We’ve added support for descendant selectors, class conditions for type selectors (previously class conditions were only registerd by themselves at the top level, i.e. “globally” instead of on a type by type basis), and id conditions for both type selectors as well as globally. These selectors were chosen as they were seen as the most requested by the community.

A few known issues that will be fixed shortly after alpha include allowing combinations of conditions at the top level (e.g. a top level id and class selector together in a selector chain, “.specialButton#button12″);

For strongly typed objects, you can implement the mx.rpc.xml.IXMLSchemaInstance interface to provide a QName for the xsiType property to target the subclass to be used during encoding. See: http://livedocs.adobe.com/flex/3/langref/mx/rpc/xml/IXMLSchemaInstance.html#xsiType

For anonymous ActionScript Objects, however, you may not know that you can wrap your object in an mx.utils.ObjectProxy instance and set its type property with a QName to achieve the same effect. See:
http://livedocs.adobe.com/flex/3/langref/mx/utils/ObjectProxy.html#type

Using the following XML Schema as an example…

We may want to provide an Employee instance as a Record’s person value, but unless we tell the encoder we have something more than a Person instance, the Employee-specific properties will not be encoded.JohnSmith

To avoid having to create Person or Employee strong types, here’s a snippet showing how to create an ObjectProxy wrapper to instruct the encoder to encode an anonymous Object as an Employee:

import mx.utils.object_proxy;import mx.utils.ObjectProxy;...var emp:Object = {firstName:"John", lastName:"Smith", employeeId:1000};var employee:ObjectProxy = new ObjectProxy(emp);var employeeType:QName = new QName("urn:MyWebService", "Employee");employee.object_proxy::type = employeeType;

Now the encoder should know to include the Employee specific employeeId property:JohnSmith1000

The source for a complete example is attached as a file to download.

This can be a pain when your network architecture has one or more firewalls between external Flash Player clients and your application server. If authentication or session management is performed at the firewall, session timeouts can introduce an annoying problem. If a client makes an AMF request after a session has timed out, the session management layer may challenge the client to re-authenticate. This challenge is unlikely to be an AMF formatted response and so NetConnection is unable to process the information. While the client knows the request failed, the exact cause of failure is not known.

So… I hacked together a prototype replacement for NetConnection based on flash.net.URLLoader. This new “AMFConnection” class creates binary flash.net.URLRequests and sends HTTP POST data as an AMF formatted request and processes the AMF formatted response returned to URLLoader. One could subclass AMFConnection and intercept the response data and try to detect that an HTML re-authentication page has been returned to the client.

Other benefits this approach include being able to set custom HTTP request headers (and even receive HTTP response headers for AMF when used in an AIR application), receive progress events for large AMF response data as it is streaming back to the client, being able to fully customize the batching behavior of multiple AMF requests made in quick succession, or even customize the AMF serialization or deserialization behavior as this is no longer exclusively native code.

I tried to follow the existing NetConnection behavior for AMF over HTTP where possible… even if it meant slightly slower code. One complication has to do with AMF packets in that they reset the by-reference serialization tables for each AMF header or AMF message body (as multiple headers and bodies may be batched in a single request, i.e. AMF packet). I had to use flash.net.ByteArray buffers for each header value or message body (in either a request or response) to ensure the reference indexes were reset to 0.

There are a few minor issues I still need to work on, such as only switching to AMF 3 on encountering a complex object (right now my class starts out in AMF 0 as normal, but it always switches to AMF 3 if the objectEncoding has been set to version 3 regardless of the data type), and exposing an API to control batching (right now each request is sent individually).

One annoying thing I ran into is flash.net.Responder’s constructor takes two Functions for the result and status handlers – but these are not exposed after construction in ActionScript. So instead I had to introduce a custom AMFResponder that must be passed to AMFConnection.call().

Connections in BlazeDS are abstracted by Channels. To test my replacement of NetConnection I created a copy of AMFChannel and replaced the usages of NetConnection with my new AMFConnection. I ran some initial tests and Flex RemoteObject worked smoothly.

I’ve uploaded an unsupported prototype amf.swc as a binary distribution for now. To test it out with RemoteObject you add it to your library path and create an instance of the temporary mx.messaging.channels.AMFChannel2 class and use it in a custom ChannelSet.

import mx.messaging.channels.AMFChannel2;import mx.messaging.channels.Channel;import mx.messaging.channels.ChannelSet;...var channelSet:ChannelSet = new ChannelSet();var channel:Channel = new AMFChannel2(null, "http://localhost:8400/team/messagebroker/amf");channelSet.addChannel(channel);ro.channelSet = channelSet;......

Alternatively, you may want to try out the raw flex.net.AMFConnection class – either directly or using a subclass and custom event listeners for the usual URLLoader events (which are simply redispatched by AMFConnection).

package flex.net{import flash.events.*;import flash.net.URLLoader;import flash.utils.ByteArray;public class AMFConnection extends EventDispatcher{public function AMFConnection(url:String=null);public function get client():Object;public function set client(value:Object):void;public function get connected():Boolean;public static function get defaultObjectEncoding():uint;public static function set defaultObjectEncoding(value:uint):void;public function get objectEncoding():uint;public function set objectEncoding(value:uint):void;public function get url():String;[Deprecated("Please use the 'url' property instead.")]public function get uri():String;protected var responseCounter:uint;protected var urlLoader:URLLoader;protected var pendingRequests:Object = {};public function addHeader(name:String, mustUnderstand:Boolean=false, data:*=undefined):void;public function call(command:String, responder:IAMFResponder, ...arguments:Array):void;public function close():void;public function connect(url:String):void;public function removeHeader(name:String):Boolean;protected function completeHandler(event:Event):void;protected function errorHandler(event:ErrorEvent):void;protected function httpStatusHandler(event:HTTPStatusEvent):void;protected function ioErrorHandler(event:IOErrorEvent):void;protected function progressHandler(event:ProgressEvent):void;protected function securityErrorHandler(event:SecurityErrorEvent):void;protected function getResponseURI():String;protected function response(bytes:ByteArray):void;protected function send(data:ByteArray):void;}}

http://www.bostonfug.org/

I’ll be speaking at this event, most of the demonstration will be hands on, but my slides as a PDF are here:

Download file

http://opensource.adobe.com/

Flex Builder 3 is live too!

http://www.adobe.com/products/flex/

But wait, there’s more! AIR 1.0 is also live:

http://www.adobe.com/products/air/

Woo hoo!

http://www.360conferences.com/360flex/

I’ll be presenting at 10am on Tuesday with an in-depth look at the open source Flex 3 SDK! Drop on by if you’re around at the conference!

I’m not sure if the announcement of BlazeDS has quite sunk in yet, but with the open sourcing of BlazeDS this really does make many Flex applications that much easier to build.

For example, I’d really like people to see the community take advantage of the Proxy Service and to contribute to its functionality going forward.

The Proxy Service is often overlooked, but did you know that it provides the following capabilities?

1. It provides better REST functionality with support for HTTP 1.1 PUT, DELETE, HEAD, TRACE, OPTIONS in addition to just GET and POST methods?

2. It provides access to non-UTF8 formatted text as the Proxy should be able to read in many more character set encodings – because it is Java based the stream will be converted into UCS-2 internally and then the Proxy will always format this data back to the Flash Player as UTF-8?

3. It allows 3rd party URLs to be aliased so that they do not have to be hard coded or exposed in your application (and Proxy destinations can also be locked down so that only authorized users can tunnel though to a 3rd party destination).

4. It provides a way to get back the response data even when the HTTP status code is not 200?

5. It provides a way to login to a 3rd party endpoint that issues a Basic Authentication challenge without exposing the pop-up to the end user (that is, you can build a custom Flex UI as a login form and set the remote credentials for the proxy to use in pre-authenticating to a 3rd party endpoint).

Also, there’s more that could be done here. Features that I’d like to see in the future:

A. Restoring the ability to stream back binary data instead of just text data.

B. Multipart POST support.

C. Maybe further WEBDAV support?

Download file

December 7, 2007
8am-5pm
Bentley College, Waltham

See the website:
http://flexcampboston.com/page.cfm/agenda

My session will be an advanced discussion covering LiveCycle Data Services configuration, a review of things to consider when deploying your application, and tips and tricks when debugging data driven Flex applications!

See Matt’s blog entry for details:
http://weblogs.macromedia.com/mchotin/archives/2007/10/we_need_help_te.cfm

Please help us out!!