Manage PTZ Cameras with Phoenix

José C García-Sacristán

@jgsacristan

“Phoenix is a framework for building HTML5 apps, API backends and distributed systems to take on the modern Web.”

“Written in Elixir, you get beautiful syntax, productive tooling and a fast runtime”

2 million connections per server

400 million users, 30 engineers

Erlang

• Created in 1986

- Windows in 1985

- Linux in 1991

• Handles 50% of the worlds telecom traffic

• Reported 99.9999999% availability (nine nines)

Elixir

Elixir is a functional, concurrent, general-purpose programming language that runs on the Erlang virtual machine (BEAM). Elixir builds on top of Erlang to provide distributed, fault-tolerant, soft real-time, non-stop applications but also extends it to support metaprogramming with macros and polymorphism via protocols.

Productivity in Phoenix

• Short term productivity

- Documentation / Guides / Generators

- Eliminates trivial choices

• Long term productivity

- Maintainability

- Introspection

Easy installation

• $mix local.hex

• $ mix archive.installhttps://github.com/phoenixframework/phoenix/releases/download/v1.0.2/phoenix_new-1.0.2.ez

• $mix phoenix.new my_app

Endpoints

Routers

Controllers

Generators

$ mix phoenix.gen.html

$ mix phoenix.gen.json

$ mix phoenix.gen.channel

Views & Templates

• Precompiled. Fast

• Views render templates.

• Views serve as a presentation layer

• Beyond HTML

Performance

Robust Concurrency Model

• “processes” – extreme lightweight units of concurrency

• Garbage collection is per process

- No global pauses

• Load balances on IO and CPU

Channels

Trivial realtime communication for connected devices

But there is more ..

• Form builders

• Static build tools with ES6 by default

• Live reloading

• First class test tools

• Packages via hex.pm (+2MM downloads)

Applications

• Package and run our code

• Can be started and stopped as a unit

• Provide unified configuration

• Hold processes and state in the supervision tree

:observer.start

:observer.start

• The ONVIF specification defines a common protocol for the exchange of information between network video devices including automatic device discovery, video streaming and intelligence metadata.

Onvif Specification

Based on relevant Web Services standards including security and IP configuration requirements. Areas covered:• IP configuration• Device discovery• Device management• Media configuration• Real time viewing• Event handling• PTZ camera control• Video analytics• Security

http://www.onvif.org/onvif/ver20/util/operationIndex.html

Integration with evercam-media

Problems:

• Poor SOAP support in Erlang/Elixir.

• WS-Security not implemented.

• SOAP operations return XML.

• evercam-media needs JSON responses.

Integration with evercam-media

Solution:

• HTTPotion for HTTP requests

Integration with evercam-media

Solution:

• HTTPotion for HTTP requests

• Own implementation of SOAP Envelope and WS-Security headers.

Integration with evercam-media

Solution:

• HTTPotion for HTTP requests

• Own implementation of SOAP Envelope and WS-Security headers.

• Own implementation of XML to Elixir Map transformations using Erlang xmerl library

Integration with evercam-media

• Definition of needed operations using onvif_client methods.

Integration with evercam-media

• Definition of needed operations using onvif_client methods.

• Add REST routes to web/router.ex

Integration with evercam-media

• Definition of needed operations using onvif_client methods.

• Add REST routes to web/router.ex

• Implement controllers that will invoke ONVIF operations and return the responses as Elixir Map structures.

Integration with evercam-media

• Definition of needed operations using onvif_client methods.

• Add REST routes to web/router.ex

• Implement controllers that will invoke ONVIF operations and return the responses as Elixir Map structures.

• Phoenix translate these Maps into JSON structures without the need of extra coding

Demo