Create Channel
Programmatically create KubeMQ channels of different types using the C++ SDK administration API.
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.
The generic CreateChannel(name, type) method registers a channel with the server using a type constant such as kChannelTypeEvents or kChannelTypeQueues; typed methods like CreateEventsChannel() do the same without one.
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 - C++ SDK installed (vcpkg or CMake FetchContent)
- C++17 compiler (GCC 9+, Clang 9+, MSVC 2019+)
Code
// Example: management/create_channel
//
// Demonstrates creating channels of different types (events, queues, etc.)
// using both generic and typed convenience methods.
//
// Channel: cpp-management.create-channel
// Client ID: cpp-management-create-channel-client
//
// Run with a KubeMQ server on localhost:50000
// (see https://docs.kubemq.io/deploy).
#include <kubemq/kubemq.h>
#include <iostream>
int main() {
std::cout << "[1] Connecting to localhost:50000" << std::endl;
kubemq::ClientOptions options;
options.set_address("localhost", 50000);
options.set_client_id("cpp-management-create-channel-client");
auto client_result = kubemq::Client::Create(options);
if (!client_result.ok()) {
std::cerr << "[ERROR] Failed to create client: " << client_result.status().message()
<< std::endl;
return 1;
}
auto& client = *client_result;
// Create an events channel using generic method.
auto status =
client->CreateChannel("cpp-management.create-channel.events", kubemq::kChannelTypeEvents);
if (!status.ok()) {
std::cerr << "[ERROR] CreateChannel events: " << status.message() << std::endl;
} else {
std::cout << "[2] Created events channel: cpp-management.create-channel.events"
<< std::endl;
}
// Create a queues channel using generic method.
status =
client->CreateChannel("cpp-management.create-channel.queues", kubemq::kChannelTypeQueues);
if (!status.ok()) {
std::cerr << "[ERROR] CreateChannel queues: " << status.message() << std::endl;
} else {
std::cout << "[3] Created queue channel: cpp-management.create-channel.queues" << std::endl;
}
// Create an events store channel using generic method.
status =
client->CreateChannel("cpp-management.create-channel.es", kubemq::kChannelTypeEventsStore);
if (!status.ok()) {
std::cerr << "[ERROR] CreateChannel events_store: " << status.message() << std::endl;
} else {
std::cout << "[4] Created events store channel: cpp-management.create-channel.es"
<< std::endl;
}
// Typed convenience methods.
status = client->CreateEventsChannel("cpp-management.typed.events");
if (!status.ok()) {
std::cerr << "[ERROR] CreateEventsChannel: " << status.message() << std::endl;
} else {
std::cout << "[5] Created events channel (typed): cpp-management.typed.events" << std::endl;
}
status = client->CreateQueuesChannel("cpp-management.typed.queues");
if (!status.ok()) {
std::cerr << "[ERROR] CreateQueuesChannel: " << status.message() << std::endl;
} else {
std::cout << "[6] Created queues channel (typed): cpp-management.typed.queues" << std::endl;
}
status = client->CreateCommandsChannel("cpp-management.typed.commands");
if (!status.ok()) {
std::cerr << "[ERROR] CreateCommandsChannel: " << status.message() << std::endl;
} else {
std::cout << "[7] Created commands channel (typed): cpp-management.typed.commands"
<< std::endl;
}
// Close the client explicitly.
// Note: Client destructor would also handle cleanup (RAII)
auto close_status = client->Close();
if (!close_status.ok()) {
std::cerr << "[ERROR] Close failed: " << close_status.message() << std::endl;
return 1;
}
std::cout << "[8] Client closed" << std::endl;
return 0;
}How It Works
- Creates channels using the generic
CreateChannel(name, type)method. - Uses channel type constants:
kChannelTypeEvents,kChannelTypeQueues,kChannelTypeEventsStore. - Also demonstrates typed convenience methods like
CreateEventsChannel(),CreateQueuesChannel(). - Channels are created idempotently -- creating an existing channel is a no-op.
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