mqtt

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README

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Eclipse Paho MQTT Go client

This repository contains the source code for the Eclipse Paho MQTT 3.1/3.11 Go client library.

This code builds a library which enable applications to connect to an MQTT broker to publish messages, and to subscribe to topics and receive published messages.

This library supports a fully asynchronous mode of operation.

A client supporting MQTT V5 is also available.

Installation and Build

The process depends upon whether you are using modules (recommended) or GOPATH.

Modules

If you are using modules then import "github.com/eclipse/paho.mqtt.golang" and start using it. The necessary packages will be download automatically when you run go build.

Note that the latest release will be downloaded and changes may have been made since the release. If you have encountered an issue, or wish to try the latest code for another reason, then run go get github.com/eclipse/paho.mqtt.golang@master to get the latest commit.

GOPATH

Installation is as easy as:

go get github.com/eclipse/paho.mqtt.golang

The client depends on Google's proxy package and the websockets package, also easily installed with the commands:

go get github.com/gorilla/websocket
go get golang.org/x/net/proxy

Usage and API

Detailed API documentation is available by using to godoc tool, or can be browsed online using the pkg.go.dev service.

Samples are available in the cmd directory for reference.

Note:

The library also supports using MQTT over websockets by using the ws:// (unsecure) or wss:// (secure) prefix in the URI. If the client is running behind a corporate http/https proxy then the following environment variables HTTP_PROXY, HTTPS_PROXY and NO_PROXY are taken into account when establishing the connection.

Troubleshooting

If you are new to MQTT and your application is not working as expected reviewing the MQTT specification, which this library implements, is a good first step. MQTT.org has some good resources that answer many common questions.

Error Handling

The asynchronous nature of this library makes it easy to forget to check for errors. Consider using a go routine to log these:

t := client.Publish("topic", qos, retained, msg)
go func() {
    _ = t.Wait() // Can also use '<-t.Done()' in releases > 1.2.0
    if t.Error() != nil {
        log.Error(t.Error()) // Use your preferred logging technique (or just fmt.Printf)
    }
}()
Logging

If you are encountering issues then enabling logging, both within this library and on your broker, is a good way to begin troubleshooting. This library can produce various levels of log by assigning the logging endpoints, ERROR, CRITICAL, WARN and DEBUG. For example:

func main() {
	mqtt.ERROR = log.New(os.Stdout, "[ERROR] ", 0)
	mqtt.CRITICAL = log.New(os.Stdout, "[CRIT] ", 0)
	mqtt.WARN = log.New(os.Stdout, "[WARN]  ", 0)
	mqtt.DEBUG = log.New(os.Stdout, "[DEBUG] ", 0)

	// Connect, Subscribe, Publish etc..
}
Common Problems
  • Seemingly random disconnections may be caused by another client connecting to the broker with the same client identifier; this is as per the spec.
  • Unless ordered delivery of messages is essential (and you have configured your broker to support this e.g. max_inflight_messages=1 in mosquitto) then set ClientOptions.SetOrderMatters(false). Doing so will avoid the below issue (deadlocks due to blocking message handlers).
  • A MessageHandler (called when a new message is received) must not block (unless ClientOptions.SetOrderMatters(false) set). If you wish to perform a long-running task, or publish a message, then please use a go routine (blocking in the handler is a common cause of unexpected pingresp not received, disconnecting errors).
  • When QOS1+ subscriptions have been created previously and you connect with CleanSession set to false it is possible that the broker will deliver retained messages before Subscribe can be called. To process these messages either configure a handler with AddRoute or set a DefaultPublishHandler. If there is no handler (or DefaultPublishHandler) then inbound messages will not be acknowledged. Adding a handler (even if it's opts.SetDefaultPublishHandler(func(mqtt.Client, mqtt.Message) {})) is highly recommended to avoid inadvertently hitting inflight message limits.
  • Loss of network connectivity may not be detected immediately. If this is an issue then consider setting ClientOptions.KeepAlive (sends regular messages to check the link is active).
  • Reusing a Client is not completely safe. After calling Disconnect please create a new Client (NewClient()) rather than attempting to reuse the existing one (note that features such as SetAutoReconnect mean this is rarely necessary).
  • Brokers offer many configuration options; some settings may lead to unexpected results.
  • Publish tokens will complete if the connection is lost and re-established using the default options.SetAutoReconnect(true) functionality (token.Error() will return nil). Attempts will be made to re-deliver the message but there is currently no easy way know when such messages are delivered.

If using Mosquitto then there are a range of fairly common issues:

  • listener - By default Mosquitto v2+ listens on loopback interfaces only (meaning it will only accept connections made from the computer its running on).
  • max_inflight_messages - Unless this is set to 1 mosquitto does not guarantee ordered delivery of messages.
  • max_queued_messages / max_queued_bytes - These impose limits on the number/size of queued messages. The defaults may lead to messages being silently dropped.
  • persistence - Defaults to false (messages will not survive a broker restart)
  • max_keepalive - defaults to 65535 and, from version 2.0.12, SetKeepAlive(0) will result in a rejected connection by default.

Reporting bugs

Please report bugs by raising issues for this project in github https://github.com/eclipse/paho.mqtt.golang/issues

A limited number of contributors monitor the issues section so if you have a general question please see the resources in the more information section for help.

We welcome bug reports, but it is important they are actionable. A significant percentage of issues reported are not resolved due to a lack of information. If we cannot replicate the problem then it is unlikely we will be able to fix it. The information required will vary from issue to issue but almost all bug reports would be expected to include:

  • Which version of the package you are using (tag or commit - this should be in your go.mod file)
  • A full, clear, description of the problem (detail what you are expecting vs what actually happens).
  • Configuration information (code showing how you connect, please include all references to ClientOption)
  • Broker details (name and version).

If at all possible please also include:

  • Details of your attempts to resolve the issue (what have you tried, what worked, what did not).
  • A Minimal, Reproducible Example. Providing an example is the best way to demonstrate the issue you are facing; it is important this includes all relevant information (including broker configuration). Docker (see cmd/docker) makes it relatively simple to provide a working end-to-end example.
  • Broker logs covering the period the issue occurred.
  • Application Logs covering the period the issue occurred. Unless you have isolated the root cause of the issue please include a link to a full log (including data from well before the problem arose).

It is important to remember that this library does not stand alone; it communicates with a broker and any issues you are seeing may be due to:

  • Bugs in your code.
  • Bugs in this library.
  • The broker configuration.
  • Bugs in the broker.
  • Issues with whatever you are communicating with.

When submitting an issue, please ensure that you provide sufficient details to enable us to eliminate causes outside of this library.

Contributing

We welcome pull requests but before your contribution can be accepted by the project, you need to create and electronically sign the Eclipse Contributor Agreement (ECA) and sign off on the Eclipse Foundation Certificate of Origin.

More information is available in the Eclipse Development Resources; please take special note of the requirement that the commit record contain a "Signed-off-by" entry.

More information

Stack Overflow has a range questions/answers covering a range of common issues (both relating to use of this library and MQTT in general). This is the best place to ask general questions (including those relating to the use of this library).

Discussion of the Paho clients takes place on the Eclipse paho-dev mailing list.

General questions about the MQTT protocol are discussed in the MQTT Google Group.

There is much more information available via the MQTT community site.

Documentation

Overview

Package mqtt provides an MQTT v3.1.1 client library.

Index

Constants

View Source 
const (
	NET component = "[net]     "
	PNG component = "[pinger]  "
	CLI component = "[client]  "
	DEC component = "[decode]  "
	MES component = "[message] "
	STR component = "[store]   "
	MID component = "[msgids]  "
	TST component = "[test]    "
	STA component = "[state]   "
	ERR component = "[error]   "
	ROU component = "[router]  "
)

Component names for debug output

Variables

View Source 
var ErrInvalidQos = errors.New("invalid QoS")

ErrInvalidQos is the error returned when an packet is to be sent with an invalid Qos value

View Source 
var ErrInvalidTopicEmptyString = errors.New("invalid Topic; empty string")

ErrInvalidTopicEmptyString is the error returned when a topic string is passed in that is 0 length

View Source 
var ErrInvalidTopicMultilevel = errors.New("invalid Topic; multi-level wildcard must be last level")

ErrInvalidTopicMultilevel is the error returned when a topic string is passed in that has the multi level wildcard in any position but the last

View Source 
var ErrNotConnected = errors.New("not Connected")

ErrNotConnected is the error returned from function calls that are made when the client is not connected to a broker

Functions

func ConnectMQTT 

func ConnectMQTT(conn net.Conn, cm *packets.ConnectPacket, protocolVersion uint) (byte, bool)

ConnectMQTT takes a connected net.Conn and performs the initial MQTT handshake. Parameters are: conn - Connected net.Conn cm - Connect Packet with everything other than the protocol name/version populated (historical reasons) protocolVersion - The protocol version to attempt to connect with

Note that, for backward compatibility, ConnectMQTT() suppresses the actual connection error (compare to connectMQTT()).

func DefaultConnectionLostHandler 

func DefaultConnectionLostHandler(client Client, reason error)

DefaultConnectionLostHandler is a definition of a function that simply reports to the DEBUG log the reason for the client losing a connection.

func NewWebsocket 

func NewWebsocket(host string, tlsc *tls.Config, timeout time.Duration, requestHeader http.Header, options *WebsocketOptions) (net.Conn, error)

NewWebsocket returns a new websocket and returns a net.Conn compatible interface using the gorilla/websocket package

Types

type Client 

type Client interface {
	// IsConnected returns a bool signifying whether
	// the client is connected or not.
	IsConnected() bool
	// IsConnectionOpen return a bool signifying whether the client has an active
	// connection to mqtt broker, i.e not in disconnected or reconnect mode
	IsConnectionOpen() bool
	// Connect will create a connection to the message broker, by default
	// it will attempt to connect at v3.1.1 and auto retry at v3.1 if that
	// fails
	Connect() Token
	// Disconnect will end the connection with the server, but not before waiting
	// the specified number of milliseconds to wait for existing work to be
	// completed.
	Disconnect(quiesce uint)
	// Publish will publish a message with the specified QoS and content
	// to the specified topic.
	// Returns a token to track delivery of the message to the broker
	Publish(topic string, qos byte, retained bool, payload interface{}) Token
	// Subscribe starts a new subscription. Provide a MessageHandler to be executed when
	// a message is published on the topic provided, or nil for the default handler.
	//
	// If options.OrderMatters is true (the default) then callback must not block or
	// call functions within this package that may block (e.g. Publish) other than in
	// a new go routine.
	// callback must be safe for concurrent use by multiple goroutines.
	Subscribe(topic string, qos byte, callback MessageHandler) Token
	// SubscribeMultiple starts a new subscription for multiple topics. Provide a MessageHandler to
	// be executed when a message is published on one of the topics provided, or nil for the
	// default handler.
	//
	// If options.OrderMatters is true (the default) then callback must not block or
	// call functions within this package that may block (e.g. Publish) other than in
	// a new go routine.
	// callback must be safe for concurrent use by multiple goroutines.
	SubscribeMultiple(filters map[string]byte, callback MessageHandler) Token
	// Unsubscribe will end the subscription from each of the topics provided.
	// Messages published to those topics from other clients will no longer be
	// received.
	Unsubscribe(topics ...string) Token
	// AddRoute allows you to add a handler for messages on a specific topic
	// without making a subscription. For example having a different handler
	// for parts of a wildcard subscription or for receiving retained messages
	// upon connection (before Sub scribe can be processed).
	//
	// If options.OrderMatters is true (the default) then callback must not block or
	// call functions within this package that may block (e.g. Publish) other than in
	// a new go routine.
	// callback must be safe for concurrent use by multiple goroutines.
	AddRoute(topic string, callback MessageHandler)
	// OptionsReader returns a ClientOptionsReader which is a copy of the clientoptions
	// in use by the client.
	OptionsReader() ClientOptionsReader
}

Client is the interface definition for a Client as used by this library, the interface is primarily to allow mocking tests.

It is an MQTT v3.1.1 client for communicating with an MQTT server using non-blocking methods that allow work to be done in the background. An application may connect to an MQTT server using: 

	A plain TCP socket (e.g. mqtt://test.mosquitto.org:1833)
	A secure SSL/TLS socket (e.g. tls://test.mosquitto.org:8883)
	A websocket (e.g ws://test.mosquitto.org:8080 or wss://test.mosquitto.org:8081)
 Something else (using `options.CustomOpenConnectionFn`)

To enable ensured message delivery at Quality of Service (QoS) levels described in the MQTT spec, a message persistence mechanism must be used. This is done by providing a type which implements the Store interface. For convenience, FileStore and MemoryStore are provided implementations that should be sufficient for most use cases. More information can be found in their respective documentation. Numerous connection options may be specified by configuring a and then supplying a ClientOptions type. Implementations of Client must be safe for concurrent use by multiple goroutines

func NewClient 

func NewClient(o *ClientOptions) Client

NewClient will create an MQTT v3.1.1 client with all of the options specified in the provided ClientOptions. The client must have the Connect method called on it before it may be used. This is to make sure resources (such as a net connection) are created before the application is actually ready.

type ClientOptions 

type ClientOptions struct {
	Servers             []*url.URL
	ClientID            string
	Username            string
	Password            string
	CredentialsProvider CredentialsProvider
	CleanSession        bool
	Order               bool
	WillEnabled         bool
	WillTopic           string
	WillPayload         []byte
	WillQos             byte
	WillRetained        bool
	ProtocolVersion     uint

	TLSConfig              *tls.Config
	KeepAlive              int64 // Warning: Some brokers may reject connections with Keepalive = 0.
	PingTimeout            time.Duration
	ConnectTimeout         time.Duration
	MaxReconnectInterval   time.Duration
	AutoReconnect          bool
	ConnectRetryInterval   time.Duration
	ConnectRetry           bool
	Store                  Store
	DefaultPublishHandler  MessageHandler
	OnConnect              OnConnectHandler
	OnConnectionLost       ConnectionLostHandler
	OnReconnecting         ReconnectHandler
	OnConnectAttempt       ConnectionAttemptHandler
	WriteTimeout           time.Duration
	MessageChannelDepth    uint
	ResumeSubs             bool
	HTTPHeaders            http.Header
	WebsocketOptions       *WebsocketOptions
	MaxResumePubInFlight   int // // 0 = no limit; otherwise this is the maximum simultaneous messages sent while resuming
	Dialer                 *net.Dialer
	CustomOpenConnectionFn OpenConnectionFunc
	AutoAckDisabled        bool
	// contains filtered or unexported fields
}

ClientOptions contains configurable options for an Client. Note that these should be set using the relevant methods (e.g. AddBroker) rather than directly. See those functions for information on usage. WARNING: Create the below using NewClientOptions unless you have a compelling reason not to. It is easy to create a configuration with difficult to trace issues (e.g. Mosquitto 2.0.12+ will reject connections with KeepAlive=0 by default).

func NewClientOptions 

func NewClientOptions() *ClientOptions

NewClientOptions will create a new ClientClientOptions type with some default values. 

Port: 1883
CleanSession: True
Order: True (note: it is recommended that this be set to FALSE unless order is important)
KeepAlive: 30 (seconds)
ConnectTimeout: 30 (seconds)
MaxReconnectInterval 10 (minutes)
AutoReconnect: True

func (*ClientOptions) AddBroker 

func (o *ClientOptions) AddBroker(server string) *ClientOptions

AddBroker adds a broker URI to the list of brokers to be used. The format should be scheme://host:port Where "scheme" is one of "tcp", "ssl", or "ws", "host" is the ip-address (or hostname) and "port" is the port on which the broker is accepting connections.

Default values for hostname is "127.0.0.1", for schema is "tcp://".

An example broker URI would look like: tcp://foobar.com:1883

func (*ClientOptions) SetAutoAckDisabled 

func (o *ClientOptions) SetAutoAckDisabled(autoAckDisabled bool) *ClientOptions

SetAutoAckDisabled enables or disables the Automated Acking of Messages received by the handler. 

By default it is set to false. Setting it to true will disable the auto-ack globally.

func (*ClientOptions) SetAutoReconnect 

func (o *ClientOptions) SetAutoReconnect(a bool) *ClientOptions

SetAutoReconnect sets whether the automatic reconnection logic should be used when the connection is lost, even if disabled the ConnectionLostHandler is still called

func (*ClientOptions) SetBinaryWill 

func (o *ClientOptions) SetBinaryWill(topic string, payload []byte, qos byte, retained bool) *ClientOptions

SetBinaryWill accepts a []byte will message to be set. When the client connects, it will give this will message to the broker, which will then publish the provided payload (the will) to any clients that are subscribed to the provided topic.

func (*ClientOptions) SetCleanSession 

func (o *ClientOptions) SetCleanSession(clean bool) *ClientOptions

SetCleanSession will set the "clean session" flag in the connect message when this client connects to an MQTT broker. By setting this flag, you are indicating that no messages saved by the broker for this client should be delivered. Any messages that were going to be sent by this client before disconnecting previously but didn't will not be sent upon connecting to the broker.

func (*ClientOptions) SetClientID 

func (o *ClientOptions) SetClientID(id string) *ClientOptions

SetClientID will set the client id to be used by this client when connecting to the MQTT broker. According to the MQTT v3.1 specification, a client id must be no longer than 23 characters.

func (*ClientOptions) SetConnectRetry 

func (o *ClientOptions) SetConnectRetry(a bool) *ClientOptions

SetConnectRetry sets whether the connect function will automatically retry the connection in the event of a failure (when true the token returned by the Connect function will not complete until the connection is up or it is cancelled) If ConnectRetry is true then subscriptions should be requested in OnConnect handler Setting this to TRUE permits messages to be published before the connection is established

func (*ClientOptions) SetConnectRetryInterval 

func (o *ClientOptions) SetConnectRetryInterval(t time.Duration) *ClientOptions

SetConnectRetryInterval sets the time that will be waited between connection attempts when initially connecting if ConnectRetry is TRUE

func (*ClientOptions) SetConnectTimeout 

func (o *ClientOptions) SetConnectTimeout(t time.Duration) *ClientOptions

SetConnectTimeout limits how long the client will wait when trying to open a connection to an MQTT server before timing out. A duration of 0 never times out. Default 30 seconds. Currently only operational on TCP/TLS connections.

func (*ClientOptions) SetConnectionAttemptHandler 

func (o *ClientOptions) SetConnectionAttemptHandler(onConnectAttempt ConnectionAttemptHandler) *ClientOptions

SetConnectionAttemptHandler sets the ConnectionAttemptHandler callback to be executed prior to each attempt to connect to an MQTT broker. Returns the *tls.Config that will be used when establishing the connection (a copy of the tls.Config from ClientOptions will be passed in along with the broker URL). This allows connection specific changes to be made to the *tls.Config.

func (*ClientOptions) SetConnectionLostHandler 

func (o *ClientOptions) SetConnectionLostHandler(onLost ConnectionLostHandler) *ClientOptions

SetConnectionLostHandler will set the OnConnectionLost callback to be executed in the case where the client unexpectedly loses connection with the MQTT broker.

func (*ClientOptions) SetCredentialsProvider 

func (o *ClientOptions) SetCredentialsProvider(p CredentialsProvider) *ClientOptions

SetCredentialsProvider will set a method to be called by this client when connecting to the MQTT broker that provide the current username and password. Note: without the use of SSL/TLS, this information will be sent in plaintext across the wire.

func (*ClientOptions) SetCustomOpenConnectionFn 

func (o *ClientOptions) SetCustomOpenConnectionFn(customOpenConnectionFn OpenConnectionFunc) *ClientOptions

SetCustomOpenConnectionFn replaces the inbuilt function that establishes a network connection with a custom function. The passed in function should return an open `net.Conn` or an error (see the existing openConnection function for an example) It enables custom networking types in addition to the defaults (tcp, tls, websockets...)

func (*ClientOptions) SetDefaultPublishHandler 

func (o *ClientOptions) SetDefaultPublishHandler(defaultHandler MessageHandler) *ClientOptions

SetDefaultPublishHandler sets the MessageHandler that will be called when a message is received that does not match any known subscriptions.

If OrderMatters is true (the defaultHandler) then callback must not block or call functions within this package that may block (e.g. Publish) other than in a new go routine. defaultHandler must be safe for concurrent use by multiple goroutines.

func (*ClientOptions) SetDialer 

func (o *ClientOptions) SetDialer(dialer *net.Dialer) *ClientOptions

SetDialer sets the tcp dialer options used in a tcp connection

func (*ClientOptions) SetHTTPHeaders 

func (o *ClientOptions) SetHTTPHeaders(h http.Header) *ClientOptions

SetHTTPHeaders sets the additional HTTP headers that will be sent in the WebSocket opening handshake.

func (*ClientOptions) SetKeepAlive 

func (o *ClientOptions) SetKeepAlive(k time.Duration) *ClientOptions

SetKeepAlive will set the amount of time (in seconds) that the client should wait before sending a PING request to the broker. This will allow the client to know that a connection has not been lost with the server.

func (*ClientOptions) SetMaxReconnectInterval 

func (o *ClientOptions) SetMaxReconnectInterval(t time.Duration) *ClientOptions

SetMaxReconnectInterval sets the maximum time that will be waited between reconnection attempts when connection is lost

func (*ClientOptions) SetMaxResumePubInFlight 

func (o *ClientOptions) SetMaxResumePubInFlight(MaxResumePubInFlight int) *ClientOptions

SetMaxResumePubInFlight sets the maximum simultaneous publish messages that will be sent while resuming. Note that this only applies to messages coming from the store (so additional sends may push us over the limit) Note that the connect token will not be flagged as complete until all messages have been sent from the store. If broker does not respond to messages then resume may not complete. This option was put in place because resuming after downtime can saturate low capacity links.

func (*ClientOptions) SetMessageChannelDepth 

func (o *ClientOptions) SetMessageChannelDepth(s uint) *ClientOptions

SetMessageChannelDepth DEPRECATED The value set here no longer has any effect, this function remains so the API is not altered.

func (*ClientOptions) SetOnConnectHandler 

func (o *ClientOptions) SetOnConnectHandler(onConn OnConnectHandler) *ClientOptions

SetOnConnectHandler sets the function to be called when the client is connected. Both at initial connection time and upon automatic reconnect.

func (*ClientOptions) SetOrderMatters 

func (o *ClientOptions) SetOrderMatters(order bool) *ClientOptions

SetOrderMatters will set the message routing to guarantee order within each QoS level. By default, this value is true. If set to false (recommended), this flag indicates that messages can be delivered asynchronously from the client to the application and possibly arrive out of order. Specifically, the message handler is called in its own go routine. Note that setting this to true does not guarantee in-order delivery (this is subject to broker settings like "max_inflight_messages=1" in mosquitto) and if true then handlers must not block.

func (*ClientOptions) SetPassword 

func (o *ClientOptions) SetPassword(p string) *ClientOptions

SetPassword will set the password to be used by this client when connecting to the MQTT broker. Note: without the use of SSL/TLS, this information will be sent in plaintext across the wire.

func (*ClientOptions) SetPingTimeout 

func (o *ClientOptions) SetPingTimeout(k time.Duration) *ClientOptions

SetPingTimeout will set the amount of time (in seconds) that the client will wait after sending a PING request to the broker, before deciding that the connection has been lost. Default is 10 seconds.

func (*ClientOptions) SetProtocolVersion 

func (o *ClientOptions) SetProtocolVersion(pv uint) *ClientOptions

SetProtocolVersion sets the MQTT version to be used to connect to the broker. Legitimate values are currently 3 - MQTT 3.1 or 4 - MQTT 3.1.1

func (*ClientOptions) SetReconnectingHandler 

func (o *ClientOptions) SetReconnectingHandler(cb ReconnectHandler) *ClientOptions

SetReconnectingHandler sets the OnReconnecting callback to be executed prior to the client attempting a reconnect to the MQTT broker.

func (*ClientOptions) SetResumeSubs 

func (o *ClientOptions) SetResumeSubs(resume bool) *ClientOptions

SetResumeSubs will enable resuming of stored (un)subscribe messages when connecting but not reconnecting if CleanSession is false. Otherwise these messages are discarded.

func (*ClientOptions) SetStore 

func (o *ClientOptions) SetStore(s Store) *ClientOptions

SetStore will set the implementation of the Store interface used to provide message persistence in cases where QoS levels QoS_ONE or QoS_TWO are used. If no store is provided, then the client will use MemoryStore by default.

func (*ClientOptions) SetTLSConfig 

func (o *ClientOptions) SetTLSConfig(t *tls.Config) *ClientOptions

SetTLSConfig will set an SSL/TLS configuration to be used when connecting to an MQTT broker. Please read the official Go documentation for more information.

func (*ClientOptions) SetUsername 

func (o *ClientOptions) SetUsername(u string) *ClientOptions

SetUsername will set the username to be used by this client when connecting to the MQTT broker. Note: without the use of SSL/TLS, this information will be sent in plaintext across the wire.

func (*ClientOptions) SetWebsocketOptions 

func (o *ClientOptions) SetWebsocketOptions(w *WebsocketOptions) *ClientOptions

SetWebsocketOptions sets the additional websocket options used in a WebSocket connection

func (*ClientOptions) SetWill 

func (o *ClientOptions) SetWill(topic string, payload string, qos byte, retained bool) *ClientOptions

SetWill accepts a string will message to be set. When the client connects, it will give this will message to the broker, which will then publish the provided payload (the will) to any clients that are subscribed to the provided topic.

func (*ClientOptions) SetWriteTimeout 

func (o *ClientOptions) SetWriteTimeout(t time.Duration) *ClientOptions

SetWriteTimeout puts a limit on how long a mqtt publish should block until it unblocks with a timeout error. A duration of 0 never times out. Default never times out

func (*ClientOptions) UnsetWill 

func (o *ClientOptions) UnsetWill() *ClientOptions

UnsetWill will cause any set will message to be disregarded.

type ClientOptionsReader 

type ClientOptionsReader struct {
	// contains filtered or unexported fields
}

ClientOptionsReader provides an interface for reading ClientOptions after the client has been initialized.

func (*ClientOptionsReader) AutoReconnect 

func (r *ClientOptionsReader) AutoReconnect() bool

func (*ClientOptionsReader) CleanSession 

func (r *ClientOptionsReader) CleanSession() bool

CleanSession returns whether Cleansession is set

func (*ClientOptionsReader) ClientID 

func (r *ClientOptionsReader) ClientID() string

ClientID returns the set client id

func (*ClientOptionsReader) ConnectRetry 

func (r *ClientOptionsReader) ConnectRetry() bool

ConnectRetry returns whether the initial connection request will be retried until connection established

func (*ClientOptionsReader) ConnectRetryInterval 

func (r *ClientOptionsReader) ConnectRetryInterval() time.Duration

ConnectRetryInterval returns the delay between retries on the initial connection (if ConnectRetry true)

func (*ClientOptionsReader) ConnectTimeout 

func (r *ClientOptionsReader) ConnectTimeout() time.Duration

func (*ClientOptionsReader) HTTPHeaders 

func (r *ClientOptionsReader) HTTPHeaders() http.Header

func (*ClientOptionsReader) KeepAlive 

func (r *ClientOptionsReader) KeepAlive() time.Duration

func (*ClientOptionsReader) MaxReconnectInterval 

func (r *ClientOptionsReader) MaxReconnectInterval() time.Duration

func (*ClientOptionsReader) MessageChannelDepth 

func (r *ClientOptionsReader) MessageChannelDepth() uint

func (*ClientOptionsReader) Order 

func (r *ClientOptionsReader) Order() bool

func (*ClientOptionsReader) Password 

func (r *ClientOptionsReader) Password() string

Password returns the set password

func (*ClientOptionsReader) PingTimeout 

func (r *ClientOptionsReader) PingTimeout() time.Duration

func (*ClientOptionsReader) ProtocolVersion 

func (r *ClientOptionsReader) ProtocolVersion() uint

func (*ClientOptionsReader) ResumeSubs 

func (r *ClientOptionsReader) ResumeSubs() bool

ResumeSubs returns true if resuming stored (un)sub is enabled

func (*ClientOptionsReader) Servers 

func (r *ClientOptionsReader) Servers() []*url.URL

Servers returns a slice of the servers defined in the clientoptions

func (*ClientOptionsReader) TLSConfig 

func (r *ClientOptionsReader) TLSConfig() *tls.Config

func (*ClientOptionsReader) Username 

func (r *ClientOptionsReader) Username() string

Username returns the set username

func (*ClientOptionsReader) WebsocketOptions 

func (r *ClientOptionsReader) WebsocketOptions() *WebsocketOptions

WebsocketOptions returns the currently configured WebSocket options

func (*ClientOptionsReader) WillEnabled 

func (r *ClientOptionsReader) WillEnabled() bool

func (*ClientOptionsReader) WillPayload 

func (r *ClientOptionsReader) WillPayload() []byte

func (*ClientOptionsReader) WillQos 

func (r *ClientOptionsReader) WillQos() byte

func (*ClientOptionsReader) WillRetained 

func (r *ClientOptionsReader) WillRetained() bool

func (*ClientOptionsReader) WillTopic 

func (r *ClientOptionsReader) WillTopic() string

func (*ClientOptionsReader) WriteTimeout 

func (r *ClientOptionsReader) WriteTimeout() time.Duration

type ConnectToken 

type ConnectToken struct {
	// contains filtered or unexported fields
}

ConnectToken is an extension of Token containing the extra fields required to provide information about calls to Connect()

func (*ConnectToken) Done 

func (b *ConnectToken) Done() <-chan struct{}

Done implements the Token Done method.

func (*ConnectToken) Error 

func (b *ConnectToken) Error() error

func (*ConnectToken) ReturnCode 

func (c *ConnectToken) ReturnCode() byte

ReturnCode returns the acknowledgement code in the connack sent in response to a Connect()

func (*ConnectToken) SessionPresent 

func (c *ConnectToken) SessionPresent() bool

SessionPresent returns a bool representing the value of the session present field in the connack sent in response to a Connect()

func (*ConnectToken) Wait 

func (b *ConnectToken) Wait() bool

Wait implements the Token Wait method.

func (*ConnectToken) WaitTimeout 

func (b *ConnectToken) WaitTimeout(d time.Duration) bool

WaitTimeout implements the Token WaitTimeout method.

type ConnectionAttemptHandler 

type ConnectionAttemptHandler func(broker *url.URL, tlsCfg *tls.Config) *tls.Config

ConnectionAttemptHandler is invoked prior to making the initial connection.

type ConnectionLostHandler 

type ConnectionLostHandler func(Client, error)

ConnectionLostHandler is a callback type which can be set to be executed upon an unintended disconnection from the MQTT broker. Disconnects caused by calling Disconnect or ForceDisconnect will not cause an OnConnectionLost callback to execute.

type CredentialsProvider 

type CredentialsProvider func() (username string, password string)

CredentialsProvider allows the username and password to be updated before reconnecting. It should return the current username and password.

type DisconnectToken 

type DisconnectToken struct {
	// contains filtered or unexported fields
}

DisconnectToken is an extension of Token containing the extra fields required to provide information about calls to Disconnect()

func (*DisconnectToken) Done 

func (b *DisconnectToken) Done() <-chan struct{}

Done implements the Token Done method.

func (*DisconnectToken) Error 

func (b *DisconnectToken) Error() error

func (*DisconnectToken) Wait 

func (b *DisconnectToken) Wait() bool

Wait implements the Token Wait method.

func (*DisconnectToken) WaitTimeout 

func (b *DisconnectToken) WaitTimeout(d time.Duration) bool

WaitTimeout implements the Token WaitTimeout method.

type DummyToken 

type DummyToken struct {
	// contains filtered or unexported fields
}

func (*DummyToken) Done 

func (d *DummyToken) Done() <-chan struct{}

Done implements the Token Done method.

func (*DummyToken) Error 

func (d *DummyToken) Error() error

func (*DummyToken) Wait 

func (d *DummyToken) Wait() bool

Wait implements the Token Wait method.

func (*DummyToken) WaitTimeout 

func (d *DummyToken) WaitTimeout(t time.Duration) bool

WaitTimeout implements the Token WaitTimeout method.

type FileStore 

type FileStore struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

FileStore implements the store interface using the filesystem to provide true persistence, even across client failure. This is designed to use a single directory per running client. If you are running multiple clients on the same filesystem, you will need to be careful to specify unique store directories for each.

func NewFileStore 

func NewFileStore(directory string) *FileStore

NewFileStore will create a new FileStore which stores its messages in the directory provided.

func (*FileStore) All 

func (store *FileStore) All() []string

All will provide a list of all of the keys associated with messages currently residing in the FileStore.

func (*FileStore) Close 

func (store *FileStore) Close()

Close will disallow the FileStore from being used.

func (*FileStore) Del 

func (store *FileStore) Del(key string)

Del will remove the persisted message associated with the provided key from the FileStore.

func (*FileStore) Get 

func (store *FileStore) Get(key string) packets.ControlPacket

Get will retrieve a message from the store, the one associated with the provided key value.

func (*FileStore) Open 

func (store *FileStore) Open()

Open will allow the FileStore to be used.

func (*FileStore) Put 

func (store *FileStore) Put(key string, m packets.ControlPacket)

Put will put a message into the store, associated with the provided key value.

func (*FileStore) Reset 

func (store *FileStore) Reset()

Reset will remove all persisted messages from the FileStore.

type Logger 

type Logger interface {
	Println(v ...interface{})
	Printf(format string, v ...interface{})
}

Logger interface allows implementations to provide to this package any object that implements the methods defined in it. 

var (
	ERROR    Logger = NOOPLogger{}
	CRITICAL Logger = NOOPLogger{}
	WARN     Logger = NOOPLogger{}
	DEBUG    Logger = NOOPLogger{}
)

Internal levels of library output that are initialised to not print anything but can be overridden by programmer

type MId 

type MId uint16

MId is 16 bit message id as specified by the MQTT spec. In general, these values should not be depended upon by the client application.

type MemoryStore 

type MemoryStore struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

MemoryStore implements the store interface to provide a "persistence" mechanism wholly stored in memory. This is only useful for as long as the client instance exists.

func NewMemoryStore 

func NewMemoryStore() *MemoryStore

NewMemoryStore returns a pointer to a new instance of MemoryStore, the instance is not initialized and ready to use until Open() has been called on it.

func (*MemoryStore) All 

func (store *MemoryStore) All() []string

All returns a slice of strings containing all the keys currently in the MemoryStore.

func (*MemoryStore) Close 

func (store *MemoryStore) Close()

Close will disallow modifications to the state of the store.

func (*MemoryStore) Del 

func (store *MemoryStore) Del(key string)

Del takes a key, searches the MemoryStore and if the key is found deletes the Message pointer associated with it.

func (*MemoryStore) Get 

func (store *MemoryStore) Get(key string) packets.ControlPacket

Get takes a key and looks in the store for a matching Message returning either the Message pointer or nil.

func (*MemoryStore) Open 

func (store *MemoryStore) Open()

Open initializes a MemoryStore instance.

func (*MemoryStore) Put 

func (store *MemoryStore) Put(key string, message packets.ControlPacket)

Put takes a key and a pointer to a Message and stores the message.

func (*MemoryStore) Reset 

func (store *MemoryStore) Reset()

Reset eliminates all persisted message data in the store.

type Message 

type Message interface {
	Duplicate() bool
	Qos() byte
	Retained() bool
	Topic() string
	MessageID() uint16
	Payload() []byte
	Ack()
}

Message defines the externals that a message implementation must support these are received messages that are passed to the callbacks, not internal messages

type MessageHandler 

type MessageHandler func(Client, Message)

MessageHandler is a callback type which can be set to be executed upon the arrival of messages published to topics to which the client is subscribed.

type NOOPLogger 

type NOOPLogger struct{}

NOOPLogger implements the logger that does not perform any operation by default. This allows us to efficiently discard the unwanted messages.

func (NOOPLogger) Printf 

func (NOOPLogger) Printf(format string, v ...interface{})

func (NOOPLogger) Println 

func (NOOPLogger) Println(v ...interface{})

type OnConnectHandler 

type OnConnectHandler func(Client)

OnConnectHandler is a callback that is called when the client state changes from unconnected/disconnected to connected. Both at initial connection and on reconnection

type OpenConnectionFunc 

type OpenConnectionFunc func(uri *url.URL, options ClientOptions) (net.Conn, error)

OpenConnectionFunc is invoked to establish the underlying network connection Its purpose if for custom network transports. Does not carry out any MQTT specific handshakes.

type OrderedMemoryStore 

type OrderedMemoryStore struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

OrderedMemoryStore implements the store interface to provide a "persistence" mechanism wholly stored in memory. This is only useful for as long as the client instance exists.

func NewOrderedMemoryStore 

func NewOrderedMemoryStore() *OrderedMemoryStore

NewOrderedMemoryStore returns a pointer to a new instance of OrderedMemoryStore, the instance is not initialized and ready to use until Open() has been called on it.

func (*OrderedMemoryStore) All 

func (store *OrderedMemoryStore) All() []string

All returns a slice of strings containing all the keys currently in the OrderedMemoryStore.

func (*OrderedMemoryStore) Close 

func (store *OrderedMemoryStore) Close()

Close will disallow modifications to the state of the store.

func (*OrderedMemoryStore) Del 

func (store *OrderedMemoryStore) Del(key string)

Del takes a key, searches the OrderedMemoryStore and if the key is found deletes the Message pointer associated with it.

func (*OrderedMemoryStore) Get 

func (store *OrderedMemoryStore) Get(key string) packets.ControlPacket

Get takes a key and looks in the store for a matching Message returning either the Message pointer or nil.

func (*OrderedMemoryStore) Open 

func (store *OrderedMemoryStore) Open()

Open initializes a OrderedMemoryStore instance.

func (*OrderedMemoryStore) Put 

func (store *OrderedMemoryStore) Put(key string, message packets.ControlPacket)

Put takes a key and a pointer to a Message and stores the message.

func (*OrderedMemoryStore) Reset 

func (store *OrderedMemoryStore) Reset()

Reset eliminates all persisted message data in the store.

type PacketAndToken 

type PacketAndToken struct {
	// contains filtered or unexported fields
}

PacketAndToken is a struct that contains both a ControlPacket and a Token. This struct is passed via channels between the client interface code and the underlying code responsible for sending and receiving MQTT messages.

type PlaceHolderToken 

type PlaceHolderToken struct {
	// contains filtered or unexported fields
}

PlaceHolderToken does nothing and was implemented to allow a messageid to be reserved it differs from DummyToken in that calling flowComplete does not generate an error (it is expected that flowComplete will be called when the token is overwritten with a real token)

func (*PlaceHolderToken) Done 

func (p *PlaceHolderToken) Done() <-chan struct{}

Done implements the Token Done method.

func (*PlaceHolderToken) Error 

func (p *PlaceHolderToken) Error() error

func (*PlaceHolderToken) Wait 

func (p *PlaceHolderToken) Wait() bool

Wait implements the Token Wait method.

func (*PlaceHolderToken) WaitTimeout 

func (p *PlaceHolderToken) WaitTimeout(t time.Duration) bool

WaitTimeout implements the Token WaitTimeout method.

type ProxyFunction 

type ProxyFunction func(req *http.Request) (*url.URL, error)

type PublishToken 

type PublishToken struct {
	// contains filtered or unexported fields
}

PublishToken is an extension of Token containing the extra fields required to provide information about calls to Publish()

func (*PublishToken) Done 

func (b *PublishToken) Done() <-chan struct{}

Done implements the Token Done method.

func (*PublishToken) Error 

func (b *PublishToken) Error() error

func (*PublishToken) MessageID 

func (p *PublishToken) MessageID() uint16

MessageID returns the MQTT message ID that was assigned to the Publish packet when it was sent to the broker

func (*PublishToken) Wait 

func (b *PublishToken) Wait() bool

Wait implements the Token Wait method.

func (*PublishToken) WaitTimeout 

func (b *PublishToken) WaitTimeout(d time.Duration) bool

WaitTimeout implements the Token WaitTimeout method.

type ReconnectHandler 

type ReconnectHandler func(Client, *ClientOptions)

ReconnectHandler is invoked prior to reconnecting after the initial connection is lost

type Store 

type Store interface {
	Open()
	Put(key string, message packets.ControlPacket)
	Get(key string) packets.ControlPacket
	All() []string
	Del(key string)
	Close()
	Reset()
}

Store is an interface which can be used to provide implementations for message persistence. Because we may have to store distinct messages with the same message ID, we need a unique key for each message. This is possible by prepending "i." or "o." to each message id

type SubscribeToken 

type SubscribeToken struct {
	// contains filtered or unexported fields
}

SubscribeToken is an extension of Token containing the extra fields required to provide information about calls to Subscribe()

func (*SubscribeToken) Done 

func (b *SubscribeToken) Done() <-chan struct{}

Done implements the Token Done method.

func (*SubscribeToken) Error 

func (b *SubscribeToken) Error() error

func (*SubscribeToken) Result 

func (s *SubscribeToken) Result() map[string]byte

Result returns a map of topics that were subscribed to along with the matching return code from the broker. This is either the Qos value of the subscription or an error code.

func (*SubscribeToken) Wait 

func (b *SubscribeToken) Wait() bool

Wait implements the Token Wait method.

func (*SubscribeToken) WaitTimeout 

func (b *SubscribeToken) WaitTimeout(d time.Duration) bool

WaitTimeout implements the Token WaitTimeout method.

type Token 

type Token interface {
	// Wait will wait indefinitely for the Token to complete, ie the Publish
	// to be sent and confirmed receipt from the broker.
	Wait() bool

	// WaitTimeout takes a time.Duration to wait for the flow associated with the
	// Token to complete, returns true if it returned before the timeout or
	// returns false if the timeout occurred. In the case of a timeout the Token
	// does not have an error set in case the caller wishes to wait again.
	WaitTimeout(time.Duration) bool

	// Done returns a channel that is closed when the flow associated
	// with the Token completes. Clients should call Error after the
	// channel is closed to check if the flow completed successfully.
	//
	// Done is provided for use in select statements. Simple use cases may
	// use Wait or WaitTimeout.
	Done() <-chan struct{}

	Error() error
}

Token defines the interface for the tokens used to indicate when actions have completed.

type TokenErrorSetter 

type TokenErrorSetter interface {
	// contains filtered or unexported methods
}

type UnsubscribeToken 

type UnsubscribeToken struct {
	// contains filtered or unexported fields
}

UnsubscribeToken is an extension of Token containing the extra fields required to provide information about calls to Unsubscribe()

func (*UnsubscribeToken) Done 

func (b *UnsubscribeToken) Done() <-chan struct{}

Done implements the Token Done method.

func (*UnsubscribeToken) Error 

func (b *UnsubscribeToken) Error() error

func (*UnsubscribeToken) Wait 

func (b *UnsubscribeToken) Wait() bool

Wait implements the Token Wait method.

func (*UnsubscribeToken) WaitTimeout 

func (b *UnsubscribeToken) WaitTimeout(d time.Duration) bool

WaitTimeout implements the Token WaitTimeout method.

type WebsocketOptions 

type WebsocketOptions struct {
	ReadBufferSize  int
	WriteBufferSize int
	Proxy           ProxyFunction
}

WebsocketOptions are config options for a websocket dialer

Source Files

View all Source files

Directories

Path Synopsis
cmd
custom_store
httpproxy
routing
sample
simple
ssl
stdinpub
stdoutsub

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