What is Message

Message content the actual data and its metadata, that need to pass to other services. The message is having 2 parts

• Header

  The header contains the metadata about the message like

• Payload

  It contains the data that needs to pass in the message.

It consists of a payload and headers. The payload is actual data of any type. The headers can contain information such as correlation Id, timestamp, and return address.

Implementation of Message

GenericMessage

The GenericMessage is an implementation of the Message interface. It provides two constructors. The first one accepts the only payload as a parameter and another payload with a header as a parameter.

new GenericMessage<T>(T payload);

new GenericMessage<T>(T payload, Map<String, Object> headers)

MessageBuilder

The Message Interface does not have setter methods. Message builder used to create a new message object. You can use the MessageBuilder class if you want to create a new message from the old existing message. You can create a message with a new payload. or create a message with that header from another message using copyHeader message.

You can use the copyHeaderIfAbsent method when you do not want to override the existing header information.

Error message

This is a special time of message implementation, to communicate error information. The implementation takes only a throwable object as payload.

You can create an ErrorMessage object as below -

Message message = new ErrorMessage(throwable);

What’s next?

Keep following this series of blogs that have many topics that need to cover in later blogs.