![DeclarativeConcentrate on “What” rather than “How”.The programs are concise.qsort([]) -> [];qsort([Pivot|T]) -> qsort([X || X <- T, X =< Pivot]) ++ [Pivot] ++ qsort([X || X <- T, X > Pivot]).Programs are readable and easy to maintain.It increases productivity.](https://image.slidesharecdn.com/erlangrealtime-100821061326-phpapp02/85/Erlang-real-time-13-320.jpg)
![ConcurrencyCreate a processPid = spawn(Module, fun, [Arguments])Send and receivePid ! message receive message1 -> actions1; message2 -> actions2; …… after Time -> time out actions; end.](https://image.slidesharecdn.com/erlangrealtime-100821061326-phpapp02/85/Erlang-real-time-15-320.jpg)
![An example -module(echo). -export([start/0, loop/o]). start() -> Pid = spawn (echo, loop, [ ] ),Pid ! { self (), hello}, receive { Pid, Msg } ->io:format ( “~w~n”, [Msg]) end,Pid ! stop.loop() -> receive { From, Msg } -> From ! { self(), Msg}, loop(); stop -> true end.{<0.1.0>, hello}{<0.1.0>, hello}shellPid{<0.2.0>, hello}stop<0.1.0><0.2.0>](https://image.slidesharecdn.com/erlangrealtime-100821061326-phpapp02/85/Erlang-real-time-16-320.jpg)
Erlang real time
- 1. Study of Erlang for Building Real-Time SystemsByDinesh RajpootRoll no. 09305043Under the guidance of Prof. Kavi AryaAugust 20, 2010
- 4. Declarative
- 5. Concurrency
- 8. Multi Core Programming Applications of ErlangRobot Programming in Erlang
- 10. Case Study(Adaptive Cruise Control)
- 11. Conclusion and Future Work
- 12. ReferencesIntroduction to ErlangErlang was designed by Ericcson.It is a functional programming language.Variables are immutable.No side- effect(pure functions)Referential Transparency Int G =1; \\ G is globalintplusG(int x){ return x + G;}intplusOne(int x){ return x+1;}
- 13. DeclarativeConcentrate on “What” rather than “How”.The programs are concise.qsort([]) -> [];qsort([Pivot|T]) -> qsort([X || X <- T, X =< Pivot]) ++ [Pivot] ++ qsort([X || X <- T, X > Pivot]).Programs are readable and easy to maintain.It increases productivity.
- 14. ConcurrencyEach concurrent activity is called “process”.Processes don’t share data.Processes belong to language not operating system.Processes communicate through “message passing”not shared memory.Less process creation and message passing time.
- 15. ConcurrencyCreate a processPid = spawn(Module, fun, [Arguments])Send and receivePid ! message receive message1 -> actions1; message2 -> actions2; …… after Time -> time out actions; end.
- 16. An example -module(echo). -export([start/0, loop/o]). start() -> Pid = spawn (echo, loop, [ ] ),Pid ! { self (), hello}, receive { Pid, Msg } ->io:format ( “~w~n”, [Msg]) end,Pid ! stop.loop() -> receive { From, Msg } -> From ! { self(), Msg}, loop(); stop -> true end.{<0.1.0>, hello}{<0.1.0>, hello}shellPid{<0.2.0>, hello}stop<0.1.0><0.2.0>
- 17. 1,000erlangjavaC#100Microseconds/process101101001,00010,000100,000Number of processesProcess creation times (LOG/LOG scale)> 200,000processesSource:Joe ArmstrongSICS
- 18. 100,000erlangjava10,000C#1,000Microseconds/message1001011101001,00010,000100,000Number of processesMessage passing times (LOG/LOG scale)> 200,000processesSource:Joe ArmstrongSICS
- 19. Fault TolerantErlang provides fault tolerance through isolating errors and ensuring nonstop operation. {‘EXIT’, Pid, Reason} {‘EXIT’, Pid, Reason} {‘EXIT’, Pid, Reason}
- 20. Hot Code SwappingEmbedded systems are reactive.How can I update my system without shutting down?In Erlang , we can change code on-the-fly. We can keep 2 version of same module running.
- 21. Multi-core ProgrammingHow to achieve?Use lots of processes.Avoid side effects.Avoid sequential bottleneck.Write “small message, big computation”.What is special about Erlang?Message passing system.No mutable data structure = No lock.No mutable data structure = Easy to parallelize.
- 22. Applications of ErlangErlang is useful when applications are concurrent, distributed and soft-real time.It is used in telecommunication systems from Ericsson. Some other commercial applications are:Facebook uses Erlang to power the backend of its chat service, handling more than 100 million active users. Mobile arts (GSM and UMTS services) T-Mobile uses Erlang in its SMS and authentication systems.
- 23. Robot Programming in Erlang
- 24. Challenges & SolutionsChallengesErlang can’t directly interact with hardware.Erlang can’t be converted into it’s equivalent C code.Communication latency between PC and Firebird-V.SolutionsUse C as middle-layer between Erlang and Micro-controller.Use PC as master and Firebird as slave mode.We can use small, low cost, fan-less processor and run Erlang on it.
- 25. Case StudyAdaptive Cruise ControlRobot will follow white line while maintaining safe distance from other robots. Robot usingFireBird V (8051 micro-controller)Sensors usingWhiteline sensors(Left, Middle, Right)Front sharp sensor
- 26. Communication ModelErlangPC Micro-controllerread_sensorSensingvalue C programActuatingTake corrective measure
- 27. Conclusion & Future WorkPrograms in functional languages are concise and readable.Concurrency model of Erlang helps in making concurrent programs without worrying about deadlocks.We have seen the possibility of implementing robotic system using Erlang.Since concurrency is crucial in building autonomous robotics applications, Erlang can be used in building such applications.
- 28. ReferencesJoe Armstrong “Programming Erlang”, May 2007John Hughes "Why Functional programming Matters", 1984, revised in 1989 and 1990.Francesco Cesarini and Simon Thompson, "Erlang Programming, O'Reilly, June 2009 .Philip wadler "Functional Programming in the Real World“ http://homepages.inf.ed.ac.uk/wadler/realworld/ .Video lectures by Erlang- Training Consultancy
- 29. Thank You