Autorefresher Component

If you have been working on applications which serve highly dynamic data on the screen, you are most likely to have had to rely on the “polling” mechanism to get updated data from the back-end. We had similar requirement in our project and we created a tiny component using Flex’s Timer Class to fire a specific method at set frequencies.

And as usual, we didn’t to go around writing code all across the application to do this. The component we created can take in a function as an attribute. This function could be anything. It could be one that fires an SQL query and updates an ArrayCollection, or it could be one that sends out a Feed request or whatever! 🙂 It’s pretty easy to use the AutoRefresher. All you have to do is add the AutoRefresher to your view –

<flexed:AutoRefresher id="exampleAutoRefresh" delay="5000" refreshFunction="FunctionToBeFiredPeriodically" />

The view then, refreshes every x milliseconds specified for delay. The default is 15000 milliseconds or 15 seconds. In the init method of your view, before starting the autorefresher, set the owner of the refresher to the parent like this-

exampleAutoRefresh.owner = this;
exampleAutoRefresh.start();


Setting the owner is to make sure that our refresher stops and starts based on the views visibility. In most cases, Polling mechanism ends up being really costly on the back-end. Especially if you are dealing with multi-tiered architecture and trying to talk to a web server, database server etc over the network. And its very much possible, that multiple views in your application might be required to autorefresh periodically. If you are polling in all the screens whether they are required or not, you are most likely to end up crashing the back-end infrastructure. In order to address this problem and minimize the load on the back-end, we built in a mechanism into the refresher by which it stops if the view is visible and starts automatically when the view is visible. This is why we are setting the owner in the init method. So, if you have autorefresher running on view A and B; and the user is viewing view B, then only view B is refreshing and when the user moves to view A; view B stops refreshing and view A starts.

Special thanks to Easwar for making this idea work! This component might come in handy for many 🙂 . It sure saved a lot of effort for us 😉 . Check it out.

Note: The demo is very basic. All it does is gets the time every 3 seconds and updates the label in the view.

[ Demo | Source | ASDocs ]

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Flex Explorers

I have been collecting all the “flex explorers” from time to time as they are rolled out. The Flex explorers have been really really handy when it comes to checking for some stuff which you are not sure whether is possible. Without the style explorer, we would have been completely lost! From a styling perspective, the api documentation seems a little complex for a designer to get an idea of how go about styling a component on screen.

On many occasions when I have an idea, instead of reading through the api docs, I just checkout the explorers to see if it is possible in flex. As for stuff like effects, filters etc., I have found it impossible to figure it out from the api docs.

Over the past months, we have seen many explorers being released by adobe and other developers around the world. I have consolidated them under the FLEX EXPLORERS heading on the right side (below the Flex Components section). Check it out. If I have missed out anything, do drop a comment 🙂 .

Silverlight, Sparkle and Flex

First it was Sparkle and now the new babe in the block is Sliverlight. A month ago, I saw a video covering the Sparkle developers showcasing some pretty cool stuff about Sparkle. Ok. So, I am not one of those bunch who hate anything that comes out of Microsoft because it comes out of Microsoft. The way I see it, this is how it all maps –

• Sparkle (XAML) = Flex (MXML)
• Flash Player = Silverlight

There seems to be some really uncanny similarities between XAML and MXML… (Of course they are both XML!). Check it out. The graphics that these bunch of Latin-Greek-Hieroglyphs churn up are pretty good.

<Canvas xmlns=”http://schemas.microsoft.com/winfx/2006/xaml/presentation&#8221; xmlns:x=”http://schemas.microsoft.com/winfx/2006/xaml&#8221; x:Name=”_119_red_scanlione_gloss” Width=”1056″ Height=”816″> <Canvas x:Name=”Layer_1″> <Rectangle x:Name=”Rectangle” Canvas.Left=”0″ Canvas.Top=”0″ Width=”1056″ Height=”816″ Stretch=”Fill” Fill=”#FFFF0000″/> <Path x:Name=”Path” Canvas.Left=”404.558″ Canvas.Top=”258.867″ Width=”258.844″ Height=”258.844″ Stretch=”Fill” Fill=”#FFFFFFFF” Data=”F1 M 411.029,258.867L 656.931,258.867C 660.505,258.867 663.402,261.764 663.402,265.338L 663.402,511.24C 663.402,514.814 660.505,517.711 656.931,517.711L 411.029,517.711C 407.455,517.711 404.558,514.814 404.558,511.24L 404.558,265.338C 404.558,261.764 407.455,258.867 411.029,258.867 Z “/> <Rectangle x:Name=”Rectangle_0″ Canvas.Left=”0″ Canvas.Top=”0″ Width=”1056″ Height=”816″ Stretch=”Fill”> <Rectangle.Fill>

I really don’t think Sparkle or Silverlight is a threat to Flex or Flash Player. But, I definitely think here begins a competition. With Apollo, Adobe definitely has a head start over any new web 2.0 stuff. Lets not forget that Flash Player is what? 10+ years older than anything that will be born 2 years from now 😀 . As they say, we ARE living in interesting times!!! Definitely, we are!

Honestly, I think everyone has to learn from Microsoft to create such lovely sexy logos! It doesn’t make any sense. But, then who cares? Its a damn Logo and it looks great! 😉

Silverlight samples – Pretty Impressive! (You will need to install Silverlight for this)

1. http://channel9.msdn.com/playground/wpfe/wpfepad/
2. http://channel9.msdn.com/playground/wpfe/grandpiano/
3. http://channel9.msdn.com/playground/wpfe/tiletext/

ANT task to generate ASDoc

I am sure most of you would have already seen this. I was googling around for some documentation on how to generate ASDocs. The command line arguements for asdoc.exe is pretty cryptic and its definitely not a tool for someone who is new to the whole thing. I guess I am not the only one on that boat either !!! 😉 Then, I stumbled across some links for ANT scripts for ASDoc generation. The build.xml that I finally downloaded was from BitTubeBlog and it worked right out of the box! 🙂

Just make a few configurations in the script for setting your source directory and you are good to go!

How to run ANT tasks in Eclipse?
Check out the document at Eclipse’s site for this or click here. here’s an excerpt from the eclipse help (Slightly modified!). For many, this should help getting started 😉 .

To run an Ant buildfile in the Workbench:

1. Copy the build.xml to the root or a folder in your project path.
2. Set the appropriate folder name in the build.xml
3. In one of the navigation views, select the XML file.
4. From the file’s pop-up menu, select Run Ant…. The launch configuration dialog opens.
5. Select one or more targets from the Targets tab. The order in which you select the items is the order in which they will run. The order is displayed in the Target execution order box at the bottom of the tab. You can change the order of the targets by clicking the Order… button.
6. (Optional) Configure options on the other tabs. For example, on the Main tab, type any required arguments in the Arguments field.
7. Click Run.

[ Download the ANT Task Script ]

Client/User Idle Timeout Component

I was looking around in the net for an effective client/user IDLE TIMEOUT mechanism. My requirement was very simple – The UI should time-out if the user is idle for more than 5 minutes. In geek terminology, IDLE translates to zero keystrokes and zero mouse movements.

After googling around and then spending some time at Flexcoders, I came across a link from the CFML site – an example for just what I wanted to do 🙂 . So, we went and took that script and added a few bells and whistles to it before converting it into a re-usable component. And here’s what we have :-

The ClientIdleTimeOut component can be added to an application using-
<flexed:ClientIdleTimeOut id="TimerId" onTimeOut="FunctionPassedFromCaller" listenKeyStroke="true|false" listenMouseMove="true|false" timeOutInterval="1" confirmInterval="1" />
Now, when the application starts, the timer starts. If there is no user activity for the timeOutInterval specified, then a timeout warning pops up and stays up for confirmInterval time. Once the confirmInterval has been crossed, the application is timedout. At this point, three actions happen – 1. The application is disabled; 2. The FunctionPassedFromCaller set to the onTimeOut attribute is fired; 3. An event of type appTimedOut is dispatched. We can have a listener for this event and fire our actions at this point apart from the onTimeOut function.

So, thats what the ClientIdleTimeOut does 🙂 . Check it out. Enjoy

PS: The Demo has an idle timeout for 3 mins. and a warning prompt of 2 mins. The ASDocs provided is more of an experiment 😉 .

[ Demo | Source | ASDocs ]

Warn on flex application exit

If you have been developing web based applications which require login, I am pretty sure you would have come across this question – How do you safe-logout the user if the user just closes the window/tab when there is unsaved information on the user’s screen?

My current Flex project requires the user to login and logout. And most of the time, the users never use the logout button. They just close the browser and walk away! 😡 So, I needed a mechanism which will warn the user that there is unsaved information before closing the window. The way, I got this working was by using the FABridge.

In the application, I had an isAppDirty boolean.

public var isAppDirty:Boolean = false;

This variable is set to true whenever there is unsaved information in the application from any view. Now, add a few lines of javascript to your html wrapper. You can do this to the html file in the html-template folder.

————————————————————————————-

window.onbeforeunload = confirmExit;

function confirmExit(){
var flexApp = FABridge.flash.root();
var appDirty = flexApp.isAppDirty();

// note that the isAppDirty var is called like a function. This is done deliberately. Thats the way FABridge works 🙂

if(appDirty == true){
return “The configuration changes performed in this session have not been saved. If you wish to save the config, please click CANCEL.”;
}
}

————————————————————————————-

Do not forget to include the FABridge libraries in the html -<script language=”JavaScript” type=”text/javascript” src=”bridge/FABridge.js”></script. You can download the FABridge libraries from here.

And you are set to go 🙂 . Quiet simple, isn’t it?

Styling Alerts – CAlerts v1.0

We’ve been busy for the last couple of weeks. And some posts have been DRAFT for quiet some time. I guess its high time I completed those posts and getting back into active posting mode 😉 .

Back to Flex. This time we are looking at Alert Messages in Flex. While the flex alerts are nice looking, they are a bit too simple. So, I started looking at options for styling the alerts and found that it quiet easy to get a really sexy look and feel for the Alerts. Here goes,

Alert{
color : #0f3177;
title-style-name : “alertTitle”;
header-height:19;
border-thickness: 1;
drop-shadow-enabled: true;
drop-shadow-color :#d1ddf7;
background-color: #ffffff;
corner-radius :6;
border-style :solid;
header-colors : #90a4d1, #5970a0;
footer-colors : #9db6d9, #ffffff;
border-color : #5970a0;
}

.alertTitle{
font-family :Verdana;
font-size :10;
font-weight :bold;
text-align :left;
color :#ffffff;
}

The output of this would look like this –

Note: Thanks to Kumaran for churning up this sexy style 🙂 .

Now, that we have applied some nice looking styles to our alerts. Lets, look at what else we can do to Alerts 😉 .

Next, we needed a standard set of alerts that the team can use when they want a popup message anywhere in the application. So, I set about extending the Alert class to create alert.as. With alert class, the developer can popup different messages like this –

Information
alert.info('This is an info message');
//you can also pass a clickHandler here.

Confirmation
alert.confirmation('Are you sure you wish to delete all files?', clickHandler);

Error
alert.error('This is an error message');
//you can also pass a clickHandler here.

So, its as simple as that 🙂 . Check out the source for more details. I will post a demo of this soon.

[ Demo | Source ]