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Concurrent Programming in Erlang

J. Armstrong, R. Virding, C. Wikström, M. Williams

2:nd Edition
Prentice Hall, 1996, ISBN 0-13-508301-X

Erlang is a concurrent functional programming language designed for programming large industrial real-time systems. Erlang is dynamically typed and has a pattern matching syntax. Functions are defined using recursion equations. Erlang provides explicit concurrency, has asynchronous message passing and is relatively free from side effects.

Distributed Erlang programs can run transparently on cross-platform multi-vendor systems. The language has primitives for detecting run-time errors and for dynamic code replacement (i.e. changes to code can be made in a running real-time system, without stopping system).

Erlang has real-time GC, modules and a foreign language interface.

Erlang was developed at the Ellemtel Telecommunication Systems Laboratories and is used within Ericsson for product development and prototyping.

Part I. Programming.

Chapter 1 An Erlang Tutorial
        1.1 Sequential Programming
        1.2 Data Types
        1.3 Pattern Matching
        1.4 Built-In Functions
        1.5 Concurrency

Chapter 2 Sequential Programming
        2.1 Terms
        2.2 Pattern Matching
        2.3 Expression Evaluation
        2.4 The Module System
        2.5 Function Definition
        2.6 Primitives
        2.7 Arithmetic Expressions
        2.8 Scope of Variables

Chapter 3 Programming with Lists
        3.1 List Processing BIFs
        3.2 Some Common List Processing Functions
        3.3 Examples
        3.4 Common Patterns of Recursion on Lists
        3.5 Functional Arguments

Chapter 4 Programming with Tuples
        4.1 Tuple Processing BIFs
        4.2 Multiple Return Values
        4.3 Encrypting PIN Codes
        4.4 Dictionaries
        4.5 Unbalanced Binary Trees
        4.6 Balanced Binary Trees

Chapter 5 Concurrent Programming
        5.1 Process Creation
        5.2 Inter-Process Communication
        5.3 Timeouts
        5.4 Registered Processes
        5.5 Client--Server Model
        5.6 Process Scheduling, Real Time and Priorities
        5.7 Process Groups 
Basic concurrent programming techniques. Creating and monitoring processes. Sending messages between process. Monitoring processes. The client-server model is introduced. Primitives for real-time programming.
Chapter 6 
            Distributed Programming
        6.1 Motivation
        6.2 Distributed mechanisms
        6.3 Registered Processes
        6.4 Connections
        6.5 A Banking Example
The language primitives have the same properties in a distributed system as in a single node system.
Chapter 7 Error Handling
        7.1 Catch and Throw
        7.2 Process Termination
        7.3 Linked Processes
        7.4 Run-Time Failure
        7.5 Changing the Default Signal Reception Action
        7.6 Undefined Functions and Unregistered Names
        7.7 Catch versus Trapping Exits
Basic error handling mechanisms. Catch and throw. Detecting process termination.
Chapter 8 Programming Robust Applications
        8.1 Guarding against Bad Data
        8.2 Robust Server Processes
        8.3 Isolating Computations
        8.4 Keeping Processes Alive
        8.5 Discussion
Basic programming techniques for programming fault-tolerant applications.
Chapter 9 Miscellaneous Items
        9.1 Last Call Optimisation
        9.2 References
        9.3 Code Replacement
        9.4 Ports
        9.5 Binaries
        9.6 Process Dictionary
        9.7 The Net Kernel 
        9.8 Hashing        
        9.8 Efficiency     
Changing code in a running system without stopping the system. Interfacing to foreign languages.

Part II. Applications

The applications part of the book is a set of case studies. Here we build on the programming techniques of Part I to construct complete programs. Many of the studies are based on real-world applications.

Chapter 9 Databases
        9.1 The Access Functions
        9.2 Simple Database
        9.3 A Multi-Level Database
        9.4 Transaction Management
        9.5 External Databases
Simple database programs, with transactions, roll-back, fault-tolerance, etc..
Chapter 10 
              Distributed Programming Techniques
        10.1  Remote Procedure Calls (RPC)
        10.2  Multicalls
        10.3  Broadcasting
        10.4  Global Registration
        10.5  Promises
        10.6  Mulitcasting to Process Groups
        10.7  Negotiation Techniques
        10.8  Adaptive Load Distribution
        10.9  Relay Techniques
        10.10 Parallel Evaluation for Speed 
        10.11 Discussion
RPC, the ability to evaluate a function transparently an a remote node.
Promises, an asyncrounous RPC.

Erlang provides simpler primitives for RPC, global name servers, error detection etc. than many operating systems.

Chapter 11 
             Distributed Data
        11.1 Shared Data
        11.2 Partial Replication
        11.3 Transactions
Many applications may wish to have some common data structures available for access and modification by several processes on several nodes. This chapter describes various techniques for sharing data between physically separated nodes.

Chapter 12 Operating Systems
        12.1 Overview of the Standard Erlang OS
        12.2 System Startup
        12.3 Code Management
        12.4 The Input/Output System
        12.5 The Standard Shell
An overview of the standard Erlang operating system.

Chapter 13 Real-Time Control
        13.1 A Lift Control System
        13.2 A Satellite Control System
Two real-time (process control) applications.

Chapter 14 Telephony
        14.1 Typical Aspects of Switching System Software
        14.2 POTS
        14.3 Robustness
        14.4 SDL
A telephony application. This is sub-set of a much larger program which used to control an Ericsson PABX in a real-world application.
Chapter 15 An ASN.1 Compiler
        15.1 Background
        15.2 About ASN.1
        15.3 BER -- Basic Encoding Rules
        15.4 Implementation
        15.5 ASN.1 Applications
A cross compiler from ASN.1 (The CCITT specified data transport definition language) to Erlang. This again is from a real-world application.
Chapter 16 Graphics
        16.1 The User Interface
        16.2 Basic Graphics Primitives
        16.3 A Pocket Calculator
        16.4 A Prompter
        16.5 A TV Simulation
Building a graphic user interface in Erlang. This shows how Erlang can be interfaced to the X-windows system to build an advanced GUI.
Chapter 17 Object-Oriented Programming
        17.1 Basic Concepts
        17.2 Mapping to Erlang
        17.3 An Object-Oriented Interface
        17.4 Object-Oriented Programming
        17.5 Object-Oriented Design
Discusses the relation between Erlang and Object-Orientated programming.
Updated: 2000-02-08