# Client connection timeout **URL:** \ **Category:** HiveMQ Client Library\ **Created:** [April 21, 2022, 8:59am UTC](https://community.hivemq.com/t/client-connection-timeout/1155 "2022-04-21T08:59:58Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![mtorak](https://avatars.discourse-cdn.com/v4/letter/m/e47c2d/32.png) [@mtorak](https://community.hivemq.com/u/mtorak)\ **Post date:** [April 21, 2022, 8:59am UTC](https://community.hivemq.com/t/client-connection-timeout/1155/1 "2022-04-21T08:59:59Z")
Hello, I’m trying to set a connection timeout for a client(blocking/async), to put simply, i just want client throw an exception when it can not connect in a certain amount of time. I’ve tried two approaches so far: - Async client ```auto Mqtt5AsyncClient client = MqttClient.builder() .useMqttVersion5() .serverHost(hivemqHost) .serverPort(hivemqPort) .identifier(clientIdMqtt5) .automaticReconnect(MqttClientAutoReconnectImpl.DEFAULT) .transportConfig() .mqttConnectTimeout(5, TimeUnit.SECONDS) .socketConnectTimeout(5,TimeUnit.SECONDS) .applyTransportConfig() .buildAsync(); log.info("Built mqtt v5 client.."); client.connectWith() .cleanStart(false) .noSessionExpiry() .send() .whenComplete((connAck, throwable) -> { if (connAck != null) { log.info("whenComplete: MQTT connect success with code {}", connAck.getReasonCode()); } else { if (throwable instanceof Mqtt5ConnAckException) { log.info("whenComplete: Connect failed because of Negative CONNACK with code {} ", ((Mqtt5ConnAckException) throwable).getMqttMessage().getReasonCode()); } else { log.info("whenComplete: MQTT connect failed because of {}", throwable.getMessage()); } } }); ``` When hivemq broker is not running this whenComplete() callback is never called. I expect it should be called in connect timeout seconds(5s here). - Blocking approach: ```auto client = MqttClient.builder() .useMqttVersion5() .identifier(clientIdMqtt5) .automaticReconnect(MqttClientAutoReconnectImpl.DEFAULT) .transportConfig() .serverHost(hivemqHost) .serverPort(hivemqPort) .socketConnectTimeout(5, TimeUnit.SECONDS) .mqttConnectTimeout(5, TimeUnit.SECONDS) .applyTransportConfig() .build(); log.info("Built mqtt v5 client.."); Mqtt5ConnAck connAck = client.toBlocking() .connectWith() .cleanStart(false) .noSessionExpiry() .send(); ``` When hivemq broker is not running this one hangs indefinetely, ignoring transport timeout parameters. So, how can i know a connection attempt failed? Thanks KR ---
**Author:** ![Daria\_H](https://avatars.discourse-cdn.com/v4/letter/d/dfb087/32.png) [@Daria\_H](https://community.hivemq.com/u/Daria_H)\ **Post date:** [April 22, 2022, 1:23pm UTC](https://community.hivemq.com/t/client-connection-timeout/1155/2 "2022-04-22T13:23:15Z")
Hi @mtorak , I see that you are using automatic reconnect strategy. So you can add following two lines in order to know a connection attempt failed or succeeded: ```auto Mqtt5AsyncClient client = Mqtt5Client.builder() .serverHost("localhost") .serverPort(1883) .identifier("my-java-client") .automaticReconnect(MqttClientAutoReconnectImpl.DEFAULT) .addConnectedListener(context -> System.out.println("connected " + LocalTime.now())) .addDisconnectedListener(context -> System.out.println("disconnected " + LocalTime.now())) .transportConfig() .mqttConnectTimeout(5, TimeUnit.SECONDS) .socketConnectTimeout(5,TimeUnit.SECONDS) .applyTransportConfig() .buildAsync(); ``` When the broker is not running, the client will print: ```auto disconnected 15:17:38.346839 disconnected 15:17:41.747628 disconnected 15:17:51.353332 disconnected 15:18:07.575575 disconnected 15:18:42.680786 ``` You can find this and more examples here: [https://github.com/hivemq/hivemq-mqtt-client/tree/master/examples/src/main/java/com/hivemq/client/mqtt/examples](https://github.com/hivemq/hivemq-mqtt-client/tree/master/examples/src/main/java/com/hivemq/client/mqtt/examples) I hope this helps, Kind regards, Dasha from HiveMQ team ---
**Author:** ![mtorak](https://avatars.discourse-cdn.com/v4/letter/m/e47c2d/32.png) [@mtorak](https://community.hivemq.com/u/mtorak)\ **Post date:** [April 22, 2022, 1:46pm UTC](https://community.hivemq.com/t/client-connection-timeout/1155/3 "2022-04-22T13:46:50Z")
Hi Daria, Meanwhile I’ve also discovered those connect/disconnect listeners.They are handy. Also tried the autoReconnect option, which allows frequent checking if the server is back online. ```auto MqttClientAutoReconnect mqttClientAutoReconnect = MqttClientAutoReconnect.builder() .initialDelay(1, TimeUnit.SECONDS) .maxDelay(5, TimeUnit.SECONDS) .build(); ``` But, still i couldn’t grasp the purpose of these two options: ```auto .mqttConnectTimeout(5, TimeUnit.SECONDS) .socketConnectTimeout(5,TimeUnit.SECONDS) ``` Any idea? And also, discovered a scenario like this: - Started async client while HiveMQ broker is offline - Sent several messages via async client like this: ```auto client.publishWith() .topic(topic) .messageExpiryInterval(messageExpiryIntervalMs) .payload(payload) .userProperties(userPropertiesBuilder.build()) .qos(MqttQos.AT_LEAST_ONCE) .send() .whenComplete((mqtt5Publish, throwable) -> { if (throwable != null) { log.warn("Publish failed!! Details: " + throwable.getMessage()); } else { log.info("Published successfully to hivemq topic: " + topic); } }); ``` - It didn’t trigger whenComplete() callback, i expected it should… Why wasn’t it triggered? - After HiveMQ broker went online, client auto reconnected and sent those messages to broker. So hivemq-mqtt-client must be buffering those messages locally. Is this correct? If so what is limit of this behaviour(i.e. how much data can be buffered?) P.S. And also thank you for pointing out additional example api usages. KR ---
**Author:** ![Daria\_H](https://avatars.discourse-cdn.com/v4/letter/d/dfb087/32.png) [@Daria\_H](https://community.hivemq.com/u/Daria_H)\ **Post date:** [April 27, 2022, 12:24pm UTC](https://community.hivemq.com/t/client-connection-timeout/1155/4 "2022-04-27T12:24:43Z")
Hi @mtorak , `mqttConnectTimeout(long timeout, @NotNull TimeUnit timeUnit)` Sets the [`timeout between sending the Connect and receiving the ConnAck message`](https://javadoc.io/static/com.hivemq/hivemq-mqtt-client/1.2.2/com/hivemq/client/mqtt/MqttClientTransportConfig.html#getMqttConnectTimeoutMs--). `socketConnectTimeout(long timeout, @NotNull TimeUnit timeUnit)` Sets the [`timeout for connecting the socket to the server`](https://javadoc.io/static/com.hivemq/hivemq-mqtt-client/1.2.2/com/hivemq/client/mqtt/MqttClientTransportConfig.html#getSocketConnectTimeoutMs--). Your code I could make work like this: ```auto String topic = "topic/1"; client.connectWith() .cleanStart(false) .noSessionExpiry() .keepAlive(2) .send() .thenAccept(connAck -> System.out.println("connected " + connAck)) .thenCompose(v -> client.publishWith() .topic(topic) .payload("PAYLOAD".getBytes(StandardCharsets.UTF_8)) .send() .whenComplete((mqtt5Publish, throwable) -> { if (throwable != null) { System.out.println("Publish failed!! Details: " + throwable.getMessage()); } else { System.out.println("Published successfully to hivemq topic: " + topic); } })) .thenAccept(someResult -> System.out.println("Result " + someResult)); ``` I hope this helps, Dasha from HiveMQ team ---
**Author:** ![mtorak](https://avatars.discourse-cdn.com/v4/letter/m/e47c2d/32.png) [@mtorak](https://community.hivemq.com/u/mtorak)\ **Post date:** [April 29, 2022, 2:48pm UTC](https://community.hivemq.com/t/client-connection-timeout/1155/5 "2022-04-29T14:48:20Z")
Hi Daria, Thank you for sample usage and pointing out javadoc; but i need example usage of these two methods: ```auto .mqttConnectTimeout(MQTT_CONNECT_TIMEOUT_S, TimeUnit.SECONDS) .socketConnectTimeout(SOCKET_CONNECT_TIMEOUT_S, TimeUnit.SECONDS) ``` As far as i can see, there are also no usages for these options in mqtt-cli code base. So i wonder purpose/usage of them. Thank you, KR ---
**Author:** ![Daria\_H](https://avatars.discourse-cdn.com/v4/letter/d/dfb087/32.png) [@Daria\_H](https://community.hivemq.com/u/Daria_H)\ **Post date:** [May 6, 2022, 8:27am UTC](https://community.hivemq.com/t/client-connection-timeout/1155/6 "2022-05-06T08:27:54Z")
Hi @mtorak , True, these two methods aren’t in the MQTT CLI. This means that MQTT CLI is reusing whatever is set in the MQTT Client library, take a look [here](https://github.com/hivemq/hivemq-mqtt-client/blob/master/src/main/java/com/hivemq/client/internal/mqtt/MqttClientTransportConfigImplBuilder.java): ```auto private int socketConnectTimeoutMs = MqttClientTransportConfigImpl.DEFAULT_SOCKET_CONNECT_TIMEOUT_MS; private int mqttConnectTimeoutMs = MqttClientTransportConfigImpl.DEFAULT_MQTT_CONNECT_TIMEOUT_MS; ``` I hope this helps, Dasha from HiveMQ team