true

Default value is false. When true, instances of java.util.Collection are returned as ActionScript arrays. When false, inxtances of java.util.Collection are returned as mx.collections.ArrayCollection.

XML works fine when you have small data sets and do not control what is on the other side. In this case I’d stick with what works best which is probably Flex with ArrayCollections.

-James

I built a simple reporting app for my department. Presently, I use the webservice component and hook it up to a .NET webservice. Depending on the webservice it will return either an ArrayList of objects or a DataTable. In either case, Flex populates an Array (ArrayList) and an ArrayCollection(DataTable) which is then used for databinding. My questions to you are …

1. ArrayList or DataTable – which would you prefer when using/not using AMF?

2. Is my approach correct? If not, what approach would you take? Using my approach, which would yield better results – with/without AMF?

3. When creating an app with features such as friends list, photo sharing, etc…. would you recommend using Flex? If so, with/without AMF, and using an array or arrayCollection?

The scenario in which the problem was discovered is a very large project with thousands of classes in an object graph. When an initial request at application startup is made to the server hundreds of thousands of objects are turned into AMF and sent back to the Flex applications. The deserialization was taking a very long time on the client. The reason turned out to be the amount of time it takes to instantiate and add items to ArrayCollections. Arrays are much faster but require a lot of extra work to deal with. There is not a good way to specify which collections should use Arrays and which should use ArrayCollections. Also creating custom serialization (read/write External) would be way too much work. Ideally Flex would deal with this scenario in a more efficient manner.

-James

if 1, i think we can safely say you can use the source array element (when you have large datasets) and get a close comparison of the performance an array gets you.
if 2, then you should investigate whether there is performance issues with ArrayCollection serialization vs Array serializations. I would bet you would be quite amazed that the underlying serialization method of readExternal doesn’t use addItem or addItemAt but probably serializes the source data which is actually most likely an array. I would bet the ArrayList is even like this.

So I did a performance test based upon your code but changed the addItem to the .source = myA, then I added the writeObject & readObject of the data. And wouldn’t you know it it’s about 65 millis difference between the two.

Anyway I’m posting the updated source code

<![CDATA[
var i:int;
myA = [];
myAC.removeAll();
myACNAU.disableAutoUpdate();
myDBAC.removeAll();
myDDBAC.removeAll();

var startTime:Date = new Date();
var b:ByteArray = new ByteArray();
if( useA.selected )
{
for( i = 0 ; i < numObjects.value ; i++ )
{
myA.push({prop1:’asdf’, prop2:startTime, prop3:i});
}
b.writeObject(myA);
}
else if( useAC.selected )
{
for( i = 0 ; i < numObjects.value ; i++ )
{
myA.push({prop1:’asdf’, prop2:startTime, prop3:i});
}
myAC.source = myA;
myAC.refresh();
b.writeObject(myAC);
}
else if( useACNAU.selected )
{

for( i = 0 ; i < numObjects.value ; i++ )
{
myA.push({prop1:’asdf’, prop2:startTime, prop3:i});
}
myACNAU.source = myA;
myACNAU.refresh();
b.writeObject(myACNAU);
}
else if( useDBAC.selected )
{
for( i = 0 ; i < numObjects.value ; i++ )
{
myA.push({prop1:’asdf’, prop2:startTime, prop3:i});
}
myDBAC.source = myA;
myDBAC.refresh();
b.writeObject(myDBAC);
}
else if( useDDBAC.selected )
{
for( i = 0 ; i

@James Ward

You might not be using large datasets and complex objects graphs but there are certainly many out there who do. My friend Jon encountered this problem on a real project.

-James

See the comment above. The problem is that you have very little control over how AMF collections are deserialized.

-James

Greetz
Alex