Introduction to AllJoyn

Paloma Maisterra, Alex Gonzalez
March 2014
Introduction to AllJoyn

Overview
• AllJoyn is an open sourced framework to enable proximity based peer to
peer mobile networking.
• It provides an abstraction layer with a clean API to the underlying networks
stacks (wireless, bluetooth) which is relatively easy to extend with new
network implementations (takers for zigbee?).
• AllJoyn provides service advertisement and discovery abstraction, as well
as various application to application security mechanisms and a Remote
Method Invocation abstraction.

OnBoarding
The problem:
• Small embedded devices need to connect to a local wireless network but
lack a proper user interface.
• Adding a user interface just to, for example, input wireless authentication,
is wasteful.
The solution:
• The embedded devices run a small AllJoyn thin client and use an AllJoyn
router to “onboard” the local wireless network.

Audio/data distribution
The problem:
• Data is either centrally stored (media server) or distributed (several media
devices) but need to be accessed by all devices.
The solution:
• Embedded devices running the AllJoyn thin client can access a central
media storage server running an AllJoyn router and can access each other’
s data.

Control Panel/Configuration
The problem:
• Small embedded devices that need to configured and managed but lack a
user interface or a web server.
The solution:
• The embedded devices run an AllJoyn thin client that can be managed
using a remote control panel on another UI capable device running the
AllJoyn router.

Notification
The problem:
• Devices without a display need to inform the user of
events.
The solution:
• They ran an AllJoyn client and use another AllJoyn
device with a display for event notification.

(the eternal) Smart home example
• What about telling the coffee maker you want a coffee
when you arrive home?
• Controlling your home security from your Smartphone?
• The fridge reminding you what you must buy?
• Adjusting the temperature,or the lighting?
• Sharing media with other devices?

Smart energy example
AllJoyn Thin CLient
Router/Gateway

AllJoyn
• A software framework that allows devices and systems
to autonomously discover and interact with nearby
products regardless of brand, transport layer, platform or
operating system.
• Open source licensed, Apache 2.0 (source)
• Originally developed by and being contributed to the
Alliance by Qualcomm Innovation Center, Inc.
• Initial set of capabilities include:
o Service discovery (learning about the features and
functions of other nearby devices)
o Onboarding to add a device to the user’s network
o User notifications
o A common control panel for creating rich user
experiences
o Audio streaming for simultaneous playback on
multiple speakers.
• First Allseen alliance framework release is 14.02 (SDKs)
• Releases every 4 months, (April/June/October).
• The AllJoyn framework is written in C++ and has bindings
for the following languages:
o Java (inc. Android)
o Objective C
o Unity
o Javascript
o C
• The AllJoyn thin client (in C) for embedded devices
includes Linux, Windows 7, Arduino, ThreadX and more.

Allseen Alliance
• Recently formed, around 4 montsh old.
• Consortium of companies that collaborate on the AllJoyn framework development, including:
o Qualcomm
o Cisco
o Panasonic
o Sharp
o LG
o HTC
• Structured in a set of working groups, currently core, base services and development tools.

Products
• LG smart TV
• Muzzleys is integrating Alljoyn in their cloud
• ITTIA DB SQL supports Alljoyn, which allows to monitor, control, and
distribute stored data.
• Musiac’s multi room music system
• Android featured apps

High level architecture
• An AllJoyn network is composed of routing nodes and leaf nodes. Leaf
nodes can only connect to routing nodes, and routing nodes connect to
other routing nodes to form a mesh of stars.
• Nodes form a distributed software bus that enables to publish, discover
and use APIs. Applications that expose APIs are services, if they consume
them, clients, and if they do both peers.

AllJoyn Bus
• This is the most basic abstraction providing a fast lightweight way to move marshalled
messages around a distributed system.
• The bus formation is ad hoc, based on application or service discovery. The wire protocol is an
extended backwards compatible d-bus protocol which can run over any medium, WiFi, WiFi
direct, ethernet, PLC, bluetooth etc.
• When a session is created the bus is extended. Peers are notified on join and leave events and
can interact via their APIs or with multicast events.

Bus extension
Advertisement and Discovery
• When a service is started it reserves a well known name in the bus and
advertises it existence. This advertisement will be different on the different
underlying technologies, UDP multicast over WiFi, pre-association service
advertisement on WiFi direct or bluetooth service discovery message.
• Client applications may declare their interest in receiving advertisements
by initiating a discovery operation.

Alljoyn Interfaces
● The published interfaces are discovered and introspected remotely using the About service
framework and they are formed by three types of members:
○ Methods: which can be called and return a result.
○ Signals: broadcast, multicast or point to point asynchronous event notifications. Also sessionless.
○ Properties: Accessed by getter and setter methods.
● They can contain basic and complex data types defined by the dbus specification:
● Interfaces can be defined in XML, or inline code, C++, Java, C...

AllJoyn Software components
• AllJoyn has two main components, AllJoyn applications (leaf nodes) and the router (routing
node). Both are implemented with the AllJoyn client library which comes in two flavours,
standard client, for applications running on high level OSes, and thin client, for deeply
embedded devices (device firmware).
• The standard client is implemented in C++ and has bindings for various other languages, while
the thin client is a C implementation and it depends on a routing node running off the device
itself. The client library is represented by the AllJoyn SDK API.
• Routers are built using the standard client library so they must run on a high level OS. It can
either run standalone (only supported under Linux) or integrated on an AllJoyn application.
Routers perform bus management and message routing tasks.

AllJoyn Bus implementation
The Daemon
• The part of the bus running on a device is called a bus segment. Each
segment needs an AllJoyn daemon, which are background processes
which act as representatives of the AllJoyn bus.
• In order for the clients and servers to communicate with the bus daemon,
they contain a representative of the bus called bus attachment.

AllJoyn Bus Implementation
Bus attachments, interfaces and objects
• The bus attachment is a local language specific object that represents the AllJoyn bus to a
client, server or peer. It lives in each process that needs to communicate with the bus.
• A bus interface is a group of bus methods, properties and signals along with their associated
type signatures.
• This org.alljoyn.Bus interface is implemented in bus objects. As there might be multiple bus
objects on a bus attachment, an object path is used to differentiate them, for example
/org/alljoyn/bus/1.
• Remote bus objects are accessed through proxy bus objects which are local representatives of
the remote bus object.

AllJoyn Sessions
• Sessions are created between client and servers before they can interact.
• A server half association has the form [options,bus name,session port]
• And the client’s [options, unique name, session ID]
• A session will join these two half associations in [options, bus name,
unique name, session ID]
• The final options are negotiated in the session negotiation, as well as
security checks.

Sessions
So the service advertises:
[reliable IP , org.alljoyn.samples.chat.1 , 42]
Asumming there is a bus attachment :2.1 on a remote daemon wanting
to connect:
[reliable IP , org.alljoyn.samples.chat.1 , :2,1 , 1025]
The session ID 1025 is assigned by the system.

Code Flow Example
The framework usage is the same independently of the language binding used:
1. Create a BusAttachment.
2. Register listeners.
3. Create a BusInterterface.
4. Optionally perform 1 or more of the following:
a. Create and register a BusObject that implements 1 or more BusInterfaces.
b. Register Signal handlers.
c. Advertise and/or Discover.
d. Create a Session.
e. Join a Session.
5. Remove listeners.
6. Release the BusAttachment.

AllJoyn Base Services
● Build on top of the allJoyn framework for accelerated application development.
● They all use the About feature for advertisement and discovery.
● Each service framework will need to setup AllJoyn and the About feature.
● They are:
● Notification Service Framework: Sends and receives text messages, with the possibility of
referencing media, with priority and filtering.
● Onboarding Service Framework: Standard way to get devices into a Wifi network. The
onboarder device discovers a device that needs to be onboarded (onboardee), it connects to
it, provides configuration information, and the onboardee verifies the connection.
● Audio Service Framework
● Control Panel Service Framework

Developing from SDKs
Supported operating systems include:
• Android (Java,needs SDK and NDK installed)
• iOS and OSX (Objective C)
• Windows and Linux (C++)
• Windows and Linux thin client (C)

Resources
• Video webminars
• Documentation
o Environment setup guides:
▪ Android
▪ Thin Client (Arduino, Linux,
Windows, embedded OSes)
▪ Objective C (iOS and OSX)
▪ Java (Linux, Windows)
▪ Unity
▪ C++ (Windows , Linux)
o Development guides:
▪ Java
▪ Troubleshooting guide
▪ Thin Client
• Getting started
• Building an application

Service frameworks
• About feature
o Getting started (Java)
o Usage guide (Java, C, Objective C, C++)
o Best practises
o Interface specification
• Audio service
o Getting Started (Java, C++)
o Usage guide (C++)
o Best practises
• Configuration service
o Getting Started (Java)
o Best practises
• Control panel
o Best practises
• Notification
o Best practises
• Onboarding
o Usage guide (Java)
o Best practises

Framework APIs
Framework APIs:
• Java (Android, Linux, Windows 7)
• C++ (Android, Linux, Windows 7)
• C (Linux, Arduino, Thin Client, )
• Objective C (iOS and OSX)
• Javascript (Linux, WIndows 7)
• C# (Unity)

This presentation is shared with an Attribution-NonCommercial-ShareAlike 3.0 Unported license.

Introduction to AllJoyn

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