ActionScript 3.0 Cookbook

Chapter 24. Socket Programming

Introduction

Socket connections allow the Flash Player to send and load data from a server over a specified network port. The main difference between socket and server connections in Chapter 20 is that socket connections don’t automatically close after data transfer is complete.

When a socket connection is made, the connection stays open until the client (the Flash Player) or the server explicitly closes it. Because of this, sockets enable a special type of communication called data push, which means that the server sends information to the Flash Player at any time without a request coming from the Player itself.

Socket connections are typically used to create multiuser applications. An example of one such application would be an online chat room. The chat program might consist of a central chat server with various connected Flash Player clients. Each time a client .swf sends a message to the server, the server determines which client should receive the message and pushes the message to that specific client over the open connection. In this case, the receiving client didn’t ask for the message, but rather the message was simply pushed out to it by the server. When a client closes a connection, the server notifies the other clients that someone has logged off of the system.

Two types of socket connections can be made from the Flash Player to a socket server. They are very similar in behavior and operation, but have a few subtle differences. The first is ...