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Middleware for Cooperative Computing on Large Ad-hoc Networks of Embedded Systems*

Middleware for Cooperative Computing on Large Ad-hoc Networks of Embedded Systems*. Cristian Borcea, Deepa Iyer, Porlin Kang, Akhilesh Saxena and Liviu Iftode Division of Computer and Information Sciences Rutgers University http://discolab.rutgers.edu/sm/

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Middleware for Cooperative Computing on Large Ad-hoc Networks of Embedded Systems*

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  1. Middleware for Cooperative Computing on Large Ad-hoc Networks of Embedded Systems* Cristian Borcea, Deepa Iyer, Porlin Kang, Akhilesh Saxena and Liviu Iftode Division of Computer and Information Sciences Rutgers University http://discolab.rutgers.edu/sm/ *This work is supported in part by NSF Grant ANI-0121416

  2. Motivation • Pervasive Computing = Large Ad-hoc Networks of Embedded Systems • Examples: sensor networks, car networking on a highway, network of appliances at home • How to perform distributed tasks on these networks ? • Simple tasks: data collection, data dissemination • How to program these networks to execute user-defined distributed tasks ?

  3. Example of a Distributed Task 75 F 85 F 75 F 95 F 75 F 85 F 0 F 70 F 80 F 80 F 80 F Determine average temperature in town

  4. Traditional Message-Passing Distributed Computing Does Not Work • Number of nodes is extremely large • how to name nodes ? • Only selected nodes are of interest • how to find them ? • Dynamic configuration • nodes come and go, or become inaccessible • No routing support • end-to-end semantics hard to provide

  5. Our Solution: Cooperative Computing • Cooperative node middleware • an architecture-independent execution environment: VM • a name-based global memory space: Tag Space • simple admission control, scheduling and synchronization • Smart Messages (SM): migratory execution units • multiple code and data bricks plus execution state • handler for content-based addressing • migrate through the network and execute on each hop • self-routing

  6. Node Architecture Virtual Machine Admission Manager Tag Space Incoming SM Outgoing SM Embedded System

  7. Tag Space Name ACL Lifetime Data Temperature TempACL 7200 80 Image ImgACL 300 Img.jpg • Named data persistent across SM execution • Protected • Limited lifetime • Operations: create, delete, read(get), write(put)

  8. Smart Message Execution Cycle SM2 Tag Space SM1 d2 c2 d2 d1 c2 c1 VM SM1 d2 d1 c2 c1 Node • Admission (SM presents a resource table to node) • Conditional arrival (use handler to check for tags of interest) • Execution (possible blocking on tags to be updated) • Spawning new SM • Migration or exit

  9. Smart Message Primitives • construct_SM(code_bricks, data_bricks, handler) • send(sm, destination) • send_myself(destination) • returns 0 in the SM that was sent • returns SM id in the sender SM • migrate(destination) • SM continues at destination • block(tag, count, timeout) • SM blocks waiting for count writes on tag or timeout

  10. Proof of Concept • Implement two simple applications for sensor networks using SM • data collection: Directed Diffusion [ESTRIN ’99] • data propagation: SPIN [HEINZELMAN ’99] • Evaluate their performance using an SM network simulator

  11. Directed Diffusion – Explore Mobile SM.data, SM.sender; /* Exploration Phase */ while (!get_tag(DATA_RATE)) { /* flood to source; wait for rate */ if (send_myself(forward_neighbors)) block(DATA_RATE, count(forward_neighbors), timeout) } if (SM.sender) { /* send rate back, if not sink*/ SM.data = get_tag(DATA_RATE); migrate(SM.sender); tempData = get_Tag(DATA_RATE); if (SM.data > tempData) { put_tag(SM.sender, BEST_ROUTE); put_tag(SM.data, DATA_RATE); } else { put_tag(tempData, DATA_RATE); /* increments count for block */ } exit(); }

  12. Directed Diffusion - Reinforce /* Reinforcement Phase */ while (!get_tag(DATA_VALUE)) /* send to source; wait for data*/ if (send_myself(get_tag(BEST_ROUTE)) block(DATA_VALUE, 1, timeout); for(;;) { SM.data = get_tag(DATA_VALUE); if (SM.sender){ /* send data back, if not sink */ if (send_myself(SM.sender)==0) { put_tag(SM.data, DATA_VALUE); exit(); } } else /* output of the sink */ output (DATA_VALUE) block(DATA_VALUE, 1, timeout); /* wait for new data */ }

  13. SPIN for(;;) { block(DATA_VALUE,1, timeout); /* wait new data */ SM.data = get_tag(DATA_TIME); if (send_myself(all_neighbors)==0) { /* send ad */ if (get_tag(DATA_TIMESTAMP)>=SM.data) exit(); put_tag(DATA_TIME, SM.data) /* ad update time and */ if (send_myself(SM_sender)==0) { /* request data */ SM.data = get_tag(DATA_VALUE); migrate(SM.sender); put_tag(DATA_VALUE, SM.data); /* bring data */ exit(); } /* go to wait for data */ } else if (SM_sender) /* if not source */ exit(); /* exit after sending ad */ }

  14. Preliminary results

  15. Status and Future Plans • Prototype using iPAQs and Bluetooth under development • Design advanced ad-hoc routing algorithms using SM • Develop distributed applications for networks of embedded systems using SM

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