsaslclient（clientfactoryimpl。java:97)在javax.security.sasl.sasl.createsaslclient（sasl。java:384)在com.ibm.messagehub.login.messagehubsalslclientfactory.createsaslclient（messagehubsalslclientfactory）。java:77)在javax.security.sasl.sasl.createsaslclient（sasl。java:384)在org.apache.kafka.common.security.authenticator.saslclientauthenticator$1.run（saslclientauthenticator。java:107)在org.apache.kafka.common.security.authenticator.saslclientauthenticator$1.run（saslclientauthenticator。java:102)位于javax.security.auth.subject.doas（subject）的java.security.accesscontroller.doprivileged（本机方法）。java:422)在org.apache.kafka.common.security.authenticator.saslclientauthenticator.createsaslclient（saslclientauthenticator。java:102) ... 11更多2016-06-21 18:38:22-[错误]org.apache.kafka.clients.producer.internals.sender.run（130）：kafka producer i/o线程中未捕获的错误：java.lang.nullpointerexception at org.apache.kafka.common.network.selector.poll（selector）。java:268)在org.apache.kafka.clients.networkclient.poll（networkclient。java:256)在org.apache.kafka.clients.producer.internals.sender.run（sender。java:216)在org.apache.kafka.clients.producer.internals.sender.run（sender。java:128)在java.lang.thread.run（线程。java:745)
producer的设置如下所示：

compression.type = none
metric.reporters = []
metadata.max.age.ms = 300000
metadata.fetch.timeout.ms = 60000
reconnect.backoff.ms = 50
sasl.kerberos.ticket.renew.window.factor = 0.8
bootstrap.servers = [kafka01-prod01.messagehub.services.us-south.bluemix.net:9093]
retry.backoff.ms = 100
sasl.kerberos.kinit.cmd = /usr/bin/kinit
buffer.memory = 33554432
timeout.ms = 30000
key.serializer = class org.apache.kafka.common.serialization.StringSerializer
sasl.kerberos.service.name = null
sasl.kerberos.ticket.renew.jitter = 0.05
ssl.keystore.type = JKS
ssl.trustmanager.algorithm = PKIX
block.on.buffer.full = false
ssl.key.password = null
max.block.ms = 60000
sasl.kerberos.min.time.before.relogin = 60000
connections.max.idle.ms = 540000
ssl.truststore.password = [hidden]
max.in.flight.requests.per.connection = 5
metrics.num.samples = 2
client.id = kafka01-prod01.messagehub.services.us-south.bluemix.net%3A9093_8qp87X32V6PK5epv.1
ssl.endpoint.identification.algorithm = HTTPS
ssl.protocol = TLSv1.2
request.timeout.ms = 30000
ssl.provider = null
ssl.enabled.protocols = [TLSv1.2]
acks = -1
batch.size = 16384
ssl.keystore.location = null
receive.buffer.bytes = 32768
ssl.cipher.suites = null
ssl.truststore.type = JKS
security.protocol = SASL_SSL
retries = 1
max.request.size = 1048576
value.serializer = class org.apache.kafka.common.serialization.StringSerializer
ssl.truststore.location = /Users/jiangph/tools/liberty/usr/shared/resources/keystore.jks
ssl.keystore.password = null
ssl.keymanager.algorithm = SunX509
metrics.sample.window.ms = 30000
send.buffer.bytes = 131072
linger.ms = 0

使用上述设置，使用MessageHub rest api创建主题没有问题。尝试发布消息时出现问题。
任何想法都非常感谢。