emqx4.3/docs/source/guide.rst

.. _guide:

==========
User Guide
==========

------------------------
Pluggable Authentication
------------------------

----------
MQTT Basic
----------

Publish/Subscribe
-----------------

Understanding QoS
-----------------

Retained Message
----------------

Will Message
------------

----------------
HTTP Publish API
----------------

emqttd support HTTP API to publish message from your application server to MQTT clients. For example::

curl -v --basic -u user:passwd -d "qos=1&retain=0&topic=/a/b/c&message=hello from http..." -k http://localhost:8083/mqtt/publish

HTTP API URL
------------

HTTP POST http://host:8083/mqtt/publish

HTTP Parameters
---------------

Name    |  Description
--------|---------------
client  |  ClientId
qos     |  QoS(0, 1, 2)
retain  |  Retain(0, 1)
topic   |  Topic
message |  Message


-------------------
MQTT Over WebSocket
-------------------

## Overview

emqttd 0.7.0 release support MQTT over WebSocket(SSL).

## URI

```
ws(s)://host:8083/mqtt 
```

## Sec-WebSocket-Protocol

'mqttv3.1', 'mqttv3.1.1' 


-----------------------
Trace Topic or Client
-----------------------

## Overview

emqttd could trace packets received/sent from/to specific client, or trace publish/subscribe to specific topic.

emqttd use lager:trace_file api and write trace log to file.


## Trace Commands

### Trace client

```
./bin/emqttd_ctl trace client "ClientId" "trace_clientid.log"
```

### Trace topic

```
./bin/emqttd_ctl trace topic "Topic" "trace_topic.log"
```

### Stop Trace

```
./bin/emqttd_ctl trace client "ClientId" off
./bin/emqttd_ctl trace topic "Topic" off
```

### Lookup Traces

```
./bin/emqttd_ctl trace list
```



-------------------
$SYS Topics
-------------------

NOTICE: This is the design of 0.9.0 release

## Overview

For emqttd is clustered, $SYS Topics of broker is started with:

```
$SYS/brokers/${node}
```

${node} is erlang node of clustered brokers. For example:

```
$SYS/brokers/emqttd@host1/version
$SYS/brokers/emqttd@host2/version
```

## Broker $SYS Topics

Topic                          | Description
-------------------------------|------------
$SYS/brokers                   | Broker nodes
$SYS/brokers/${node}/version   | Broker Version
$SYS/brokers/${node}/uptime    | Broker Uptime
$SYS/brokers/${node}/datetime  | Broker DateTime
$SYS/brokers/${node}/sysdescr  | Broker Description
 
## Client $SYS Topics

Start with: $SYS/brokers/${node}/clients/

Topic                 |   Payload(json)     | Description
----------------------|---------------------|--------------- 
${clientid}/connected | {ipaddress: "127.0.0.1", username: "test", session: false, version: 3, connack: 0, ts: 1432648482} | Publish when client connected 
${clientid}/disconnected | {reason: "normal" | "keepalive_timeout" | "conn_closed"}

Parameters of 'connected' Payload:

```
ipaddress: "127.0.0.1", 
username: "test", 
session: false, 
protocol: 3, 
connack: 0, 
ts: 1432648482
```

Parameters of 'disconnected' Payload:

```
reason: normal,
ts: 1432648486
```

## Statistics $SYS Topics

Start with '$SYS/brokers/${node}/stats/'

### Client Stats

Topic                                | Description
-------------------------------------|------------
clients/count   | count of current connected clients
clients/max     | max connected clients in the same time

### Session Stats

Topic            | Description
-----------------|------------
sessions/count   | count of current sessions
sessions/max     | max number of sessions

### Subscriber Stats

Topic             | Description
------------------|------------
subscriptions/count | count of current subscriptions
subscriptions/max   | max number of subscriptions

### Topic Stats

Topic             | Description
------------------|------------
topics/count      | count of current topics
topics/max        | max number of topics

### Queue Stats

Topic             | Description
------------------|------------
queues/count      | count of current queues
queues/max        | max number of queues


## Metrics $SYS Topics

Start with '$SYS/brokers/${node}/metrics/'

### Bytes sent and received

Topic                               | Description
------------------------------------|------------
bytes/received | MQTT Bytes Received since broker started
bytes/sent     | MQTT Bytes Sent since the broker started

### Packets sent and received
 
Topic                    | Description
-------------------------|------------
packets/received         | MQTT Packets received
packets/sent             | MQTT Packets sent
packets/connect          | MQTT CONNECT Packet received
packets/connack          | MQTT CONNACK Packet sent
packets/publish/received | MQTT PUBLISH packets received
packets/publish/sent     | MQTT PUBLISH packets sent
packets/subscribe        | MQTT SUBSCRIBE Packets received
packets/suback           | MQTT SUBACK packets sent
packets/unsubscribe      | MQTT UNSUBSCRIBE Packets received
packets/unsuback         | MQTT UNSUBACK Packets sent
packets/pingreq          | MQTT PINGREQ packets received
packets/pingresp         | MQTT PINGRESP Packets sent
packets/disconnect       | MQTT DISCONNECT Packets received

### Messages sent and received

Topic                                  | Description
---------------------------------------|-------------------
messages/received | Messages Received
messages/sent     | Messages Sent
messages/retained | Messages Retained
messages/stored   | TODO: Messages Stored
messages/dropped  | Messages Dropped

## Alarm Topics

Start with '$SYS/brokers/${node}/alarms/'

Topic            | Description
-----------------|-------------------
${alarmId}/alert | New Alarm
${alarmId}/clear | Clear Alarm

## Log

'$SYS/brokers/${node}/logs/${severity}'

Severity   |  Description
-----------|-------------------
debug      | Debug Log
info       | Info Log
notice     | Notice Log
warning    | Warning Log
error      | Error Log
critical   | Critical Log

## Sysmon

Start with '$SYS/brokers/${node}/sysmon/'

Topic            | Description
-----------------|-------------------
long_gc          | Long GC Warning
long_schedule    | Long Schedule
large_heap       | Large Heap Warning
busy_port        | Busy Port Warning
busy_dist_port   | Busy Dist Port

## Log

'$SYS/brokers/${node}/log/${severity}'

Severity    | Description
------------|-------------------
debug       | Debug
info        | Info Log
notice      | Notice Log
warning     | Warning Log
error       | Error Log
critical    | Critical Log
alert       | Alert Log

## VM Load Topics

Start with '$SYS/brokers/${node}/vm/'

Topic            | Description
-----------------|-------------------
memory/*         | TODO
cpu/*            | TODO
processes/*      | TODO

## Sys Interval

sys_interval: 1 minute default