Overview

KubeMQ auto-creates a channel the first time a client publishes or subscribes to it — convenient for prototyping, but a liability once channels are infrastructure you need to reason about. Pre-creating channels with the management API lets you provision topology before any producer or consumer connects: enforce naming conventions in a startup script, stand up the channels a service depends on as part of deployment, or fail fast if a required channel is missing instead of it silently springing into existence.

Channel creation is pattern-specific: createEventsChannel and createEventsStoreChannel live on PubSubClient, createQueuesChannel on QueuesClient, and createCommandsChannel / createQueriesChannel on CQClient — each registering the channel directly with the broker.

Gotchas: the call is idempotent for a matching name and type, so it's safe to call on every startup — but a channel's type is fixed at creation, and reusing the name with a different type fails rather than migrating it. Creation only registers the channel; it does not start a consumer, so a freshly created queue or events channel happily accepts messages with nothing yet reading them.

Prerequisites

KubeMQ server running on localhost:50000
Java SDK installed (implementation 'io.kubemq.sdk:kubemq-sdk-Java:3.1.1' (Gradle) or Maven dependency from Getting Started)

Code

CreateChannelExample.java

package io.kubemq.example.management;

import io.kubemq.sdk.cq.CQClient;
import io.kubemq.sdk.pubsub.PubSubClient;
import io.kubemq.sdk.queues.QueuesClient;

public class CreateChannelExample {
    private static final String ADDRESS = "localhost:50000";
    private static final String CLIENT_ID = "java-management-create-channel-client";

    public static void main(String[] args) {
        System.out.println("=== Create Channels ===\n");

        // Create PubSub channels (events and events-store)
        try (PubSubClient pubsub = PubSubClient.builder().address(ADDRESS).clientId(CLIENT_ID + "-pubsub").build()) {
            pubsub.createEventsChannel("java-management.events-test");
            System.out.println("Events channel created.");
            pubsub.createEventsStoreChannel("java-management.store-test");
            System.out.println("EventsStore channel created.");
            // Clean up: delete the created channels
            pubsub.deleteEventsChannel("java-management.events-test");
            pubsub.deleteEventsStoreChannel("java-management.store-test");
        }

        // Create Queues channel
        try (QueuesClient queues = QueuesClient.builder().address(ADDRESS).clientId(CLIENT_ID + "-queues").build()) {
            queues.createQueuesChannel("java-management.queues-test");
            System.out.println("Queues channel created.");
            // Clean up: delete the created channel
            queues.deleteQueuesChannel("java-management.queues-test");
        }

        // Create Commands and Queries channels
        try (CQClient cq = CQClient.builder().address(ADDRESS).clientId(CLIENT_ID + "-cq").build()) {
            cq.createCommandsChannel("java-management.commands-test");
            System.out.println("Commands channel created.");
            cq.createQueriesChannel("java-management.queries-test");
            System.out.println("Queries channel created.");
            cq.deleteCommandsChannel("java-management.commands-test");
            cq.deleteQueriesChannel("java-management.queries-test");
        }

        System.out.println("\nAll channels created and cleaned up.");
    }
}

How It Works

Channel creation is pattern-specific: createEventsChannel / createEventsStoreChannel live on PubSubClient; createQueuesChannel on QueuesClient; and createCommandsChannel / createQueriesChannel on CQClient.
Creating a channel that already exists is idempotent — the broker returns success without duplicating the channel.
The example creates and immediately deletes each channel to leave the broker clean after the demo; in production you would omit the delete calls.
Each client is constructed in its own try-with-resources block so the gRPC connection is released as soon as the management call completes.

Create Channel

Overview

Prerequisites

Code

How It Works

Related

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