Data

Data can come in many formats. It can be a text file, XML file located on a file system, or dynamic data/XML generated by a server at run-time.

In ActionScript you can load data from external sources into an SWF file. You can also send data from an SWF file for processing by an application server (such as Microsoft IIS, Macromedia ColdFusion MX, Macromedia JRun, IBM Websphere, BEA Weblogic, and so on) or another type of server-side script, such as ASP, PHP or Perl.

Macromedia Flash Player can send and load data over HTTP or HTTPS, or load from a local text file or XML file. You can also create persistent TCP/IP socket connections for real time messaging applications.

The following are the different ways that you can exchange data that are available in ActionScript.

1. getURL(), loadVariables(), loadVariablesNum(), loadMovie(), and loadMovieNum() methods
2. LoadVars Class
3. MovieClipLoader class
4. XML Class
5. XMLSocket Class

The methods listed as the title of this section use the HTTP or HTTPS protocol to send information in URL-encoded format.

getURL(): This method loads a document from a specific URL into a window or passes variables to another application at a defined URL. This method can used when you want to load a different URL onto the existing one. You also have the option of passing the data to a different URL using http POST and GET methods.

Example:

//opens
http://www.devarticles.comin a blank window

getURL("http://www.devarticles.com", "_blank");

//sends the variables from flash to
http://www.devarticles.com
using POST method

getURL("http://www.devarticles.com", "_blank", ”POST”); 

loadVariables() , loadVariablesNum():These methods reads data from any external file, such as a text file or text generated by any server-side scripting technology such as ColdFusion, CGI script, ASP, PHP, Perl, and so on, and set the values for variables in a Flash.

The main difference between the loadVariables() method and the loadVariablesNum() method is that loadVariables() sets the values for variables in a target movie clip, while loadVariablesNum() sets the values for variables in a level. You can also use this method to update variables in the active SWF file with new values.

The text in the text files, or the text generated by the server-side script, should be in the standard MIME format application/x-www-form-urlencoded (a standard format used by CGI scripts). Any number of variables can be specified, as in the string shown below.

name=Jhon&age=22&zip=534235

Example:

// Variables from data.txt will be loaded into target_mc movie clip

loadVariables("data.txt", target_mc);

// Variables from data.txt will be loaded into level 1

loadVariablesNum("data.txt", 1);

You can also use the movie clip’s loadVariables() method to load data directly into the movie clip.

Ex: target_mc. loadVariables ("data.txt");

loadMovie() , loadMovieNum(): These methods let you load external SWF files and JPEG files into the existing SWF file and are similar to loadVariables() and loadVariablesNum() methods. The difference between loadMovie() and loadMovieNum() is also the same, target and level.

Example:

// Loads play.swf file into target_mc movie clip

loadMovie("play.swf", target_mc);

// Loads play.jpg image into level 1

loadMovieNum("play.jpg", 1);

You can also use the movie clip’s loadMovie() method to load external SWF files or JPEG images into the movie clip directly.

Ex: target_mc.loadMovie("play.jpg");

The LoadVars Class can be used in lieu of loadVariables() and loadVariablesNum() methods. It has three methods that use the HTTP or HTTPS protocol to send and load information in URL-encoded format.

This class was introduced in Flash Player 6 to provide a cleaner, much more object-oriented interface for the common task of exchanging data with a server or text files.

When compared to loadVariables() and loadVariablesNum() methods, LoadVars class has many advantages.

Example:

The following example instantiates a LoadVars object, assigns a couple of variables to it and sends those variables to a PHP page with http POST method.

var sample_lv:LoadVars = new LoadVars();

sample _lv.name = “Jhon”;

sample _lv.age = “36”;

sample _lv.send("setid.php", "_blank", "POST");

The MovieClipLoader Class can be used in lieu of the loadMovie() method.

This class lets you implement listener call backs that provide status information while SWF or JPEG files are being loaded into movie clips.

Instead of using loadMovie()or MovieClip.loadMovie() methods, you need to use MovieClipLoader.loadClip() to use the features of the MovieClipLoader class.

The following events will take place in the order listed when you use MovieClipLoader Class:

MovieClipLoader.onLoadStart– This event listener will fire when the first bytes of the SWF or JPEG file are downloaded.

MovieClipLoader.onLoadProgress– This event listener will continuously fire during the loading process, and can be used to show the loading progress to the users. During the load process you can call MovieClipLoader.getProgress()at any time to know the progress of the loading.

MovieClipLoader.onLoadComplete– This event listener will fire when the entire file has been downloaded.

MovieClipLoader.onLoadInit– This event listener will fire after the downloaded file’s first frame actions have been executed. This will be helpful for performing any actions on the loaded file. Until this event listener fires, you cannot perform any actions on the loaded file.

Note: If there is any problem loading the file then MovieClipLoader.onLoadErrorevent listener will fire and return the error code.

Now let us see an example of how to use the MovieClipLoader class in action. 

Example:

// Instantiate MovieClipLoader Class

var adloader:MovieClipLoader = new MovieClipLoader();

// use loadClip to load SWF file into a movie clip header_mc

adloader.loadClip("mainad.swf","header_mc");

// Add an onLoadStart event listener to show the progress of the loading

adloader.onLoadStart = function (targetMC){

         var loadProgress:Object = adloader.getProgress(targetMC);

         var loaded:Number = loadProgress.bytesLoaded;

         var total:Number = loadProgress.bytesTotal;

         adprogress_txt.text = loaded+" of "+ total+" bytes loaded";

}

// Add an onLoadComplete event listener to clear the loading information

adloader.onLoadComplete = function (targetMC){

         adprogress_txt.text = "";

}

// Add an onLoadError event listener to trace the load errors

adloader.onLoadError = function (targetMC, errorCode){

         adprogress_txt.text = "ERRORCODE:" + errorCode + " failed to load";

}

XMLSocket class in ActionScript lets you open a continuous connection with a server. A socket connection lets the server publish, or  push, information to the client as soon as that information is available. The data is sent over the socket connection as one string and should be formatted as XML. You can use the XML class to structure the data.

The methods of XMLSocket Class create and use TCP/IP socket connections to send and load information as XML.

You can use the connect()and send()methods of the XMLSocket class to transfer XML to and from a server over a socket connection. The connect()method establishes a socket connection with a Web server port. The send()method passes an XML object to the server specified in the socket connection.

Now let us see an example that shows how to use the XMLSocket Class.

Example:

// Create XMLSocket object

var sample_socket:XMLSocket = new XMLSocket();

// Connects to localhost server with port number 1024

sample_socket.connect("localhost", 1024);

// Displays connection status information

sample_socket.onConnect = function(status) {

 if (status) {

   conn_txt.text = "connection successful";

 } else {

   conn_txt.text = "no connection made";

 }

};

// Function that creates data to send it to the server using

send() method

function sendData() {

 var data:XML = new XML();

 var send = data.createElement("user");

 send.attributes.id = "asp123";

 data.appendChild(send);

 sample_socket.send(data);

}

// onData event handler function to track the data returned from

socket connection and perform actions based on that data

sample_socket.onData = function(msg:String):Void {

 trace(msg);

};

Note:The XMLSocket.connect()method can connect only to TCP port numbers greater than or equal to 1024. Port numbers below 1024 are often used by system services such as FTP, Telnet, and HTTP, so XMLSocket objects are barred from these ports for security reasons.