Korea Advanced Institute of Science and Technology
Active Sensor Networks(Mate)(Published by Philip Levis, David Gay, and David Culler in NSDI 2005)
11/11/09Internet System technology
Kim Young-Sun, Choi Sun-Tae
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Table of Content
Introduction
Background
Design
Evaluation
Pros and Cons
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Introduction
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
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Background(Requirement)
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.
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Background(Requirement)
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.
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Background(Mate)
Maté v1.0 - Architecture
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Background(Mate)
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
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Design
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
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Design 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
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Design
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.
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Design
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.11
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Design
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.12
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Design
Building an ASVM
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Evaluation
Concurrency
Propagation
Flexibility: Languages
Flexibility: Applications
Efficiency: Microbenchmarks
Efficiency: Application
Efficiency: Interpretation
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Evaluation
Concurrency measured the overhead of ASVM concurrency
control, using the cycle counter of a mica mote.
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Evaluation
Propagation
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Evaluation
Flexibility: Languages Support three languages
TinyScript
Mottle
TinySQL
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Evaluation
Flexibility: Applications Specific sample ASVMs
RegionsVM
QueryVM
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Evaluation
Efficiency: Microbenchmarks Tradeoff between including functions and
writing
operations in script code… operations are powerful but what about energy
efficient?
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Evaluation
Efficiency: Application QueryVM
motlle-based ASVM execution of TinySQL
data collection queries.
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Evaluation
Efficiency: Application
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Evaluation
Efficiency: Interpretation
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Evaluation(Pros) 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 functions
need to be update frequently
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Evaluation(Cons) 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
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Evaluation(Cons) Flexibility
Application level propagation is very concise.But, we cannot update low level binaries such asan interpreter Flexible enough?
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