Adobe® Flex® 4 Language Reference
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flash.net.dns 
DNSResolver 
Packageflash.net.dns
Classpublic class DNSResolver
InheritanceDNSResolver Inheritance EventDispatcher Inheritance Object

Language Version: ActionScript 3.0
Runtime Versions: AIR 2

The DNSResolver class lets you lookup Domain Name System (DNS) resource records.

You can look up the following types of resource records:

  • ARecord: IPv4 address for a host.
  • AAAARecord: IPv6 address for a host.
  • MXRecord: mail exchange record for a host.
  • PTRRecord: host name for an IP address.
  • SRVRecord: service record for a service

View the examples

See also



Public Properties
 PropertyDefined By
 Inheritedconstructor : Object
A reference to the class object or constructor function for a given object instance.
Object
  AIR-only isSupported : Boolean
[static] [read-only] Indicates whether DNS lookups are supported on the client system.
DNSResolver
 Inheritedprototype : Object
[static] A reference to the prototype object of a class or function object.
Object
Public Methods
 MethodDefined By
  
Creates a DNSResolver object.
DNSResolver
 Inherited
addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void
Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.
EventDispatcher
 Inherited
Dispatches an event into the event flow.
EventDispatcher
 Inherited
Checks whether the EventDispatcher object has any listeners registered for a specific type of event.
EventDispatcher
 Inherited
Indicates whether an object has a specified property defined.
Object
 Inherited
Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.
Object
  
AIR-only lookup(host:String, recordType:Class):void
Looks up a DNS resource record based on a query string.
DNSResolver
 Inherited
Indicates whether the specified property exists and is enumerable.
Object
 Inherited
removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void
Removes a listener from the EventDispatcher object.
EventDispatcher
 Inherited
Sets the availability of a dynamic property for loop operations.
Object
 Inherited
Returns the string representation of this object, formatted according to locale-specific conventions.
Object
 Inherited
Returns the string representation of the specified object.
Object
 Inherited
Returns the primitive value of the specified object.
Object
 Inherited
Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.
EventDispatcher
Events
 Event Summary Defined By
 Inherited[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.EventDispatcher
 Inherited[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.EventDispatcher
  Dispatched when an error occurred during a DNS lookup.DNSResolver
  Dispatched when a DNS look-up is complete.DNSResolver
Property Detail
AIR-only 

isSupported

property
isSupported:Boolean  [read-only]

Runtime Versions: AIR 2

Indicates whether DNS lookups are supported on the client system.



Implementation
    public static function get isSupported():Boolean
Constructor Detail
AIR-only 

DNSResolver

()Constructor
public function DNSResolver()

Language Version: ActionScript 3.0
Runtime Versions: AIR 2

Creates a DNSResolver object.

Method Detail

AIR-only lookup

()method
public function lookup(host:String, recordType:Class):void

Language Version: ActionScript 3.0
Runtime Versions: AIR 2

Looks up a DNS resource record based on a query string.

The lookup() method performs a DNS lookup asynchronously. Listen for the lookup event to get the results of the lookup. Listen for the error event to receive errors. Results are dispatched in a DNSResolverEvent object.

To specify the type of resource record to look up, pass the corresponding class in the recordType parameter. (Pass the class name itself and not a string containing the class name.)

The content of the query string passed to the method depends on the type of resource record being looked up. The following list illustrates the query string to use for each record type.

Record typeQuery stringExample
ARecordhost name"example.com"
AAAARecordhost name"example.com"
MXRecordhost name"example.com"
PTRRecordIP address"208.77.188.166"
SRVRecord_service._protocol.host."_sip._tcp.example.com."

Parameters

host:String — the query string, such as a host name, IP address, or service locator.
 
recordType:Class — The class representing the type of DNS resource record to look up.


Events
lookup:DNSResolverEvent — dispatched when the lookup is completed successfully.
 
error:ErrorEvent — dispatched when the lookup fails (including when no records exist).

Throws
ArgumentError — The host parameter value is not an appropriate query string or the recordType class is not recognized.

See also

Event Detail
AIR-only 

error

Event
Event Object Type: flash.events.ErrorEvent
property ErrorEvent.type = flash.events.ErrorEvent.ERROR

Language Version: ActionScript 3.0
Runtime Versions: AIR 2

Dispatched when an error occurred during a DNS lookup.

Defines the value of the type property of an error event object.

This event has the following properties:

PropertyValue
bubblesfalse
cancelablefalse; there is no default behavior to cancel.
currentTargetThe object that is actively processing the Event object with an event listener.
targetThe object experiencing a network operation failure.
textText to be displayed as an error message.
AIR-only 

lookup

Event  
Event Object Type: flash.events.DNSResolverEvent
property DNSResolverEvent.type = flash.events.DNSResolverEvent.LOOKUP

Language Version: ActionScript 3.0
Runtime Versions: AIR 2

Dispatched when a DNS look-up is complete.

Defines the value of the type property of a lookup event object.
DNSResolverExample.as

The following example shows how to look up the supported types of DNS records:
package
{
    import flash.desktop.NativeApplication;
    import flash.display.Sprite;
    import flash.events.DNSResolverEvent;
    import flash.events.ErrorEvent;
    import flash.events.Event;
    import flash.events.MouseEvent;
    import flash.net.dns.AAAARecord;
    import flash.net.dns.ARecord;
    import flash.net.dns.DNSResolver;
    import flash.net.dns.MXRecord;
    import flash.net.dns.PTRRecord;
    import flash.net.dns.SRVRecord;
    import flash.utils.getQualifiedClassName;
    
    public class DNSResolverExample extends Sprite
    {
        private var resolver:DNSResolver = new DNSResolver();
        
        public function DNSResolverExample()
        {
            resolver.addEventListener( DNSResolverEvent.LOOKUP, lookupComplete );
            resolver.addEventListener( ErrorEvent.ERROR, lookupError );
            
            //Look up records
            resolver.lookup( "www.example.com", ARecord );
            resolver.lookup( "example.com", AAAARecord );
            resolver.lookup( "example.com", MXRecord );
            resolver.lookup( "208.77.188.166", PTRRecord );
            resolver.lookup( "127.0.0.1", PTRRecord );
            resolver.lookup( "2001:1890:110b:1e19:f06b:72db:7026:3d7a", PTRRecord );
            resolver.lookup( "_sip._tcp.example.com.", SRVRecord );
            resolver.lookup( "www.example.com", ARecord );
            
            this.stage.nativeWindow.activate();
        }
        
        private function lookupComplete( event:DNSResolverEvent ):void
        {
            trace( "Query string: " + event.host );
            trace( "Record type: " +  flash.utils.getQualifiedClassName( event.resourceRecords[0] ) + 
                ", count: " + event.resourceRecords.length );
            for each( var record in event.resourceRecords )
            {
                if( record is ARecord ) trace( record.name + " : " + record.address );
                if( record is AAAARecord ) trace( record.name + " : " + record.address );
                if( record is MXRecord ) trace( record.name + " : " + record.exchange + ", " + record.preference );
                if( record is PTRRecord ) trace( record.name + " : " + record.ptrdName );
                if( record is SRVRecord ) trace( record.name + " : " + record.target + ", " + record.port +
                    ", " + record.priority + ", " + record.weight );
            }            
        }
        
        private function lookupError( error:ErrorEvent ):void
        {
            trace("Error: " + error.text );
        }
    }
}