Kafka is a common default for event-driven architectures, but adapting it to legacy environments introduces an impedance mismatch. In a few cases, we've had success minimizing the legacy complexity using Confluent Kafka REST Proxy. The proxy allows developers to access Kafka through an HTTP interface, which is useful in environments that make using the native Kafka protocol difficult. For example, we were able to consume events emitted through SAP simply by having the SAP team invoke an HTTP POST command through a preconfigured SAP remote function call, avoiding the need to spin up a Java abstraction around SAP (and a team to manage it). The proxy is quite full-featured, although, as with any such adapter tool, we recommend caution and a clear-eyed view of the trade-offs involved. We believe the proxy is valuable when it enables legacy producers to send events, but would be careful creating event consumers through the proxy as the abstraction gets more complex. The proxy doesn't change the fact that Kafka consumers are stateful, which means that consumer instances created through the REST API are tied to a specific proxy, and the need to make an HTTP call to consume messages from a topic changes the standard semantics of Kafka eventing.
