DOCSLIB.ORG

Improving the Scalability of the Erlang Distributed Actor Platform

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Improving the Scalability of the Erlang Distributed Actor Platform P. Trinder, N. Chechina, N. Papaspyrou, K. Sagonas, S. Thompson, et al. • Scaling Reliably • 2017 Scaling Reliably: Improving the Scalability of the Erlang Distributed Actor Platform Phil Trinder,Natalia Chechina,Nikolaos Papaspyrou, Konstantinos Sagonas,Simon Thompson,Stephen Adams,Stavros Aronis, Robert Baker,Eva Bihari,Olivier Boudeville,Francesco Cesarini, Maurizio Di Stefano,Sverker Eriksson,Viktoria Fordos,Amir Ghaffari, Aggelos Giantsios,Rockard Green,Csaba Hoch,David Klaftenegger, Huiqing Li,Kenneth Lundin,Kenneth MacKenzie,Katerina Roukounaki, Yiannis Tsiouris,Kjell Winblad RELEASE EU FP7 STREP (287510) project www.release-project.eu/ April 25, 2017 Abstract Distributed actor languages are an effective means of constructing scalable reliable systems, and the Erlang programming language has a well-established and influential model. While the Erlang model conceptually provides reliable scalability, it has some inherent scalability limits and these force developers to depart from the model at scale. This article establishes the scalability limits of Erlang systems, and reports the work of the EU RELEASE project to improve the scalability and understandability of the Erlang reliable distributed actor model. We systematically study the scalability limits of Erlang, and then address the issues at the virtual machine, language and tool levels. More specifically: (1) We have evolved the Erlang virtual machine so that it can work effectively in large scale single-host multicore and NUMA architectures. We have made important changes and architectural improvements to the widely used Erlang/OTP release. (2) We have designed and implemented Scalable Distributed (SD) Erlang libraries to address language-level scalability issues, and provided and validated a set of semantics for the new language constructs. (3) To make large Erlang systems easier to deploy, monitor, and debug we have developed and made open source releases of five complementary tools, some specific to SD Erlang. Throughout the article we use two case studies to investigate the capabilities of our new technologies and arXiv:1704.07234v2 [cs.PL] 8 May 2017 tools: a distributed hash table based Orbit calculation and Ant Colony Optimisation (ACO). Chaos Monkey experiments show that two versions of ACO survive random process failure and hence that SD Erlang preserves the Erlang reliability model. While we report measurements on a range of NUMA and cluster architectures, the key scalability experiments are conducted on the Athos cluster with 256 hosts (6144 cores). Even for programs with no global recovery data to maintain, SD Erlang partitions the network to reduce network traffic and hence improves performance of the Orbit and ACO benchmarks above 80 hosts. ACO measurements show that maintaining global recovery data dramatically limits scalability; however scalability is recovered by partitioning the recovery data. We exceed the established scalability limits of distributed Erlang, and do not reach the limits of SD Erlang for these benchmarks at this scale (256 hosts, 6144 cores). 1 I. Introduction stant messaging server [77]. In Erlang, the actors are termed processes Distributed programming languages and and are managed by a sophisticated Virtual frameworks are central to engineering large Machine on a single multicore or NUMA scale systems, where key properties include host, while distributed Erlang provides rela- scalability and reliability. By scalability we tively transparent distribution over networks mean that performance increases as hosts and of VMs on multiple hosts. Erlang is supported cores are added, and by large scale we mean by the Open Telecom Platform (OTP) libraries architectures with hundreds of hosts and tens that capture common patterns of reliable dis- of thousands of cores. Experience with high tributed computation, such as the client-server performance and data centre computing shows pattern and process supervision. Any large- that reliability is critical at these scales, e.g. scale system needs scalable persistent stor- host failures alone account for around one fail- age and, following the CAP theorem [39], ure per hour on commodity servers with ap- Erlang uses and indeed implements Dynamo- proximately 105 cores [11]. To be usable, pro- style NoSQL DBMS like Riak [49] and Cassan- gramming languages employed on them must dra [50]. be supported by a suite of deployment, moni- While the Erlang distributed actor model toring, refactoring and testing tools that work conceptually provides reliable scalability, it has at scale. some inherent scalability limits, and indeed Controlling shared state is the only way to large-scale distributed Erlang systems must de- build reliable scalable systems. State shared by part from the distributed Erlang paradigm in multiple units of computation limits scalability order to scale, e.g. not maintaining a fully con- due to high synchronisation and communica- nected graph of hosts. The EU FP7 RELEASE tion costs. Moreover shared state is a threat project set out to establish and address the scal- for reliability as failures corrupting or perma- ability limits of the Erlang reliable distributed nently locking shared state may poison the actor model [67]. entire system. After outlining related work (Section II) and Actor languages avoid shared state: actors or the benchmarks used throughout the article processes have entirely local state, and only in- (Section III) we investigate the scalability lim- teract with each other by sending messages [2]. its of Erlang/OTP, seeking to identify specific Recovery is facilitated in this model, since ac- issues at the virtual machine, language and tors, like operating system processes, can fail persistent storage levels (Section IV). independently without affecting the state of We then report the RELEASE project work to other actors. Moreover an actor can supervise address these issues, working at the following other actors, detecting failures and taking re- three levels. medial action, e.g. restarting the failed actor. 1. We have designed and implemented a Erlang [6, 19] is a beacon language for re- set of Scalable Distributed (SD) Erlang li- liable scalable computing with a widely em- braries to address language-level reliabil- ulated distributed actor model. It has in- ity and scalability issues. An operational fluenced the design of numerous program- semantics is provided for the key new ming languages like Clojure [43] and F# [74], s_group construct, and the implementa- and many languages have Erlang-inspired tion is validated against the semantics (Sec- actor frameworks, e.g. Kilim for Java [73], tion V). Cloud Haskell [31], and Akka for C#, F# and Scala [64]. Erlang is widely used for build- 2. We have evolved the Erlang virtual machine ing reliable scalable servers, e.g. Ericsson’s so that it can work effectively in large-scale AXD301 telephone exchange (switch) [79], the single-host multicore and NUMA archi- Facebook chat server, and the Whatsapp in- tectures. We have improved the shared 2 P. Trinder, N. Chechina, N. Papaspyrou, K. Sagonas, S. Thompson, et al. • Scaling Reliably • 2017 ETS tables, time management, and load ter (Section VIII). balancing between schedulers. Most of Contributions. This article is the first sys- these improvements are now included in tematic presentation of the coherent set of the Erlang/OTP release, currently down- technologies for engineering scalable reliable loaded approximately 50K times each Erlang systems developed in the RELEASE month (Section VI). project. Section IV presents the first scalability study 3. To facilitate the development of scalable covering Erlang VM, language, and storage Erlang systems, and to make them main- scalability. Indeed we believe it is the first tainable, we have developed three new comprehensive study of any distributed ac- tools: Devo, SDMon and WombatOAM, tor language at this scale (100s of hosts, and and enhanced two others: the visualisa- around 10K cores). Individual scalability stud- tion tool Percept, and the refactorer Wran- ies, e.g. into Erlang VM scaling [8], or lan- gler. The tools support refactoring pro- guage and storage scaling have appeared be- grams to make them more scalable, eas- fore [38, 37]. ier to deploy at large scale (hundreds of At the language level the design, implemen- hosts), easier to monitor and visualise their tation and validation of the new libraries (Sec- behaviour. Most of these tools are freely tion V) have been reported piecemeal [21, 60], available under open source licences; the and are included here for completeness. WombatOAM deployment and monitor- While some of the improvements made to ing tool is a commercial product (Sec- the Erlang Virtual Machine (Section i) have tion VII). been thoroughly reported in conference pub- Throughout the article we use two bench- lications [66, 46, 47, 69, 70, 71], others are re- marks to investigate the capabilities of our new ported here for the first time (Sections iii, ii). technologies and tools. These are a compu- In Section VII, the WombatOAM and SD- tation in symbolic algebra, more specifically Mon tools are described for the first time, as an algebraic ‘orbit’ calculation that exploits is the revised Devo system and visualisation. a non-replicated distributed hash table, and The other tools for profiling, debugging and an Ant Colony Optimisation (ACO) parallel refactoring developed in the project have previ- search program (Section III). ously been published piecemeal [52, 53, 55, 10], We report on the reliability and scalability
Load more

Recommended publications
  • Introducing Elixir Getting Started in Functional Programming [St. Laurent & Eisenberg 2014-09-25].Pdf
    Introducing Elixir Introducing Elixir Introducing Elixir is an excellent language if you want to learn about functional programming, and with this hands-on introduction, you’ll discover just how powerful and fun Elixir can be. This language combines the robust functional programming of Erlang with a syntax similar to Ruby, and includes powerful features for metaprogramming. This book shows you how to write simple Elixir programs by teaching one skill at a time. Once you pick up pattern matching, process-oriented programming, and other concepts, you’ll understand why Elixir makes it easier to build concurrent and resilient programs that scale up and down with ease. ■ Get comfortable with IEx, Elixir’s command-line interface ■ Discover atoms, pattern matching, and guards: the foundations of your program structure ■ Delve into the heart of Elixir with recursion, strings, lists, and higher-order functions ■ Create processes, send messages among them, and apply pattern matching to incoming messages ■ Store and manipulate structured data with Erlang Term Storage and the Mnesia database ■ Build resilient applications with Erlang’s Open Telecom Platform Introducing ■ Define macros with Elixir’s metaprogramming tools St. Laurent & Eisenberg Laurent St. Simon St. Laurent is a Strategic Content Director at O’Reilly Media, Inc., focusing primarily on web-related topics. He is co-chair of O’Reilly’s Fluent and OSCON conferences. Simon has written or co-written books, including Introducing Erlang, Learning Rails 3, and XML Pocket Reference, Third Edition (all O’Reilly). J. David Eisenberg is a programmer and instructor in San Jose, California, with a talent for teaching and explaining.
    [Show full text]
  • Mnesia Database Management System (MNESIA)
    Mnesia Database Management System (MNESIA) version 4.4 Typeset in LATEX from SGML source using the DocBuilder-0.9.8.5 Document System. Contents 1 Mnesia User’s Guide 1 1.1 Introduction.......................................... 1 1.1.1AboutMnesia..................................... 1 1.1.2TheMnesiaDataBaseManagementSystem(DBMS)............... 2 1.2 GettingStartedwithMnesia................................. 4 1.2.1StartingMnesiaforthefirsttime.......................... 4 1.2.2AnIntroductoryExample.............................. 5 1.3 BuildingAMnesiaDatabase................................. 14 1.3.1DefiningaSchema.................................. 15 1.3.2TheDataModel................................... 16 1.3.3StartingMnesia.................................... 16 1.3.4CreatingNewTables................................. 19 1.4 TransactionsandOtherAccessContexts.......................... 21 1.4.1TransactionProperties................................ 22 1.4.2Locking........................................ 23 1.4.3DirtyOperations................................... 27 1.4.4RecordNamesversusTableNames......................... 28 1.4.5ActivityConceptandVariousAccessContexts................... 30 1.4.6Nestedtransactions.................................. 32 1.4.7PatternMatching................................... 33 1.4.8Iteration........................................ 35 1.5 MiscellaneousMnesiaFeatures................................ 36 1.5.1Indexing........................................ 37 1.5.2DistributionandFaultTolerance.........................
    [Show full text]
  • Implementing Erlang/OTP on Intel Galileo
    DEGREE PROJECT, IN INFORMATION TECHNOLOGY, FIRST LEVEL STOCKHOLM, SWEDEN 2015-06-22 Implementing Erlang/OTP on Intel Galileo Paul Coada, Erkut Kaya KTH ROYAL INSTITUTE OF TECHNOLOGY INFORMATION AND COMMUNICATION TECHNOLOGY Abstract The Intel Galileo, inspired by the well-known Arduino board, is a development board with many possibilities because of its strength. The Galileo is has an Intel processor capable of running GNU/Linux and can be connected to the internet, which opens up the possibility to be controlled remotely. The programming language that comes with the Intel Galileo is the same as for the Arduino development boards, and is therefore very limited and does not utilize the Galileo’s entire strength. Our aim with this project is to integrate a more suitable programming language; a language that can make better use of the relatively powerful processor to control the components of the board. The programming language of choice is Erlang, and the reason is obvious. Erlang can be described as a process-oriented programming language based on the functional programming paradigm and its power in concurrency. The result of the project was the successful integration of a complete version of GNU/Linux on the board and the cross-compilation of Erlang/OTP onto the board. Having Erlang running on the system opens up many possibilities for future work, amongst all: creating Erlang programs for the Intel Galileo, integrating an effective API, and measuring the pros and cons of using Erlang on an Intel Galileo. Keywords Embedded, Arduino, multiprogramming, concurrency, Internet of Things, cross-compilation, API Sammanfattning Intel Galileo är ett utvecklingskort som bygger på Arduinos succé.
    [Show full text]
  • Erlang – a Platform for Developing Distributed Software Systems
    Erlang – a platform for developing distributed software systems Lars-Ake˚ Fredlund 1 / 55 Problems of distributed systems ■ Distributed programming is hard ■ Challenges for concurrency: ◆ process coordination and communication 2 / 55 Problems of distributed systems ■ Distributed programming is hard ■ Challenges for concurrency: ◆ process coordination and communication ■ And challenges for distributed software: ◆ heterogeneous systems ◆ security, reliability (lack of control) ◆ performance 2 / 55 Distributed Programming Today Todays contrasts: ■ Vision – easy programming of distributed systems ■ The nightmare/reality – Web services, XML, Apache, SOAP, WSDL, . ■ Why are Web services a nightmare? Too many standards, too many tools, too many layers, too complex! ■ Erlang is an Industrially proven solution for developing and maintaining demanding distributed applications ■ Good qualities of Erlang as a distributed systems platform: Complexity encapsulated in a programming language, good performance, efficient data formats, debuggable, not complex 3 / 55 Erlang as a component platform: a summary ■ Processes are the components 4 / 55 Erlang as a component platform: a summary ■ Processes are the components ■ Components (processes) communicate by binary asynchronous message passing 4 / 55 Erlang as a component platform: a summary ■ Processes are the components ■ Components (processes) communicate by binary asynchronous message passing ■ Component communication does not depend on whether components are located in the same node, or physically remote
    [Show full text]
  • The Implementation and Use of a Generic Dataflow Behaviour in Erlang
    The Implementation and Use of a Generic Dataflow Behaviour in Erlang Christopher Meiklejohn Peter Van Roy Basho Technologies, Inc. Universite´ catholique de Louvain Bellevue, WA, United States Louvain-la-Neuve, Belgium [email protected] [email protected] Abstract concurrent programming: developers author code that adheres to a 2 We propose a new “generic” abstraction for Erlang/OTP that aids in specific “behaviour” and these abstractions then provide a com- the implementation of dataflow programming languages and mod- mon way to supervise, manage, and reason about processing con- els on the Erlang VM. This abstraction simplifies the implemen- current messages to a single actor. tation of “processing elements” in dataflow languages by provid- We propose a new Erlang/OTP “generic” abstraction for dataflow ing a simple callback interface in the style of the gen server and programming on the Erlang VM called gen flow. This abstraction gen fsm abstractions. We motivate the use of this new abstraction allows for the arbitrary composition of stateful actors into larger by examining the implementation of a distributed dataflow pro- dataflow computations. This abstraction is sufficiently generic to gramming variant called Lasp. aid in the implementation of an arbitrary dataflow language in Erlang/OTP: we motivate the use of gen flow through the im- Categories and Subject Descriptors D.1.3 [Programming Tech- plementation of a deterministic distributed dataflow variant called niques]: Concurrent Programming; E.1 [Data Structures]: Dis- Lasp. [14, 15] tributed data structures This paper contains the following contributions: Keywords Dataflow Programming, Erlang, Concurrent Program- • gen flow abstraction: We propose gen flow, a new abstrac- ming tion in the style of the “generic” abstractions provided by Er- lang/OTP for building dataflow “processing elements.” 1.
    [Show full text]
  • Making Reliable Distributed Systems in the Presence of Sodware Errors Final Version (With Corrections) — Last Update 20 November 2003
    Making reliable distributed systems in the presence of sodware errors Final version (with corrections) — last update 20 November 2003 Joe Armstrong A Dissertation submitted to the Royal Institute of Technology in partial fulfilment of the requirements for the degree of Doctor of Technology The Royal Institute of Technology Stockholm, Sweden December 2003 Department of Microelectronics and Information Technology ii TRITA–IMIT–LECS AVH 03:09 ISSN 1651–4076 ISRN KTH/IMIT/LECS/AVH-03/09–SE and SICS Dissertation Series 34 ISSN 1101–1335 ISRN SICS–D–34–SE c Joe Armstrong, 2003 Printed by Universitetsservice US-AB 2003 iii To Helen, Thomas and Claire iv Abstract he work described in this thesis is the result of a research program T started in 1981 to find better ways of programming Telecom applica- tions. These applications are large programs which despite careful testing will probably contain many errors when the program is put into service. We assume that such programs do contain errors, and investigate methods for building reliable systems despite such errors. The research has resulted in the development of a new programming language (called Erlang), together with a design methodology, and set of libraries for building robust systems (called OTP). At the time of writing the technology described here is used in a number of major Ericsson, and Nortel products. A number of small companies have also been formed which exploit the technology. The central problem addressed by this thesis is the problem of con- structing reliable systems from programs which may themselves contain errors. Constructing such systems imposes a number of requirements on any programming language that is to be used for the construction.
    [Show full text]
  • The Implementation and Use of a Generic Dataflow Behaviour in Erlang
    The Implementation and Use of a Generic Dataflow Behaviour in Erlang Christopher Meiklejohn Peter Van Roy Basho Technologies, Inc. Universite´ catholique de Louvain Bellevue, WA, United States Louvain-la-Neuve, Belgium [email protected] [email protected] Abstract concurrent programming: developers author code that adheres to a 2 We propose a new “generic” abstraction for Erlang/OTP that aids in specific “behaviour” and these abstractions then provide a com- the implementation of dataflow programming languages and mod- mon way to supervise, manage, and reason about processing con- els on the Erlang VM. This abstraction simplifies the implemen- current messages to a single actor. tation of “processing elements” in dataflow languages by provid- We propose a new Erlang/OTP “generic” abstraction for dataflow ing a simple callback interface in the style of the gen server and programming on the Erlang VM called gen flow. This abstraction gen fsm abstractions. We motivate the use of this new abstraction allows for the arbitrary composition of stateful actors into larger by examining the implementation of a distributed dataflow pro- dataflow computations. This abstraction is sufficiently generic to gramming variant called Lasp. aid in the implementation of an arbitrary dataflow language in Erlang/OTP: we motivate the use of gen flow through the im- Categories and Subject Descriptors D.1.3 [Programming Tech- plementation of a deterministic distributed dataflow variant called niques]: Concurrent Programming; E.1 [Data Structures]: Dis- Lasp. [14, 15] tributed data structures This paper contains the following contributions: Keywords Dataflow Programming, Erlang, Concurrent Program- • gen flow abstraction: We propose gen flow, a new abstrac- ming tion in the style of the “generic” abstractions provided by Er- lang/OTP for building dataflow “processing elements.” 1.
    [Show full text]
  • Getting Started with Erlang
    Getting Started with Erlang version 5.2 Typeset in LATEX from SGML source using the DOCBUILDER 3.2.2 Document System. Contents 1 Getting Started with Erlang 1 1.1 GettingStartedwithErlang................................. 1 1.1.1Introduction...................................... 1 1.1.2WorkingwithErlang................................. 2 1.1.3TheErlangShell................................... 5 1.1.4 Compiling . 13 1.1.5DebuggingwithPman................................ 16 1.1.6DistributedErlang.................................. 18 1.1.7Configuration..................................... 22 List of Figures 23 List of Tables 25 Bibliography 27 Getting Started with Erlang iii iv Getting Started with Erlang Chapter 1 Getting Started with Erlang 1.1 Getting Started with Erlang 1.1.1 Introduction This chapter describes the most common tasks users perform in Erlang/OTP and is intended for readers who are running Erlang/OTP for the first time. It also contains references to more detailed information. This manual assumes that you have another source of information about how the language Erlang works. The first chapter of the book Concurrent Programming in ERLANG,[Concurrent Programming in ERLANG [1]], is available online in PDF1 format. This manual will describe how to ¯ compile and run Erlang programs ¯ work with the Erlang shell, this is the most central part of the development environment ¯ use the basic tools, Debugger and Pman This manual will also describe differences in development environment on the Unix and Windows platforms. Manual conventions The following conventions are used to describe commands, which are entered from the keyboard in the Erlang shell, or on the Emacs command line: window-based ¯ to enter the command C-c: Press the Control key and the letter c simultaneously. C-c is equivalent to ^c.
    [Show full text]
  • Go Big - Scaling Erlang
    Informatix Solutions GO BIG - SCALING ERLANG Richard Croucher Page 1 © - Informatix Solutions, 2014 Version 1.0 Informatix Background and Biases – Richard Croucher Solutions • Platform architect • Chief Architect at Sun Microsystems where I helped create the dotcom deployment standard and designed and deployed a 1024 server cluster • Principle DevOPs Architect at Microsoft for all its Internet properties . Adding 4000 servers a month. Established the dynamic computing working group to create design patterns for Cloud computing • Primary focus over the last decade has been High Frequency Trading systems for Banks - pushing technology to extremes • Involved with several Cloud startups • Code in multiple languages • Transitioned through Assembler, Pascal, C, C++, Java , C# and Erlang • Love new technology and finding novel ways to use existing technologies • Degrees in Physics, Electronics and Materials Science • Elected Fellow of the British Computer Society and Fellow of STAC Research • See www.informatix-sol.com Page 2 © - Informatix Solutions, 2014 Version 1.0 Informatix My Erlang journey Solutions Wow! Erlang is great Page 3 © - Informatix Solutions, 2014 Version 1.0 Informatix My Erlang journey Solutions OTP has all I need Wow! Erlang is great Page 4 © - Informatix Solutions, 2014 Version 1.0 Informatix My Erlang journey Solutions c("tcp-test"). tcp-test.erl:4: bad module declaration Immutable variables take some getting used to OTP has Where’s ‘while’ all I OTP is so hard need Limited atoms Slow maths chatty Wow! OOM Erlang is great Page 5 © - Informatix Solutions, 2014 Version 1.0 Informatix My Erlang journey Solutions c("tcp-test"). tcp-test.erl:4: bad module declaration Immutable variables take some getting used to OTP has Where’s ‘while’ all I OTP is so hard need Limited atoms Slow maths chatty Wow! OOM Erlang is great Page 6 © - Informatix Solutions, 2014 Version 1.0 Informatix My Erlang journey Solutions c("tcp-test").
    [Show full text]
  • Elixir in Action
    SECOND EDITION Saša Juric´ Sample Chapter MANNING Elixir in Action by Saša Jurić Chapter 1 Copyright 2019 Manning Publications brief contents 1 ■ First steps 1 2 ■ Building blocks 16 3 ■ Control flow 63 4 ■ Data abstractions 102 5 ■ Concurrency primitives 129 6 ■ Generic server processes 159 7 ■ Building a concurrent system 179 8 ■ Fault-tolerance basics 201 9 ■ Isolating error effects 224 10 ■ Beyond GenServer 251 11 ■ Working with components 277 12 ■ Building a distributed system 305 13 ■ Running the system 334 v First steps This chapter covers 1 ¡ Overview of Erlang ¡ Benefits of Elixir This is the beginning of your journey into the world of Elixir and Erlang, two effi- cient and useful technologies that can significantly simplify the development of large, scalable systems. Chances are, you’re reading this book to learn about Elixir. But because Elixir is built on top of Erlang and depends heavily on it, you should first learn a bit about what Erlang is and the benefits it offers. So let’s take a brief, high-level look at Erlang. 1.1 About Erlang Erlang is a development platform for building scalable and reliable systems that constantly provide service with little or no downtime. This is a bold statement, but it’s exactly what Erlang was made for. Conceived in the mid-1980s by Ericsson, a Swedish telecom giant, Erlang was driven by the needs of the company’s own tele- com systems, where properties like reliability, responsiveness, scalability, and con- stant availability were imperative. A telephone network should always operate 1 2 CHAPTER 1 First steps regardless of the number of simultaneous calls, unexpected bugs, or hardware and software upgrades taking place.
    [Show full text]
  • Programming Languages for Distributed Applications
    Invited paper for New Generation Computing 1 Programming Languages for Distributed Applications Seif Haridi, Peter Van Roy,† Per Brand,‡ and Christian Schulte§ June 14, 1998 Abstract Much progress has been made in distributed computing in the areas of distribution structure, open computing, fault tolerance, and security. Yet, writing distributed applications remains diffi- cult because the programmer has to manage models of these areas explicitly. A major challenge is to integrate the four models into a coherent development platform. Such a platform should make it possible to cleanly separate an application’s functionality from the other four concerns. Concurrent constraint programming, an evolution of concurrent logic programming, has both the expressiveness and the formal foundation needed to attempt this integration. As a first step, we have designed and built a platform that separates an application’s functionality from its distri- bution structure. We have prototyped several collaborative tools with this platform, including a shared graphic editor whose design is presented in detail. The platform efficiently implements Distributed Oz, which extends the Oz language with constructs to express the distribution struc- ture and with basic primitives for open computing, failure detection and handling, and resource control. Oz appears to the programmer as a concurrent object-oriented language with dataflow synchronization. Oz is based on a higher-order, state-aware, concurrent constraint computation model. 1 Introduction Our society is becoming densely interconnected through computer networks. Transferring informa- tion around the world has become trivial. The Internet, built on top of the TCP/IP protocol family, has doubled in number of hosts every year since 1981, giving more than 20 million in 1997.
    [Show full text]
  • Introducing Concurrent Functional Programming in the Telecommunications Industry
    Introducing Concurrent Functional Programming in the Telecommunications Industry Bjarne Dacker Computer Science Laboratory, Ericsson Utvecklings AB, Box 1505, 12525 Sweden Key words: Functional programming, Concurrent programming, Technology dissemination Abstract: This paper gives an overview of the concurrent functional programming language and its development, dissemination, and use. Erlang was developed at Ericsson and is used for several large and important telecom systems. It is also available externally, both supported and through open source. Erlang provides a highly relevant case-study of technology diffusion since its development touches upon many relevant topics such as applied research in the industrial environment and spread of technology through open source. 1. INTRODUCTION Telecommunications systems place very difficult demands on the underlying programming and computer technology, such as large number of concurrent activities, systems distributed over several computers, large and complex software systems, software maintenance (reconfiguration, etc.) while the system is in operation, fault tolerance to hardware failures and software errors, etc. The concurrent junctional programming language Erlang [3, 5] was developed as a software technology to meet these requirements and to facilitate the design of telecommunications systems. Section 2 gives a short The original version of this chapter was revised: The copyright line was incorrect. This has been corrected. The Erratum to this chapter is available at DOI: 10.1007/978-0-387-35404-0_19 M. A. Ardis et al. (eds.), Diusing Software Product and Process Innovations © IFIP International Federation for Information Processing 2001 242 Bjarne Dacker overview over Erlang and the subsequent sections describe how Erlang was developed and experiences from its spread both inside and outside Ericsson.
    [Show full text]