Custom protocol support

By default Hermes Consumer can serve data using HTTP, HTTPS and JMS (HornetQ) protocols. In case that is not enough, it is possible to implement support for any custom protocol.

Creating message sender

The most important bit is creating the ProtocolMessageSenderProvider which acts as a factory that produces the instance of MessageSender. This should be registered on application startup via HermesConsumerBuilder:

builder.withMessageSenderProvider("myProtocol", (serviceLocator) -> {
    new MyProtocolMessageSenderProvider()

The HermesConsumerBuilder#withMessageSenderProvider method accepts a lazy evaluated function which gives access to containers ServiceLocator. In some more advanced cases it might be beneficial to use some internal components, however there are no compatibility guarantees.

Extending HTTP message sender

In case you would like to build on existing implementation of HTTP messages sender, it can be created and registered to support other protocols. This is commonly used to add some pseudo-protocols support.

This example shows how to implement the service:// pseudo protocol. We use it internally to integrate with Service Discovery: service://my-service means that address of the endpoint should be resolved by querying Service Discovery for instances of my-service service.

To achieve this, implement EndpointAddressResolver interface and inject the implementation into the new instance of JettyHttpMessageSenderProvider:

builder.withMessageSenderProvider("http", (s) ->
                        new JettyHttpMessageSenderProvider(
                            new DefaultHttpMetadataAppender())

Management support

Hermes Management validates user input, including protocols used. For management to recognize custom protocols, specify all custom protocols in the configuration:

  additionalEndpointProtocols: service, myProtocol