Secure Language-Based Adaptive Service Platform (SLAP) for Large-Scale Embedded Sensor Networks David Culler Eric Brewer Dave Wagner Shankar Sastry Kris Pister University of California, Berkeley

6/5/2001NEST Kickoff Wireless OEP2 OEP will deliver to you... An Open, interesting, flexible, low-power experimental wireless sensor/actuator platform early in the program –6 months, then 30 months at significant scale –100+ tiny nodes per kit With a novel event-driven tiny component OS –easily customized to particular applications FSM programming environment for distributed control algorithms and applications Powerful adversarial simulation environment Empirical test-bed facility and develop a challenge application

6/5/2001NEST Kickoff Wireless OEP3 Composition of the Team David E Culler (PI). Networked systems: architecture, OS, PL. NOW, Active Messages, TAM, dataflow. Eric Brewer. SW Arch. Scalable Services. Inktomi, Ninja, BARWAN, infopad. David Wagner. Security, PL. Twofish, WEP, Janus. Shankar Sastry. Distributed Control, Robotics, Game theory. Kris Pister. MEMS, low-power design, microrobotics. SmartDust. Collaboration with Intel Berkeley Lab, crossbow.

6/5/2001NEST Kickoff Wireless OEP4 low-power radio signal-strength sense and control 1 in 1.5 in one inch motherboard Flexible, low-power wireless platform secondary storage integrated microcontroller std expansion connector I 2 C, SPI, analog,... appln specific sensors power reg & monitor packaging

6/5/2001NEST Kickoff Wireless OEP5 Current Prototype system board –ATMEL 4Mhz, 8bit MCU, 512 bytes RAM, 8K pgm flash –900Mhz Radio (RF Monolithics) ft. range –ATMEL network pgming assist –Radio Signal strength control and sensing –I2C EPROM (logging) –Base-station ready –stackable expansion connector »all ports, i2c, pwr, clock… sensor boards –basic photo, temp + proto –vibrations (2d acc, temp, LIGHT) –accelerometers –magnetometers –tiny weather station (temp,light,hum,press) –current, temp, light power controller 15 mA peak, 15uA standby

6/5/2001NEST Kickoff Wireless OEP6 Platform Roll-Out Phase 6 months => algorithm studies –inch-scale, low-power, 900 MHz wireless, sense/act nodes –TinyOS event-driven system environment –100+ nodes base-stations, tinyOS, tools for < 25K$ –Jan Tutorial Workshop Phase 2: 30 months => composition of alg’s –similar physical scale and numbers –ARM power, Bluetooth phy –integrated system –Secure NEST OS –FSM programming with resilient aggregation –Tutorial Workshop Phase 3: 40 months ultra-low power design study

6/5/2001NEST Kickoff Wireless OEP7 SW Platform Tiny event-driven component OS –allows NEST abstractions to emerge and each level Language-based robustness and optimization –eg., critical path and jitter analysis –inter-component transformations –narrow interface with simple IDL Tiny networking –power-aware appln-specific ad hoc routing, MAC, transmission control –in network aggregation –in situ programming Algorithm building blocks –Local multicast –event-driven reception –intelligent pruning of retransmission –non-blocking execution

6/5/2001NEST Kickoff Wireless OEP8 Tiny OS: Concepts Scheduler + Graph of Components –constrained two-level scheduling model: threads + events Component: –Commands, –Event Handlers –Frame (storage) –Tasks (concurrency) Constrained Storage Model –frame per component, shared stack, no heap Rich expression of concurrency Very lean multithreading Efficient Layering Messaging Component init Power(mode) TX_packet(buf) TX_pack et_done (success ) RX_pack et_done (buffer) Internal State init power(mode) send_msg (addr, type, data) msg_rec(type, data) msg_sen d_done) internal thread Commands Events

6/5/2001NEST Kickoff Wireless OEP9 TinyOS: Application = Component Graph RFM Radio byte Radio Packet UART Serial Packet ADC Tempphoto Active Messages clocks bit byte packet Route map routersensor appln application HW SW Example: ad hoc, multi-hop routing of photo sensor readings entire: 3.5 kb typical comp: 100s b

6/5/2001NEST Kickoff Wireless OEP10 Programming Environment & Tools Provide support for: event-driven programming, composition, debugging & visualization in the small (node) and large (collection) Emulation => simulation => real devices –identical APIs, range of visibility, and reality Debugging and visualization tools –geared toward many interacting nodes & event-centric development Application-Specific Virtual Machines –analogous to query-plan vs query-processing engine FSM-based programming abstractions Macrocomputing

6/5/2001NEST Kickoff Wireless OEP11 FSM-based Software Approach Fundamentally, we are not computing, we are moving data intelligently –threads are a computing abstraction, FSMs are a protocol abstraction  use FSMs as the base then add some computing natural high concurrency natural handling of events, exceptions, and the environment tools for understanding stability (e.g markov models, game theory, control theory) composition is separate from creation –late bind the callee in a separate step called "composition"

6/5/2001NEST Kickoff Wireless OEP12 Macrocomputing Program a large, unstructured collection in aggregate –Single program, multiple data »but errors and probabilistic behavior »unstructured collection –“global” variables that reflect collections »need to handle error propagation –scatter/gather for collections? –online query processing? multi-WEbS abstractions

6/5/2001NEST Kickoff Wireless OEP13 Security Individual nodes may be compromised, but hard to get large fraction of nodes. Attacks introduce another form of unreliability in the data. Lightweight encryption/decryption, authentication. Novel protocols to support aggregate operations, eg., broadcast, w/o shared root key Resilient aggregation

6/5/2001NEST Kickoff Wireless OEP14 Resilient Aggregators operate in the face of faulty nodes, intermittent communication, and security attacks –ex max is not resilient, nine-tile is. develop algebra of resilient aggregators Random sampling as implementation foundation for security model –easy to attack a node –hard to attack large fraction of the nodes

6/5/2001NEST Kickoff Wireless OEP15 Simulation Large-scale NEST simulator –very large number of small nodes –integrated with event-driven OS design for efficiency –checkpointing Adversarial simulation mode –Detecting “composition” bugs and scaling bugs Target failure: search for bugs –test race conditions automatically –pick orders that consume resources –more efficient than random-walk testing –simulator is an adversary… –guided search Hybrid simulator/testbed

6/5/2001NEST Kickoff Wireless OEP16 Test-bed Kits in situ programming/upgrade and debugging synchronized logging (trace extraction) passive monitoring data collection

6/5/2001NEST Kickoff Wireless OEP17 Challenge App: pursuer/evader contest obstacles evader UAVs active markers UAVs (pursuers) capable of: *flying between obstacles *seeing a limited region *placing active markers Terrain: with obstacles *not accurately mapped Evader capable of: *moving between obstacles (possibly actively avoiding detection) Active Markers : *form sensor field

6/5/2001NEST Kickoff Wireless OEP18 Closed-loop at many levels Within a node –behavior adapts to available energy, physical measurements, network condition Across the network –discovery and routing, transmission rate and schedule –adopting roles, Within the middleware components –synchronization, scheduling On the vehicle –direction, stability, probabalistic map building Among the vehicles –competitive, hidden markov decision processes

6/5/2001NEST Kickoff Wireless OEP19 Intermediate Applications “active space” starter –steerable cameras and other fixed assets –mobile agents with transponders –stationary (partially) sensor field –interactive control loop “flocks” of moving vehicle intermediate

6/5/2001NEST Kickoff Wireless OEP20 Integration & Linkages Receive platform wish-list till aug. freeze Major tutorial workshop to deliver platform and train at 6 and 30 months –SW platform releases ~every 6 months Intermediate SW platform releases Push platform kits so middleware developed AND tested in your labs at scale with real limits Group archive, calendar, etc – –mailto: Sequence of application development forums

6/5/2001NEST Kickoff Wireless OEP21 Specific Problems addressed Unattended, low-power, small form-factor connected devices deployed in large number Tiny OS for comm/sense/control Power Constrained Networking, Security Programming environment and tools –component analysis and optimization –FSM programming & composition –Resilient Aggregation Macrocomputing: programming the collection Analysis and testing of integrated distributed systems Pursuer/Evader challenge in fine-grain distributed control