All 10 entries tagged Development
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May 09, 2008
Chris was talking today about intra-team/department skills sharing, which I think is a great idea. With regard to Flash and Flex development at Warwick we’ve recently embarked on something along these lines, with the formation of a University Flash and Flex developers group consisting of people actively using (or just interested in) Actionscript development. It started with a forum that was initially populated with ITS people (plus one or two others), but since starting to deliver some Flash courses for ITS Training I wanted to maintain contact with what attendees did with the skills they’d acquired after the course, and the forum was opened up to allow more people to contribute. We held the first ‘skills session’ a couple of weeks ago, in the Teaching Grid. It was purposely an informal gathering, consisting of developers from ITS and departments, plus lots of coffee and biscuits. The session was an opportunity for everyone to show what they’d been working on and share expertise and a mix of ongoing Flash, Flex and AIR projects were demonstrated, plus discussion on development approaches and potential applications in the future.
Overall I thought it went well (we ran out of time in the end) and although next time some structure to the session might help us cover ground more efficiently, the informality and range of projects kept it interesting, and it was especially good to share ideas with others while receiving questions and feedback. As a result of the session, I’ve been asked to present a more formal hour-long session on AIR to the CIS Team next week, which I think I’ll prepare some slides for.
Anyway, my point is that personally I found it quite fun/rewarding to find out what other people were doing or planning to do with the technology, and to see and discuss approaches/methodologies and alternatives; we should definitely do more of this kind of thing in future. Time will tell whether we maintain the Flash/Flex/AIR group sessions but I hope we can.
May 06, 2008
Writing about web page http://code.google.com/p/fxspy/
I’ve been using Flex-Spy today for the first time, and it’s really useful. It allows you to inspect and affect pretty much any parameter of a component while the application is running which is way faster than constantly building and running the app for trying small tweaks, and saves waiting for the CSS previewer or refreshing the Design View. Installation is a snap as it’s packaged as an SWC.
View a demo of Flex Spy (press the FlexSpy button top right to launch the inspector)
April 29, 2008
Moving to doing some optimisation within my AIR application now, using the Flex 3 Profiler. I was noticing some interesting results, primarily that removing redundant event listeners and display children doesn’t always result in memory being freed up back to the system. Not as bad as a memory leak, but not quite what I wanted. As a result I’ve just been reading up a bit on optimising memory and garbage collection in Flex/AIR. From what I can see, although garbage collection in AS3 is actually quite good, there are a few tips, tricks and caveats…
It’s possible to help garbage collection along a little by using weak references on events listeners:
The last parameter being the weak reference flag. This saves having to manually remove the listener and means objects will be automatically removed by the garbage collector, but it can make debugging problems difficult because the collector won’t necessarily remove the object on its next pass. A solution to this is to force the collector to sweep and remove de-referenced objects.
myObject.addEventListener("eventName", handlerFunction, false, 0, true);
Manual garbage collection
Sean Christmann (eBay Desktop) demonstrates a method whereby it’s possible to manually force the garbage collector to sweep and remove memory objects using
(yes you need to call it twice, once to flag objects, once to remove them). As Sean describes though, using weakly-referenced objects can make it harder to track problems:
Trust me when I say that its a lot easier to debug an application with memory leaks due to strong listeners, then it is to debug an app in which users report random failures because underneath the hood weakly referenced objects are getting accidentally destroyed when the GC kicks in.
Flash Player’s garbage collector may sometimes ‘swap out’ dereferenced-but-not-yet-destroyed objects for new ones under its normal garbage collection process, that is it will maintain a certain memory ceiling and not go above it, but some object types are harder to destroy than others because they get referenced into the player – these are generally the types of object that work asynchronously, Loaders being one example; see Flash’s Dirty Secret, and Timers are another. Memory paging can also get quite fragmented because Flash was never optimised for the kinds of application where it might be running for hours, days or even weeks as an AIR application in the System Tray.
I’d not really considered this before moving to AIR, but the windowing capabilities mean that managing objects and garbage collection across multiple windows should be handled with care, because it’s possible to lose the ability to reference objects when application windows can be closed, or the application is running in the Tray and therefore has no focus. Sean describes another caveat where any EnterFrame handlers (which you might be using to control the collector) must be re-referenced across multiple windows.
The Elastic Racetrack
Finally, although this isn’t a memory thing, a word about execution time in Flex/AIR; each ‘frame’ of execution in your application is tied to the elastic racetrack concept. Flex has to balance the load between AS code execution, rendering and event broadcast/handling around a single continuous loop of execution, with allocation within each cycle dependent on the load for each. The depth of the display tree, or the execution time of a method will affect what gets done when during a particular frame or ‘lap’.
April 15, 2008
Writing about web page http://code.google.com/p/cairngen/
Cairngen will set up a Cairngorm project structure for you (using Ant), and much more besides. For example it’s capable of auto-generating what are termed ‘sequences’, which are sets of event-command-delegate templates (plus other alternative combinations) that create the FrontController, ModelLocator and VOs required, plus all the relevant mappings and basic classes. The core templates can also be modified so that classes contain whatever boilerplate text you need. A little downtime now learning how to use Cairngen should save me work in future, and if I set up a basic project script anyone else using Flex/AIR here can should be able to get projects up and running more quickly.
April 02, 2008
Writing about web page http://adamflater.blogspot.com/2008/02/meet-merapi.html
Merapi will provide a framework that uses Java to give AIR access to the system shell (and therefore have access to things like printing, scanning, hardware etc.). It’s very early days for the project but in a few months time it may be possible to create desktop applications using Merapi that do really useful things, without going near Swing. One to watch…