I am using Kafka with Spring Boot. Is it possible to return the HTTP response when the result need to wait for Kafka event finish first?
I have some services and sub-processes. Service A receives HTTP request from user and it sends message to Kafka in order to do some sub-processes. Before service A returns the HTTP response, it needs to wait for service B to update the record in database.
I think it's better if service B produces the "done" message to a different Kafka topic and service A consumes it if you want to implement event driven model, as service A should not be aware and care about what happens behind the scenes, the DB update in this case.
And regarding how service A can wait and return, here's my idea in a conceptual code:
class RestController {
getInfo(input){
Future future = KF_bean.produce(input,random_req_id)
return future.get()
}
}
class KF_bean {
Map map = Hashmap...
CompletableFuture produce(input, random_req_id){
kafkalib.produce(input).withHeader(random_req_id)
future = new CompletableFuture()
map.put(random_req_id, future)
return future
}
void onConsume(msg){
req_id = msg.getHeader("vin")
map.get(req_id).complete()
}
}
It should work if none of instances of the service A are in same consumer group, or they should be group less consumers.