PMQ: MQTT Message Broker and Message bus

PMQ will be a high-performance, distributed MQTT broker (aka. message broker ) and message bus.

PMQ implements the MQTT 3.1, 3.1.1 specifiaction with qualaty of service 1 and shared subscription from MQTT 5

Feature

Distributed configuration

With PMQ it is possible to distribute configurations. Imagine that you have to configure many microservices and they do not have a REST interface. In this case, the distribution of configurations via PMQ can be helpful. Configurations are transferred in JSON format and defined as YAML.The configuration is organized hierarchically. The hierarchy is three-level global, General for a client family and Specific for a single client.

TLS and non-TLS Connection on the same port

PMQ supports TLS and non-TLS connections on the same port at the same time. This means that a client can connect to the server using a certificate and another client can can connect to the server via a raw socket connection.

Roadmap

• REST API to configure and manage PMQ Message Broker
• Distribute configuration to broker clients Finished
• Support QOS 2
  • QOS 2 receiver case
  • QOS 2 sender case
• Support MQTT 5
  • shared subscription Finished
• Support WILL messages Finished
• Support Wildcard subscriptions Finished
  • # Wildcard (Multi level Wildcard)
  • + Wildcard (Single level Wildcard)
• Support Authentification: Client authentificate server - Finished!
• Support Authentification: Server authentificate client - Finished!
• Support TLS - Finished!
• Support for Websockets

Contribution

Everybody is welcome! If you want to start developing for this project, you can use the development docker container. To generate the image, use follow command

$ cd dockerfiles/dev_image
$ docker build -t pmqtt/dev_test .

After generation you can use the container

$ docker run --it -v[path to pmq]:/pmq pmqtt/dev_test /bin/bash

or use the docker image from https://hub.docker.com

$ docker pull pmqtt/dev
$ docker run -it -v[path to pmq]:/pmq pmqtt/dev /bin/bash

Releated projects

• eclipse mosquitto https://github.com/eclipse/mosquitto
• vernemq https://github.com/vernemq/vernemq

Building PMQ

Note: PMQ requires

• BOOST 1.65 or newer
• microsofts cpprestsdk
• yaml-cpp

$ cd $PMQ
$ cmake .
$ make
$ sh run_test.sh

Troubleshooting

On MAC OS X I have recognized that building PMQ with cpprestsdk is a little bit difficult. If you see this error message from cmake

Could NOT find OpenSSL, try to set the path to OpenSSL root folder in the
  system variable OPENSSL_ROOT_DIR (missing: OPENSSL_INCLUDE_DIR)

Try to call cmake with this command

$cmake -DOPENSSL_ROOT_DIR=[PATH TO OPENSSL_ROOT_DIR e.g  /usr/local/Cellar/openssl/1.0.2p/]

Starting PMQ

Once you've successfully built PMQ, you can start the server with the following commands:

$ cd $PMQ/
$ ./PMQ

PMQ will start on port 1883. It is also possible to start PMQ with a configuration file

$ ./PMQ -c configuration.yaml

Starting PMQ with different connection type

For raw connection

$ ./PMQ  --allowed-connection-type plain

For TLS connection

$ ./PMQ  --allowed-connection-type tls --tls-certificat [server certificat] --tls-private-key [private key file] --tls-dh-file [Diffie file]

For both connection types

$ ./PMQ  --allowed-connection-type plain-tls --tls-certificat [server certificat] --tls-private-key [private key file] --tls-dh-file [Diffie file]

Starting PMQ with permited anonymous connection

$ ./PMQ --anonymous-login false

Now the server allows only connection with user name and password. To set a user and password, you have to use the REST interface. The REST interface is callable for example by curl with this command

$ curl -d '{"user":"pmqtt", "password":"test1"}' -H 'Content-Type: application/json' -X POST http://localhost:1884/rest/api/v0.1/create_user

Show all connected clients with will messages

To see all clients with it's will messages and will topics, use the REST API of PMQ. For example, to show the clients with curl, use the following command

$ curl http://localhost:1884/rest/api/v0.1/get_will_messages

How to, distribute configuration

$ ./PMQ  --client-configuration-file configuration.yaml

The format of the configuration file must look like this

# General configuration for all clients
GLOBAL:
- PROXY: 127.0.0.14:8888
- NTP: 127.0.0.15:8177

MACHINE_SERVICE_01:
- CONNECTION: 192.168.0.133
MACHINE_SERVICE_01/01:
- PORT: 2001


MACHINE_SERVICE_01/02:
- PORT: 2002

To subscribe for the configuration, you have to use the special topic $CONFIG_MODULE/[YAML RULE]. For example with mosquitto_sub:

$ mosquitto_sub -t '$CONFIG_MODULE/MACHINE_SERVICE_01/02'

You will received from PMQ this message:

{
  "GLOBAL":
  {
    "PROXY":"127.0.0.14:8888",
    "NTP":"127.0.0.15:8177"
  },
  "GENERAL":
  {
    "CONNECTION":"192.168.0.133"
  },
  "SPECIFIC":
  {
    "PORT":"2002"
  }
}