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The Ruby Programming Language

Cover of The Ruby Programming Language by Yukihiro Matsumoto... Published by O'Reilly Media, Inc.
  1. The Ruby Programming Language
    1. SPECIAL OFFER: Upgrade this ebook with O’Reilly
    2. A Note Regarding Supplemental Files
    3. Preface
      1. Acknowledgments
      2. Conventions Used in This Book
      3. Using Code Examples
      4. How to Contact Us
      5. Safari® Enabled
    4. 1. Introduction
      1. A Tour of Ruby
      2. Try Ruby
      3. About This Book
      4. A Sudoku Solver in Ruby
    5. 2. The Structure and Execution of Ruby Programs
      1. Lexical Structure
      2. Syntactic Structure
      3. File Structure
      4. Program Encoding
      5. Program Execution
    6. 3. Datatypes and Objects
      1. Numbers
      2. Text
      3. Arrays
      4. Hashes
      5. Ranges
      6. Symbols
      7. True, False, and Nil
      8. Objects
    7. 4. Expressions and Operators
      1. Literals and Keyword Literals
      2. Variable References
      3. Constant References
      4. Method Invocations
      5. Assignments
      6. Operators
    8. 5. Statements and Control Structures
      1. Conditionals
      2. Loops
      3. Iterators and Enumerable Objects
      4. Blocks
      5. Altering Control Flow
      6. Exceptions and Exception Handling
      7. BEGIN and END
      8. Threads, Fibers, and Continuations
    9. 6. Methods, Procs, Lambdas, and Closures
      1. Defining Simple Methods
      2. Method Names
      3. Methods and Parentheses
      4. Method Arguments
      5. Procs and Lambdas
      6. Closures
      7. Method Objects
      8. Functional Programming
    10. 7. Classes and Modules
      1. Defining a Simple Class
      2. Method Visibility: Public, Protected, Private
      3. Subclassing and Inheritance
      4. Object Creation and Initialization
      5. Modules
      6. Loading and Requiring Modules
      7. Singleton Methods and the Eigenclass
      8. Method Lookup
      9. Constant Lookup
    11. 8. Reflection and Metaprogramming
      1. Types, Classes, and Modules
      2. Evaluating Strings and Blocks
      3. Variables and Constants
      4. Methods
      5. Hooks
      6. Tracing
      7. ObjectSpace and GC
      8. Custom Control Structures
      9. Missing Methods and Missing Constants
      10. Dynamically Creating Methods
      11. Alias Chaining
      12. Domain-Specific Languages
    12. 9. The Ruby Platform
      1. Strings
      2. Regular Expressions
      3. Numbers and Math
      4. Dates and Times
      5. Collections
      6. Files and Directories
      7. Input/Output
      8. Networking
      9. Threads and Concurrency
    13. 10. The Ruby Environment
      1. Invoking the Ruby Interpreter
      2. The Top-Level Environment
      3. Practical Extraction and Reporting Shortcuts
      4. Calling the OS
      5. Security
    14. Index
    15. About the Authors
    16. Colophon
    17. SPECIAL OFFER: Upgrade this ebook with O’Reilly
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Networking

Ruby’s networking capabilities are provided by the standard library rather than by core classes. For this reason, the subsections that follow do not attempt to enumerate each available class or method. Instead, they demonstrate how to accomplish common networking tasks with simple examples. Use ri for more complete documentation.

At the lowest level, networking is accomplished with sockets, which are a kind of IO object. Once you have a socket opened, you can read data from, or write data to, another computer just as if you were reading from or writing to a file. The socket class hierarchy is somewhat confusing, but the details are not important in the following examples. Internet clients use the TCPSocket class, and Internet servers use the TCPServer class (also a socket). All socket classes are part of the standard library, so to use them in your Ruby program, you must first write:

require 'socket'

A Very Simple Client

To write Internet client applications, use the TCPSocket class. Obtain a TCPSocket instance with the TCPSocket.open class method, or with its synonym TCPSocket.new. Pass the name of the host to connect to as the first argument and the port as the second argument. (The port should be an integer between 1 and 65535, specified as a Fixnum or String object. Different internet protocols use different ports. Web servers use port 80 by default, for example. You may also pass the name of an Internet service, such as “http”, as a string, in place of a port number, ...

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