Erlang, The Road Movie [GOTO:CPH 2011 Keynote]

Erlang, The Road Movie Lessons learned in Erlang Land @drkrab Kresten Krab Thorup CTO, Trifork1

About Me ■ Language Geek Emacs/TeX Hacker, GCC: Objective C, NeXT, Compiled Java, Ph.D. from Århus [language design] ■ Developer J2EE AppServer, CORBA/RMI, XA-TM, Java Firefighter ■ Trifork CTO Technology Adoption Conference Editor, GOTO/QCon2

’90s Object Revolution3

’90s Object Revolution Increased Complexity4

’90s Object Revolution Increased Complexity Program Structure4

’90s Object Revolution Increased Complexity Component Reuse Program Structure4

’90s Object Revolution Increased Complexity Domain Modeling Component Reuse Program Structure4

Languages C# Ruby C++ Smalltalk Java Simula Objective-C5

Thinking Tools Patterns DDD UML OOA&D C# Ruby C++ Smalltalk Java Simula Objective-C6

American Scandinavian School School Increased Complexity Domain Modeling Component Reuse Program Structure7

American Scandinavian School School Increased Conceptual Complexity Modeling Pa rticipatory Design Domain Modeling Component Reuse Program Structure7

American Scandinavian School School Economics Increased Conceptual Reuse Complexity Modeling Engineering Pa rticipatory Design Domain Modeling Component Reuse Program Structure7

American Scandinavian School School Internet Increased Complexity Domain Modeling Component Reuse Program Structure8

Internet Increased Complexity Domain Modeling Component Reuse Program Structure9

More Complexity10

More Complexity Infrastructure made of Software10

More Complexity Infrastructure made of Software Fault Tolerance, Availability, QoS12

More Complexity Infrastructure made of Software Integration, Coordination Fault Tolerance, Availability, QoS12

More Complexity Infrastructure made of Software Cloud, Multi-Core Integration, Coordination Fault Tolerance, Availability, QoS12

More Complexity We ’re struggling to n dle these with an haSoftware Infrastructure made of object mindset! Cloud, Multi-Core Integration, Coordination Fault Tolerance, Availability, QoS12

Time for a new revolution? Cloud, Multi-Core Integration, Coordination Fault Tolerance, Availability, QoS13

What’s a Revolution? Thomas Kuhn The Structure of Scientific Revolutions14

paradigm paradigm15

paradigm paradigm normal science15

paradigm observe anomalies paradigm normal science15

paradigm observe anomalies paradigm CRISIS normal science15

paradigm observe anomalies paradigm CRISIS normal revolutionary science science15

paradigm observe anomalies normal science paradigm CRISIS normal revolutionary science science15

What is the right paradigm to cope with these? Cloud, Multi-Core Integration, Coordination Fault Tolerance, Availability, QoS16

What is the right paradigm to cope with these? Cloud, Multi-Core Integration, Coordination Fault Tolerance, Availability, QoS Parallel Compilers Erlang, Actor Models Functional, Data-Parallel16

Johnso n’s blog Ralph Next J ava” What is the “Erl ang, the right paradigm to a very with these? g to be cope rlang is goin Its main ... E uage ... imp orta nt lang erfectly e is tha t it is p a Cloud, Multi-Core core, web dvantag for the multi- suite d Integration, Coordinationt, i t is the future . In fac services -QoSd ck soli NLY ma ture, ro Fault Tolerance, Availability, ble for O ge that is suita lang ua Parallel stems able sy Compilers hly scal ing hig Erlang, Actor iModels h nes. writ ore mac run on multic to Functional, Data-Parallel16

Objects Actors17

Actors Objects17

Actors Objects American School Performance Engineering17

Actors Objects American Scandinavian School School Performance Conceptual Engineering Modeling17

Actors anomalies Objects American Scandinavian School School Performance Conceptual Engineering Modeling17

Actors Quest in this talk: anomalies Objects If Actor-Prog ramming Paradigm, is the new Scandinavian American School re the What a anomalies School ance uld see Coow? tual Perform sho we n ncep Engineering Modeling17

Making reliable distributed control systems in the presence of errors19

Making reliable distributed control systems in the presence of errors ■ The “secret weapon” for Ericsson’s market leading, real-time telephony systems.19

Making reliable distributed control systems in the presence of errors ■ The “secret weapon” for Ericsson’s market leading, real-time telephony systems. ■ 20+ years of experience to learn from.19

Erlang/OTP Open Telecommunications Platform ■ Embedded Distributed Systems ■ High Availability ■ In-Production Upgrades20

How to Learn Erlang21

How to Learn Erlang diss ect a frog, Don’t Build One! Nicolas Negropont e21

Your Erlang Program Platform Framework BEAM BEAM Emulator BIFs Your favorite OS22

Your Erlang Program Platform Framework BEAM ERJANG BIFs JVM Java Virtual Machine Your favorite OS23

Anomalies in the object-oriented world view24

Figure 2-1 Interface and implementation interface implementation 11 10 9 8 7 625 Looking at such a unit from the inside, as the implem Graphics from Object-Oriented Programming with Objective C, Apple, 2011

Figure 3-1 An object Encapsulation m et h o d me et h o d data thod m m et h o d26

and a data structure that serves Figure 3-1 An object fields of its data structure are it hide them from the rest of the The insight of object-oriented programming is to combine st m et h o da high-level unit, an object, and to give it language su data—in Figure 3-1 An object me and a data structure that serves those functions. The function m et h o d data thod fields of its data structure are its instanceovariables. The met hide them from the rest of the program, m et has Figure 3-1 illustrat d me m et h o d m et h o d data thod Figure 3-1 An object m et h o d m et h o d If you’ve ever tackled any kind of difficult programming problem groups of functions that work on a particular kind of data—implic me m et h o d Object-oriented programming makes these function groups expl data thod group, rather than its components.If you’ve ever tackled any kind The only way to an object’s dat m et h o d groups of functions that work o Object-oriented programming By combining both state and behavior in a single unit, an object b really is greater than the sum of itsgroup, rather thanis a componen parts. An object its kind of se over a specific functional area. It can play a full-fledged modular If you’ve ever tackled any kind By difficult programmingand be of combining both state prob really is greater than the sum o groups of functions that work on a particular kind of data—im27 Terminology: Object-oriented terminology varies from language

and a data structure that serves Figure 3-1 An object fields of its data structure are it hide them from the rest of the The insight of object-oriented programming is to combine st m et h o da high-level unit, an object, and to give it language su data—in Figure 3-1 An object ma ly no me and a data structure that serves those functions. The function m et h o d data A thod fields of its data structure are its instanceovariables. The met hide them from the rest of the program, m et has Figure 3-1 illustrat d me m et h o d m et h o d data thod Figure 3-1 An object m et h o d m et h o d If you’ve ever tackled any kind of difficult programming problem groups of functions that work on a particular kind of data—implic me m et h o d Object-oriented programming makes these function groups expl data thod group, rather than its components.If you’ve ever tackled any kind The only way to an object’s dat m et h o d groups of functions that work o Object-oriented programming By combining both state and behavior in a single unit, an object b really is greater than the sum of itsgroup, rather thanis a componen parts. An object its kind of se over a specific functional area. It can play a full-fledged modular If you’ve ever tackled any kind By difficult programmingand be of combining both state prob really is greater than the sum o groups of functions that work on a particular kind of data—im27 Terminology: Object-oriented terminology varies from language

and a data structure that serves those functions. The functions are known as the object’s methods, a fields of its data structure are its instance variables. The methods wrap around the instance variable hide them from the rest of the program, as Figure 3-1 illustrates. The insight of object-oriented programming is to 3-1 Figure combineAn object behavior—data The insight of object-oriented programming is to combine state and and operations on CHAPTER a high-level unit, an object, and to give it language support. An object is a group of related functions data—in 3 data—in a high-level unit, an object, and to give it languag et h o d and a data structure that serves those functions.m functions are known as the object’s methods, and the serves those functions. The funct The and a data structure that fields of its data structure are its instance variables. The methods wrap around the instance variables and fields of its data structure are its instance variables. The m me m et h o d hide them from the rest of the program, as Figuredata illustrates. 3-1 hide them from the rest of the program, as Figure 3-1 illus thod Figure 3-1 An object m et h o d Figure 3-1 An object The Object Model m et h o d CHAPTER 3 m et h o d me me If you’ve ever tackled any kind of difficult programming problem, it’s likely that your design has inclu m et h o d m et h o d data groups of functions that work on a particular kind data thod thod of data—implicit “objects” without the language su Object-oriented programming makes these function groups explicit and permits you to think in terms m et h o d m et h o d group, rather than its components. The only way to an object’s data, the only interface, is through its me The insight of object-oriented programming is to combine state and behavior—data single unit, an object becomes more than either alone; the By combining both state and behavior in a and operations on The Object Model data—in a high-level unit, an object, and toreallyit language support.sumobjectparts. An object is a kind of self-sufficient “subprogram” with juris give is greater than the An of its is a group of related functions If you’ve ever tackled any kind of difficult programming problem, known that your design has included and a data structure that serves those functions. The functions areit’s likelyas the object’s methods,tackled any kind of difficult programming pr If you’ve ever and the over a specific functional area. It can play a full-fledged modular role within a larger program design groups its data structure are on a particular kind of The methods “objects” without groups variables and fields ofof functions that work its instance variables. data—implicitwrap around the instanceof functions that work on a particular kind of data— the language support. Object-oriented programming program, as function groups explicit and permits you to think in terms programming makes these function group hide them from the rest of the makes these Figure 3-1 illustrates. Object-oriented of the Terminology: Object-oriented terminology variesratherlanguage to language.The only way to an objec group, from than its components. For example, in C++, m group, rather than its components. The only way to an object’s data, the only interface, is through its methods. are called member functions and instance variables are known as data members. This document uses Figure 3-1 An object By combining both state and behavior in a terminology ofobject becomes more than basis in Smalltalk. state and behavior in a single unit, an o single unit, an Objective-C, which has its either alone; the whole By combining both The insighta kind of self-sufficient “subprogram” iscombinethan the sum of its parts. An object is a kin really is greater than the sum of its parts. An object is of object-oriented programming is to greater state and behavior—data and operations really with jurisdiction m et h o d functional area. It can play a full-fledged modular rolean object, and toover a specific functional area. It can play a full-fledged fun over a specific data—in a high-level unit, within a larger program design. support. An object is a group of related mo give it language For example, if you were to write a program that The functions are known as the object’s methods, a and a data structure that serves those functions. modeled home water usage, you might invent obje me m et h o d data fields of its data structure are its instance variables. The methods wrap around Faucet object that represent the various components of the water-delivery system. One might be a the instance variable thod Terminology: Object-oriented terminology varies from language and stopprogram, ofTerminology:methods hide methods to start to language. flow as water, set the rate of have them from the rest of the the For example, in3-1 illustrates.flow, return the amount of water con Figure C++, Object-oriented terminology varies from lan are called member functions and instance variables are known as so on. To do this work, acalled member functions and instance variables to keep m et h o d in a given period, and data members. 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and a data structure that serves those functions. The functions are known as the object’s methods, a fields of its data structure are its instance variables. The methods wrap around the instance variable hide them from the rest of the program, as Figure 3-1 illustrates. The insight of object-oriented programming is to 3-1 Figure combineAn object behavior—data The insight of object-oriented programming is to combine state and and operations on CHAPTER 3 CHAPTER a high-level unit, an object, and to give it language support. An object is a group of related functions data—in 3 data—in a high-level unit, an object, and to give it languag et h o d and a data structure that serves those functions.m functions are known as the object’s methods, and the serves those functions. The funct The and a data structure that fields of its data structure are its instance variables. The methods wrap around the instance variables and fields of its data structure are its instance variables. The m me m et h o d hide them from the rest of the program, as Figuredata illustrates. 3-1 hide them from the rest of the program, as Figure 3-1 illus thod Figure 3-1 An object Figure 3-1 An object The Object Model m et h o d The Object Model m et h o d CHAPTER 3 m et h o d me me If you’ve ever tackled any kind of difficult programming problem, it’s likely that your design has inclu m et h o d m et h o d data groups of functions that work on a particular kind data thod thod of data—implicit “objects” without the language su Object-oriented programming makes these function groups explicit and permits you to think in terms m et h o d m et h o d group, rather than its components. The only way to an object’s data, the only interface, is through its me The insight of object-oriented programming is to combine The insight of object-oriented programming is to combine state and behavior—data data—in a high-level unit, an object, and to give it languag and operations on The Object Model By combining both state and behavior in a single unit, an object becomes more than either alone; the data—in a high-level unit, an object, and toreallyit language support.sumobjectparts. An object is a kind of self-sufficient “subprogram” withfunct give is greater than the An of its is a group of related functions serves those functions. The juris and a data structure that If you’ve ever tackled any kind of difficult programming problem, known that your design has included and a data structure that serves those functions. 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One might be a the instance variable thod Terminology: Object-oriented terminology varies from language and stopprogram, ofTerminology:methods hide methods to start to language. flow as water, set the rate of have them from the rest of the the For example, in3-1 illustrates.flow, return the amount of water con Figure C++, Object-oriented terminology varies from lan m et h o d are called member functions and instance variables are known as so on. To do this work, acalled member functions and instance variables to keep m et h o d in a given period, and data members. 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But even a real faucet, like any system component, ex represent functions that work on a particular kind of data—implicit “objects”be a Faucet language support. work on a particular kind of data— groups of the various components of the water-delivery system. One might without groups of functions that represent the various components of the water-delivery sy the object that would me m et h o d both state and behavior. To effectively model a system, you need programming units, like objects, th have methods toprogramming makes thesewater, data rate of flow, return the amountthink in terms of theand stop the flow of function the ra Object-oriented programming makes thesewater, set group Object-oriented start and stop the flow ofcombine state and behavior. permits you to of methods to start set the have water consumed thod function groups explicit and in a given period, and so on. To doThe only wayFaucet object would need instance variables toperiod, and so on. 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An object is atha really is greater than the sum of object can be smarter kind of self-sufficient “subprogram” with jurisdiction Clearly, to a mechanical faucet object can be smarter kin the program and is able to communicate with other objects. Objects communicate through messages over a specific functional area. It can play a full-fledged mo with a specific functional area. It can attached). But evenmodular role within a larger program design. over lots of gauges and instruments play a full-fledged to perform methods. systemwith lots of gauges and instruments attached). But even a a real faucet, like any component, exhibits are requests both state and behavior. To effectively model a system, you need programming units, like objects, that also it’s likely that your design has inclu If you’ve ever tackled any kind of difficult programming problem, To effectively model a system, yo both state and behavior. combine state and behavior. groups of functions that work on a particular kind ofstate Object-oriented terminology varies from lan combine data—implicit “objects” without the language su Terminology: and behavior. Terminology: Object-oriented terminology varies from language to language. For example, in C++, methods and permits youvariablesin terms Object-oriented programming makes these function memberexplicit and instance to think are kno are called groups functions28 are called member functions and instance variables are known ascall upon each otherdocument part of the a network interface,basis in Smalltal data members. This A programuses Objective-C, only ofhas its is through its me group, rather than its terminology of the of A program consists of a network of interconnected objects thatcomponents. The onlyto solvean object’s data, the which interconnected object way to a consists

Active Object + State Machine Figure 3-1 An object mailbox m et h o d me et h o d data thod m m et h o d29

Active Object + State Machine Figure 3-1 An object mailbox m et h o d me et h o d data thod m m et h o d30

box empty full(X)31

box empty {‘put’,X} full(X)31

box empty {‘put’,X} {‘take’,From} / send(From, X) full(X)31

box() ➞ empty(). empty() ➞ box receive {‘put’, X} ➞ full(X) end. empty full(X) ➞ {‘put’,X} {‘take’,From} / send(From, X) receive {‘take’, From} ➞ full(X) From ! X, empty() end.32

box() ➞ empty(). empty() ➞ box receive {‘put’, X} ➞ full(X) end. empty full(X) ➞ {‘put’,X} {‘take’,From} / send(From, X) receive {‘take’, From} ➞ full(X) From ! X, empty() end. {‘peek’,From} / send(From,{‘ok’, X})33

box() ➞ empty(). empty() ➞ box receive {‘put’, X} ➞ full(X) end. empty full(X) ➞ {‘put’,X} {‘take’,From} / send(From, X) receive {‘take’, From} ➞ full(X) From ! X, empty(); {‘peek’, From} ➞ {‘peek’,From} / send(From,{‘ok’, X}) From ! {‘ok’, X}, full(X) end.34

box() ➞ empty(). empty() ➞ receive {‘put’, X} ➞ full(X) end. full(X) ➞ receive {‘take’, From} ➞ From ! X, empty(); {‘peek’, From} ➞ From ! {‘ok’, X}, full(X) end.35

box() ➞ empty(). Box = spawn(fun box/0), empty() ➞ receive {‘put’, X} ➞ full(X) end. full(X) ➞ receive {‘take’, From} ➞ From ! X, empty(); {‘peek’, From} ➞ From ! {‘ok’, X}, full(X) end.35

box() ➞ empty(). Box = spawn(fun box/0), empty() ➞ Box ! {‘put’, 27}, receive {‘put’, X} ➞ full(X) end. full(X) ➞ receive {‘take’, From} ➞ From ! X, empty(); {‘peek’, From} ➞ From ! {‘ok’, X}, full(X) end.35

box() ➞ empty(). Box = spawn(fun box/0), empty() ➞ Box ! {‘put’, 27}, receive {‘put’, X} ➞ Box ! {‘take’, self()}, full(X) receive end. Value ➞ print(Value) end full(X) ➞ receive {‘take’, From} ➞ From ! X, empty(); {‘peek’, From} ➞ From ! {‘ok’, X}, full(X) end.35

Interface Objects Fixed API Protocol Actors API changes with internal state36

ma ly A no Interface Objects Fixed API Protocol Actors API changes with internal state36

Pull vs. Push37

But isn’t this expensive?38

But isn’t this expensive? ... heard in the ‘90s Use Objects!38

But isn’t this expensive? ... heard in the ‘90s 100.000’s of objects, Use Objects! are you crazy?38

But isn’t this expensive? ... heard yesterday Use Actors!38

But isn’t this expensive? ... heard yesterday 100.000’s of processes, Use Actors! silly you!38

fields of its data structu hide them from the rest Effect Containment 3-1 Figure An obje m et h o d ■ Functional languages me et h o d disallow effects data thod ■ Many object-oriented m m et h o d styles encourage side effects. ■ Actors conﬁne effects If you’ve ever tackled an groups of functions tha Object-oriented program39 group, rather than its co

From C++ to Java Garbage Collection From Java to Erlang State Containment40

Activity Composition The Object Model The Object Model The insight of object-oriented programming is to combine state and behavior—data and operations on The insight of object-oriented programming is to combine state and data—in a high-level unit, an object, and to give it language support. An object is a group of related functions give it language support. data—in a high-level unit, an object, and to and a data the object’s methods, and the and a data structure that serves those functions. The functions are known asstructure that serves those functions. The functions are k fields of its data structure are its instance variables. The methods wrap around the instance variables and variables. The methods w fields of its data structure are its instance hide them from the rest of the program, as Figure 3-1 illustrates. hide them from the rest of the program, as Figure 3-1 illustrates. Figure 3-1 An object Figure 3-1 An object m et h o d me spawn m et h o d me m et h o d m et h o d data data thod thod m et h o d m et h o d If you’ve ever tackled any kind of difficult programming problem,If you’ve ever tackled any kind included programming problem, it’ it’s likely that your design has of difficult groups of functions that work on a particular kind of data—implicit “objects” without the language a particular kind of data—implicit “ groups of functions that work on support. Object-oriented programming makes these function groups explicit and permits you to think in terms ofthese function groups explicit Object-oriented programming makes the group, rather than its components. The only way to an object’s data, the only interface, iscomponents. The only way to an object’s data, th group, rather than its through its methods. By combining both state and behavior in a single unit, an object becomes more than eitherand behavior in a single unit, an object bec By combining both state alone; the whole really is greater than the sum of its parts. An object is a kind of self-sufficient “subprogram”sum of its parts. An object is a kind of self-s really is greater than the with jurisdiction over a specific functional area. It can play a full-fledged modular role within a larger program design. play a full-fledged modular role over a specific functional area. It can Terminology: Object-oriented terminology varies from language to language. For example, in C++, methods varies from language to Terminology: Object-oriented terminology are called member functions and instance variables are known as data members. Thisfunctions and instance variables are known as da are called member document uses the terminology of Objective-C, which has its basis in Smalltalk. terminology of Objective-C, which has its basis in Smalltalk. For example, if you were to write a program that modeled home water usage, you might invent objects to that modeled home wa For example, if you were to write a program represent the various components of the water-delivery system. One mightthe a Faucet object thatof the water-delivery system. On represent be various components would have methods to start and stop the flow of water, set the rate of flow, return the amount and stop consumed water, set the rate of flow have methods to start of water the flow of41 in a given period, and so on. To do this work, a Faucet object would need instanceand so on.to keep track in a given period, variables To do this work, a Faucet object woul

Activity Composition The Object Model The Object Model The insight of object-oriented programming is to combine state and behavior—data and operations on The insight of object-oriented programming is to combine state and data—in a high-level unit, an object, and to give it language support. An object is a group of related functions give it language support. data—in a high-level unit, an object, and to and a data the object’s methods, and the and a data structure that serves those functions. The functions are known asstructure that serves those functions. The functions are k fields of its data structure are its instance variables. The methods wrap around the instance variables and variables. The methods w fields of its data structure are its instance hide them from the rest of the program, as Figure 3-1 illustrates. hide them from the rest of the program, as Figure 3-1 illustrates. Figure 3-1 An object Figure 3-1 An object m et h o d me link m et h o d me m et h o d m et h o d data data thod thod m et h o d m et h o d If you’ve ever tackled any kind of difficult programming problem,If you’ve ever tackled any kind included programming problem, it’ it’s likely that your design has of difficult groups of functions that work on a particular kind of data—implicit “objects” without the language a particular kind of data—implicit “ groups of functions that work on support. Object-oriented programming makes these function groups explicit and permits you to think in terms ofthese function groups explicit Object-oriented programming makes the group, rather than its components. The only way to an object’s data, the only interface, iscomponents. The only way to an object’s data, th group, rather than its through its methods. By combining both state and behavior in a single unit, an object becomes more than eitherand behavior in a single unit, an object bec By combining both state alone; the whole really is greater than the sum of its parts. An object is a kind of self-sufficient “subprogram”sum of its parts. An object is a kind of self-s really is greater than the with jurisdiction over a specific functional area. It can play a full-fledged modular role within a larger program design. play a full-fledged modular role over a specific functional area. It can Terminology: Object-oriented terminology varies from language to language. For example, in C++, methods varies from language to Terminology: Object-oriented terminology are called member functions and instance variables are known as data members. Thisfunctions and instance variables are known as da are called member document uses the terminology of Objective-C, which has its basis in Smalltalk. terminology of Objective-C, which has its basis in Smalltalk. For example, if you were to write a program that modeled home water usage, you might invent objects to that modeled home wa For example, if you were to write a program represent the various components of the water-delivery system. One mightthe a Faucet object thatof the water-delivery system. On represent be various components would have methods to start and stop the flow of water, set the rate of flow, return the amount and stop consumed water, set the rate of flow have methods to start of water the flow of42 in a given period, and so on. To do this work, a Faucet object would need instanceand so on.to keep track in a given period, variables To do this work, a Faucet object woul

Activity Composition The Object Model The Object Model The insight of object-oriented programming is to combine state and behavior—data and operations on The insight of object-oriented programming is to combine state and data—in a high-level unit, an object, and to give it language support. An object is a group of related functions give it language support. data—in a high-level unit, an object, and to and a data the object’s methods, and the and a data structure that serves those functions. The functions are known asstructure that serves those functions. The functions are k fields of its data structure are its instance variables. The methods wrap around the instance variables and variables. The methods w fields of its data structure are its instance hide them from the rest of the program, as Figure 3-1 illustrates. hide them from the rest of the program, as Figure 3-1 illustrates. Figure 3-1 An object Figure 3-1 An object m et h o d me link m et h o d me m et h o d m et h o d data data thod thod m et h o d m et h o d host host If you’ve ever tackled any kind of difficult programming problem,If you’ve ever tackled any kind included programming problem, it’ it’s likely that your design has of difficult groups of functions that work on a particular kind of data—implicit “objects” without the language a particular kind of data—implicit “ groups of functions that work on support. Object-oriented programming makes these function groups explicit and permits you to think in terms ofthese function groups explicit Object-oriented programming makes the group, rather than its components. The only way to an object’s data, the only interface, iscomponents. The only way to an object’s data, th group, rather than its through its methods. By combining both state and behavior in a single unit, an object becomes more than eitherand behavior in a single unit, an object bec By combining both state alone; the whole really is greater than the sum of its parts. An object is a kind of self-sufficient “subprogram”sum of its parts. An object is a kind of self-s really is greater than the with jurisdiction over a specific functional area. It can play a full-fledged modular role within a larger program design. play a full-fledged modular role over a specific functional area. It can Terminology: Object-oriented terminology varies from language to language. For example, in C++, methods varies from language to Terminology: Object-oriented terminology are called member functions and instance variables are known as data members. Thisfunctions and instance variables are known as da are called member document uses the terminology of Objective-C, which has its basis in Smalltalk. terminology of Objective-C, which has its basis in Smalltalk. For example, if you were to write a program that modeled home water usage, you might invent objects to that modeled home wa For example, if you were to write a program represent the various components of the water-delivery system. One mightthe a Faucet object thatof the water-delivery system. On represent be various components would have methods to start and stop the flow of water, set the rate of flow, return the amount and stop consumed water, set the rate of flow have methods to start of water the flow of42 in a given period, and so on. To do this work, a Faucet object would need instanceand so on.to keep track in a given period, variables To do this work, a Faucet object woul

“Let it Fail” philosophy m et h o d me et h o d data thod m m et h o d43

“Let it Fail” philosophy m et h o d ■ Write code with lots of assertions me et h o d data thod m m et h o d43

“Let it Fail” philosophy m et h o d ■ Write code with lots of assertions me et h o d ■ Let a meta-level do fault handling data thod m m et h o d43

“Let it Fail” philosophy m et h o d ■ Write code with lots of assertions me et h o d ■ Let a meta-level do fault handling data thod m ■ Defensive code is a symptom of a m et h o d weak platform (segfaults, memory leaks, ...)43

“Let it Fail” philosophy m et h o d ■ Write code with lots of assertions me et h o d ■ Let a meta-level do fault handling data thod m ■ Defensive code is a symptom of a m et h o d weak platform (segfaults, memory ly leaks, ...) ma A no43

Martin Fowler’s First Law of Distributed Objects Design rpc Starbucks doesn’t use transactions Steve Vinoski: RPC and its Offspring: Convenient, Yet Fundamentally Flawed44

Martin Fowler’s First Law of Distributed Objects Design rpc ma ly Starbucks doesn’t use A no transactions Steve Vinoski: RPC and its Offspring: Convenient, Yet Fundamentally Flawed44

Abstractions45

Abstractions ■ Any abstraction (hiding code) is problematic distribute, persist, etc.45

Abstractions ■ Any abstraction (hiding code) is problematic distribute, persist, etc. ■ You want to distribute/persist simple data (as in sql databases, document stores)45

Abstractions ■ Any abstraction (hiding code) is problematic distribute, persist, etc. ■ You want to distribute/persist simple data (as in sql databases, document stores) ■ JSON’s popularity is a testament to this anomaly.45

Abstractions ■ Any abstraction (hiding code) is problematic distribute, persist, etc. ■ You want to distribute/persist simple data (as in sql databases, document stores) ■ JSON’s popularity is a testament to this anomaly. m a ly A no45

Simple Values46

Simple Values ■ Tuple, List, Record, Number, String46

Simple Values ■ Tuple, List, Record, Number, String ■ Pattern matching is polymorphism for values46

Simple Values ■ Tuple, List, Record, Number, String ■ Pattern matching is polymorphism for values ■ Erlang data stores (like Mnesia) just store values, not bytes or objects.46

Simple Values ■ Tuple, List, Record, Number, String ■ Pattern matching is polymorphism for values ■ Erlang data stores (like Mnesia) just store values, not bytes or objects. ■ Too much of my Java programs are boilerplate code.46

“Object” Model Anomalies ■ Thread & Locks ■ Interfaces with Fixed API ■ Defensive Code ■ RPC/RMI ■ Boilerplate code for persistence47

Actor “Solutions” ■ Processes w/ state containment ■ Protocols ■ Let it Fail ■ Async Messaging ■ Send & store simple Data48

Erlang Systems49

OTP Actor Behaviors ■ Servers ■ Event Handlers ■ Finite State Machine ■ Supervisors ■ Networking: TCP, HTTP50

real problems that need to be solved to realize the potential of cloud computing51

Async Messaging53

Async Messaging State [Fault] Containment53

Async Messaging State [Fault] Containment Fault Monitoring53

Common Medicine Card55

Common Medicine Card56

Who Else Uses Erlang?57

Revolution? Smalltalk58

Revolution? Java, Internet Smalltalk58

Erlang59

Multicore, Cloud Erlang59

Multicore, Cloud Erlang American Scandinavian School School59

Multicore, Cloud Erlang American Scandinavian School School Performance Engineering59

Multicore, Cloud Erlang American Scandinavian School School Performance Conceptual Engineering Modeling59

Thank You. @drkrab60

Java either steps up, or something else will. —Cameron Purdy Thank You. @drkrab61

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Erlang, The Road Movie [GOTO:CPH 2011 Keynote]

by Kresten Krab Thorup on May 16, 2011

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Erlang, The Road Movie [GOTO:CPH 2011 Keynote] Presentation Transcript