co-leader of NervesJP, illustrates a future vision of IoT systems (right figure). • He envisions that Elixir can empower such systems, running on all of the layers such as device, edge, cloud. Cite: Hideki Takase “ElixirでIoT！？ナウでヤングで coolなNervesフレームワーク p.21” https://www.slideshare.net/takasehideki/elixiriotcoolnerves-236780506/21
vision to connect things over the layers. • Realize the vision by connecting each other via the distributed Erlang network. • Mitigate issues in developing complicated IoT systems. Everything becomes an Erlang node and connects each other via the distributed network, which is the way how we can save this complicated world.
Perception Cloud Edge Device Three-layer model Five-layer model Our model - Sensing the physical environment and actuating devices. - Transport the sensor data to the upper layer. - Processing the data, i.e., formatting, transforming, extending, etc. - Analysing the data to produce meaningful information. - Providing services to users. - Sending actuation orders to the device layer.
the complexity: 1. Various options of programming languages and communication protocols. 2. Various and bidirectional data acquisition methods. 3. Poor visibility of the dataflow throughout the IoT system.
problems mentioned earlier. • A declarative framework for describing bidirectional dataflow. Note: The word “pratipad” is borrowed from Sanskrit. It means “way” in English. CIte: kentaro/pratipad: “A Declarative Framework for Describing Bidirectional Dataflow” https://github.com/kentaro/pratipad
Local Area Network Edge Layer Device Layer Device Layer My House Wide Area Network Sensing: - CO2 concentration - air pressure - humidity Cloud Layer - visualize - analyze - send back actuation order External API - provide additional metadata (e.g. precipitation) Users - monitor situation - do some actions (e.g. open the window) mTLS connection - aggregate - transform - add more info ･･･ Running on Elixir LED blinks when the cloud system sends a notification to prompt uses to open the window.
provides a method to design and implement IoT systems in an integrated manner using the same programming language and communication protocol. 1. All the 3 layers are implemented in Elixir. ◦ Device: Nerves + Pratipad.Client ◦ Edge: Pratipad ◦ Cloud: Phoenix + Pratipad.Client 2. They are connected to each other via the Erlang distribution protocol. ◦ All connections are over TLS. ◦ Client certificates are required for authentication.
that can support push, pull, and demand methods, including bidirectional dataflow. 1. The data is retrieved from the device layer. Incidentally, there are 3 ways for that as below. Pratipad supports all of them. a. Push b. Pull c. Demand 2. Bidirectional dataflow is also supported.
that can grasp the dataflow consisting of the 3 layers under a single view. Pratipad allows us to 1. Describe dataflow in a declarative manner. 2. Separate the dataflow itself and how to process the data.
protocols such as HTTP or MQTT for IoT systems. • Elixir is built on the top of Erlang/OTP that has legendary achievements in telecom systems. • IoT is like such a system in the current era. All the 3 layers are connected each other with distributed Erlang network.
interested in connecting conventional sequential computers with no shared memory. Our idea was to connect stock hardware through TCP/IP sockets and run a cluster of machines behind a corporate firewall. We were not interested in security since we imagined all our computers running on a private network with no external access. This architecture led to a form of all-or-nothing security that makes distributed Erlang suitable for programming cluster applications running on a private network, but unsuitable for running distributed applications where various degrees of trust are involved. Cite: Joe Armstrong “A history of Erlang” “ ”
in the “external” world. To realize such a distribution with Erlang/OTP, we have to ensure 1. All connections are over TLS (Transport Layer Security) to avoid MITM (Man-In-The-Middle) attack. 2. Client certificates are required for authentication to prohibit those who don’t have permission from joining the network.
project: -proto_dist inet_tls -ssl_dist_optfile /etc/<%= System.get_env("PRATIPAD_DEVICE") %>.tls.conf -start_epmd false -erl_epmd_port 44300 CIte: pratipad_example_device/rel/vm.args.eex https://github.com/kentaro/pratipad_example_device/blob/main/rel/vm.args.eex rel/vm.args.eex ※ epmd is prevented from running because it cannot be secure; it is vulnerable to brute-force attacks. Moreover, all the nodes in the network can be known by those who can crack the network.
Using the settings as the right figure, the device001 can be both a TLS server and a TLS client try authentication in mTLS manner. 2. If both verify and fail_if_no_peer_cert are set, servers must verify client certificates to authenticate them. CIte: pratipad_example_device/rootfs_overlay/etc/device001.tls.conf https://github.com/kentaro/pratipad_example_device/blob/main/rootfs_overlay/etc/device001.tls.conf [ {server, [{cacertfile, "/etc/ca.crt"}, {certfile, "/etc/device001.pratipad.local.crt"}, {keyfile, "/etc/device001.pratipad.local.key"}, {secure_renegotiate, true}, {fail_if_no_peer_cert, true}, {verify, verify_peer} ]}, {client, [{cacertfile, "/etc/ca.crt"}, {certfile, "/etc/device001.pratipad.local.crt"}, {keyfile, "/etc/device001.pratipad.local.key"}, {secure_renegotiate, true}, {fail_if_no_peer_cert, true}, {verify, verify_peer} ]} ]. device001.tls.conf
“build concurrent and multi-stage data ingestion and data processing pipelines with Elixir.” • Pratipad is built on the top of Broadway to realize flexible and bidirectional dataflow in IoT systems. Cite: Broadway https://elixir-broadway.org/
The device layer is responsible for how many messages are emitted. • It’s useful when the time resolution of sensor data is important for the target IoT system.
The cloud layer is responsible for how many messages are emitted. • It’s useful when you need to control the message flow rate along with service levels to be offered to each system user.
The edge layer is responsible for how many messages are emitted. • It’s useful when the edge layer becomes rate-limiting for the throughput of the dataflow. • In this mode, the edge layer demands messages to the device layer only when it can handle them.
You can grasp whole the dataflow and how the data is processed at a glance. • Dataflow notation consists of 3 types below: ◦ Input ◦ Processing ◦ Direction Push <~> P1 <~> P2 <~> P3 <~> Output Processing Direction Input
as the right figures. • The names of processors are linked to their implementation as Elixir modules. • Processors are supposed to implement Pratipad.Processor behaviour’s process/2 method. • Do anything you want to do with messages in the method. Push <~> P1 <~> P2 <~> P3 <~> Output defmodule P1 do alias Pratipad.Processor use Processor @impl GenServer def init(initial_state) do %{:ok, initial_state) end @impl Processor def process(message, state) do # do something with the message end end Dataflow Processor
to meet your demand. Sequential Message Concurrent Message Message is processed sequentially Message Message Message is processed concurrently Message can be modified by the processors. Message is identical to the original.
notations are implemented by macros. defmacro left ~> right do quote do handle_unidirectional_op(unquote(left), unquote(right)) end end defp handle_unidirectional_op(left, right) when left == Push or left == Demand do %Dataflow{ mode: @input_mode_map[left], forward: %Forward{ processors: [right] }, backward_enabled: false } end CIte: pratipad/lib/pratipad/dataflow/dsl.ex https://github.com/kentaro/pratipad/blob/main/lib/pratipad/dataflow/dsl.ex
the messages to processors. Device Layer Cloud Layer Pratipad.Broadway.Forward off_broadway_otp_distribution Broadway.handle_message/3 Broadway.handle_batch/4 P1-3 implements Pratipad.Processor P1.process/1 Push <~> P1 <~> P2 <~> P3 <~> Output Above dataflow given ① ② ③ ④ ⑤ P2.process/1 P3.process/1 Invoke the process method of each processors
of Erlang nodes • Elixir can be the best candidate to build IoT systems. • Building such systems in Elixir realizes that everything ◦ Runs as an Erlang node ◦ Connects each other via the distributed network. • Pratipad can be a help of Elixir for the IoT world. Next big thing: Toward the multi-tenant Erlang distribution.
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