Its exciting to see LogBook, Comcast Interactive Media’s first open source project get some traction. There is talk of LogBook being included in other open source projects as well as people have started submitting patches and suggestions to the project.

One issue that was submitted a few days back was around the Logging implementation dispatching all logging events out of the application across the LocalConnection. Here is a quote from the issue:

Logging could add significant overhead to an application, due to
log message construction, and sending messages to LogBook.

It is good practice to minimize logging overhead, with code like:

if (Log.isInfo()) {
LOG.info(”version: {0}”, version);
}

The current implementation of class LocalConnectionTarget always
sets the log level to ALL and the log filter to “*”. This means
that all logging methods are executed, which is undesirable.

You can see the details of the issue here.

I just wanted to elaborate a little on why the LocalConnectionTarget class does not use any kind of filtering to reduce the number of LogMessages being constructed.

One of the reason we went with LogBook as an AIR application as opposed to a web application was because as far as I know, the Flash Player process on the web is independent from that in AIR. This means that LogBook could become a very elaborate application on its own but it will not impact the performance of the application using LogBook based logging. Also when we pass objects across LocalConnection, these objects do not accumulate in the application’s memory. Here is a screenshot from a quick experiment where I ran an endless loop that created a custom LogDispatcher object, had it send a log message across the LocalConnection and then get garbage collected. The memory profile of the application can be seen below:

Here is also the live objects screen capture:

As you can see, over 600 objects were constructed but all of them could be garbage collected with no overhead in terms of memory used.

So your take away from this discussion is: using LogBook has virtually no memory overhead in your application. The idea of broadcasting all messages to LogBook is to allow you to filter the data on the client at the moment of debugging or after, rather than configuring it at some pre-launch time.

Now LogBook itself is another story. Another bug submitted by the same developer who reported this also talked about LogBook’s performance when over 1000 messages were collected, and yes, I have verified that at that point, the application becomes pretty sluggish. So for the next version of the LogBook, I am considering leveraging the SQLite database that AIR comes packaged with.

More on LogBook 2.0 soon. We are already on it and it will be good . If you would like to participate in defining the functionality in 2.0 or better yet, help us develop it, join the conversation on the LogBook user group here.

Continuing with my experiments with Papervision3D, today I was looking more into creating the Qucktime VR like panoramas. There are quite a number of well done panoramas but all of them require custom cropped images etc. What I really wanted to do was to just have them be generated off images in my Flickr account. Of course this is unrealistic a bit since the way panoramas work requires the two edges of the photo being viewed to merge seamlessly with each other. This way there is a sense of continuity. However, I took some 'creative license' and the result is below.

Creating Panoramas the right way:
There is an excellent tutorial on how to create simple Panoramas the right way here. The idea is simple. Create 6 photographs of a location and map each of them on the different planes of a cube. Then set a Free Camera in the middle of the cube and then use the mouseX/mouseY properties to change the camera's rotation about the X and Y axis.

The direction I wanted to take was to load an image from Flickr and then chop it up into 4 equal sizes, and then use them as textures on my cube. I realized pretty early on that there was no way I could enable looking up/down since I couldnt take any part of the image as surfaces for those planes, so I restricted the motion to only the X-axis.

Loading an image from Flickr, taking bitmap snapshots at quarter intervals each only 1/4 of the width of the photo (thank you flickr.com/crossdomain.xml) for each surface and then mapping to the surfaces was really easy and I was pretty much done soon. It looked okay-ish but there was one big issue: As I mapped the images to planes 1,2,3 and 4 (left, front, right, back) successively, the edge between plane 4 and 1 killed the look since they did not merge seamlessly. I was about to shrug and walk away (after all this was just to get more familiar with P3D), when I had an idea. I was already taking snapshots of the images loaded in, it wouldnt be that hard to take another set of snapshots that were flipped on the Y axis (ie mirror images). Then, I mapped the original 4 pieces to just 2 planes (say left and front surfaces of the cube). The edge of the front plane then connected with its own mirror image, and the mirror images were mapped to the remaining 2 surfaces. This way there were no disjointed segments butting against each other.

[swf]http://www.arpitonline.com/blog/swf/flickr/Main.swf, 500, 600 [/swf]

I'll make another post on my mirrored image generator next but in the meanwhile check it out and let me know what you think.

P.S: It took me another 30 minutes to fix a bug when I put the swf on my server, since Loaders dont check crossdomain.xml by default. Arghhh !

I finally got around to playing a bit with Papervision3D, the open source 3D library for Flash,today. I have to say its been a lot of fun and its surprisingly easy to use. I was looking for some interface that I could build using what I was learning. The ITunes Coverflow seemed a good place to start but considering how many implementations of that I am seeing on the web, I couldn't really bring myself to write a new one. So I started monkeying around with camera motion etc and finally reached a point I was pretty happy with, at least for day one.

The idea behind CardStack was to recreate to some extent the real world shelf. When the user clicks on an element on the shelf, it moves out of the shelf and can be interacted with.

This is just my first stab at this and there will be a lot more changes before I pack it into any sort of code I can share with the community. At the very least I can put in keyboard navigation and some reflection to make it a little more interesting.

Please let me know if there is something I can add to this to give it a little more zing.