io.axoniq.axonserver.connector.query

Interface QueryHandler

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface QueryHandler

Interface representing a component that can handle queries.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	QueryHandler.UpdateHandler Interface describing a stream of updates to a subscription query.

Method Summary

Modifier and Type	Method and Description
void	handle(QueryRequest query, ReplyChannel<QueryResponse> responseHandler) Handle the given query, using given responseHandler to send the response(s).
default Registration	registerSubscriptionQuery(SubscriptionQuery query, QueryHandler.UpdateHandler updateHandler) Registers an incoming subscription query request, represented by given query, using given updateHandler to send updates when the projection for this query changes.
default FlowControl	stream(QueryRequest query, ReplyChannel<QueryResponse> responseHandler) Handle the given query, using the given responseHandler to send the response(s).

Method Detail

handle

void handle(QueryRequest query,
            ReplyChannel<QueryResponse> responseHandler)

Handle the given query, using given responseHandler to send the response(s).

Note that the query must be completed using ReplyChannel.complete() or ReplyChannel.sendLast(Object).

Parameters:

query - the message representing the query request

responseHandler - to handler to send responses with

stream

default FlowControl stream(QueryRequest query,
                           ReplyChannel<QueryResponse> responseHandler)

Handle the given query, using the given responseHandler to send the response(s). This operation is flow control aware, hence messages should be sent via responseHandler when requested.

Note that the query must be completed using ReplyChannel.complete() or ReplyChannel.sendLast(Object).

Parameters:

query - the message representing the query request

responseHandler - the handler to send responses with

Returns:

a FlowControl to request more responses and cancel sending responses

registerSubscriptionQuery

default Registration registerSubscriptionQuery(SubscriptionQuery query,
                                               QueryHandler.UpdateHandler updateHandler)

Registers an incoming subscription query request, represented by given query, using given updateHandler to send updates when the projection for this query changes.

If this handler doesn't support subscription queries for the given query, it should return null. Otherwise, it must return a handle that can be used to cancel the subscription query.

Parameters:

query - the message representing the query

updateHandler - to handler to send updates with

Returns:

a registration to cancel the subscription, or null if this handler doesn't support the subscription query