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Subject [1/2] camel git commit: Added camel-kafka docs to gitbook
Date Fri, 08 Apr 2016 11:49:00 GMT
Repository: camel
Updated Branches:
  refs/heads/master 8fb1874e0 -> 5719d8260

Added camel-kafka docs to gitbook


Branch: refs/heads/master
Commit: 5719d8260b697b363c96fc378f3214d659a7c77d
Parents: dafab12
Author: Andrea Cosentino <>
Authored: Fri Apr 8 13:47:49 2016 +0200
Committer: Andrea Cosentino <>
Committed: Fri Apr 8 13:48:32 2016 +0200

 components/camel-kafka/src/main/docs/kafka.adoc | 268 +++++++++++++++++++
 docs/user-manual/en/                  |   1 +
 2 files changed, 269 insertions(+)
diff --git a/components/camel-kafka/src/main/docs/kafka.adoc b/components/camel-kafka/src/main/docs/kafka.adoc
new file mode 100644
index 0000000..7528eb9
--- /dev/null
+++ b/components/camel-kafka/src/main/docs/kafka.adoc
@@ -0,0 +1,268 @@
+Kafka Component
+*Available as of Camel 2.13*
+The *kafka:* component is used for communicating with
+[Apache Kafka] message broker.
+Maven users will need to add the following dependency to their `pom.xml`
+for this component.
+    <groupId>org.apache.camel</groupId>
+    <artifactId>camel-kafka</artifactId>
+    <version>x.x.x</version>
+    <!-- use the same version as your Camel core version -->
+Camel 2.17 or newer
+Scala is no longer used, as we use the kafka java client.
+Camel 2.16 or older
+And then the Scala libraries of choice. camel-kafka does not include
+that dependency, but assumes it is provided. For example to use Scala
+2.10.4 add:
+    <dependency>
+      <groupId>org.scala-lang</groupId>
+      <artifactId>scala-library</artifactId>
+      <version>2.10.4</version>
+    </dependency>
+URI format
+Options (Camel 2.16 or older)
+// component options: START
+The Kafka component has no options.
+// component options: END
+// endpoint options: START
+The Kafka component supports 74 endpoint options which are listed below:
+| Name | Group | Default | Java Type | Description
+| brokers | common |  | String | *Required* This is for bootstrapping and the producer will
only use it for getting metadata (topics partitions and replicas). The socket connections
for sending the actual data will be established based on the broker information returned in
the metadata. The format is host1:port1host2:port2 and the list can be a subset of brokers
or a VIP pointing to a subset of brokers. This option is known as in
the Kafka documentation.
+| bridgeEndpoint | common | false | boolean | If the option is true then KafkaProducer will
ignore the KafkaConstants.TOPIC header setting of the inbound message.
+| clientId | common |  | String | The client id is a user-specified string sent in each request
to help trace calls. It should logically identify the application making the request.
+| groupId | common |  | String | A string that uniquely identifies the group of consumer
processes to which this consumer belongs. By setting the same group id multiple processes
indicate that they are all part of the same consumer group.
+| partitioner | common | org.apache.kafka.clients.producer.internals.DefaultPartitioner |
String | The partitioner class for partitioning messages amongst sub-topics. The default partitioner
is based on the hash of the key.
+| topic | common |  | String | *Required* Name of the topic to use. When used on a consumer
endpoint the topic can be a comma separated list of topics.
+| autoCommitEnable | consumer | true | Boolean | If true periodically commit to ZooKeeper
the offset of messages already fetched by the consumer. This committed offset will be used
when the process fails as the position from which the new consumer will begin.
+| autoCommitIntervalMs | consumer | 5000 | Integer | The frequency in ms that the consumer
offsets are committed to zookeeper.
+| autoOffsetReset | consumer | latest | String | What to do when there is no initial offset
in ZooKeeper or if an offset is out of range: smallest : automatically reset the offset to
the smallest offset largest : automatically reset the offset to the largest offset fail: throw
exception to the consumer
+| barrierAwaitTimeoutMs | consumer | 10000 | int | If the BatchingConsumerTask processes
exchange exceed the batchSize it will wait for barrierAwaitTimeoutMs.
+| batchSize | consumer | 100 | int | The batchSize that the BatchingConsumerTask processes
+| bridgeErrorHandler | consumer | false | boolean | Allows for bridging the consumer to the
Camel routing Error Handler which mean any exceptions occurred while the consumer is trying
to pickup incoming messages or the likes will now be processed as a message and handled by
the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler
to deal with exceptions that will be logged at WARN/ERROR level and ignored.
+| checkCrcs | consumer | true | Boolean | Automatically check the CRC32 of the records consumed.
This ensures no on-the-wire or on-disk corruption to the messages occurred. This check adds
some overhead so it may be disabled in cases seeking extreme performance.
+| consumerId | consumer |  | String | Generated automatically if not set.
+| consumerRequestTimeoutMs | consumer | 40000 | Integer | The configuration controls the
maximum amount of time the client will wait for the response of a request. If the response
is not received before the timeout elapses the client will resend the request if necessary
or fail the request if retries are exhausted.
+| consumersCount | consumer | 1 | int | The number of consumers that connect to kafka server
+| consumerStreams | consumer | 10 | int | Number of concurrent consumers on the consumer
+| fetchMinBytes | consumer | 1024 | Integer | The minimum amount of data the server should
return for a fetch request. If insufficient data is available the request will wait for that
much data to accumulate before answering the request.
+| fetchWaitMaxMs | consumer | 500 | Integer | The maximum amount of time the server will
block before answering the fetch request if there isn't sufficient data to immediately satisfy
+| heartbeatIntervalMs | consumer | 3000 | Integer | The expected time between heartbeats
to the consumer coordinator when using Kafka's group management facilities. Heartbeats are
used to ensure that the consumer's session stays active and to facilitate rebalancing when
new consumers join or leave the group. The value must be set lower than
but typically should be set no higher than 1/3 of that value. It can be adjusted even lower
to control the expected time for normal rebalances.
+| keyDeserializer | consumer | org.apache.kafka.common.serialization.StringDeserializer |
String | Deserializer class for key that implements the Deserializer interface.
+| maxPartitionFetchBytes | consumer | 1048576 | Integer | The maximum amount of data per-partition
the server will return. The maximum total memory used for a request will be partitions max.partition.fetch.bytes.
This size must be at least as large as the maximum message size the server allows or else
it is possible for the producer to send messages larger than the consumer can fetch. If that
happens the consumer can get stuck trying to fetch a large message on a certain partition.
+| partitionAssignor | consumer | org.apache.kafka.clients.consumer.RangeAssignor | String
| The class name of the partition assignment strategy that the client will use to distribute
partition ownership amongst consumer instances when group management is used
+| seekToBeginning | consumer | false | boolean | If the option is true then KafkaConsumer
will read from beginning on startup.
+| sessionTimeoutMs | consumer | 30000 | Integer | The timeout used to detect failures when
using Kafka's group management facilities.
+| valueDeserializer | consumer | org.apache.kafka.common.serialization.StringDeserializer
| String | Deserializer class for value that implements the Deserializer interface.
+| exceptionHandler | consumer (advanced) |  | ExceptionHandler | To let the consumer use
a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options
is not in use. By default the consumer will deal with exceptions that will be logged at WARN/ERROR
level and ignored.
+| blockOnBufferFull | producer | false | Boolean | When our memory buffer is exhausted we
must either stop accepting new records (block) or throw errors. By default this setting is
true and we block however in some scenarios blocking is not desirable and it is better to
immediately give an error. Setting this to false will accomplish that: the producer will throw
a BufferExhaustedException if a recrord is sent and the buffer space is full.
+| bufferMemorySize | producer | 33554432 | Integer | The total bytes of memory the producer
can use to buffer records waiting to be sent to the server. If records are sent faster than
they can be delivered to the server the producer will either block or throw an exception based
on the preference specified by block.on.buffer.full.This setting should correspond roughly
to the total memory the producer will use but is not a hard bound since not all memory the
producer uses is used for buffering. Some additional memory will be used for compression (if
compression is enabled) as well as for maintaining in-flight requests.
+| compressionCodec | producer | none | String | This parameter allows you to specify the
compression codec for all data generated by this producer. Valid values are none gzip and
+| connectionMaxIdleMs | producer | 540000 | Integer | Close idle connections after the number
of milliseconds specified by this config.
+| kerberosBeforeReloginMinTime | producer | 60000 | Integer | Login thread sleep time between
refresh attempts.
+| kerberosInitCmd | producer | /usr/bin/kinit | String | Kerberos kinit command path. Default
is /usr/bin/kinit
+| kerberosRenewJitter | producer | 0.05 | Double | Percentage of random jitter added to the
renewal time.
+| kerberosRenewWindowFactor | producer | 0.8 | Double | Login thread will sleep until the
specified window factor of time from last refresh to ticket's expiry has been reached at which
time it will try to renew the ticket.
+| keySerializerClass | producer |  | String | The serializer class for keys (defaults to
the same as for messages if nothing is given).
+| lingerMs | producer | 0 | Integer | The producer groups together any records that arrive
in between request transmissions into a single batched request. Normally this occurs only
under load when records arrive faster than they can be sent out. However in some circumstances
the client may want to reduce the number of requests even under moderate load. This setting
accomplishes this by adding a small amount of artificial delaythat is rather than immediately
sending out a record the producer will wait for up to the given delay to allow other records
to be sent so that the sends can be batched together. This can be thought of as analogous
to Nagle's algorithm in TCP. This setting gives the upper bound on the delay for batching:
once we get batch.size worth of records for a partition it will be sent immediately regardless
of this setting however if we have fewer than this many bytes accumulated for this partition
we will 'linger' for the specified time waiting for more records to show 
 up. This setting defaults to 0 (i.e. no delay). Setting for example would have
the effect of reducing the number of requests sent but would add up to 5ms of latency to records
sent in the absense of load.
+| maxBlockMs | producer | 60000 | Integer | The configuration controls how long sending to
kafka will block. These methods can be blocked for multiple reasons. For e.g: buffer full
metadata unavailable.This configuration imposes maximum limit on the total time spent in fetching
metadata serialization of key and value partitioning and allocation of buffer memory when
doing a send(). In case of partitionsFor() this configuration imposes a maximum time threshold
on waiting for metadata
+| maxInFlightRequest | producer | 5 | Integer | The maximum number of unacknowledged requests
the client will send on a single connection before blocking. Note that if this setting is
set to be greater than 1 and there are failed sends there is a risk of message re-ordering
due to retries (i.e. if retries are enabled).
+| maxRequestSize | producer | 1048576 | Integer | The maximum size of a request. This is
also effectively a cap on the maximum record size. Note that the server has its own cap on
record size which may be different from this. This setting will limit the number of record
batches the producer will send in a single request to avoid sending huge requests.
+| metadataFetchTimeoutMs | producer | 60000 | Integer | The first time data is sent to a
topic we must fetch metadata about that topic to know which servers host the topic's partitions.
This fetch to succeed before throwing an exception back to the client.
+| metadataMaxAgeMs | producer | 300000 | Integer | The period of time in milliseconds after
which we force a refresh of metadata even if we haven't seen any partition leadership changes
to proactively discover any new brokers or partitions.
+| metricReporters | producer |  | String | A list of classes to use as metrics reporters.
Implementing the MetricReporter interface allows plugging in classes that will be notified
of new metric creation. The JmxReporter is always included to register JMX statistics.
+| metricsSampleWindowMs | producer | 30000 | Integer | The number of samples maintained to
compute metrics.
+| noOfMetricsSample | producer | 2 | Integer | The number of samples maintained to compute
+| producerBatchSize | producer | 16384 | Integer | The producer will attempt to batch records
together into fewer requests whenever multiple records are being sent to the same partition.
This helps performance on both the client and the server. This configuration controls the
default batch size in bytes. No attempt will be made to batch records larger than this size.Requests
sent to brokers will contain multiple batches one for each partition with data available to
be sent.A small batch size will make batching less common and may reduce throughput (a batch
size of zero will disable batching entirely). A very large batch size may use memory a bit
more wastefully as we will always allocate a buffer of the specified batch size in anticipation
of additional records.
+| queueBufferingMaxMessages | producer | 10000 | Integer | The maximum number of unsent messages
that can be queued up the producer when using async mode before either the producer must be
blocked or data must be dropped.
+| receiveBufferBytes | producer | 32768 | Integer | The size of the TCP receive buffer (SO_RCVBUF)
to use when reading data.
+| reconnectBackoffMs | producer | 50 | Integer | The amount of time to wait before attempting
to reconnect to a given host. This avoids repeatedly connecting to a host in a tight loop.
This backoff applies to all requests sent by the consumer to the broker.
+| requestRequiredAcks | producer | 1 | Integer | The number of acknowledgments the producer
requires the leader to have received before considering a request complete. This controls
the durability of records that are sent. The following settings are common: acks=0 If set
to zero then the producer will not wait for any acknowledgment from the server at all. The
record will be immediately added to the socket buffer and considered sent. No guarantee can
be made that the server has received the record in this case and the retries configuration
will not take effect (as the client won't generally know of any failures). The offset given
back for each record will always be set to -1. acks=1 This will mean the leader will write
the record to its local log but will respond without awaiting full acknowledgement from all
followers. In this case should the leader fail immediately after acknowledging the record
but before the followers have replicated it then the record will be lost. acks=all Thi
 s means the leader will wait for the full set of in-sync replicas to acknowledge the record.
This guarantees that the record will not be lost as long as at least one in-sync replica remains
alive. This is the strongest available guarantee.
+| requestTimeoutMs | producer | 30000 | Integer | The amount of time the broker will wait
trying to meet the request.required.acks requirement before sending back an error to the client.
+| retries | producer | 0 | Integer | Setting a value greater than zero will cause the client
to resend any record whose send fails with a potentially transient error. Note that this retry
is no different than if the client resent the record upon receiving the error. Allowing retries
will potentially change the ordering of records because if two records are sent to a single
partition and the first fails and is retried but the second succeeds then the second record
may appear first.
+| retryBackoffMs | producer | 100 | Integer | Before each retry the producer refreshes the
metadata of relevant topics to see if a new leader has been elected. Since leader election
takes a bit of time this property specifies the amount of time that the producer waits before
refreshing the metadata.
+| saslKerberosServiceName | producer |  | String | The Kerberos principal name that Kafka
runs as. This can be defined either in Kafka's JAAS config or in Kafka's config.
+| securityProtocol | producer | PLAINTEXT | String | Protocol used to communicate with brokers.
Currently only PLAINTEXT and SSL are supported.
+| sendBufferBytes | producer | 131072 | Integer | Socket write buffer size
+| serializerClass | producer |  | String | The serializer class for messages. The default
encoder takes a byte and returns the same byte. The default class is kafka.serializer.DefaultEncoder
+| sslCipherSuites | producer |  | String | A list of cipher suites. This is a named combination
of authentication encryption MAC and key exchange algorithm used to negotiate the security
settings for a network connection using TLS or SSL network protocol.By default all the available
cipher suites are supported.
+| sslEnabledProtocols | producer | TLSv1.2,TLSv1.1,TLSv1 | String | The list of protocols
enabled for SSL connections. TLSv1.2 TLSv1.1 and TLSv1 are enabled by default.
+| sslEndpointAlgorithm | producer |  | String | The endpoint identification algorithm to
validate server hostname using server certificate.
+| sslKeymanagerAlgorithm | producer | SunX509 | String | The algorithm used by key manager
factory for SSL connections. Default value is the key manager factory algorithm configured
for the Java Virtual Machine.
+| sslKeyPassword | producer |  | String | The password of the private key in the key store
file. This is optional for client.
+| sslKeystoreLocation | producer |  | String | The location of the key store file. This is
optional for client and can be used for two-way authentication for client.
+| sslKeystorePassword | producer |  | String | The store password for the key store file.This
is optional for client and only needed if ssl.keystore.location is configured.
+| sslKeystoreType | producer | JKS | String | The file format of the key store file. This
is optional for client. Default value is JKS
+| sslProtocol | producer | TLS | String | The SSL protocol used to generate the SSLContext.
Default setting is TLS which is fine for most cases. Allowed values in recent JVMs are TLS
TLSv1.1 and TLSv1.2. SSL SSLv2 and SSLv3 may be supported in older JVMs but their usage is
discouraged due to known security vulnerabilities.
+| sslProvider | producer |  | String | The name of the security provider used for SSL connections.
Default value is the default security provider of the JVM.
+| sslTrustmanagerAlgorithm | producer | PKIX | String | The algorithm used by trust manager
factory for SSL connections. Default value is the trust manager factory algorithm configured
for the Java Virtual Machine.
+| sslTruststoreLocation | producer |  | String | The location of the trust store file.
+| sslTruststorePassword | producer |  | String | The password for the trust store file.
+| sslTruststoreType | producer | JKS | String | The file format of the trust store file.
Default value is JKS.
+| timeoutMs | producer | 30000 | Integer | The configuration controls the maximum amount
of time the server will wait for acknowledgments from followers to meet the acknowledgment
requirements the producer has specified with the acks configuration. If the requested number
of acknowledgments are not met when the timeout elapses an error will be returned. This timeout
is measured on the server side and does not include the network latency of the request.
+| exchangePattern | advanced | InOnly | ExchangePattern | Sets the default exchange pattern
when creating an exchange
+| synchronous | advanced | false | boolean | Sets whether synchronous processing should be
strictly used or Camel is allowed to use asynchronous processing (if supported).
+// endpoint options: END
+For more information about Producer/Consumer configuration:
+Camel 2.16 or older
+Consuming messages:
+Producing messages:
+See unit tests of camel-kafka for more examples
+Camel 2.17 or newer
+Consuming messages:
+                        .process(new Processor() {
+                            @Override
+                            public void process(Exchange exchange)
+                                    throws Exception {
+                                String messageKey = "";
+                                if (exchange.getIn() != null) {
+                                    Message message = exchange.getIn();
+                                    Integer partitionId = (Integer) message
+                                            .getHeader(KafkaConstants.PARTITION);
+                                    String topicName = (String) message
+                                            .getHeader(KafkaConstants.TOPIC);
+                                    if (message.getHeader(KafkaConstants.KEY) != null)
+                                        messageKey = (String) message
+                                                .getHeader(KafkaConstants.KEY);
+                                    Object data = message.getBody();
+                                    System.out.println("topicName :: "
+                                            + topicName + " partitionId :: "
+                                            + partitionId + " messageKey :: "
+                                            + messageKey + " message :: "
+                                            + data + "\n");
+                                }
+                            }
+                        }).to("log:input");
+Producing messages:
+from("direct:start").process(new Processor() {
+                    @Override
+                    public void process(Exchange exchange) throws Exception {
+                        exchange.getIn().setBody("Test Message from Camel Kafka Component
+                        exchange.getIn().setHeader(KafkaConstants.PARTITION_KEY, 0);
+                        exchange.getIn().setHeader(KafkaConstants.KEY, "1");
+                    }
+                }).to("kafka:localhost:9092?topic=test");
+Camel supports the link:message-endpoint.html[Message Endpoint] pattern
+using the
+interface. Endpoints are usually created by a
+link:component.html[Component] and Endpoints are usually referred to in
+the link:dsl.html[DSL] via their link:uris.html[URIs].
+From an Endpoint you can use the following methods
+will create a
+for sending message exchanges to the endpoint
+implements the link:event-driven-consumer.html[Event Driven Consumer]
+pattern for consuming message exchanges from the endpoint via a
+when creating a
+implements the link:polling-consumer.html[Polling Consumer] pattern for
+consuming message exchanges from the endpoint via a
+See Also
+* link:configuring-camel.html[Configuring Camel]
+* link:message-endpoint.html[Message Endpoint] pattern
+* link:uris.html[URIs]
+* link:writing-components.html[Writing Components]
diff --git a/docs/user-manual/en/ b/docs/user-manual/en/
index 99d3f6f..8ed37bf 100644
--- a/docs/user-manual/en/
+++ b/docs/user-manual/en/
@@ -154,6 +154,7 @@
     * [JMS](jms.adoc)
     * [JMX](jmx.adoc)
     * [JSON](json.adoc)
+    * [Kafka](kafka.adoc)
     * [Metrics](metrics.adoc)
     * [Mock](mock.adoc)
     * [NATS](nats.adoc)

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