Ambient-oriented Programming & AmbientTalk

Transcription

1 Ambient-oriented Programming & AmbientTalk Tom Van Cutsem Stijn Mostinckx Elisa Gonzalez Boix Andoni Lombide Christophe Scholliers Wolfgang De Meuter Software Languages Lab Brussels, Belgium

2 Agenda 2 Context: Mobile & Ubiquitous computing Approach: Ambient-oriented programming Tool: AmbientTalk Experiments: Demo applications

3 Context Mobile & Ubiquitous Computing

4 Ubiquitous Computing 4 Research vision postulated by Mark Weiser (1988, Xerox PARC)

5 Today s Applications 5 Smart Homes/Domotics RFID Inventory Management Tourism/City Guide Software Personal Area Networks

6 Issues 6 Hardware Issues: Miniaturisation Device Autonomy Interoperability Processor Speed Limited Memory Integration Cost Software Issues: Context-awareness Interaction with real world Portability New user interfaces Standards Distributed Applications

7 Issues 6 Hardware Issues: Miniaturisation Device Autonomy Interoperability Processor Speed Limited Memory Integration Cost Software Issues: Context-awareness Interaction with real world Portability New user interfaces Standards Distributed Applications

8 Mobile Ad Hoc Networks 7 Networks composed of mobile devices that communicate wirelessly

9 Mobile Ad Hoc Networks 7 Networks composed of mobile devices that communicate wirelessly Zero Infrastructure

10 Mobile Ad Hoc Networks 7 Networks composed of mobile devices that communicate wirelessly Zero Infrastructure Volatile Connections

11 Approach Ambient-oriented Programming

12 Observation #1: interaction with proximate peers Example: match making between proximate peers 9 demand type = Concert Ticket ticket.artist = U2 ticket.location = * offer type = Concert Ticket ticket.artist = U2 ticket.location = Hyde Park

13 Observation #1: interaction with proximate peers Example: match making between proximate peers 9 demand offer type = Concert Ticket ticket.artist = U2 ticket.location = Hyde Park type = Concert Ticket ticket.artist = U2 ticket.location = *

14 Observation #1: interaction with proximate peers Example: match making between proximate peers 9 demand offer type = Concert Ticket ticket.artist = U2 ticket.location = Hyde Park type = Concert Ticket ticket.artist = U2 ticket.location = * No reliance on fixed, alwaysavailable server infrastructure

15 Observation #2: intermittent connectivity 10

16 Observation #2: intermittent connectivity 10

17 Observation #2: intermittent connectivity 10

18 Observation #2: intermittent connectivity 10 Tolerate disconnections, because they occur frequently rather than exceptionally

19 Software concerns 11 umama

20 Software concerns 11 umama Discovery

21 Software concerns 11 umama Discovery Communication

22 Software concerns 11 umama 32% 21% Discovery Communication Synchronisation

23 Software concerns 12 umama Discovery Communication Synchronisation

24 Software concerns 12 umama Discovery Communication Synchronisation Failure handling

25 Tool AmbientTalk

26 AmbientTalk: fact sheet 14 Object-oriented scripting language Started in 2005 Pure implementation Runs on J2ME/CDC phones Open source implementation code.google.com/p/ambienttalk

27 How does AmbientTalk help? 15 Volatile Connections network connections are resilient to failures by default Zero Infrastructure service discovery protocol built into the language

28 Object-oriented 16 def makesong(artist, title) { object: { def printartist() { if: (artist == nil) then: { unknown artist ; } else: { artist; } } } }

29 Object-oriented 16 def makesong(artist, title) { object: { def printartist() { if: (artist == nil) then: { unknown artist ; } else: { artist; } } } } def song := makesong( U2, One ); song.printartist();

30 Event Loop Concurrency 17 AmbientTalk programs are event loops They react to events from the outside world They communicate asynchronously Event Event Queue Event Loop Event Handler

31 Examples of event loops 18 GUI Frameworks (e.g. Java AWT) Highly interactive applications (e.g. games) IPC in Operating Systems Discrete Event Modelling (e.g. simulations) Web servers

32 Event Loop Concurrency in AmbientTalk 19

33 Event Loop Concurrency in AmbientTalk 19 Event Loop Message queue

34 Event Loop Concurrency in AmbientTalk 19 local object

35 Event Loop Concurrency in AmbientTalk 19 remote object

36 Event Loop Concurrency in AmbientTalk 20

37 Event Loop Concurrency in AmbientTalk 20 do m immediately obj obj.m()

38 Event Loop Concurrency in AmbientTalk 20 do m eventually obj<-m()

39 Event Loop Concurrency in AmbientTalk 20 do m eventually obj<-m()

40 Event Loop Concurrency in AmbientTalk 20? future

41 Event Loop Concurrency in AmbientTalk 20? future when: future becomes: { value // process reply }

42 Event Loop Concurrency in AmbientTalk 20? future when: future becomes: { value // process reply }

43 Exporting & discovering objects 21 mplayer

44 Exporting & discovering objects 21 mplayer deftype MusicPlayer deftype MusicPlayer

45 Exporting & discovering objects 21 mplayer deftype MusicPlayer deftype MusicPlayer export: mplayer as: MusicPlayer

46 Exporting & discovering objects 21 mplayer deftype MusicPlayer deftype MusicPlayer export: mplayer as: MusicPlayer whenever: MusicPlayer discovered: { mplayer // open a session }

47 Exporting & discovering objects 21 mplayer deftype MusicPlayer deftype MusicPlayer export: mplayer as: MusicPlayer whenever: MusicPlayer discovered: { mplayer // open a session }

48 Far References 22 uploadsong session

49 Far References 22 uploadsong session

50 Far References 22 uploadsong session

51 Far References 22 session

52 Far References 22 session

53 Far References 22 session

54 Far References 22 session when: becomes: { ack // continue exchange } catch: TimeoutException using: { e // stop exchange }

55 Leasing 23 lease: 10.minutes session disconnect Connected (messages are forwarded) expire reconnect Expired (messages are dropped) Disconnected (messages are buffered) expire

56 Reacting to failures 24 lease: 10.minutes session disconnect Connected (messages are forwarded) expire reconnect Expired (messages are dropped) Disconnected (messages are buffered) expire

57 Reacting to failures 24 lease: 10.minutes session disconnect when: session disconnected: { // pause transmission } Connected (messages are forwarded) expire reconnect Expired (messages are dropped) Disconnected (messages are buffered) expire

58 Reacting to failures 24 lease: 10.minutes session disconnect when: session disconnected: { // pause transmission } when: session reconnected: { // resume transmission } Connected (messages are forwarded) expire reconnect Expired (messages are dropped) Disconnected (messages are buffered) expire

59 Reacting to failures 24 lease: 10.minutes session disconnect when: session disconnected: { // pause transmission } when: session reconnected: { // resume transmission } Connected (messages are forwarded) expire reconnect Expired (messages are dropped) Disconnected (messages are buffered) expire when: session expired: { // stop transmission }

60 Reacting to failures 24 lease: 10.minutes session disconnect when: session disconnected: { // pause transmission } when: session reconnected: { // resume transmission } when: session expired: { // stop transmission } Connected (messages are forwarded) expire reconnect Expired (messages are dropped) Disconnected (messages are buffered) expire when: session expired: { // clean up resources }

61 Event Notifications 25 when: type discovered: { obj... } whenever: type discovered: { obj... } when: obj disconnected: {... } whenever: obj disconnected: {... } when: obj reconnected: {... } whenever: obj reconnected: {... } when: obj expired: {... } when: 5.minutes elapsed: {... } whenever: 5.minutes elapsed: {... } when: future becomes: { result... }

62 Event Notifications 25 Discovery when: type discovered: { obj... } whenever: type discovered: { obj... } when: obj disconnected: {... } whenever: obj disconnected: {... } when: obj reconnected: {... } whenever: obj reconnected: {... } when: obj expired: {... } when: 5.minutes elapsed: {... } whenever: 5.minutes elapsed: {... } when: future becomes: { result... }

63 Event Notifications 25 when: type discovered: { obj... } Failure Handling when: obj disconnected: {... } whenever: type discovered: { obj... } whenever: obj disconnected: {... } when: obj reconnected: {... } whenever: obj reconnected: {... } when: obj expired: {... } when: 5.minutes elapsed: {... } whenever: 5.minutes elapsed: {... } when: future becomes: { result... }

64 Event Notifications 25 when: type discovered: { obj... } whenever: type discovered: { obj... } when: obj disconnected: {... } whenever: obj disconnected: {... } when: obj reconnected: {... } whenever: obj reconnected: {... } when: obj expired: {... } Synchronisation when: 5.minutes elapsed: {... } whenever: 5.minutes elapsed: {... } when: future becomes: { result... }

65 Language Interoperability 26 AmbientTalk Program AmbientTalk VM Interop. Layer Java Virtual Machine Scripting language on top of the JVM, cfr. JRuby, Jython, Groovy,... AmbientTalk can use Java libraries, Java can use AmbientTalk scripts

66 Batteries Included 27 def Button := jlobby.java.awt.button; def button := Button.new( Click Me ); button.addactionlistener(object: { def actionperformed(actionevent) { println( button clicked ); } }); button.setvisible(true);

67 Reflection 28 AmbientTalk code can introspect and change behavior of objects and actors def makesong(artist, title) { object: { def printartist() { if: (artist == nil) then: { unknown artist ; } else: { artist; } } } } def song := makesong( U2, One ); song.printartist();

68 Reflection 28 AmbientTalk code can introspect and change behavior of objects and actors def makesong(artist, title) { object: { def printartist() { if: (artist == nil) then: { unknown artist ; } else: { artist; } } } } def mirroronsong := (reflect: song); mirroronsong.invoke(song, createinvocation(`printartist, [])); mirroronsong.listslots(); mirroronsong.addslot(slot);... def song := makesong( U2, One ); song.printartist();

69 Implementation 29 Interactive interpreter ± SLOC of UDP & TCP/IP over WLAN Runs on top of J2ME/CDC QTek 9090 SmartPhones HTC Touch Cruise SmartPhones iphone [in progress] Android G1 [in progress]

70 Experiments Demo Applications

71 Case: Musical Match Maker 31 Demo

72 Experimental Results 32

73 Experimental Results 33

74 Causes 34 Explicit encoding of buffered, asynchronous communication using threads remote messages using objects timeouts using timer threads event notifications (lease expiration & renewal, calls & callbacks) using listeners + event loop threads Java RMI does not deal with service discovery

75 Case: Instant Messenger 35 Demo

76 Chat: Java vs AmbientTalk (LoC) 36

77 Chat: Java vs AmbientTalk (%) 37

78 A simple application but we do not need to explicitly manage: threads & locks low-level socket connections stubs, skeletons name server or lookup service timeouts, leasing

79 AmbientMorphic 39 Implementation of the Morphic UI framework from Self Demo: PortalPong

80 Conclusion 40 Mobile ad hoc networks: Ambient-oriented programming: AmbientTalk: Scripting language on top of the JVM Reactive, event-driven programs Applications: chat, match maker, multiplayer game

81 Conclusion 40 Mobile ad hoc networks: Zero Infrastructure Volatile Connections Ambient-oriented programming: AmbientTalk: Scripting language on top of the JVM Reactive, event-driven programs Applications: chat, match maker, multiplayer game

82 Conclusion 40 Mobile ad hoc networks: Zero Infrastructure Volatile Connections Ambient-oriented programming: Peer-to-peer Tolerate disconnections AmbientTalk: Scripting language on top of the JVM Reactive, event-driven programs Applications: chat, match maker, multiplayer game

83 Don t program the hardware of the future with the software of the past