Often, managing the integration of two or more systems is a difficult task. This task becomes even more difficult in a distributed mircoservice-oriented system. In this post I will explain how to make this communication less painless. Enter Apache Kafka feat. Apache Camel.
Configuring the Camel Routes
To configure a Provider we define a Camel input route from
exchanging the message to the URI endpoint for Kafka.
Finally, we configure a Consumer from the Kafka consumer URI to the java Bean which is invoked when an event occurs.
Anatomy of a Camel Kafka URI
- topic: The topic the Consumer/Producer is subscribed to.
- groupId: The ID of the group the Consumer/Producer is assigned to.
- autoOffsetReset: The schema to adjust the message outset.
- consumersCount: The number of consumers connecting to the Kafka server
We are using this class to configure what happens when we consume a message. We
first try to unmarshal the string into a
Notification object, where we can
then use it (in our case we do a simple toString() and stdout).
We are autowiring in the following Beans:
ProducerTemplate and a
The most important here is the
ProducerTemplate, we add the annotation
@EndpointInject(uri = "direct:kafkaRoute") to make use of the camel route we
configured in the
The Controller Routes
GET /message this route we are using to display how we can send a message
using the autowired
POST /message this route we are using to post JSON, marshal it to string, and
send it off as a message.
Communication and integration in distributed systems does not need to be difficult, rather, Apache provides some great tools like Apache Kafka and Apache Camel to make integration points less painless and distributed messaging more fun.