Flex Interview Questions with Answer for Experienced Page 2
Flex Interview Questions with Answer Page 2
21. What is adapter in Blaze DS?
Java
Adapter is used to communicate with Java and JMS adapter is used to communicate
with JMS. Java adapter class allows us to invoke methods on a Java object.
22. Explain about different types of channels
available in Blaze DS?
HTTP
Channel, AMF Channel, RTMP Channel.
AMF
Channel: A simple channel endpoint that transport data over HTTP in the binary
AMF format in an asynchronous call and response model.
HTTP
Channel: Provides the sample behaviour the AMF Channel/endpoint, but transport
data in AMFX format, which is the text based representation of AMF.
RTMP
Channel: The RTMP Channel creates a single duplex socket connection to the
server and gives the server the best notification of the player being shut
down.
23. Explain about Remote Object? What is end
point in Remote Object?
Remote
Object: Remote Service automatically
serializes and deserializes the data between Flex client and your server side
language. As a result, you can directly call methods on your
Java/.Net/ColdFusion/PHP etc… objects. This service connects to an AMF (Action
Message Format) Gateway. AMF protocol transfers data in a binary format, so the
data can be moved across the network more quickly.
endpoint: This property is used to
identify the Java web project from your flex client project.
Ex:
http://localhost:8080/JavaTest/messagebroker/amf
• http:
this is a protocol used to communicate with webserver from client. http means
“Hyper Text Transfer Protocol”
• localhost:
Host name of the machine where you have deployed your Java web project.
• 8080:
Port number of the web server where you have deployed your Java project.
• JavaTest:
Context root of the web application to identify the web project uniquely.
• Messagebroker/amf:
this is the URL pattern of the servlet which we have defined in web.xml file.
• <<protocol>>://<<hostname>>:<<port
no>>/<<context root>>/<<URL Pattern>>
24. Explain about ResultEvent and FaultEvent
in Remote Object? (OR) Explain about result handler and fault handler methods?
result:
This is the event listener for the event ResultEvent. This event is
automatically dispatched by the Flash Player when it receives the successful
results from the backend Java service.
fault:
This is the event listener for the event FaultEvent. This event is
automatically dispatched by the Flash Player when it receives any error in
calling the Java method.
25. Explain about Flex Data Services like
HTTP Service, Web service and Remote Object?
26. Difference between HTTP Service and
Remote Object? (OR) Which one you will prefer?
Data
Service(Remote Object)
1.
Remote Objects specifies named or unnamed sources.
2.
This service connects to an AMF(Action Message Format) Gateway
3.
AMF protocol transfers data in a binary format, so the data can be moved across
the network more quickly.
4.
Remote Service automatically serializes and deserializes the data between Flex
client and your server side language. As a result, you can directly call
methods on your Java/.Net/ColdFusion/PHP etc… objects
HTTP
Service/Web Service
1.
These services use named or raw URLs
2.
These services connect to an HTTP Proxy Gateway.
HTTP Service use HTTP protocol/requests
Web Services use SOAP (Simple Object Access
Protocol).
3.
These services transfer data in XML format. This is slow.
4.
Here the data transfer is in XML only.
27. Explain about component life cycle?
A
set of methods the framework calls to instantiate, control and destroy
components. OR
The
component instantiation life cycle describes the sequence of steps that occur
when you create a component object from a component class. As part of the life
cycle, Flex automatically calls component methods, dispatches events, and makes
the component visible.
3
Main Phases:
BIRTH
Construction,
configuration, attachment, initialization
LIFE
Invalidation,
validation, interaction
DEATH
Detachment,
garbage collection
override
protected function createChildren():void{
myLab=new
Label();
myLab.text="my
label";
myLab.setStyle('color',"green");
this.addChild(myLab);
}
override protected function
updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
{
myLab.move(0,0);
myLab.setActualSize(100,100);
}
28. Explain about Application life cycle?
29. Explain about the custom components
method?
What are the methods we have to override when we are creating a custom
component?
(OR)
Explain about the validation and
invalidation methods?
30. Explain about measure() method? When this
measure() method is called?
The
measure() method sets the default component size, in pixels, and optionally
sets the component's default minimum size.
This method is used for following reasons.
1) To set the components measuredWidth,
measuredHeight, measuredMinWidth and measuredMinHeight.
2) To set the default width and height
values to this component.
3) To measure the child components widths
and Heights. So that we can specify how much width and height is required for
our component.
4) Measure method is called only when you
are not specifying both width and height externally at the time of calling this
component.
5) This method can be called multiple
times by calling the invalidateSize() method.
31. Difference between Item Renderer and Item
Editors?
Both
are used for editing,but item renderer is used for displaying visual elements..
item
editor is used for editing purpose. Item editor can pass data back from the
particular control to save it as a new value for item being edited. We can also
use item renderer as editor by using boolean property renderIsEditor.
itemrenderer
is used to format and display the contents in a components whereas itemeditor
allows us to edit the displayed content
32. How to display the Check Box in Data Grid
header?
<mx:DataGridColumn headerText="ADD"
dataField="add" itemRenderer="mx.controls.Button"/>
<itemrendere>
</itemRenderer>
36. Can we use Text Input/Editable component
as Item Renderer?
Yes,
37. What are all the events dispatched in
Item Editor?
Item
Edit Beginning, Item Edit Begin, Item Edit End
38. What are the collections classes
available in Flex?
Array
Collection, XML List Collection, Grouping Collection.
39. Difference between Array and Array
Collection?
1)
Array Collection is a wrapper class based on Array.
2)
Array Collection contains sorting, filtering features but Array not.
3)
Array Collection dispatches the Event when new item is added, updated or
deleted.
4)
Array Collection automatically refreshes/updates the view whenever the change
happens in Array Collection.
40. How to get/retrieve an item from Array?
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