Erlang For Five Nines

Contents
Erlang History
Erlang Highlights
Products
Questions

Erlang History: The Telecom Industry
Complex
Reliable
Scalable
Distributed
Maintainable
Highly Available
versus Time To Market!
Access transport and switching networks Cellular PLMN PSTN/ ISDN Data/ IP Networks CATV Services Past Single-service networks Clients/applications Present Multiservice networks/client server Backbone Network Access Access Access Content Content Control Communication applications Media Gateways

Erlang History 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 “ Find the right methods - design by prototyping.” Mike Willliams, CS LAB Make mistakes on a small scale, not in a production project. Mike Willliams It’s not good enough to have ideas – you must also be able to implement them to know that they work Mike Willliams And the rest is history... Prototypes of Telecom applications First projects launched First products launched Major projects started OTP R1 released Released as Open Source Experiments started at the Computer Science Lab First Erlang Book Published First C-Based Virtual Machine

Erlang History And this is just the beginning... “ Erlang is going to be a very important language. It could be the next Java.” Ralph Johnson Co-author, “Design Patterns” (the “Gang-of-Four book”) To build a large scale message handling system that really had to be up all the time, I would unhesitatingly choose Erlang…. Tim Bray Sun Microsystems … if we had to start again we would probably use Erlang… Mike Shaver Mozilla Foundation 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 The Future January, 36,000 hits on erlang.org Bluetail AB acquired for 152M USD August, 1 million hits on erlang.org Erlang R11 goes multicore The first Erlang Factory Major new projects started within Ericsson ETC is founded

Requests to erlang.org

Contents
Erlang History
Erlang Highlights
Products
Questions

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
Functional programming language High abstraction level Pattern matching Concise readable programs

Erlang Highlights: Factorial Factorial using Recursion n! = 1 n*(n-1)! n = 0 n  1 Definition -module(ex1). -export([factorial/1]). factorial(0) -> 1; factorial(N) when N >= 1 -> N * factorial(N-1). Implementation Eshell V5.0.1 (abort with ^G) 1> c(ex1). {ok,ex1} 2> ex1:factorial(6). 720

Erlang Highlights: High-level Constructs -define(IP_VERSION, 4). -define(IP_MIN_HDR_LEN, 5). …… DgramSize = size(Dgram), <<?IP_VERSION:4, HLen:4, SrvcType:8, TotLen:16, ID:16, Flgs:3, FragOff:13, TTL:8, Proto:8, HdrChkSum:16, SrcIP:32, DestIP:32, Body/binary>> = Dgram, if (HLen >= 5) and (4*HLen =< DgramSize) -> OptsLen = 4*(HLen - ?IP_MIN_HDR_LEN), <<Opts:OptsLen/binary, Data/binary>> = Body, … .. end. Parsing an IP Datagram using the Bit Syntax

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
Either transparent or explicit concurrency Light-weight processes Highly scalable

Erlang Highlights: Concurrency Creating a new process using spawn -module(ex3). -export([activity/3]). activity(Name,Pos,Size) -> ………… Pid = spawn(ex3,activity,[Joe,75,1024]) activity(Joe,75,1024)

Erlang Highlights: Concurrency 10 100 1,000 10,000 100,000 Number of processes 1 10 100 1,000 Microseconds/process erlang java C# Source: Joe Armstrong SICS Process creation time

Erlang Highlights: Concurrency Processes communicate by asynchronous message passing Pid ! {data,12,13} receive {start} -> ……… {stop} -> ……… {data,X,Y} -> ……… end receive {start} -> ……… {stop} -> ……… {data,X,Y} -> ……… end

Erlang Highlights: Concurrency 10 100 1,000 10,000 100,000 Number of processes 1 10 1,000 100,000 Microseconds/message erlang java C# 10,000 100 1 Source: Joe Armstrong SICS Message passing times

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
Response times in the order of milliseconds Per-process garbage collection

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
Simple and consistent error recovery Supervision hierarchies "Program for the correct case"

Erlang Highlights: Robustness Robust systems can be built by layering “ Supervisors” “ Workers”

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
Explicit or transparent distribution Network-aware runtime system

Erlang Highlights: Distribution Erlang Run-Time System Erlang Run-Time System B ! Msg network C ! Msg

Erlang Highlights: Distribution loop() -> receive {From, {apply, M, F, A}} -> Answer = apply(M, F, A), From ! {rex, node(), Answer} loop(); _Other -> loop() end. {rex, Node} ! {self(), {apply, M, F, A}}, receive {rex, Node, What} -> What end {rex, Node} ! {self(), {apply, M, F, A}}, receive {rex, Node, What} -> What end {rex, Node} ! {self(), {apply, M, F, A}}, receive {rex, Node, What} -> What end loop() -> receive {From, {apply, M, F, A}} -> Answer = apply(M, F, A), From ! {rex, node(), Answer} loop(); _Other -> loop() end. loop() -> receive {From, {apply, M, F, A}} -> Answer = apply(M, F, A), From ! {rex, node(), Answer} loop(); _Other -> loop() end. loop() -> receive {From, {apply, M, F, A}} -> Answer = apply(M, F, A), From ! {rex, node(), Answer} loop(); _Other -> loop() end. Simple Remote Procedure Call

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
Easily change code in a running system Enables non-stop operation Simplifies testing

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
"Ports" to the outside world behave as Erlang processes

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
Erlang runs on a Virtual Machine ported to UNIX, Windows, VxWorks, OS X, … Supports heterogeneous networks.

Erlang Highlights
Declarative
Concurrency
Soft real-time
Robustness
Distribution
Hot code loading
External interfaces
Portability
SMP Support
Symmetric multiprocessing support. Takes full advantage of multiple CPU architectures.

Erlang SMP Erlang VM Scheduler run queue non-SMP VM Erlang VM Scheduler #2 run queue run queue run queue SMP VM Scheduler #1 Scheduler #N migration logic

Contents
Erlang History
Erlang Highlights
Products
Questions

Products: Ericsson AXD301 Switch
A Telephony-Class, scalable (10 –160 GBps) ATM switch
Designed from scratch in less than 3 years
Proof of concept in three months
1.5 million lines of Erlang code in the OM
500,000 lines of C/C++ in the switch core
13,000 lines of Java in the GUI
AXD 301 Success factors:
Competent organisation and people
Efficient process
Excellent technology (Erlang!)

Products: Ericsson AXD301 Switch
Using Erlang in Complex Systems
Fits very well with the incremental design method
High programmer satisfaction
Outstanding support for robustness and concurrency
Very few side-effects  easier to add/change single components
Small directed teams can achieve impressive results
Productivity estimates
Similar line/hour programmer productivity
4-10 fewer lines of source code (compared to C/C++, Java, PLEX)
Similar number of faults per 1000 lines of source code

Erlang: It’s Happening! Amazon Simple DB Yahoo! Delicious T-Mobile WAP, SMS, IN services Facebook Chat channel servers Powerset/Microsoft Key/Value store 37 Signals Backend servers

Erlang: It’s Happening! CouchDB Distributed Robust document database Wings 3D 3D modeller based on Nendo YAWS Yet Another Web Server RabbitMQ High performance enterprise messaging Ejabberd XMPP instant messaging server

Questions

www.planeterlang.org www.trapexit.org www.erlang-factory.com www.erlang-consulting.com www.erlang.org

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Erlang For Five Nines

by Barcamp Cork on Nov 18, 2009

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