1. Ubiquitous Computing with SIP Henning Schulzrinne (with Stefan Berger, Stelios Sidiroglou, Kundan Singh, Xiaotao Wu, Weibin Zhao) Columbia University IRT Lab Siemens Munich -- January 2003

2. Overview What is ubiquitous computing? Location-based computing in SIP On-going work at Columbia

3. What is ubiquitous computing? “Ubiquitous computing has as its goal the enhancing computer use by making many computers available throughout the physical environment, but making them effectively invisible to the user.” (Weiser, 1993) “Ubiquitous computing is not virtual reality, it is not a Personal Digital Assistant (PDA) such as Apple's Newton, it is not a personal or intimate computer with agents doing your bidding. Unlike virtual reality, ubiquitous computing endeavers to integrate information displays into the everyday physical world. It considers the nuances of the real world to be wonderful, and aims only to augment them.” (Weiser, 1993)

4. Ubiquitous computing aspects Also related to pervasive computing Mobility, but not just cell phones Computation and communications Integration of devices “borrow” capabilities found in the environment  composition into logical devices seamless mobility  session mobility adaptation to local capabilities environment senses instead of explicit user interaction from small dumb devices to PCs light switches and smart wallpaper

5. Example “ubicomp” projects Ambient Devices EU IST Disappearing Computer Project Aura, CMU  user attention UNC “office of real soon now” augmented surfaces [Reki99] Microsoft Easy Living Oxygen, MIT Portolano, Univ. of Washington Endeavour, Berkeley

6. Session mobility Walk into office, switch from cell phone to desk phone call transfer problem  REFER related problem: split session across end devices e.g., wall display + desk phone + PC for collaborative application assume devices (or stand-ins) are SIP- enabled third-party call control

7. Session mobility via 3PCC INVITE speakerphone m=audio c=pc42 INVITE display m=video c=pc42 192.0.2.1 192.0.2.7 INVITE pc42 m=video c=192.0.2.7 m=audio c=192.0.2.1 pc42

8. How to find services? Two complementary developments: smaller devices carried on user instead of stationary devices devices that can be time-shared large plasma displays projector hi-res cameras echo-canceling speaker systems wide-area network access Need to discover services in local environment SLP (Service Location Protocol) allows querying for services “find all color displays with at least XGA resolution” slp://example.com/SrvRqst?public?type=printer SLP in multicast mode SLP in DA mode Need to discover services before getting to environment “is there a camera in the meeting room?” SLP extension: find remote DA via DNS SRV

9. Service Location Protocol (SLP) Version 2 standardized June 1999 UA DA SA SrvReg SrvRply SrvRqst SrvReg DAAdvert

10. SLP attribute example URL service:printer:lpr://igore.wco.ftp.com/draft scope-list Development Language tag en Attributes (Name=Igore),(Description=For developers only), (Protocol=LPR),(location- description=12th floor), (Operator=James Dornan \3cdornan@monster\3e), (media- size=na-letter),(resolution=res-600),x-OK

11. Other service location mechanism DNS SRV/NAPTR DNS TXT records (Apple Rendezvous)  DNS-SD UPnP uses SSDP: multicast HTTP over UDP M-SEARCH * HTTP/1.1 S: uuid:ijklmnop-7dec-11d0-a765-00a0c91e6bf6 Host: 239.255.255.250:reservedSSDPport Man: "ssdp:discover“ ST: ge:fridge MX: 3 HTTP/1.1 200 OK S: uuid:ijklmnop-7dec-11d0-a765-00a0c91e6bf6 Ext: Cache-Control: no-cache="Ext", max-age = 5000 ST: ge:fridge USN: uuid:abcdefgh-7dec-11d0-a765-00a0c91e6bf6 AL:

12. Locations Geographic location latitude, longitude, altitude, velocity, heading Civil location (≠ postal location!) street address, city some countries are a bit difficult… Categorical office, library, theater, hospital, … Behavioral “public location, don't expect privacy” “silence is encouraged, don't ring the phone”

13. Determining locations SIP entities are often far away from physical user or his current network (intentionally) For many devices, can’t afford hardware to determine location different precision requirements: “in Fayette County” (within driving distance of service or person) “on campus” “in room 815” “in corner, talking to Bob” GPS doesn’t work indoors, but Assisted GPS (A-GPS) may Use location beacons: BlueTooth, 802.11 may not offer network connectivity see our 7DS project: offer local content + location Physically close by network entities: DHCP (same broadcast domain) PPP (tail circuit) Not always true with VPNs, but end system knows that it’s using a VPN

14. DHCP for locations Proposal: DHCP extensions for geographic and civil location geographic: resolution (bits), long/lat, altitude (meters or floors) civil: what: end system, switch or DHCP server hierarchical subdivisions, from country to street, landmark name, occupant Also, some LAN switches broadcast port and switch identification CDP for Cisco, EDP for Extreme Networks Can also use backtracking via SNMP switch tables locally implemented for emergency services (Perl sip-cgi script)

15. Location-based services Services: Location-aware call routing “do not forward call if time at callee location is [11 pm, 8 am]” “only forward time-for-lunch if destination is on campus” “contact nearest emergency call center” “do not ring phone if I’m in a theater” “send delivery@pizza.com to nearest branch”delivery@pizza.com Location-based events subscribe to locations, not people “Alice has entered the meeting room” subscriber may be device in room  our lab stereo changes CDs for each person that enters the room Person + location events We’re implementing SIP, caller-preferences and CPL extensions for these services

16. SIP extensions for location-based services Location information is highly sensitive complete tracking of person stalkers and burglars would kill for this information IETF GEOPRIV principle: “target” can control dissemination of location information restrict time of day, information (location, heading, velocity) resolution, number of times queried, destination, retention, … “Alice is in time zone MET” may be ok for strangers, but “Alice is at 41.872833 N, 087.624417 W, heading NE at 45 mph” is not GEOPRIV still defining application scenarios in many cases, easiest to include location information “in-band” with protocol, as this avoids delegating authorization otherwise, need to give access key to database to recipient we propose adding SIP Location header field

17. Event filtering Events are core attribute of ubiquitous computing systems tell devices about people actions tell people about device presence e.g., “Alice has entered Room 815” devices that know Alice’s preferences subscribe to Alice locations may also have presence e.g., for occupancy sensors, switches

18. Location filtering language SIP presence information will be updated using REGISTER and UPDATE Need to constrain who is allowed to see what detail  presentity privacy who wants to see what detail how often what granularity of change Proposal to allow SUBSCRIBE to include frequency limitation Working on CPL-like language invoked (logically) at publication time classes of users, e.g., based on entry in my address book classes get mapped to restriction “12 bits of long/lat resolution, 6 bits of altitude resolution, 0 bits of velocity” “time zone only”, “category only” watchers can then add filters that restrict the delivery: location difference > threshold entering or leaving certain area entering or leaving category or behavioral type

19. Columbia SIP servers (CINEMA) Internal Telephone Extn: 7040 SIP/PSTN Gateway Department PBX Web based configuration Web server Telephone switch SQL database sipd: Proxy, redirect, registrar server Extn: 7134 xiaotaow@cs NetMeeting H.323 rtspd: media server sipum: Unified messaging Quicktime RTSP clients RTSP Extn: 7136 713x Single machine SNMP (Network Management) sipconf: Conference server siph323: SIP-H.323 translator Local/long distance 1-212-5551212

20. Location-based services in CINEMA Initial proof-of-concept implementation Integrate devices: lava lamp via X10 controller  set personalized light mood setting Pingtel phone  add outgoing line to phone and register user painful: needs to be done via HTTP POST request stereo  change to audio CD track based on user Sense user presence and identity: passive infrared (PIR) occupancy sensor magnetic swipe card ibutton BlueTooth equipped PDA IR+RF badge (in progress) RFID (future) biometrics (future)

21. CINEMA system

22. All-SIP implementation

23. Pushing context-sensitive data to users User with mobile device should get location information when entering city, campus or building flight and gate information maps and directions local weather forecast special advisories (“choose security checkpoint 2”) Often does not require knowing user but interface with (e.g.) calendar Example Columbia implementation: OBEX data exchange over BlueTooth PDA pushes current appointment or event name base station delivers directions and map

24. Conclusion SIP + auxiliary protocols supports many of the core requirements for ubiquitous computing and communications: mobility modalities: terminal, user, session, service service negotiation for devices with different capabilities automatic configuration and discovery with SLP or similar event notification and triggered actions automatic actions: event filtering, CPL, LESS (for end system services) SIP offers a loosely-coupled approach (cf. Jini or object models) Also need data push functionality Avoid tendency to assume SIP users are human – want to interconnect different components and devices SIP device configuration needs automation, rather than screen- scraping