Using Flex with POST and GET

[seulater]

Tony enlightened me on Adobe FLEX. I was using FLASH to make my connections back to the board. its clear to me now that FLEX is a far better approach for me.
Years ago, when I wrote the code to talk to the NB and send data back and forth I was very excited. It was a far better way to get quick updates to a web page then the ole HTML way with the familiar "UPDATE PAGE" button or the otherwise "click" sound when the page would automatically refresh.

I have had some projects where multiple users needed to access a page at the same time and though connecting back to the board on another socket connection was great, it also prevented multiple users from connecting at the same time.

Tony, is much more knowledgeable in FLEX than I am, as I am just learning it now.
So far I have been able to send data to the board using the POST method in FLEX, now its time that I want to use the GET method so that when the page starts I can pre load values into lets say text boxes. So far I have been unable to get part working.

In my NB code I have this to listen for the GET from the FLEX app.

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int MyDoGet( int sock, PSTR url, PSTR rxBuffer )
{

	printf("MyDoGet=%s\r\n",url);
	writestring( sock, "Here You Go\r\n" );

   return ( *oldhand ) ( sock, url, rxBuffer ); //If we got  here the password was acceptable.
}

when I open the browser, I see the the MyDoGet is firing, but yet on the FLEX app I get a pop-up message saying HTTP Request Error.

I am not sure what the FLEX app is expecting for a return from the GET command.

This is my FLEX code for the GET, which fires when the page opens.

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    <mx:HTTPService 
    	id="userRequestget" 
    	url="http://192.168.0.7" 
    	useProxy="false" 
    	method="GET"
  
 		result="handle_plain(event)" 
		fault="handle_fault(event)" 
		resultFormat="text">
 
        <mx:request xmlns="">
            <sendthis>{"getme"}</sendthis>
        </mx:request>
    </mx:HTTPService>

Does anyone know what I should send back to the FLEX app from the NB board to stop this error ?

[tony]

I'm not sure if this answers your question or not but this is a simple example of how to use the Flex HTTPService. The function MyDoGet basically intercepts calls to the webserver and allows you to reply to specific web page requests.

C++ source code

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#include "predef.h"
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <startnet.h>
#include <autoupdate.h>
#include <dhcpclient.h>
#include <smarttrap.h>
#include <taskmon.h>
#include <NetworkDebug.h>


extern "C" {
void UserMain(void * pd);
}

const char * AppName="FlexHTTPService";
static http_gethandler  * oldhand;


/*-------------------------------------------------------------------
 Function to display connected message
 ------------------------------------------------------------------*/
void DisplayData( int sock, PCSTR url )
{
	writestring(sock, "This is the data...\n\r");
}

/*-------------------------------------------------------------------
 Function to display connected message
 ------------------------------------------------------------------*/
void DisplaySetup( int sock, PCSTR url )
{
	writestring(sock, "This is the setup...\n\r");
}



/*-------------------------------------------------------------------
 Override GET requests to the web server
 Parameters:
   sock     = Handle to open socket connection from client
   url      = URL client used to get here
   rxBuffer = Pointer to the complete HTTP request
 ------------------------------------------------------------------*/
int MyDoGet( int sock, PSTR url, PSTR rxBuffer )
{
   if ( strlen( url ) )
   {
      // Parse URL requrest and process images
      char dataName[] = "data.html";
      char setupName[] = "setup.html";
      
      if ( strncmp( url, dataName, strlen( dataName ) ) == 0 )
      {
		DisplayData( sock, url );
		return 0;
      }
      
      if ( strncmp( url, setupName, strlen( setupName ) ) == 0 )
      {
		DisplaySetup( sock, url );
		return 0;
      }
   }
   return ( *oldhand ) ( sock, url, rxBuffer );
}



void UserMain(void * pd) {
    InitializeStack();
    if (EthernetIP == 0) GetDHCPAddress();
    OSChangePrio(MAIN_PRIO);
    EnableAutoUpdate();
    StartHTTP();
    EnableTaskMonitor();

    oldhand = SetNewGetHandler( MyDoGet );
	
    #ifndef _DEBUG
    EnableSmartTraps();
    #endif

    #ifdef _DEBUG
    InitializeNetworkGDB_and_Wait();
    #endif

    iprintf("Application started\n");
    while (1) {
        OSTimeDly(20);
    }
}

Flex Source code

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<?xml version="1.0"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" >
	
	<mx:Script>
	<![CDATA[
		
		import mx.rpc.events.ResultEvent;

		public function displayData( event:Object  ):void
		{
			txtData.text = event.result;
		}
		
		public function displaySetup( event:Object  ):void
		{
			txtSetup.text = event.result;
		}


	]]>
	</mx:Script>
	
	<mx:HTTPService id="getHTTPData" url="data.html" resultFormat="text" result="displayData(event)" />
	<mx:HTTPService id="getHTTPSetup" url="setup.html" resultFormat="text" result="displaySetup(event)" />
	
	<mx:TextArea id="txtData" text="Data..." />
	<mx:Button label="Get Data" click="getHTTPData.send()"/>
	
	<mx:TextArea id="txtSetup" text="Setup..." />
	<mx:Button label="Get Setup" click="getHTTPSetup.send()"/>
	
	
</mx:Application>

[seulater]

Thanks Tony for the example and taking the time.

So i suppose that the only downfall to using this method of GET / POST would be if there was say an event that fired on the NB board and I needed to update the web page I would have no way of doing that.

[tony]

You could poll the server using a timer which is basically what most of the ajax examples are doing. For example you could modify the application tag to

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<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" applicationComplete="initApp()">

In the initApp function create a timer that calls some function at a specified rate. Within someFunction you could make the HTTP service request and check for any updates.

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private function initApp():void
{
      initImage();
      setInterval(someFunction, 1000);
}

The HTTPService is a very powerful tool. For example it would be useful to grab a table of data and display it in a data grid. Or even to query parameters from the host. HTTP follows the Client Server model where the host queries data from the server. Alternatively you can create a Peer to Peer model with an XMLSocket both ends can either push or pull data. By running a timer on the host you are basically polling the server to see if it has anything new to send rather than have it send it automatically.

[seulater]

Sweet! that is another one I wanted to do

You are giving me a LOT of very useful tips!
There is only one more thing I am trying to learn.

I have a unit connected up to the NB board that has 50 digital potentiometers and 50-10segment bargraphs.

I want to be able to control all these with the vertical sliders. so far I have been able to do it, but I know there must be an easier way than I am doing it.

I use this to get the current slider value.

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    <mx:HTTPService 
    	id="SliderRequest" 
    	url="http://192.168.0.7" 
 		result="handle_plain(event)" 
		fault="handle_fault(event)" 
 
        <mx:request xmlns="">
            <slider1>{slider1.value}</slider1>
        </mx:request>

    </mx:HTTPService>

Now, instead of having 50 different HTTPService calls, isn't there a way to have just one?

Im thinking there must be a way to replace the "<slider1>{slider1.value}</slider1>" with say "<slides>{some_text_variable.value}</sliders>"
and when I go to call SliderRequest.send() I could maybe pass the new text to that HTTPService call ? or at the very least, update "some_text_variable.value" with the next slider text and then just call SliderRequest.send()

Hope that made sense, another way to put it would be like this:

some_text_variable.value = "slider_1"
SliderRequest.send()
some_text_variable.value = "slider_2"
SliderRequest.send()
and so on. of course it would be best if I could pass a variable and do this is a loop but I don't know yet if I I can do the following either.

for(x=0;x<50;x++)
{
sprintf(temp,"%u",x)
some_text_variable.value = temp
SliderRequest.send()
}

[seulater]

Tony, i tried the delay thing, and was not successful, I looked in the help and tried other things but its just not firing over and over, its just fires once.
here is what I got, if you got any ideas please let me know.

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<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"
	applicationComplete="initApp()"  
	color="#060606" 
	backgroundGradientAlphas="[1.0, 1.0]"
	backgroundGradientColors="[#4B679F, #4B679F]"
 >

   
   <mx:Script>
   <![CDATA[
      


		private function initApp():void
		{
      		setInterval(GetNBTimer, 1000);
		}

		private function GetNBTimer():void
		{
	      	timers.send();
		}

      public function TimeResult( event:Object  ):void
      {
         rxdata.text = event.result;
      }

   ]]>
   </mx:Script>

		
	<mx:HTTPService
	id="timers"
   	url="http://192.168.0.7"
   	showBusyCursor="true"
   	result="TimeResult(event)"> 
   	
   	<mx:request>
    	<timers>{""}</timers>
    </mx:request>
	
	</mx:HTTPService>
		
   
   <mx:TextArea id="rxdata" height="60" x="176" y="142"/>
   <mx:Label x="176" y="116" text="Data Received From NB"/>
   
   
</mx:Application>