Rapid development of WSN applications
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The document presents a design flow for developing distributed sensor network applications. It models the application software independently of the hardware architecture to ensure separation of concerns. The design flow considers the constraints of sensor networks, such as limited resources and timing requirements. It facilitates application development through performance analysis and optimal mapping of application processes to sensor nodes. A case study is presented on an industrial multimedia sensor network application developed using this flow.
Rapid development of WSN applications
- 1. Alexios Lekidis, Paraskevas Bourgos, Simplice Djoko-Djoko, Marius! Bozga, Saddek Bensalem! Univ. Grenoble Alpes, VERIMAG, F-38000 Grenoble, France! CNRS, VERIMAG, F-38000 Grenoble, France! IEEE Sensors Applications Symposium! Zadar, Croatia ! 12-15 April, 2015! Building Distributed Sensor Network Applications using BIP! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 1/33!
- 2. Sensor Networks: Application domains! EnvironmentHealthcare Transportation High-energy physics Manufacturing Agriculture
- 3. EnvironmentHealthcare Transportation High-energy physics Manufacturing Agriculture and many more… Sensor Networks: Application domains!
- 4. Outline! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 2/33! 1) Sensor Networks: Overview and development challenges 2) Proposed design flow • Modeling the Applica?on So@ware in PPM • Code genera?on in Distributed Sensor Network PlaEorms • Background on BIP 3) Case study: Industrial Mul?media WSN Applica?on • Code genera?on from the PPM Applica?on Model • Construc?on of the System Model in BIP • BIP System Model Calibra?on 4) Conclusion and ongoing work
- 5. Outline! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 2/33! 1) Sensor Networks: Overview and development challenges 2) Proposed design flow • Modeling the Applica?on So@ware in PPM • Code genera?on in Distributed Sensor Network PlaEorms • Background on BIP 3) Case study: Industrial Mul?media WSN Applica?on • Code genera?on from the PPM Applica?on Model • Construc?on of the System Model in BIP • BIP System Model Calibra?on 4) Conclusion and ongoing work
- 6. Sensor networks: Device constraints! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 3/33! BaMery life?me is limited.. What happens in case of failure? • Scarce resources • Communica?on cost • Consumed energy • Memory usage • Network bandwidth
- 7. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 3/33! BaMery life?me is limited.. What happens in case of failure? • Scarce resources • Communica?on cost • Consumed energy • Memory usage • Network bandwidth Sensor networks: Device constraints!
- 8. Sensor networks: Timing constraints! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 4/33! • Many applica?on require accurately 3mestamped data
- 9. Sensor networks: Timing constraints! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 4/33! • Many applica?on require accurately 3mestamped data • Characteristic example: Multimedia Wireless Sensor Network (MWSN) applications
- 10. Sensor networks: Timing constraints! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 5/33! • Each sensor node has a fixed ?me granularity which varies according to the opera?ng frequency of its clock Clock Time C(t) Real Time t (Faster clock) (Reference clock) (Slower clock) t2 t1 t0 t0
- 11. Sensor networks: Timing constraints! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 5/33! How to obtain a common time reference in a distributed system? Solution: Clock synchronization Clock Time C(t) Real Time t (Faster clock) (Reference clock) (Slower clock) t2 t1 t0 t0
- 12. Sensor networks: Clock synchronization! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 6/33! • Several well known-‐protocols opera?ng either in the so6ware or hardware level • Target synchroniza3on accuracy: Microsecond scale (μs) • Improved accuracy with enhancements as: • Round-‐Trip Delay (RTD) calcula?on • Requires more energy • Dedicated drivers for hardware access • May not be available in lightweight environments
- 13. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 6/33! Sensor networks: Clock synchronization! RTD calcula3on in Precision Time Protocol (PTP) • Several well known-‐protocols opera?ng either in the so6ware or hardware level • Target synchroniza3on accuracy: Microsecond scale (μs) • Improved accuracy with enhancements as: • Round-‐Trip Delay (RTD) calcula?on • Requires more energy • Dedicated drivers for hardware access • May not be available in lightweight environments
- 14. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 6/33! • Several well known-‐protocols opera?ng either in the so6ware or hardware level • Target synchroniza3on accuracy: Microsecond scale (μs) • Improved accuracy with enhancements as: • Round-‐Trip Delay (RTD) calcula?on • Requires more energy • Dedicated drivers for hardware access • May not be available in lightweight environments • Promising protocol family using the Kalman filter algorithm • Dynamically adap?ng to the advance of the reference clock Sensor networks: Clock synchronization!
- 15. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 7/33! • Heterogeneity of devices • Communica?on latencies • Conflicts in message passing through the protocol stack Sensor networks: Application development! Considerable cost in 3me and development effort No guarantee that design errors are fixed before deployment makeSense project (www.project-‐makesense.eu)
- 16. P1 P2 P2 P3 P4 Application Software Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 8/33! Master Sound card Wifi card Node 1 WiFi Access Point (AP) Slave Sound card Wifi card Node N Sensor networks: Application deployment! Sensor Network Distributed Platform
- 17. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 8/33! Master Sound card Wifi card Node 1 WiFi Access Point (AP) Slave Sound card Wifi card Node N Sensor networks: Application deployment! Application Software Sensor Network Distributed Platform P1 P2 P2 P3 P4
- 18. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 8/33! Master Sound card Wifi card Node 1 WiFi Access Point (AP) Slave Sound card Wifi card Node N Sensor networks: Application deployment! How to choose which application process goes to ! which sensor node? Sensor Network Distributed Platform Application Software P1 P2 P2 P3 P4
- 19. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 9/33! • Design flow for the development of func3onal WSN applica?ons • Ensures separa3on of concerns • Applica?on So6ware and hardware architecture considered independently • Deployment based on the op?mal methodology for each applica?on • Model-‐based: Modularity, reusability of ar3facts • Considers all the constraints of sensor networks and facilitates applica?on development through: • Performance Analysis of system requirements • Automated Code Genera3on Proposed method!
- 20. Outline! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 10/33! 1) Sensor Networks: Overview and Development Challenges 2) Proposed Design flow • Modeling the Applica?on So@ware in PPM • Code genera?on in Distributed Sensor Network PlaEorms • Background on BIP 3) Case study: Industrial Mul?media WSN Applica?on • Code genera?on from the PPM Applica?on Model • Construc?on of the System Model in BIP • BIP System Model Calibra?on 4) Conclusion and ongoing work
- 21. Application Software (PPM) Mapping/HW information (PPM) Sensor Network HW Specifications (XML) Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 11/33! Design flow for WSN Applications ! Inputs
- 22. Abstract System Model (BIP) Application Software (PPM) modeling (1) Mapping/HW information (PPM) Sensor Network HW Specifications (XML) Sensor Network Library Components (BIP) code generation (2) Sensor Network C/C++ Code Sensor Network/ HW Code Templates +Configurations Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 11/33! Design flow for WSN Applications ! Developed framework
- 23. Abstract System Model (BIP) Application Software (PPM) System Model (BIP) modeling (1) SMC calibration (3) Mapping/HW information (PPM) Sensor Network HW Specifications (XML) Sensor Network Library Components (BIP) code generation (2) analysis (4) Sensor Network C/C++ Code Execution Sensor Network/ HW Code Templates +Configurations Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 11/33! Design flow for WSN Applications ! Outputs
- 24. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 12/33! Abstract System Model (BIP) Application Software (PPM) System Model (BIP) modeling (1) SMC calibration (3) Mapping/HW information (PPM) Sensor Network HW Specifications (XML) Sensor Network Library Components (BIP) code generation (2) analysis (4) Sensor Network C/C++ Code Execution Sensor Network/ HW Code Templates +Configurations Design flow for WSN Applications !
- 25. Pragmatic Programming Model (PPM)! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 13/33! • Descrip?on language facilita?ng the development of sensor network applica3ons • XML format providing the possibility to reference C files as external libraries • Applica?on So@ware described as a network of communica3ng processes • Communica?on through shared objects, such as: • FIFO • Shared memory • Mutexed loca?on
- 26. PPM Example: Application Software! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 14/33! synchro PLL FIFO Process Process
- 27. PPM Example: XML description ! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 14/33! <header lang="c" file="global.h"/> <process name="pll" process-‐class="WhileFire"> <port name="out" peer-‐class="FIFO" peer-‐name="in"/> <header lang="c" file="pll_state.h" x-‐state="true"/> <header lang="c" file="pll.h"/><source lang="c" file="pll.c”> <source lang="c" file="SPM_clock.c" libs="-‐lblas -‐lm -‐lrt"/> </process> ... <shared-‐object name="SO1" object-‐class="FIFO" size="4" item-‐size="64"> <port name="in"/> <port name="out"/> </shared-‐object> ... <connec?on> <port-‐ref node="SO1" port="out"/> <port-‐ref node="pll" port="in"/> </connec?on> synchro PLL FIFO Process Process
- 28. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 14/33! #include "pll_process.h” void pll_init(pll_process *p) { (p-‐>local-‐>pll).stream_size = 1; (p-‐>local-‐>pll).block_size = (unsigned int) sizeof(clockOut_t); (p-‐>local-‐>pll).data_in = malloc((p-‐>local-‐>pll).block_size); p-‐>local-‐>data_size = (p-‐>local-‐>pll).block_size; } int pll_fire(pll_process *p) { FIFO_read(p-‐>in, (p-‐>local-‐>pll).data_in, (p-‐>local-‐>pll).block_size); gelmeofday ( &(p-‐>local-‐>slave_?me), NULL ); uint64_t slave_clock = ( ( uint64_t ) p-‐>local-‐>slave_?me.tv_sec * ( uint64_t ) 1000000 ) + ( uint64_t ) p-‐>local-‐>slave_?me.tv_usec; clockOut_t* master_frameClock = ( clockOut_t* ) (p-‐>local-‐>pll).data_in; master_clock = master_frameClock-‐>?me; pll_clock_in ( slave_clock, master_clock, p-‐>local-‐>argument); return 0; } PPM Example: Process behavior! • Described as the program: • P init();while(true)P fire(); • Communica?on through: • Read (e.g. FIFO_read) • Write (e.g. FIFO_write) synchro PLL FIFO Process Process
- 29. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 14/33! PPM Example: Application deployment! Master Sound card Wifi card WiFi Access Point (AP) Slave Sound card Wifi card UDOO Node N UDOO Node 1 synchro PLL FIFO Process Process
- 30. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 14/33! <deployment> <app-‐node name="pll"/> <hw-‐element name="node" hw-‐class="udoo" index="0"/> <hw-‐property name="networkInterface" hw-‐class="node-‐inter" value="wlan0"/> <hw-‐property name="srcPort" hw-‐class="node-‐srcPort" value="375"/> <hw-‐property name="dstPort" hw-‐class="node-‐dstPort" value="250"/> <hw-‐property name="dstIP" hw-‐class="node-‐dstIP" value="10.0.0.14"/> </deployment> PPM Example: Application deployment! synchro PLL FIFO Process Process
- 31. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 15/33! • Each process is implemented as a thread • Threads allocated to sensor nodes according to applica?on deployment in PPM • Shared objects implemented according to the underlying hardware plaUorm • FIFO_read and FIFO_write primi?ves replaced by API func3on calls of the supported communica?on protocol (i.e. Linux sockets parameterized with the UDP protocol) • Applica?on Deployment also used to define configura?on parameters for the communica?on protocols • Generated code is implemented using re-‐targetable template files • Portable since it can be deployed and run in any hardware plaUorm suppor?ng Linux sockets PPM Example: Code Generation!
- 32. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 16/33! memcpy ( self.buffer, f -‐> data_in, f -‐> block_size ); iCom = sendto ( self.sock, self.buffer, self.buffer_size, 0, (struct sockaddr*) (&(self.dst_addr)), sizeof(self.dst_addr) ); if ( iCom == -‐1 ) { prinE ( "COM_eth_udp_lin process (sendto) error (%d) : %sn", errno, strerror(errno) ); return ( -‐1 ); } memset ( &recvfrom_addr, 0,sizeof( recvfrom_addr ) ); iCom = recvfrom ( self.sock, self.buffer, self.buffer_size, 0, (struct sockaddr*) &recvfrom_addr, &recvfrom_addr_len ); if ( iCom == -‐1 ) { prinE ( "COM_eth_udp_lin process (recvfrom) error (%d) : %sn", errno, strerror(errno) ); return ( -‐1 ); } PPM Example: Code Generation! synchro PLL FIFO Process Process
- 33. Abstract System Model (BIP) Application Software (PPM) System Model (BIP) modeling (1) SMC calibration (3) Mapping/HW information (PPM) Sensor Network HW Specifications (XML) Sensor Network Library Components (BIP) code generation (2) analysis (4) Sensor Network C/C++ Code Execution Sensor Network/ HW Code Templates +Configurations Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 17/33! Design flow for WSN Applications !
- 34. • BIP (Behavior-‐Interac?on-‐Priority) is a formal language for the hierarchical construc?on of heterogeneous real-‐?me systems • Provides a rich set of tools for analysis and performance evalua?on B E H A V I O R Interactions (collaboration)! Priorities (conflict resolution)! The BIP component framework! Composi?on glue Atomic components Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 18/33!
- 35. BIP component example! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 19/33! • Atomic component modeling the PLL process
- 36. BIP component example! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 19/33! • Atomic component modeling the PLL process • BIP components: transi?on systems enriched with data and func?ons in C/C++
- 37. BIP component example! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 19/33! • Atomic component modeling the PLL process • BIP components: transi?on systems enriched with data and func?ons in C/C++ • Interac?ons used to transfer data between components
- 38. BIP component example! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 19/33! • Atomic component modeling the PLL process • BIP components: transi?on systems enriched with data and func?ons in C/C++ • Interac?ons used to transfer data between components • Priori?es enforce scheduling policies amongst possible interac?ons CLK_REQ<CLK_RECV
- 39. The BIP component framework! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 20/33! • Func3onal verifica3on • BIP state-‐space explora3on tool used to verify safety requirements, such as deadlock-‐freedom, in the constructed models • Model calibra3on based on code execu?on in the target HW plaEorm • HW/SW dependent constraints injected in the form of probabilis?c distribu?ons • Aims in obtaining faithful models for a considered system • Performance Analysis of applica?on or system-‐level requirements • Sta3s3cal Model Checking (SMC) tool for quan?ta?ve verifica?on • Results provide feedback in the applica?on design/development phase Supports:
- 40. Outline! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 21/33! 1) Sensor Networks: Overview and Development Challenges 2) Proposed Design Flow • Modeling the Applica?on So@ware in PPM • Code genera?on in Distributed Sensor Network PlaEorms • Background on BIP 3) Case study: Industrial Mul?media WSN Applica?on • Code genera?on from the PPM Applica?on Model • Construc?on of the System Model in BIP • BIP System Model Calibra?on 4) Conclusion and ongoing work
- 41. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 22/33! Case study: Industrial WMSN Application ! • Clock Synchroniza?on in a Mul?media Wireless Sensor Network (WMSN) • Capturing and reproduc3on of synchronized audio data in the sink • Use of the API provided by the Advanced Linux Sound Architecture (ALSA) • Sender-‐to-‐receiver synchroniza3on Master Node Slave Node Slave Node Access Point (AP)
- 42. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 22/33! Case study: Industrial WMSN Application ! • Clock Synchroniza?on in a Mul?media Wireless Sensor Network (WMSN) • Capturing and reproduc3on of synchronized audio data in the sink • Use of the API provided by the Advanced Linux Sound Architecture (ALSA) • Sender-‐to-‐receiver synchroniza3on • Snowball SDK plaEorm configured as AP in the WSN (sta?c ad-‐hoc DHCP server capable of assigning automa?cally IP addresses) • 3 UDOO plaEorms automa?cally connected to the WSN through the AP (1 Master, 2 Slave nodes) • Master UDOO node broadcasts periodically (T=5s) a ?mestamp frame • Phase Locked Loop (PLL) synchroniza3on technique applied in the slave UDOO nodes to construct a so6ware clock • The so@ware clock follows the advance of the Master node’s clock and maintains a rela?ve offset from it
- 43. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 23/33! Case study: PPM Model!
- 44. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 24/33! Case study: WMSN Application deployment!
- 45. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 25/33! Case study: Abstract BIP System Model!
- 46. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 26/33! Case study: System Model Calibration!
- 47. ρ1 ρ3 λok ρ2 λfail λdelay Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 26/33! Case study: System Model Calibration!
- 48. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 27/33! Case study: Distribution fitting! • Method used to obtain each distribu?on: • Special case of model fiYng • Target model is a probability distribu3on • Relying on sta?s?cal methods in order learn the best probability distribu?on that fits the obtained execu3on data
- 49. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 27/33! Probability distribu3on (λdelay) Box-‐Whisker plot (λdelay) Case study: Distribution fitting! • Method used to obtain each distribu?on: • Special case of model fiYng • Target model is a probability distribu3on • Relying on sta?s?cal methods in order learn the best probability distribu?on that fits the obtained execu3on data
- 50. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 27/33! Probability distribu3on (λdelay) Box-‐Whisker plot (λdelay) Outliers Mean Case study: Distribution fitting! • Method used to obtain each distribu?on: • Special case of model fiYng • Target model is a probability distribu3on • Relying on sta?s?cal methods in order learn the best probability distribu?on that fits the obtained execu3on data
- 51. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 28/33! Case study: Analysis results! • The calibrated BIP system model was used for tes?ng: • Cri?cal func?onal and non-‐func?onal requirements, such as buffer u3liza3on • The synchroniza3on accuracy • We have expressed the following proper?es: 1) What is the probability of overflow/underflow avoidance in the transmission/recep?on buffers of the considered WMSN Applica?on? 2) Is the achieved synchroniza?on accuracy 1μs?
- 52. • Focus: Es?ma?on of the probability for overflow/underflow in the transmission/recep?on buffers of the system • The property is expressed as: 1) φ1 = (size(Sbuffer) < MAX), where MAX=400 2) φ2 = (size(Mbuffer) > 0) Property 1: Buffer utilization! P(φ1) Case study: Property verification! P(φ2) Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 29/33!
- 53. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 30/33! Case study: Property verification! Property 2: Synchronization accuracy! • Focus: Difference between the Master and the Slave so6ware clock should be bounded by a non-‐nega?ve number ∆ • The property is expressed as: φ3 = (|(θM − θS ) − A| < ∆) • A is a fixed offset between the Master and each Slave’s so@ware clock
- 54. Property 2: Synchronization accuracy! System ModelGenerated code Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 30/33! Case study: Property verification! • Focus: Difference between the Master and the Slave so6ware clock should be bounded by a non-‐nega?ve number ∆ • The property is expressed as: φ3 = (|(θM − θS ) − A| < ∆) • A is a fixed offset between the Master and each Slave’s so@ware clock
- 55. System Model Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 30/33! Here A=100μs • For Δ=1μs φ3 is not sa?sfied • For Δ=76μs φ3 is sa3sfied Case study: Property verification! Property 2: Synchronization accuracy! • Focus: Difference between the Master and the Slave so6ware clock should be bounded by a non-‐nega?ve number ∆ • The property is expressed as: φ3 = (|(θM − θS ) − A| < ∆) • A is a fixed offset between the Master and each Slave’s so@ware clock
- 56. Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 30/33! Here A=100μs • For Δ=1μs φ3 is not sa?sfied • For Δ=76μs φ3 is sa3sfied • Also observed from the results of the generated code Generated code Case study: Property verification! Property 2: Synchronization accuracy! • Focus: Difference between the Master and the Slave so6ware clock should be bounded by a non-‐nega?ve number ∆ • The property is expressed as: φ3 = (|(θM − θS ) − A| < ∆) • A is a fixed offset between the Master and each Slave’s so@ware clock
- 57. Conclusions! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 31/33! • Fully-‐fledged design flow for the development of func?onal distributed sensor applica?ons • Automated Code Genera3on and Performance Analysis using as input: • Applica?on So@ware described in PPM (XML format with reference to C/C++ func3ons) • Hardware specifica?on (for the network configura3on) • Mapping specifica?on (for the applica3on deployment) • We have applied it in a Wireless Mul?media Sensor Network (WMSN) Applica?on and our experiments focused on: • Buffer u3liza3on • Synchroniza3on accuracy • Results provide feedback for the proper configura?on of similar applica?ons
- 58. Perspectives! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 32/33! • Adapt the design flow for lower resource consump3on hardware plaUorms, which use dedicated opera?ng systems (e.g. TinyOS, Con3ki OS) • Low amount of data supported in each packet • Packet fragmenta?on may lead to: 1) Collisions in the MAC layer 2) Frequent packet losses • Mechanisms to improve clock synchroniza3on • Reduc?on of the rela?ve offset between the Slave so@ware clock and the Master clock by oscilla3ng the transmission frequency of the Master’s 3mestamp • High frequency rate may lead to higher energy consump3on • Possible change of the Kalman filter algorithm will be considered
- 59. Questions?! Thank you for your attention.! Further details: alexios.lekidis@imag.fr! Lekidis et al.! Building Distributed Sensor Network Applications using BIP! 33/33!