ACE Programmer's Guide, The: Practical Design Patterns for Network and Systems Programming

Chapter 8. Asynchronous I/O and the ACE Proactor Framework

Applications that must perform I/O on multiple endpoints—whether network sockets, pipes, or files—historically use one of two I/O models:

1. Reactive. An application based on the reactive model registers event handler objects that are notified when it's possible to perform one or more desired I/O operations, such as receiving data on a socket, with a high likelihood of immediate, successful completion. The ACE Reactor framework, described in Chapter 7, supports the reactive model.
2. Multithreaded. An application spawns multiple threads that each perform synchronous, often blocking, I/O operations. This model doesn't scale very well for applications with large numbers of open endpoints.