[CAMEL-8790] Kafka producer hard coded to use Strings

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.14.2, 2.15.2, 2.16.0
• Fix Version/s: 2.15.3, 2.16.0
• Component/s: camel-kafka
• Patch Info: Patch Available
• Estimated Complexity: Unknown
• Flags: Patch
• Assignee: Claus Ibsen
• Reporter: Mark Mindenhall
• Created: 22/May/15 02:39
• Updated: 16/Jul/15 16:10
• Resolved: 16/Jul/15 15:45

Description

Kafka natively supports two encoders for messages:

1. kafka.serializer.DefaultEncoder - encodes as byte arrays
2. kafka.serializer.StringEncoder - encodes as Strings

Camel-kafka exposes settings to select the encoder ((serializerClass and keySerializerClass), but the org.apache.camel.component.kafka.KafkaProducer class hard-codes String for both the key and value types. This results in a ClassCastException when using the DefaultDecoder.

The attached patch fixes this as follows (conforming to kafka itself):

• If no serializerClass option is specified, the DefaultDecoder is used.
• If no keySerializerClass option is specified, the same encoder as serializerClass is used

This fix shouldn't break any existing code, as there was not previously a default setting (i.e., StringEncoder always had to be specified).

I created the patch against master, but it should backport easily to 2.15.x and 2.14.x.