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Learn about namespace differences and some of the other differences between Flex 3 and Flex 4.
Click Namespace02 to run the Flex program from this lesson. (Click the "Back" button in your browser to return to this page.)

Table of contents



This tutorial lesson is part of a series of lessons dedicated to programming using Adobe Flex.

The material in these lessons is based on Flex version 3 and Flex version 4. A distinction between the two will usually be made in those situations wherethat distinction is important.

A previous lesson in this series titled XML - Namespaces - Flex 3 concentrated on teaching the XML concept of namespaces and illustrated the concept using a program written in Flex version 3.

Differences in namespaces between Flex 3 and Flex 4

Some of the first things that one is likely to notice when comparing Flex version 3 to Flex version 4 are some obvious differences in the use of namespaces. Therefore, this is an opportune place in the series tointroduce Flex version 4 and to explain some of the differences between the two versions.

Viewing tip

I recommend that you open another copy of this document in a separate browser window and use the following links to easily find and view the figuresand listings while you are reading about them.


  • Figure 1 . Output from Namespace01.
  • Figure 2 . Output from Namespace02.
  • Figure 3 . Project treefor the project named Namespace02.


  • Lasting 1 . Skeleton mxml code for a new Flex 3 project.
  • Listing 2 . Skeleton mxml code for a new Flex 4 project.
  • Listing 3 . The main mxml file forNamespace01.
  • Listing 4 . The main mxml file for Namespace02.
  • Listing 5 . Contents of the file named Label.mxml.
  • Listing 6 . Contents of the file named Button.mxml.

Supplemental material

I recommend that you also study the other lessons in my extensive collection of online programming tutorials. You will find a consolidated index at www.DickBaldwin.com .

General background information

Historical perspective

Adobe's Flex is an XML-based programming language that is used to create programs that execute in the Adobe Flash Player .

Teaching XML using Flex

In the Spring semester of 2010, I introduced Adobe's Flex version 3 and the Flex Builder 3 IDE into a course named Introduction to XML that I had been teaching for several years at Austin Community College in Austin, TX. The concept of usingFlex as the programming vehicle to teach XML was well received by the students.

During that same semester, Adobe released Flex version 4 and replaced Flex Builder 3 with a new IDE named Flash Builder 4 . The new IDE supports both Flex 3 and Flex 4.

A fortunate circumstance

This is a fortunate circumstance insofar as the concept of using Flex to teach XML is concerned. Flex 4 is similar to, but very different from, andsomewhat more complicated than Flex 3. The availability of the two versions of Flex makes it possible for the students to gain experience with two similar butdifferent flavors of XML, both supported by the same IDE and both supported by similarly formatted documentation.

Questions & Answers

The eyes of some reptiles are sensitive to 850 nm light. If the minimum energy to trigger the receptor at this wavelength is 3.15 x 10-14 J, what is the minimum number of 850 nm photons that must hit the receptor in order for it to be triggered?
razzyd Reply
A teaspoon of the carbohydrate sucrose contains 16 calories, what is the mass of one teaspoo of sucrose if the average number of calories for carbohydrate is 4.1 calories/g?
ifunanya Reply
4. On the basis of dipole moments and/or hydrogen bonding, explain in a qualitative way the differences in the boiling points of acetone (56.2 °C) and 1-propanol (97.4 °C), which have similar molar masses
Kyndall Reply
Calculate the bond order for an ion with this configuration: (?2s)2(??2s)2(?2px)2(?2py,?2pz)4(??2py,??2pz)3
Gabe Reply
Which of the following will increase the percent of HF that is converted to the fluoride ion in water? (a) addition of NaOH (b) addition of HCl (c) addition of NaF
Tarun Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Introduction to xml. OpenStax CNX. Dec 02, 2014 Download for free at https://legacy.cnx.org/content/col11207/1.18
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