BonAHA: A Framework for Ad-Hoc Applications Suman Srinivasan, Henning Schulzrinne Internet Real Time Lab

Introduction Problem Approach Service discovery and Bonjour BonAHA framework Demos Related Work

Problem

Approach

Service discovery and Bonjour

BonAHA framework

Demos

Related Work

Motivation Mobile nodes; highly mobile networks No infrastructure OLPC; mesh networks “Ad-hoc applications” “Mobile P2P applications” 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

“Ad-hoc applications”

“Mobile P2P applications”

Applications need to

Be aware of network transitions

State/metadata of nodes in the network

Background Started out with raw multicast Service discovery protocols Apple’s Bonjour Still requires a learning curve Lots of repeated code

Started out with raw multicast

Service discovery protocols

Apple’s Bonjour

Still requires a learning curve

Lots of repeated code

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)

Problems Bonjour API Three 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

Bonjour API

Three 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

BonAHA Aim to make 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 make 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

BonAHA – OO Network Events Node 1 Node 2 key1 = value1 key2 = value2 key3 = value3 key4 = value4 Key2_1 = Value2_1 Key2_2 = Value2_2 Key2_3 = Value2_3 Key2_4 = Value2_4 [2] node1.get(key3) [1] node1.register() [3] data = node1.fileGet( “ filename.doc”);

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 Scenario Two nodes meet each other Lack global knowledge of location Each can find out other’s last location information

Scenario

Two nodes meet each other

Lack global knowledge of location

Each can find out other’s last location information

Code: LocationFinder

Compare: Bonjour Code

Comparison in numbers ~60 ~8 Only ad-hoc application functionality 148 79 Complete class Bonjour Code BonAHA Code LocationFinder Lines of Code

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

BonAHA sample application

Shows use in

Multi-player games

Mutual awareness

Demo

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

Proem (2001)

Needs to run on “peerlet engine”

No public documentation of API

JXTA

Excellent for P2P

Heavyweight for our goals

Peer2Me

Only 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)

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

Future Work Fix some non-OO API features Allow one BService object to create several instances. E.g.: one node may want to serve HTTP on two ports. Demarcate BService and BNode objects further to reduce discrepancy in working Perhaps add high-level communications API for simple networking tasks. E.g.: getFile() , notifyPeer() , sendObject()

Fix some non-OO API features

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

Demarcate BService and BNode objects further to reduce discrepancy in working

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

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 Or Suggestions

Or Suggestions

Backup Slides

Problem Initial version of 7DS (circa 2005) “Dumb” multicasting to announce and get information from peers

Initial version of 7DS (circa 2005)

“Dumb” multicasting to announce and get information from peers

Solution Late 2005 / Early 2006 Looked at writing our own framework for solving this problem But, good news: Service discovery does exactly this ZeroConf: Most widely implemented Apple’s Bonjour, Avahi, …

Late 2005 / Early 2006

Looked at writing our own framework for solving this problem

But, good news:

Service discovery does exactly this

ZeroConf: Most widely implemented

Apple’s Bonjour, Avahi, …

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.

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