The document outlines a study on using the Erlang programming language for building real-time systems. It discusses key features of Erlang like concurrency, fault tolerance, and hot code swapping that make it suitable for real-time applications. It also presents a case study on implementing adaptive cruise control for a robot using Erlang and highlights challenges in interfacing Erlang with hardware.

1. Study of Erlang for Building Real-Time SystemsByDinesh RajpootRoll no. 09305043Under the guidance of Prof. Kavi AryaAugust 20, 2010

2. OutlineIntroduction to Erlang

3. Erlang Highlights

4. Declarative

5. Concurrency

6. Fault-tolerant

7. Hot Code Swapping

8. Multi Core Programming Applications of ErlangRobot Programming in Erlang

9. Challenges and Solutions

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.