Powering Flash Applications with a Server, Part 2—Flash Remoting

n part 1 of this series, I discussed various ways to connect a Flash application to a server. Why? Connecting Flash to a server allows for more robust, dynamic, and useful applications than is otherwise possible. More and more companies are replacing traditional Web applications on intranets, extranets and public sites with rich Internet apps, providing the interactivity and responsiveness of a client-server application with the fully distributed nature of an Internet application. To make this possible, it is necessary to integrate external data.

Introducing Flash Remoting
Flash Remoting allows data to be exchanged between a Flash Player and an application server using a format called AMF (ActionScript Messaging Format), which is a Macromedia proprietary binary format based on SOAP. On the client side, native Flash objects are sent by the Player to the Flash Remoting gateway using AMF. At the gateway, they are serialized into native objects for the application server and passed on to the appropriate server-side services.

Table 1 shows the serializations from Flash into .NET, Java, and ColdFusion data types, while Table 2 shows the serializations performed from the application server data types back into ActionScript.

Table 1. Serializing Data from Flash Objects

ActionScript	C#	Java	ColdFusion
Number	Double	Double	Number
Boolean	Boolean	Boolean	Boolean
String	String	String	String
Object	ICollection	java.util.map	Arguments Collection
Ordered Array	ArrayList	ArrayList	Array
Named Array	Hashtable	java.util.map	Structure
Date	DateTime	Date	Date
XML	XmlDocument	org.w3c.dom.Document	XML

Table 2. Serializing Data into Flash Objects

ActionScript	C#	Java	ColdFusion
Array	Array, ICollection	Object[], Array of primitive types, Collection, Map	Array
Boolean	Bool	Boolean	Boolean
Number	Int, float, double	Number	Numeric
String	String	Character	String
Date	DateTime	Date	Date
RecordSet	DataTable	java.sql.ResultSet, flashgateway.sql.PageableResultSet	Query
Object	HashTable	Throwable, flashgateway.io.ASObject, Dictionary, Serializable	Structure
XML	XmlDocument	org.w3c.dom.Document, flashgateway.io.ASXMLString	XML

When results are returned, the gateway serializes them back into native Flash objects and sends them on to the Flash client via AMF. When the data arrives in Flash, it is already in native object format, so it can be used without any further translation. Further, all the data transfer between the client and server is done in AMF over HTTP, so there are no new firewall restrictions for Flash applications using Remoting.

There are two pieces needed to use Flash Remoting: The Flash Remoting gateway (also called the Remoting Server) and a Flash application into which the Flash Remoting components are compiled. In the next section, I'll discuss how each of these pieces work, as well as the basics of AMF, then, later, I'll try out Flash Remoting with a simple application.

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