Flex RPC services
May 25, 2021 Flex
Table of contents
Flex provides RPC services to provide server-side data to clients. /b10> Flex provides considerable control over server-side data.
-
With the Flex RPC service, we can define the user actions to be performed on the server side.
-
Flex RPC services can be integrated with any server-side technology.
-
One of the Flex RPC services provides built-in support for compressed binary data transmitted over the line and is very fast.
Flex offers three types of RPC services
| RPC services | Describe |
|---|---|
| HttpService | The httpService label is used to represent the HTTPService object in the MXML file. /b11> When you call the send() method of the HTTP Service object, it makes an HTTP request to the specified URL and returns the HTTP response. Y ou can also use the HTTP HEAD, OPTIONS, TRACE and DELETE methods. |
| WebService | The webservice tag is used to access SOAP-compliant Web services. |
| RemoteObject | The remoteObject tag is used to represent the HTTPService object in the MXML file. /b11> This tag enables you to encode methods for accessing Java objects using the Action Message Format (AMF). |
We'll discuss HTTP services in more detail. We will use the XML source file placed on the server and access it on the client side through the HTTP service
Items.xml
<items> <item name="Book" description="History of France"></item> <item name="Pen" description="Parker Pen"></item> <item name="Pencil" description="Stationary"></item> <items>
HTTPService statement
Now declare an HTTP Server and pass the url of the above file
<fx:Declarations> <mx:HTTPService id="itemRequest" url="//www.w3cschool.cn/flex/Items.xml" /> </fx:Declarations>
RPC call
Call the itemRequest.send() method and bind the value from the itemRequest webservice's lastResult object to the Flex UI component.
...
itemRequest.send();
...
<mx:DataGrid id="dgItems" height="80%" width="75%"
dataProvider="{itemRequest.lastResult.items.item}">
<mx:columns>
<mx:DataGridColumn headerText="Name" dataField="name"/>
<mx:DataGridColumn headerText="Description" dataField="description"/>
</mx:columns>
</mx:DataGrid>
Example of an RPC service call
Now let's test the RPC service in a Flex application by following these steps:
| Steps | Describe |
|---|---|
| 1 | As described in the Flex - Create Applications section, create a project called HelloWorld under package com.tutorialspoint.client. |
| 2 | Modify HelloWorld.mxml, as described below. /b10> Keep the rest of the file unchanged. |
| 3 | Compile and run the application to ensure that the business logic works as required. |
The following is the contents of the modified mxml file src / com.tutorialspoint / HelloWorld.mxml.
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx"
minWidth="500" minHeight="500" creationComplete="init(event)">
<fx:Style source="/com/tutorialspoint/client/Style.css"/>
<fx:Script>
<![CDATA[
import mx.events.FlexEvent;
import mx.rpc.events.FaultEvent;
import mx.rpc.events.ResultEvent;
protected function init(event:FlexEvent):void
{
itemRequest.send();
}
]]>
</fx:Script>
<fx:Declarations>
<mx:HTTPService id="itemRequest"
url="//www.w3cschool.cn/flex/Items.xml" />
</fx:Declarations>
<s:BorderContainer width="630" height="480" id="mainContainer"
styleName="container">
<s:VGroup width="100%" height="100%" gap="10"
horizontalAlign="center" verticalAlign="middle">
<s:Label id="lblHeader" text="RPC Service Demonstration"
fontSize="40" color="0x777777" styleName="heading"/>
<s:Panel id="parentPanel" title="Using RPC Services"
width="500" height="200" >
<s:layout>
<s:VerticalLayout gap="10"
verticalAlign="middle" horizontalAlign="center"/>
</s:layout>
<mx:DataGrid id="dgItems" height="80%" width="75%"
dataProvider="{itemRequest.lastResult.items.item}">
<mx:columns>
<mx:DataGridColumn headerText="Name"
dataField="name"/>
<mx:DataGridColumn headerText="Description"
dataField="description"/>
</mx:columns>
</mx:DataGrid>
</s:Panel>
</s:VGroup>
</s:BorderContainer>
</s:Application>
When all the changes are ready, let's compile and run the application in normal mode, as in the Flex - Create Application chapter. If all goes well with your application, this will result in the following results:
