Messages

Messages

Messages consist of a fixed-size header, a variable length opaque key byte array and a variable length opaque value byte array. The header contains the following fields:

• A CRC32 checksum to detect corruption or truncation.
• • A format version.
• An attributes identifier
• A timestamp

Leaving the key and value opaque is the right decision: there is a great deal of progress being made on serialization libraries right now, and any particular choice is unlikely to be right for all uses. Needless to say a particular application using Kafka would likely mandate a particular serialization type as part of its usage. The MessageSet interface is simply an iterator over messages with specialized methods for bulk reading and writing to an NIO Channel.