Distributed Computing with DAFFIE

1. Distributed Computing with DAFFIE Glenn Bresnahan Boston University Scientific Computing and Visualization (http://scv.bu.edu/DAFFIE/Earlab-Oct02)

2. Agenda • DAFFIE overview • DAFFIE live example • DAFFIE distributed computing components • Earlab “leaky” example • Advanced display demonstrations (CGL) Scientific Computing and Visualization

3. What is DAFFIE? DistributedApplicationsFrameworkForImmersiveEnvironments System for easily creating distributed and shared virtual environments Authored by Glenn Bresnahan, Erik Brisson, Robert Putnam Scientific Computing and Visualization

4. Background & Motivation • Distributed/remote visualization (~1992) • CM to networked SGI workstations • IWay (1995) • NSF (vBNS) Connections Program (1996) • Alliance computing and visualization grid (NSF PACI) (1997) • ImmersaDesk • Alliance ‘98 Scientific Computing and Visualization

5. Distributed Application Issues • Analysis of application communication requirements • Sensitivity to bandwidth • Sensitivity to latency • Testing and debugging • Performance measurement and analysis • Robustness • Interoperability of software tools • Management and scheduling of resources in multiple administrative domains • Hardware bottlenecks • Scalability of applications • Security and privacy Scientific Computing and Visualization

6. The VR Experience - Immersion • Real-time, realistic 3D graphics • Stereopsis • Wide (complete) field of view • Viewer based point-of-view • Navigability • Natural interaction modes • Realistic audio Scientific Computing and Visualization

7. Distributed VR • Multi-person, multi-site shared virtual space • Navigation • Avatar representation • Telephony Scientific Computing and Visualization

8. DAFFIE Distributed VR Model • Objective • State consistency • Minimize and/or hide latency • Persistence • Equipotent clients • Network visible state • Message (event) based • Message classes • Delivery service classes • Globally sequenced, reliable delivery • Message class subscription Scientific Computing and Visualization

9. DAFFIE Components • Messaging system (events) • VR (upper layer) protocol • Client applications (agents) FOR MORE INFO... http://scv.bu.edu/DAFFIE Scientific Computing and Visualization

10. DAFFIE Application Clients • Viewer • Sound server • Telephony generator • Sound player • Behavior agents • Audio/video generators/processors • Object generators/manipulators Scientific Computing and Visualization

11. DAFFIE Environment telephony behavior agent viewer behavior agent sound player event server behavior agent sound player telephony viewer Scientific Computing and Visualization

12. DAFFIE Viewer • SGI Performer based • Mono or stereo display • Workstation, CAVE/Immersadesk, HMD • Interactive and server (video) modes • Six-degree of freedom head-tracking • Six-degree of freedom navigation • Texture-mapped streaming video Scientific Computing and Visualization

13. DAFFIE Viewer • Simple "script-based" world description • Geometric models • Animation • Sounds • Many 3D model formats • Interaction by picking and/or proximity • Local control of time-sensitive animation and sound • Global update of avatar motion and object state Scientific Computing and Visualization

14. DAFFIE Sound Server • Telephony generator • Digitize microphone input • Broadcasts "packetized" audio stream • Echo suppression Scientific Computing and Visualization

15. DAFFIE Sound Server • Sound player input • Multiple sound sources • Real-time audio streams (e.g. telephony) • Prerecorded object sound files • Audio attachment objects (3D location) • Avatar position in virtual space • Listener position in physical space • Sound player output • Multi-channel localized audio signals Scientific Computing and Visualization

16. DAFFIE Agents • Control object behavior • Computational modules • Proximity triggers • Portals • Device interfaces • Kinematic sculptures, robotics • Audio and video sourcing (e.g. camera) • Audio and video processing Scientific Computing and Visualization

17. DAFFIE Live Example Telephony gen. Telephony generator Sound player Sound player Navigation client event server Renderer (viewer) Render server Proximity detector Video broadcaster Starfish Video director Chair Video player Skater Butterfly Scientific Computing and Visualization

18. DAFFIE Messaging System • Application protocol • Client services • Client application library (API) • Message router (“event server”) Scientific Computing and Visualization

19. Message Routing • Message router (“event server”) • Multiple delivery service classes • Globally sequenced, reliable delivery • Client management • Message subscription • Multiprocessor, high bandwidth • Hierarchical servers • Proxy routers • Fan-in/fan-out • Tunneling • Direct routing for P2P Scientific Computing and Visualization

20. DAFFIE Message routing client client client proxy client client event server client client proxy client client Scientific Computing and Visualization

21. Message Transports • TCP/IP • Single channel or striped • Shared memory • Myrinet • IP Multicast Scientific Computing and Visualization

22. Application Architecture App thread App thread App thread … App thread Services (timing, streaming, file sharing) Event Messaging Message Transport Scientific Computing and Visualization

23. DAFFIE VR Protocol • Compound objects • Geometry • Transformation • Audio hook • Video texture map • Component ownership/object locking • Request ownership • Broadcast changes • Release ownership • Ownership transfer • Real and effective ownership Scientific Computing and Visualization

24. Defining Upper Layer Protocol • Components • Event type ID (#define in a .h) • Data layout (compile-time) (C struct in a .h) • Data layout (run-time) (event_define) • Needed for canonical byte ordering • Types statically (compile time) defined • Protocol compiler Scientific Computing and Visualization

25. Messaging API • Multithreaded, non-blocking • Dynamic join and leave • Point-to-point and broadcast messages • Polled or callback (active messages) • Subscription based receive • Low level services • Registration, timing, synchronization, query Scientific Computing and Visualization

26. Service Discovery • Client registration/identification • Class (Viewer, Audio, Video, Agent) • Species (video: source, broadcaster, sink, processor) • Instance (video: stream-name) • ID • Hostname • Client location services • Service request/acknowledgement Scientific Computing and Visualization

27. Client Services • Streaming • Data chunking • Bandwidth management • Dynamic tuning • File sharing • File servers • Conditional upload/download Scientific Computing and Visualization

28. Job Initiation & Monitoring • Rely on external authentication and job initiation (e.g. ssh, Globus) • Launch scripts (ad hoc) • cgl-video; visible.bu.edu:vgrab -compress -process; -:vswirl -steps 9999999 -np 4; -:vbroadcast; .:vdirect -object poolanim_grp ; • Agent initiation daemon • Logging daemon Scientific Computing and Visualization

29. Client Monitoring • Dynamic clients • JOIN, EXIT, IDENTIFICATION events • Event server monitoring • Heart beat • Latency monitor • Congestion control • Statistic generation • Client monitoring • Process level monitoring • Congestion management • Remote process termination Scientific Computing and Visualization

30. Leaky Example: Headers typedef struct { EVENT_HEAD head; char filename[200]; } EVENT_GETPARAM; typedef struct { EVENT_HEAD head; int logger, frame_size, sample_rate); } EVENT_START; typedef struct { EVENT_HEAD head; char msg[1000]; } EVENT_LOGINFO; Scientific Computing and Visualization

31. Leaky Example: Headers typedef struct { EVENT_HEAD head; int client; int size; float pressure[1]; } EVENT_ADVANCE; Scientific Computing and Visualization

32. Leaky Example: Headers #define ET_START 1001 #define ET_GETPARAM 1002 #define ET_LOGINFO 1003 #define ET_ADVANCE 1004 #define ET_STOP 1005 event_define(ET_START, “start”, 1, 3, EVENT_DATA_INT); event_define(ET_GETPARAM, “getparam”, 1, 200, EVENT_DATA_CHAR); event_define(ET_ADVANCE, “advance”, 3, 1, EVENT_DATA_INT, 1, EVENT_DATA_INT, 0, EVENT_DATA_FLOAT); Scientific Computing and Visualization

33. Leaky Example: Initialization id = event_join(“earlab.bu.edu”, &nc); printf(“Joined as client id %d of %d\n”, id, nc); event_register(“integrator”, “leaky”, “1.0”); event_receive_type(ET_GETPARAM, ET_START, ET_ADVANCE, ET_STOP); event_callback(ET_START, do_start); event_callback(ET_GETPARAM, do_getparam); … Scientific Computing and Visualization

34. Leaky Example: File Service GotParamFile = 0; efs_init(); efs_chdir_receive(“/tmp/earlab”); Scientific Computing and Visualization

35. Leaky Example: GetParameters do_getparams(EVENT_GETPARM *egp) { efs_download_cond(egp->filename, egp->filename, xfer_done, 0); return(1); } xfer_done(int reqid, int fsid, inr rc, char *file, int tag) { char path[1000]; strcpy(path, “/tmp/earlab/”); strcat(path, file); GotParamFile = 1; Leaky_GetParameters(path); ); Scientific Computing and Visualization

36. Leaky Example: Start do_start(EVENT_START *est) { Logger = est->logger; while (!GotParamFile) event_sleep(100); Leaky_Start(egp->frame_size, egp->sample_rate); return(1); } Scientific Computing and Visualization

37. Leaky Example: LogInfo void LogInfo(char *msg) { EVENT_LOGINFO einfo; strcpy(einfo->msg, msg); event_send(Logger, ET_LOGINFO, &einfo, sizeof(einfo)); } Scientific Computing and Visualization

38. Leaky Example: Advance do_advance(EVENT_ADVANCE *ein) { int bytes; EVENT_ADVANCE *eout; bytes = sizeof(EVENT_ADVANCE) + (ein->size-1)*sizeof(float); eout = (EVENT_ADVANCE *) malloc(bytes); Leaky_Advance(&ein->pressure, &eout->pressure); eout->client = event_clientid(); eout->size = ein->size; event_send(ein->client, ET_ADVANCE, eout, bytes); free(ein); return(1); } Scientific Computing and Visualization

39. Demonstrations • Computer Graphics Lab (Room 203) • ImmersaDesk • Display Wall Scientific Computing and Visualization

40. VR/AG Bridging • Interconnect VR and AG spaces • VR image display over AG • Bridge audio in both directions • Provide interactivity for AG participants • AG navigation • AG interaction tools • Couple external a/v to both AG and VR Scientific Computing and Visualization

41. VR/AG Bridging Boston Cyberarts Festival SC Global FOR MORE INFO... http://scv.bu.edu/hipart/GoGrid/ Scientific Computing and Visualization

42. VR/AG Bridging AG node view renderer video bridge navigation Multicast DAFFIE audio renderer AG audio AG node viewer Scientific Computing and Visualization

43. Tiled Display Wall • Benefits • Low cost • Scalable • Multi-use • Passive stereo • Construction • Linux cluster display driver • Inexpensive LCD projectors • Cheap polarizing filters Scientific Computing and Visualization

44. Tiled Display Wall • One Linux node for every 1 or 2 projectors • One additional “control” or “head” node • Two projectors per tile • Linear polarizing filters • Polarization-preserving projection screen • Custom fabricated projector mounts • 6 DoF adjusters Scientific Computing and Visualization

45. Tiled Display Wall • Prototype configuration • 2x2 stereo array (8 projectors) • 4 Linux display nodes + one control node • Fast Ethernet interconnect • Final configuration • 4x3 stereo array (2 x 9.4 Mpixel) • 24 Linux display nodes + one control node • 52 Linux compute nodes • Myrinet interconnect Scientific Computing and Visualization

46. Tiled Display Wall • Software • WireGL/Chromium • VTK • Performer + local synchronization • Movie player (several) Scientific Computing and Visualization

47. Tiled Display Wall • Issues • Software • Alignment • Custom projector mounts • Computerized motor control • Imaging transformation warps • Autocalibration • Edge blending • Opto-mechanical • Software Scientific Computing and Visualization

48. Access Grid Overview • Suite of commodity hardware and software • Open source, Open protocol • Multicast • Tiled projection wall • Approximately 90 installations world-wide (7 countries) FOR MORE INFO... http://www-fp.mcs.anl.gov/fl/accessgrid/ http://scv.bu.edu/accessgrid Scientific Computing and Visualization