Adobe Flex Authors: Matthew Lobas, PR.com Newswire, Shelly Palmer, Kevin Benedict

Related Topics: Adobe Flex, Java IoT, ColdFusion, Machine Learning

Adobe Flex: Article

Flex 2 Metadata Tags

Telling the compiler how to compile

Most Flex developers have seen and used the [Bindable] tag but not many know what this tag does or even what it is. [Bindable] is what is known as a metadata tag. Metadata tags are special tags that are inserted in your source code that give the compiler information on how to compile the application. These tags aren't actually compiled into the generated SWF file but provide instructions on how the compiler should create the SWF. There are 12 documented metadata tags. This article will offer definitions of these metadata tags and give examples of their use. By the end of this article you will understand when and where to use metadata tags in your Flex 2 applications.

Defining an array is usually very generic in nature because the elements of the array can be any type. However, using the ArrayElementType metadata tag lets you define the data types of the array elements. Here is the sample syntax of [ArrayElementType]:

    public var arrayOfStrings:Array;

    public var arrayOfNumbers:Array;

    public var arrayOfUIComponents:Array;

The Bindable metadata tag is one of the most used metadata tags because it allows for easy data synchronization within the components of your application. Bindable can be used to bind simple data, classes, complex data, and functions. To bind a simple piece of data, you must simply define the data with the metadata tag included, as shown in Listing 1. Figure 1 shows the results of Listing 1

Bindable also allows binding to events. Listing 2 shows how to bind a property using getters and setters, along with an event binding. This example has a private variable named phoneNumber, as well as a public getter and setter. The getter method uses the Bindable tag to bind to an event named phoneNumberChanged. This setter method dispatches the phoneNumberChanged even whenever its data changes. By using a setter method, the data can be manipulated before it's set to the private variable. In this example, the data is formatted only when the length of the value coming into the method is 10. When the phoneNumberChanged event is dispatched, the second TextInput component updates because its text property is bound to the phoneNumber variable.

Figure 2 and Figure 3 show the results of Listing 2.

The DefaultProperty metadata tag is used to set a single property as a default property of a class. This allows the property to be set within a container tag without needing to define the property name. A simple example of this would be a custom Button class. Listing 3 shows a simple Button class that has the label property set as the DefaultProperty. Listing 4 shows how the label is defined as a string within the custom Button container tags.

The Embed metadata tag is used to import images into your application. There are two ways to use Embed. You can either embed the image in ActionScript and assign it to a variable (as in the first example in the following code), or you can assign it directly to the component property (using the syntax shown in the second example of the following code).

public var myIcon:Class;

<mx:Button label="Icon Button 1" icon="{myIcon}"/>

<mx:Button label="Icon Button 2" icon="{myIcon}"/>

The output from the following is identical to the previous code block. The benefits of creating the myIcon class are that it can be defined one time in a single class and bound to multiple components in your application.

<mx:Button label="Icon Button 1" icon="@Embed(source=myIcon.gif')"/>

<mx:Button label="Icon Button 2" icon="@Embed(source=myIcon.gif')"/>

The Event metadata tag is used to declare events that will be dispatched by your custom class. Adding this metadata tag to your class definition allows you to add an event handler function to the MXML tag used to instantiate your custom class. Listing 5 creates a custom Button class that will dispatch an event whenever its label property changes. The main application file shown in Listing 6 instantiates the custom Button and creates the event handler function, which dumps the new label property to a TextArea component to show the occurring changes.

Figure 4 shows the results of Listing 5 and Listing 6.

The Effect metadata tag is used to define a custom effect that will be dispatched when an event occurs. This can be easily demonstrated by building on the earlier Event examples. By simply changing a single line to the ButtonLabel class (Listing 7), an effect is defined that can be assigned to an Effect instance (Listing 8).

More Stories By Rich Tretola

Rich Tretola, Vice President at WowWee Maui's Corp., is a Contributing Author at IFBIN Networks and the lead author of Professional Flex 2, upcoming April 2007 from Wrox Press. Rich is also creator of EverythingFlex.com, to which he's also an ongoing contributor.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.

@ThingsExpo Stories
Digital Transformation: Preparing Cloud & IoT Security for the Age of Artificial Intelligence. As automation and artificial intelligence (AI) power solution development and delivery, many businesses need to build backend cloud capabilities. Well-poised organizations, marketing smart devices with AI and BlockChain capabilities prepare to refine compliance and regulatory capabilities in 2018. Volumes of health, financial, technical and privacy data, along with tightening compliance requirements by...
Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life settlement products to hedge funds and investment banks. After, he co-founded a revenue cycle management company where he learned about Bitcoin and eventually Ethereal. Andrew's role at ConsenSys Enterprise is a mul...
DXWordEXPO New York 2018, colocated with CloudEXPO New York 2018 will be held November 11-13, 2018, in New York City and will bring together Cloud Computing, FinTech and Blockchain, Digital Transformation, Big Data, Internet of Things, DevOps, AI, Machine Learning and WebRTC to one location.
DXWorldEXPO LLC announced today that "Miami Blockchain Event by FinTechEXPO" has announced that its Call for Papers is now open. The two-day event will present 20 top Blockchain experts. All speaking inquiries which covers the following information can be submitted by email to [email protected] Financial enterprises in New York City, London, Singapore, and other world financial capitals are embracing a new generation of smart, automated FinTech that eliminates many cumbersome, slow, and expe...
DXWorldEXPO | CloudEXPO are the world's most influential, independent events where Cloud Computing was coined and where technology buyers and vendors meet to experience and discuss the big picture of Digital Transformation and all of the strategies, tactics, and tools they need to realize their goals. Sponsors of DXWorldEXPO | CloudEXPO benefit from unmatched branding, profile building and lead generation opportunities.
The best way to leverage your Cloud Expo presence as a sponsor and exhibitor is to plan your news announcements around our events. The press covering Cloud Expo and @ThingsExpo will have access to these releases and will amplify your news announcements. More than two dozen Cloud companies either set deals at our shows or have announced their mergers and acquisitions at Cloud Expo. Product announcements during our show provide your company with the most reach through our targeted audiences.
DevOpsSummit New York 2018, colocated with CloudEXPO | DXWorldEXPO New York 2018 will be held November 11-13, 2018, in New York City. Digital Transformation (DX) is a major focus with the introduction of DXWorldEXPO within the program. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of bus...
With 10 simultaneous tracks, keynotes, general sessions and targeted breakout classes, @CloudEXPO and DXWorldEXPO are two of the most important technology events of the year. Since its launch over eight years ago, @CloudEXPO and DXWorldEXPO have presented a rock star faculty as well as showcased hundreds of sponsors and exhibitors! In this blog post, we provide 7 tips on how, as part of our world-class faculty, you can deliver one of the most popular sessions at our events. But before reading...
Cloud Expo | DXWorld Expo have announced the conference tracks for Cloud Expo 2018. Cloud Expo will be held June 5-7, 2018, at the Javits Center in New York City, and November 6-8, 2018, at the Santa Clara Convention Center, Santa Clara, CA. Digital Transformation (DX) is a major focus with the introduction of DX Expo within the program. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive ov...
As IoT continues to increase momentum, so does the associated risk. Secure Device Lifecycle Management (DLM) is ranked as one of the most important technology areas of IoT. Driving this trend is the realization that secure support for IoT devices provides companies the ability to deliver high-quality, reliable, secure offerings faster, create new revenue streams, and reduce support costs, all while building a competitive advantage in their markets. In this session, we will use customer use cases...
DXWorldEXPO LLC announced today that ICOHOLDER named "Media Sponsor" of Miami Blockchain Event by FinTechEXPO. ICOHOLDER give you detailed information and help the community to invest in the trusty projects. Miami Blockchain Event by FinTechEXPO has opened its Call for Papers. The two-day event will present 20 top Blockchain experts. All speaking inquiries which covers the following information can be submitted by email to [email protected] Miami Blockchain Event by FinTechEXPO also offers s...
With tough new regulations coming to Europe on data privacy in May 2018, Calligo will explain why in reality the effect is global and transforms how you consider critical data. EU GDPR fundamentally rewrites the rules for cloud, Big Data and IoT. In his session at 21st Cloud Expo, Adam Ryan, Vice President and General Manager EMEA at Calligo, examined the regulations and provided insight on how it affects technology, challenges the established rules and will usher in new levels of diligence arou...
Dion Hinchcliffe is an internationally recognized digital expert, bestselling book author, frequent keynote speaker, analyst, futurist, and transformation expert based in Washington, DC. He is currently Chief Strategy Officer at the industry-leading digital strategy and online community solutions firm, 7Summits.
Digital Transformation and Disruption, Amazon Style - What You Can Learn. Chris Kocher is a co-founder of Grey Heron, a management and strategic marketing consulting firm. He has 25+ years in both strategic and hands-on operating experience helping executives and investors build revenues and shareholder value. He has consulted with over 130 companies on innovating with new business models, product strategies and monetization. Chris has held management positions at HP and Symantec in addition to ...
Cloud-enabled transformation has evolved from cost saving measure to business innovation strategy -- one that combines the cloud with cognitive capabilities to drive market disruption. Learn how you can achieve the insight and agility you need to gain a competitive advantage. Industry-acclaimed CTO and cloud expert, Shankar Kalyana presents. Only the most exceptional IBMers are appointed with the rare distinction of IBM Fellow, the highest technical honor in the company. Shankar has also receive...
Enterprises have taken advantage of IoT to achieve important revenue and cost advantages. What is less apparent is how incumbent enterprises operating at scale have, following success with IoT, built analytic, operations management and software development capabilities - ranging from autonomous vehicles to manageable robotics installations. They have embraced these capabilities as if they were Silicon Valley startups.
Internet-of-Things discussions can end up either going down the consumer gadget rabbit hole or focused on the sort of data logging that industrial manufacturers have been doing forever. However, in fact, companies today are already using IoT data both to optimize their operational technology and to improve the experience of customer interactions in novel ways. In his session at @ThingsExpo, Gordon Haff, Red Hat Technology Evangelist, shared examples from a wide range of industries – including en...
The standardization of container runtimes and images has sparked the creation of an almost overwhelming number of new open source projects that build on and otherwise work with these specifications. Of course, there's Kubernetes, which orchestrates and manages collections of containers. It was one of the first and best-known examples of projects that make containers truly useful for production use. However, more recently, the container ecosystem has truly exploded. A service mesh like Istio addr...
Rodrigo Coutinho is part of OutSystems' founders' team and currently the Head of Product Design. He provides a cross-functional role where he supports Product Management in defining the positioning and direction of the Agile Platform, while at the same time promoting model-based development and new techniques to deliver applications in the cloud.
Predicting the future has never been more challenging - not because of the lack of data but because of the flood of ungoverned and risk laden information. Microsoft states that 2.5 exabytes of data are created every day. Expectations and reliance on data are being pushed to the limits, as demands around hybrid options continue to grow.