BonAHA framework - Lab presentation
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BonAHA is a framework that aims to simplify building ad-hoc applications for mobile and mesh networks by handling service discovery and maintaining state of nodes and metadata, without requiring applications to resolve services or maintain their own state. It provides object-oriented APIs and events to register services, browse for other nodes and services, and get updated when the network changes. This allows building ad-hoc applications with much less code than using the lower-level Bonjour APIs directly. Examples demonstrate how it can reduce the code needed for a location sharing application from 148 lines to just 8 lines.
![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”);](https://image.slidesharecdn.com/spr08bonahaframework-090326112459-phpapp01/85/BonAHA-framework-Lab-presentation-10-320.jpg)
BonAHA framework - Lab presentation
- 1. BonAHA: A Framework for Ad-Hoc Applications Suman Srinivasan, Henning Schulzrinne Internet Real Time Lab
- 2. Introduction Problem Approach Service discovery and Bonjour BonAHA framework Demos Related Work
- 3. 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
- 4. Background Started out with raw multicast Service discovery protocols Apple’s Bonjour Still requires a learning curve Lots of repeated code
- 5. 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
- 6. 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)
- 7. 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
- 8. 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
- 9. 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
- 10. 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”);
- 11. TXTRecord DNSRegistration RegisterListener serviceRegistered() DNSSDService BrowseListener serviceFound() serviceLost() DNSSDService ResolveListener serviceResolved() DNSSD.resolve() DNSSD.register() TXTRecord Host IP DNSSD.browse() set() Bonjour State Diagram
- 12. BService BListener serviceUpdated() set() register() setListener() serviceExited() BNode get() getHostName() getHostAddress() BonAHA State Diagram
- 13. Example: LocationFinder Scenario Two nodes meet each other Lack global knowledge of location Each can find out other’s last location information
- 16. Comparison in numbers ~60 ~8 Only ad-hoc application functionality 148 79 Complete class Bonjour Code BonAHA Code LocationFinder Lines of Code
- 17. TicTacToe BonAHA sample application Shows use in Multi-player games Mutual awareness Demo
- 18. 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
- 19. 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();
- 20. 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)
- 21. Related Work - LightPeers http://www.daimi.au.dk/~bentor/LightPeers/
- 22. 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()
- 23. 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
- 25. Backup Slides
- 26. Problem Initial version of 7DS (circa 2005) “Dumb” multicasting to announce and get information from peers
- 27. 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, …
- 28. 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
- 29. 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
- 30. 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
- 31. 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.
- 32. TXTRecord DNSRegistration RegisterListener serviceRegistered() DNSSDService BrowseListener serviceFound() serviceLost() DNSSDService ResolveListener serviceResolved() DNSSD.resolve() DNSSD.register() TXTRecord Host IP DNSSD.browse() set() Bonjour State Diagram
- 33. BService BListener serviceUpdated() set() register() setListener() serviceExited() BNode get() getHostName() getHostAddress() BonAHA State Diagram