Active Sensor Networks(Mate) (Published by Philip Levis, David Gay, and David Culler in NSDI 2005)

1. Internet system technology Active Sensor Networks(Mate) (Published by Philip Levis, David Gay, and David Culler in NSDI 2005) 11/11/09 Internet System technology Kim Young-Sun, Choi Sun-Tae

2. Table of Content Internet system technology • Introduction • Background • Design • Evaluation • Pros and Cons

3. Introduction Internet system technology • Wireless sensor networks have limited resources and • tight energy budgets. • These constraints make in-network processing a prerequisite for scalable and long-lived applications. • as sensor networks are embedded in uncontrolled environments, a user often does not know exactly what the sensor data will look like, and so must be able to reprogram sensor network nodes after deployment. • ※ This paper propose using application specific virtual machines • (ASVMs) to reprogram deployed wireless sensor networks

4. Background(Requirement) Internet system technology • Requirement extraction from Maté v1.0 • Flexibility : Maté VM : Very concise programs, but is designed for a single application domain. To provide support for in-network processing, a runtime must be flexible enough to be customized to a wide range of application domains. • Concurrency : Limited resources and a constrained application domain allowed Mate to address the corresponding synchronization and atomicity issues by only having a single shared variable. This restriction is not suitable for all VMs.

5. Background(Requirement) Internet system technology • Propagation : As every handler could fit in a single packet, these instructions were just a simple broadcast. it requires every program to include propagation algorithms. As not all programming models can fit their programs in a single packet, a runtime needs to be able to handle larger data images and should provide an efficient but rapid propagation service. • To provide useful systems support for a wide range of programming models, a runtime must meet these three requirements without imposing a large energy burden.

6. Background(Mate) Internet system technology • Maté v1.0 - Architecture

7. Background(Mate) Internet system technology • Maté v1.0 - instructions • 0 OPhalt 0x00 00000000 • 1 OPreset 0x01 00000001 clear stack • 2 OPand 0x02 00000010 push($0 & $1), 3 OPor 0x03 00000011 push($0 | $1) … SCLASS • 72 OPgetmb 0x48-4f 01001xxx push(byte xxx from msg header) • 108 OPsetfs 0x70-77 01110xxx short xxx of frame = $0 … XCLASS • 128 OPpushc 0x80-bf 10xxxxxx push(xxxxxx) (unsigned) • 192 OPblez 0xC0-ff 11xxxxxx if ($0 <= 0) jump xxxxxx

8. Design Internet system technology • ASVMs have three major abstractions. • Handlers : Code routines that run in response to system events • Operations : The units of execution functionality • Capsules : The units of code propagation

9. Design Internet system technology • The components of an ASVM. • Template : Which every ASVM includes - Scheduler : executes runnable threads in a FIFO round-robin fashion - Concurrency manager : controls what Threads are runnable, ensuring race-free and deadlock-free handler execution - Capsule store : manages code storage and loading, propagating code capsules and notifying the ASVM when new code arrives • Extensions : The application-specific components that define a particular ASVM

10. Design Internet system technology • Scheduler : Execution • The core of an ASVM : a simple FIFO thread scheduler. • Maintains a run queue. • Interleaves execution at a very fine granularity. • Executes a thread by fetching its next bytecode from the capsule store. • Dispatching to the corresponding operation component through a nesC parameterized interface.

11. Design Internet system technology • Concurrency Manager : Parallelism • The concurrency manager of the ASVM template supports race free execution through implicit synchronization based on a handler’s operation. • When a handler event occurs, the handler’s implementation submits a run request to the concurrency manager. • The concurrency manager only allows a handler to run if it can exclusively access all of the shared resources it needs.

12. Design Internet system technology • Capsule Store: Propagation • ASVM template’s capsule store follows a policy of propagating new code to every node. (Rather than selective propagation) but only some nodes execute it. • To propagate code,capsule store maintains three network trickles - Version packets, which contain the 32-bit version numbers of all installed capsules, - Capsule status packets, which describe what fragments a mote needs (essentially, a bitmask) - Capsule fragments, which are pieces of a capsule.

13. Design Internet system technology • Building an ASVM

14. Evaluation Internet system technology • Concurrency • Propagation • Flexibility: Languages • Flexibility: Applications • Efficiency: Microbenchmarks • Efficiency: Application • Efficiency: Interpretation

15. Evaluation Internet system technology • Concurrency • measured the overhead of ASVM concurrency control, using the cycle counter of a mica mote.

16. Evaluation Internet system technology • Propagation

17. Evaluation Internet system technology • Flexibility: Languages • Support three languages • TinyScript • Mottle • TinySQL

18. Evaluation Internet system technology • Flexibility: Applications • Specific sample ASVMs • RegionsVM • QueryVM

19. Evaluation Internet system technology • Efficiency: Microbenchmarks • Tradeoff between including functions and writingoperations in script code… • operations are powerful but what about energy efficient?

20. Evaluation Internet system technology • Efficiency: Application • QueryVM • motlle-based ASVM • execution of TinySQLdata collection queries.

21. Evaluation Internet system technology • Efficiency: Application

22. Evaluation Internet system technology • Efficiency: Interpretation

23. Evaluation(Pros) Internet system technology • Performance • Low power consumption • very efficient propagation • can be optimized in specific condition • Developer's view • an ASVM would be a component in TinyOS • When a developer has to choose an OS for WSN… • Choose TinyOS and utilize an ASVM for functionsneed to be update frequently

24. Evaluation(Cons) Internet system technology • Approach • Extend and generalize prior work (Maté) • Maintain basic characteristics of prior work • Impact and influence could be restricted • Performance • High-level abstraction might not be helpful to implement complex algorithms • Would be appropriated for specific situations • Updates occur frequently • Long term, low-duty-cycle data collection

25. Evaluation(Cons) Internet system technology • Flexibility • Application level propagationis very concise.But, we cannot update low level binaries such asan interpreter • Flexible enough?