1. March/2001Distributed Computing With Small Mobile Wireless Devices1 Rochester Institute of Technology Distributed Computing with Small Mobile Wireless Devices Alan Kaminsky/Hans-Peter Bischof Information Technology Laboratory/CS Department Rochester Institute of Technology ark @ it.rit.edu/hpb @ cs.rit.edu

2. March/2001Distributed Computing With Small Mobile Wireless Devices2 The Problem and the Opportunity The Anhinga Project Part 1: Distributed Services Part 2: Distributed Collaboration First Steps

3. March/2001Distributed Computing With Small Mobile Wireless Devices3 The Changing Computing Milieu (1) Yesterday/Today: large sessile wired hosts

4. March/2001Distributed Computing With Small Mobile Wireless Devices4 The Changing Computing Milieu (2) Tomorrow: small mobile wireless devices Bluetooth™ is a trademark of Telefonaktiebolaget LM Ericsson.

5. March/2001Distributed Computing With Small Mobile Wireless Devices5 Device Characteristics Compared to standard PCs/workstations, small mobile wireless devices have... – Slower CPUs – Smaller memories – Slower network connections – Limited input/output capabilities – Heterogeneous operating environments – Transitory interconnections Huge applications won’t work Distributed applications are needed

6. March/2001Distributed Computing With Small Mobile Wireless Devices6 Infrastructure Barriers The sessile infrastructure: – Server machines, client machines, wired network – Client-server architectures – Mobile device = just another client machine The problem: – Servers crash, networks go down – Mobile devices go where there’s no wireless access The opportunity: – Ad-hoc networks solely of mobile devices – Peer-to-peer architectures with mobile devices – “No Sessile Infrastructure”

7. March/2001Distributed Computing With Small Mobile Wireless Devices7 Wireless Personal Area Networks The “Personal Bubble” 10 meters

8. March/2001Distributed Computing With Small Mobile Wireless Devices8 Missing Technology Low-level technology: present – Wireless local area networks IEEE 802.11 (Wireless Ethernet), Bluetooth – Java: write once run anywhere – Java 2 Micro Edition (J2ME) High-level technology: not there yet – Mobile device network routing protocols: not finished IETF’s MobileIP, MANET – Distributed middleware standards: too big CORBA, Jini Network Technology There is a lack of distributed middleware designed specifically for ad-hoc networks of mobile devices

9. March/2001Distributed Computing With Small Mobile Wireless Devices9 The Anhinga Project

10. March/2001Distributed Computing With Small Mobile Wireless Devices10 Purpose and Goals Purpose – “Develop an infrastructure for distributed communication and collaboration using small mobile wireless devices, thus realizing such devices’ latent potential for building ad-hoc peer-to-peer distributed applications.” Goals – Distributed services infrastructure – Distributed communication & collaboration infrastructure – Proof-of-concept applications Device-to-device instant messaging Device-to-device collaborative groupware Use of Anhinga/Java Space

11. March/2001Distributed Computing With Small Mobile Wireless Devices11 What’s an Anhinga? Photograph courtesy Philip Greenspun http://www.photo.net/philg/

12. March/2001Distributed Computing With Small Mobile Wireless Devices12 Part 1: Distributed Services

13. March/2001Distributed Computing With Small Mobile Wireless Devices13 Federated Service Architectures Hardware? Software?  Service Everything is a service – Printer  Print service – Scanner, Camera  Image capture service – CPU Server  CPU service – E-mail  E-mail service Federated services – Dynamic discovery – Ad hoc connections Limited CPU power, memory, bandwidth No sessile infrastructure

14. March/2001Distributed Computing With Small Mobile Wireless Devices14 Java Write once, run anywhere Supported on small mobile wireless devices Remote method invocation (RMI) Moveable objects — state & behavior – MarshalledObject = serialized state + codebase URL Ideal for programming a heterogenous collection of devices Java™ is a trademark of Sun Microsystems.

15. March/2001Distributed Computing With Small Mobile Wireless Devices15 Jini Network Technology Infrastructure for a federated service architecture Service interfaces — to define services Service proxy objects — to use services Lookup Service — to find services Discovery protocol — to find the Lookup Service Join process — to register services Jini™ is a trademark of Sun Microsystems.

16. March/2001Distributed Computing With Small Mobile Wireless Devices16 Java and the Device Space Great Big Java – Java 2 Standard Edition (J2SE) Middle Sized Java – Java 2 Micro Edition (J2ME) Connected Device Configuration (CDC) Wee Little Java – Java 2 Micro Edition (J2ME) Connected Limited Device Configuration (CLDC)

17. March/2001Distributed Computing With Small Mobile Wireless Devices17 Edition Configu- rationProfileVMROMRAMTypical Use J2MECLDCMIDP*KVM136K32KCellphones, pagers, PIMs J2MECLDCPDA ProfileKVM512KHandheld personal digital assistants J2MECDCFoundation Profile CVM1.0M128KNetworked devices J2MECDCPersonal Profile CVM2.5M1.0MSet-top boxes, web appliances J2MECDCRMI ProfileCVM2.5M1.0MJini capable devices J2SE——JVM—LotsDesktop applications J2ME Profiles *Mobile Information Device Profile

18. March/2001Distributed Computing With Small Mobile Wireless Devices18 Jini Runs Here Jini ClientJini Service J2SE J2ME CDC

19. March/2001Distributed Computing With Small Mobile Wireless Devices19 Jini Doesn’t Run Here Jini ClientJini Service J2SEJ2ME CLDC

20. March/2001Distributed Computing With Small Mobile Wireless Devices20 Why Jini Doesn’t Run There J2ME CLDC lacks... – Security manager – User-defined classloaders – Reflection – Object serialization – Marshalled objects... therefore cannot access the Lookup Service It also lacks Remote Method Invocation (RMI)

21. March/2001Distributed Computing With Small Mobile Wireless Devices21 Getting Jini to Run There (1) Jini Surrogate Project Jini WirelessDevice Project “No Sessile Infrastructure” PC/Workstation Camera Cellphone

22. March/2001Distributed Computing With Small Mobile Wireless Devices22 Getting Jini to Run There (2) Anhinga Project CameraCellphone Wireless

23. March/2001Distributed Computing With Small Mobile Wireless Devices23 Anhinga Project Part 1 Tasks Develop extensions to J2ME CLDC – Lightweight classloading, security, serialization, RMI – Support for mobile objects in limited device memory – Bluetooth support Develop Jini Mobile Edition (JiniME) – Variation of Jini for J2ME CLDC devices – Service discovery with self-hosted Lookup Services – Bridge to a sessile Jini federation Environment – Linux PDAs with Bluetooth modules – Palm PDAs with Bluetooth modules

24. March/2001Distributed Computing With Small Mobile Wireless Devices24 Anhinga Project Part 1 Results JiniME Federation JiniME Bridge Jini Federation

25. March/2001Distributed Computing With Small Mobile Wireless Devices25 Part 2: Distributed Collaboration

26. March/2001Distributed Computing With Small Mobile Wireless Devices26 Communication Patterns Service interactions – One-to-one Collaborative applications – Many-to-many (M2M)

27. March/2001Distributed Computing With Small Mobile Wireless Devices27 Network Protocols TCP/IP was designed for one-to-one communication between distant sessile hosts IP multicasting was designed for one-to-many communication The IETF is trying to shoehorn mobile devices into a sessile mold – MobileIP: Make IP addresses work for mobile devices – MANET: Make IP routing work for ad-hoc networks Need new protocols specifically designed for M2M communication in ad-hoc networks of proximal mobile devices

28. March/2001Distributed Computing With Small Mobile Wireless Devices28 Distributed Programming Paradigms Shared memory: doesn’t match hardware Message passing: too complex Tuple space: just right – Invented by David Gelernter, Yale U. – Linda, JavaSpaces JavaSpaces™ is a trademark of Sun Microsystems.

29. March/2001Distributed Computing With Small Mobile Wireless Devices29 Tuple Space Abstraction Tuple Space Device 3. Read 4. Take 2. Write tuple 1. Read template

30. March/2001Distributed Computing With Small Mobile Wireless Devices30 Anhinga Project Part 2 Tasks Develop M2M communication protocol – Designed specifically for ad-hoc networks of proximal mobile devices – Don’t rely on addressing individual devices – Work over various physical layers (802.11, Bluetooth) Develop distributed tuple space implementation – Tuple resides in writing device – Tuple transferred to reading or taking device – M2M protocol announces all tuple space operations – Hashing used for tentative template matching

31. March/2001Distributed Computing With Small Mobile Wireless Devices31 Security Issues Unauthorized users – Authentication provided by secret authentication keys – Authentication = authorization in this case Passive intruders (network sniffers) – Foiled by encrypting all packets Active intruders (network spoofers) – Replay attacks foiled by challenge-response protocol

32. March/2001Distributed Computing With Small Mobile Wireless Devices32 Design Idea Design Idea…

33. March/2001Distributed Computing With Small Mobile Wireless Devices33 Application Layer

34. March/2001Distributed Computing With Small Mobile Wireless Devices34 Distributed Infrastructure I

35. March/2001Distributed Computing With Small Mobile Wireless Devices35 Distributed Infrastructure II

36. March/2001Distributed Computing With Small Mobile Wireless Devices36 Java Layer I

37. March/2001Distributed Computing With Small Mobile Wireless Devices37 Java Layer II

38. March/2001Distributed Computing With Small Mobile Wireless Devices38 Native Layer

39. March/2001Distributed Computing With Small Mobile Wireless Devices39 Questions?

40. March/2001Distributed Computing With Small Mobile Wireless Devices40 Thanks