BonAHA : Service Discovery Framework for Mobile Ad-Hoc Applications Suman Srinivasan, Arezu Moghadam, Henning Schulzrinne Internet Real Time Lab, Columbia University, New York, USA IEEE CCNC 2009: M1-2 Personal Ad Hoc and Sensor Networks

Topics Problem/motivation Approach Service discovery and Bonjour BonAHA framework Demos Applications developed Related Work

Problem/motivation

Approach

Service discovery and Bonjour

BonAHA framework

Demos

Applications developed

Related Work

Motivation Mobile nodes; highly mobile networks No infrastructure OLPC; mesh networks New class of applications “ Ad-hoc/Mobile-P2P applications” Opportunistic networks Applications need to Be aware of network transitions State/metadata of nodes in the network

Mobile nodes; highly mobile networks

No infrastructure

OLPC; mesh networks

New class of applications

“ Ad-hoc/Mobile-P2P applications”

Opportunistic networks

Applications need to

Be aware of network transitions

State/metadata of nodes in the network

Examples of applications Group chat File transfer File synchronization Local multiplayer games

Group chat

File transfer

File synchronization

Local multiplayer games

Solution 1: Raw multicast Initial solution “ Dumb” multicasting to announce and get information from peers

Initial solution

“ Dumb” multicasting to announce and get information from peers

Solution 2: Service Discovery Looked at writing our own framework for solving this problem But, good news: Service discovery does exactly this Actually, something very similar ZeroConf: Most widely implemented Apple’s Bonjour, Avahi, … Apple’s Bonjour Still requires a learning curve Developer has to rewrite code

Looked at writing our own framework for solving this problem

But, good news:

Service discovery does exactly this

Actually, something very similar

ZeroConf: Most widely implemented

Apple’s Bonjour, Avahi, …

Apple’s Bonjour

Still requires a learning curve

Developer has to rewrite code

Problems Bonjour API Three event listeners, five function calls Have to be completely implemented if an ad-hoc application wants to announce and listen Two other major problems No internal state maintained by Bonjour for services, related IP address and TXT records Resolution can be done only on arrival or exit of services/nodes

Bonjour API

Three event listeners, five function calls

Have to be completely implemented if an ad-hoc application wants to announce and listen

Two other major problems

No internal state maintained by Bonjour for services, related IP address and TXT records

Resolution can be done only on arrival or exit of services/nodes

BonAHA Aim to create a framework that solves these problems Much simpler , and more intuitive, API for ad-hoc applications Applications need not maintain state or do “resolution” BonAHA will maintain state No need for resolution; all nodes and metadata are objects

Aim to create a framework that solves these problems

Much simpler , and more intuitive, API for ad-hoc applications

Applications need not maintain state or do “resolution”

BonAHA will maintain state

No need for resolution; all nodes and metadata are objects

BonAHA For registration service = new BService("7ds_location2", "tcp"); service.set("Latitude", lat); service.set("Longitude", lon); service.register(); service.setListener(this); For network transitions (nodes entering/leaving) nodeUpdated() nodeExited() No need for maintaining state

For registration

service = new BService("7ds_location2", "tcp");

service.set("Latitude", lat);

service.set("Longitude", lon);

service.register();

service.setListener(this);

For network transitions (nodes entering/leaving)

nodeUpdated()

nodeExited()

No need for maintaining state

register() function

BonAHA framework Node 2 Node 1 key21 = value21 key22 = value22 key23 = value23 key24 = value24 key11 = value11 key12 = value12 key13 = value13 key14 = value14 [2] node1.get(key13) [1] node1.register() [3] data = node1.fileGet( value13);

TXTRecord DNSRegistration RegisterListener serviceRegistered() DNSSDService BrowseListener serviceFound() serviceLost() DNSSDService ResolveListener serviceResolved() DNSSD.resolve() DNSSD.register() TXTRecord Host IP DNSSD.browse() set() Bonjour State Diagram

BService BListener serviceUpdated() set() register() setListener() serviceExited() BNode get() getHostName() getHostAddress() BonAHA State Diagram

Example: LocationFinder Very simple, impractical application Only for providing a quick code sample Scenario Two nodes meet each other Lack global knowledge of location Each can find out other’s last location information and update their own location

Very simple, impractical application

Only for providing a quick code sample

Scenario

Two nodes meet each other

Lack global knowledge of location

Each can find out other’s last location information and update their own location

Code: LocationFinder

Compare: Bonjour Code

TicTacToe BonAHA sample application Shows use in Multi-player games Mutual awareness

BonAHA sample application

Shows use in

Multi-player games

Mutual awareness

BonAHA Applications BBS application Runs on iPod/iPhone Allows users to upload “posts” Other users can pick up “posts” and share their own Information on events, etc that they are interested in sharing

BBS application

Runs on iPod/iPhone

Allows users to upload “posts”

Other users can pick up “posts” and share their own

Information on events, etc that they are interested in sharing

BonAHA Applications BBS Application

BBS Application

BonAHA Applications Group chat Allows users to discover peers in local network and chat Rooms can be set up for private chats

Group chat

Allows users to discover peers in local network and chat

Rooms can be set up for private chats

BonAHA Applications File Sharing Users can share files with each other by dragging and dropping files onto peers’ computers Handles peers entering and leaving network

File Sharing

Users can share files with each other by dragging and dropping files onto peers’ computers

Handles peers entering and leaving network

Related Work Proem (2001) Needs to run on “peerlet engine” No public documentation of API JXTA Excellent for P2P Heavyweight for our goals Peer2Me File transfer on Bluetooth

Proem (2001)

Needs to run on “peerlet engine”

No public documentation of API

JXTA

Excellent for P2P

Heavyweight for our goals

Peer2Me

File transfer on Bluetooth

Related Work LightPeers Sep 2007 PhD dissertation (B. Christensen) Similar model to BonAHA “ Application”: Each application has its own GUID that identifies it “ Session”: A group of nodes registered as running the application Code Application app = new Application(appid); lpconn = new Connection(app); ses = lpconn.CreateSession(); List<Session> sessions = lpconn.GetSessionList();

LightPeers

Sep 2007 PhD dissertation (B. Christensen)

Similar model to BonAHA

“ Application”: Each application has its own GUID that identifies it

“ Session”: A group of nodes registered as running the application

Code

Application app = new Application(appid);

lpconn = new Connection(app);

ses = lpconn.CreateSession();

List<Session> sessions = lpconn.GetSessionList();

Related Work - LightPeers Differences with BonAHA PING packet sent every second to search for peers In Bonjour, there is exponential backoff No library-daemon interface LP “server” listens to packets Reimplementation of entire architecture (service discovery + framework)

Differences with BonAHA

PING packet sent every second to search for peers

In Bonjour, there is exponential backoff

No library-daemon interface

LP “server” listens to packets

Reimplementation of entire architecture (service discovery + framework)

Future Work Develop useful applications Fix some API features Allow one BService object to create several instances. E.g.: one node may want to serve HTTP on two ports. Perhaps add high-level communications API for simple networking tasks. E.g.: getFile() , notifyPeer() , sendObject()

Develop useful applications

Fix some API features

Allow one BService object to create several instances. E.g.: one node may want to serve HTTP on two ports.

Perhaps add high-level communications API for simple networking tasks. E.g.: getFile() , notifyPeer() , sendObject()

Conclusion New scenario: highly mobile networks without infrastructure Require a new class of application – “ad-hoc” or “mobile P2P” apps Require a new framework for programming these applications BonAHA , built on top of ZeroConf service discovery: a framework towards building such applications Questions?

New scenario: highly mobile networks without infrastructure

Require a new class of application – “ad-hoc” or “mobile P2P” apps

Require a new framework for programming these applications

BonAHA , built on top of ZeroConf service discovery: a framework towards building such applications

Backup Slides

Apple’s Bonjour Implementation of Zero Configuration Networking (ZeroConf) by Apple Computer This is what enables sharing in iTunes, iChat, etc. Implemented on Mac OS, Windows, Linux and some other POSIX platforms Ported to Windows CE as well

Implementation of Zero Configuration Networking (ZeroConf) by Apple Computer

This is what enables sharing in iTunes, iChat, etc.

Implemented on Mac OS, Windows, Linux and some other POSIX platforms

Ported to Windows CE as well

Apple’s Bonjour Two main components mDNS Daemon Takes care of all Zeroconf events Listens to network events (link up, down, …) Listens to mDNS traffic and keeps track of all service announcements and requests Library (Interfaces for C, Java, …) Allows applications to announce, browse for and resolve services

Two main components

mDNS Daemon

Takes care of all Zeroconf events

Listens to network events (link up, down, …)

Listens to mDNS traffic and keeps track of all service announcements and requests

Library (Interfaces for C, Java, …)

Allows applications to announce, browse for and resolve services

Apple’s Bonjour Details: Presented in Fall 2006 http://developer.apple.com/networking/bonjour/ Important things to remember IP address autoconfiguration: Link-local addressing Pick random from 169.254/16 Hostname resolution: mDNS DNS-like protocol, each host listens on 224.0.0.251, port 5353

Details: Presented in Fall 2006

http://developer.apple.com/networking/bonjour/

Important things to remember

IP address autoconfiguration: Link-local addressing

Pick random from 169.254/16

Hostname resolution: mDNS

DNS-like protocol, each host listens on 224.0.0.251, port 5353

Apple’s Bonjour Service Discovery: DNS-SD DNS PTR records Announcement of form: ServiceName._http._tcp.local. Browsing for _http._tcp.local. gives list of web service instances Resolving ServiceName yields hostname, TXT records, etc.

Service Discovery: DNS-SD

DNS PTR records

Announcement of form: ServiceName._http._tcp.local.

Browsing for _http._tcp.local. gives list of web service instances

Resolving ServiceName yields hostname, TXT records, etc.

Bonjour API Factory class: DNSSD Interfaces: Callback functions for events BrowseListener : Service browsing ResolveListener : Name Resolution RegisterListener: Service Registration QueryListener : DNS Record Resolution DomainListener : Domain Resolution

Factory class: DNSSD

Interfaces: Callback functions for events

BrowseListener : Service browsing

ResolveListener : Name Resolution

RegisterListener: Service Registration

QueryListener : DNS Record Resolution

DomainListener : Domain Resolution

Bonjour API BrowseListener serviceFound() when services appear serviceLost() when service leaves ResolveListener : serviceResolved() to get hostname, TXT records RegisterListener: serviceRegistered() when registration succeeds (or fails)

BrowseListener

serviceFound() when services appear

serviceLost() when service leaves

ResolveListener :

serviceResolved() to get hostname, TXT records

RegisterListener:

serviceRegistered() when registration succeeds (or fails)

Related Work - LightPeers http://www.daimi.au.dk/~bentor/LightPeers/

TXTRecord DNSRegistration RegisterListener serviceRegistered() DNSSDService BrowseListener serviceFound() serviceLost() DNSSDService ResolveListener serviceResolved() DNSSD.resolve() DNSSD.register() TXTRecord Host IP DNSSD.browse() set() Bonjour State Diagram

BService BListener serviceUpdated() set() register() setListener() serviceExited() BNode get() getHostName() getHostAddress() BonAHA State Diagram