A MQTT Client application that keep connections to one or more MQTT brokers, handles subscriptions, and expose a publisher for publishing messages to the broker.
Amongst other things Tortoise supports:
- Keeping a connection to a MQTT server (version 3.1.1 for now)
- Retry connecting with incremental back-off
- Publishing and subscribing to topics of QoS 0, 1, and 2
- Connections support last will message
- Connecting via TCP and SSL
- The fundamentals are there, but some of the API's might change in the near future
- A PubSub system where one can listen to system events. For now connection status and ping response times can be subscribed for statistics and administrative purposes.
Most of the public facing interface should be in the Tortoise
module. See the GitHub issues for work in progress "known issues in
the design", "what needs to be done", and so forth; feel free to open
your own issues if something is confusing or broken.
I would love to get some feedback and help building this thing.
A supervised connection can be started like this:
# connect to the server and subscribe to foo/bar with QoS 0
Tortoise.Supervisor.start_child(
client_id: "my_client_id",
handler: {Tortoise.Handler.Logger, []},
server: {Tortoise.Transport.Tcp, host: 'localhost', port: 1883},
subscriptions: [{"foo/bar", 0}])
# publish a message on the broker
Tortoise.publish("my_client_id", "foo/bar", "Hello from the World of Tomorrow !", qos: 0)To connect to a MQTT server using SSL the Tortoise.Transport.SSL
transport can be used. This requires configuration of the server's
CA certificate, and possibly a client certificate and key. For
example, when using the certifi
package as the CA trust store:
Tortoise.Supervisor.start_child(
client_id: "smart-spoon",
handler: {Tortoise.Handler.Logger, []},
server: {
Tortoise.Transport.SSL,
host: host, port: port,
cacertfile: :certifi.cacertfile(),
key: key, cert: cert
},
subscriptions: [{"foo/bar", 0}])Alternatively, for testing purposes, server certificate verification
can be disabled by passing verify: :verify_none in the server
options. In that case there is no need for CA certificates, but an
attacker could intercept the connection without detection!
Look at the connection_test.exs-file for more examples.
Example Handler
defmodule Tortoise.Handler.Example do
use Tortoise.Handler
def init(args) do
{:ok, args}
end
def connection(status, state) do
# `status` will be either `:up` or `:down`; you can use this to
# inform the rest of your system if the connection is currently
# open or closed; tortoise should be busy reconnecting if you get
# a `:down`
{:ok, state}
end
# topic filter room/+/temp
def handle_message(["room", room, "temp"], payload, state) do
# :ok = Temperature.record(room, payload)
{:ok, state}
end
def handle_message(topic, payload, state) do
# unhandled message! You will crash if you subscribe to something
# and you don't have a 'catch all' matcher; crashing on unexpected
# messages could be a strategy though.
{:ok, state}
end
def subscription(status, topic_filter, state) do
{:ok, state}
end
def terminate(reason, state) do
# tortoise doesn't care about what you return from terminate/2,
# that is in alignment with other behaviours that implement a
# terminate-callback
:ok
end
endThe subscribe/3, unsubscribe/3, subscribe_sync/3, and
unsubscribe_sync/3 is no longer exposed on the Tortoise
module. The functionality has been moved to the Tortoise.Connection
module. The functions has the same arities and functionality, so the
upgrade path is a simple search and replace:
"Tortoise.subscribe(" -> "Tortoise.Connection.subscribe(""Tortoise.subscribe_sync(" -> "Tortoise.Connection.subscribe_sync(""Tortoise.unsubscribe(" -> "Tortoise.Connection.unsubscribe(""Tortoise.unsubscribe_sync(" -> "Tortoise.Connection.unsubscribe_sync("
This change is done because the Tortoise.Connection module should be
in charge of changes to the connection life-cycle.
Tortoise can be installed by adding tortoise to your list of
dependencies in mix.exs:
def deps do
[
{:tortoise, "~> 0.9"}
]
endDocumentation should be available at https://hexdocs.pm/tortoise.
To start developing, run the following commands:
mix deps.get
MIX_ENV=test mix eqc.install --mini
mix test
To build the documentation run the following command in a terminal emulator:
MIX_ENV=docs mix docsThis will build the documentation in place them in the doc-folder in the root of the project. These docs will also find their way to the Hexdocs website when the project is published on Hex.
Copyright 2018 Martin Gausby
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
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