# MQTT Connection Properties

## `host` (string, required)

The host name of the broker

Example: `"test.mosquitto.org"`

## `port` (integer)

The port of the broker

Default: `1883`

Example: `1883`

## `scheme` (string, enum)

The protocol scheme

This element must be one of the following enum values:

* `mqtt`
* `mqtts`
* `tcp`
* `tls`
* `ws`
* `wss`

Default: `"mqtt"`

Example: `"mqtt"`

## `url` (string)

Complete connection string (takes precedence over host, port and scheme)

Examples: `"mqtt://some.host.org:1883"`, `"mqtts://some.host.org:8883"`

## `keepalive` (integer)

Time to keep the connection alive without any message send (in seconds)

Default: `0`

Example: `60`

## `reschedulePings` (boolean)

Whether to reschedule pings after sending packets

Default: `true`

## `clientId` (string)

The client id used when connecting to the broker

Example: `"mqttjs_13462"`

## `connectionId` (string)

DEPRECATED - this is probably going to be removed soon, right? The id of the connection

Example: `"MQTT"`

## `protocolVersion` (integer)

The protocol version used for the connection to the broker

Example: `4`

## `clean` (boolean)

Set to false to receive QoS 1 and 2 messages while offline

Default: `true`

## `reconnectPeriod` (integer)

Interval between two reconnections (milliseconds)

Default: `1000`

## `connectTimeout` (integer)

Time (in ms) to wait before a CONNACK is received

Default: `30000`

## `username` (string)

The username required by your broker, if any

Example: `""`

## `password` (string)

The password required by your broker, if any

Example: `""`

## `queueQoSZero` (boolean)

If connection is broken, queue outgoing QoS zero messages

Default: `true`

## `trustAllCertificates` (boolean)

If true, all broker certificates will be accepted, regardless of whether they can be validated or not. Use this option if self-signed server certificates should be accepted, or if there are other reasons which prevent this client to validate the certificates.

Default: `false`

## `mutualAuthentication` (boolean)

If true, a full certificate chain including client certificate is expected to connect properly with validated certificates.

Default: `false`

## `caCert` (string)

The root CA certificate as Base64 encoded PEM file content

## `clientCert` (string)

The device certificate as Base64 encoded PEM CRT file content

## `clientPrivateKey` (string)

The device private key as Base64 encoded PEM CRT file content

## `will` (object)

Properties of the `will` object:

#### `topic` (string, required)

Last will topic (LWT)

Example: `"last/will/topic"`

#### `payload` (string, required)

Last will message payload

Example: `""`

#### `qos` (integer, enum)

Last will message quality of service

This element must be one of the following enum values:

* `0`
* `1`
* `2`

Default: `0`

Example: `1`

#### `retain` (boolean)

Retain last message (Last-Value-Cached)

Default: `false`

#### `contentType` (string)

String describing the content of the Application Message (mqtt5 only)

#### `correlationData` (string)

The Correlation Data is used by the sender of the Request Message to identify which request the Response Message is for when it is received (mqtt5 only)

#### `messageExpiryInterval` (number)

Lifetime in seconds of the Will Message (mqtt5 only)

#### `payloadFormatIndicator` (boolean)

Will Message is UTF-8 Encoded Character Data or not (mqtt5 only)

#### `responseTopic` (string)

String which is used as the Topic Name for a response message in a request/response context (mqtt5 only)

#### `userProperties` (object)

Application specific key value pairs (mqtt5 only)

#### `willDelayInterval` (number)

Delay in seconds until the server publishes the Client's Will Message (mqtt5 only)

## `authenticationMethod` (string)

Identifier of the Authentication Method (mqtt5 only)

## `authenticationData` (string)

Binary data containing authentication data (mqtt5 only)

## `maximumPacketSize` (number)

Maximum Packet Size in bytes the Client is willing to accept (mqtt5 only)

## `receiveMaximum` (number)

The Client uses this value to limit the number of QoS 1 and QoS 2 publications that it is willing to process concurrently (mqtt5 only)

## `requestResponseInformation` (boolean)

The Client uses this value to request the Server to return Response Information in the CONNACK (mqtt5 only)

## `requestProblemInformation` (boolean)

The Client uses this value to indicate whether the Reason String or User Properties are sent in the case of failures (mqtt5 only)

## `sessionExpiryInterval` (number)

Session Expiry Interval in seconds (mqtt5 only)

## `topicAliasMaximum` (number)

The Client uses this value to limit the number of Topic Aliases that it is willing to hold on this Connection (mqtt5 only)

## `userProperties` (object)

Application specific key value pairs (mqtt5 only)