Boost Asio Code Sample Is
Boost.AsioChristopher KohlhoffCopyright 2003 - 2008 Christopher M. You can use Boost with compilers where these are not available.The code sample is messy and explanations are not comprehensive.The writer is struggling to explain something new to the reader and he fails, while the whole book is as simple as 30 lines of code.What makes teaching this topic challenging is that every detail needs deep explanations, e.g. Threads, mutex, asynchronous processing and network socket interface.I will update this review and suggest better resources for reading Boost. S, buffers, boost::asio::transferall (), handler) This function is used to asynchronously read a certain number of bytes of data from a stream.
Examples that illustrate the use of Boost.Asio in more complex applications. A tutorial that introduces the fundamental concepts required to use Boost.Asio, and shows how to use Boost.Asio to develop simple client and server programs. Includes information on library dependencies and supported platforms. How to use Boost.Asio in your applications. Overview Using Boost.Asio Tutorial Examples Reference Index An overview of the features included in Boost.Asio, plus rationale and design information. (See accompanying file LICENSE_1_0.txt or copy at ) Boost.Asio is a cross-platform C++ library for network and low-level I/O programming that provides developers with a consistent asynchronous model using a modern C++ approach.
This poses particular challenges to application development. Sometimes, as is the case with networking, individual I/O operations can take a long time to complete. Book-style text index of Boost.Asio documentation.Overview Rationale Core Concepts and Functionality Basic Boost.Asio Anatomy The Proactor Design Pattern: Concurrency Without Threads Threads and Boost.Asio Strands: Use Threads Without Explicit Locking Buffers Streams, Short Reads and Short Writes Reactor-Style Operations Line-Based Operations Custom Memory Allocation Networking TCP, UDP and ICMP Socket Iostreams The BSD Socket API and Boost.Asio TimersXML to PDF by RenderX XEP XSL-FO Formatter, visit us at Serial Ports POSIX-Specific Functionality UNIX Domain Sockets Stream-Oriented File Descriptors Windows-Specific Functionality Stream-Oriented HANDLEs Random-Access HANDLEs SSL Platform-Specific Implementation NotesRationaleMost programs interact with the outside world in some way, whether it be via a file, a network, a serial cable, or the console.
The library should support techniques such as scatter-gather I/O, and allow programs to minimise data copying. The library implementation for each operating system should use the mechanism that best enables this scalability. The library should facilitate the development of network applications that scale to thousands of concurrent connections. The library should support a range of commonly used operating systems, and provide consistent behaviour across these operating systems. In particular, Boost.Asio addresses the following goals: Portability. The Boost.Asio library is intended for programmers using C++ for systems programming, where access to operating system functionality such as networking is often required.
For example, implementations of commonly used protocols such as HTTP. The library should permit the development of other libraries that provide higher levels of abstraction. Basis for further abstraction. After that, a library user should only need to understand the specific functions that are being used. That is, it should try to minimise the up-front investment in time to just learning a few basic rules and guidelines.
Your program initiates the connect operation by calling the I/O object:2. The io_service represents your program's link to the operating system's I/O services.boost::asio::io_service io_service To perform I/O operations your program will need an I/O object such as a TCP socket:boost::asio::ip::tcp::socket socket(io_service) When a synchronous connect operation is performed, the following sequence of events occurs: 1. We shall start by examining synchronous operations.Your program will have at least one io_service object. As an introductory example, let's consider what happens when you perform a connect operation on a socket. Before using Boost.Asio it may be useful to get a conceptual picture of the various parts of Boost.Asio, your program, and how they work together.
The I/O object throws an exception of type boost::system::system_error if the operation failed. The result is then forwarded back up to the I/O object. An error_code may be compared with specific values, or tested as a boolean (where a false result means that no error occurred). The io_service translates any error resulting from the operation into a boost::system::error_code. The operating system returns the result of the operation to the io_service. The io_service calls on the operating system to perform the connect operation.
The I/O object forwards the request to the io_service.3. The reference documentation indicates the appropriate form for each operation. Your program initiates the connect operation by calling the I/O object:socket.async_connect(server_endpoint, your_completion_handler) Where your_completion_handler is a function or function object with the signature:void your_completion_handler(const boost::system::error_code& ec) The exact signature required depends on the asynchronous operation being performed. When an asynchronous operation is used, a different sequence of events occurs.1.
While inside the call to io_service::run(), the io_service dequeues the result of the operation, translates it into an error_code, and then passes it to your completion handler. A call to io_service::run() blocks while there are unfinished asynchronous operations, so you would typically call it as soon as you have started your first asynchronous operation. Your program must make a call to io_service::run() (or to one of the similar io_service member functions) in order for the result to be retrieved. The operating system indicates that the connect operation has completed by placing the result on a queue, ready to be picked up by the io_service. (In the synchronous case this wait would have been contained entirely within the duration of the connect operation.)4.
The advantages and disadvantages of this approach, when compared to a synchronous-only or Reactor approach, are outlined below. The asynchronous support is based on the Proactor design pattern. You will want to delve further into the documentation if your needs are more advanced, such as extending Boost.Asio to perform other types of asynchronous operations.The Proactor Design Pattern: Concurrency Without ThreadsThe Boost.Asio library offers side-by-side support for synchronous and asynchronous operations.
Completion Event Queue Buffers completion events until they are dequeued by an asynchronous event demultiplexer. From a high-level point of view, services like stream_socket_service are asynchronous operation processors. Asynchronous Operation Processor Executes asynchronous operations and queues events on a completion event queue when operations complete.
Proactor Calls the asynchronous event demultiplexer to dequeue events, and dispatches the completion handler (i.e. Asynchronous Event Demultiplexer Blocks waiting for events to occur on the completion event queue, and returns a completed event to its caller. These are function objects, often created using boost::bind.
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