GET and POST
In an earlier article, we looked at creating a generic "NetOp" script and a specialised "NetOp.Preloader" script that would extend this. In this tutorial, we will create a "NetOp.Transaction" script to send information to (and get responses from) a server using METHOD-GET or METHOD-POST type transactions.
Here is the "NetOp.Transaction" script. If you pass a 'data' parameter (a property list), it will use the POST method. If this parameter is not provided, it assumes that the data is encoded in the URL string and will use GET.
-- "NetOp.transaction" Parent Script (v.1)
property ancestor
property NetID
property URL, FORMDATA
on new (me, netAddress, data)
me.URL = netAddress
me.FORMDATA = data
ancestor = script("NetOp").rawNew()
callAncestor(#new, me)
return me
end
on Start (me)
if voidP(FORMDATA) then me.NetID = getNetText(me.URL )
else me.NetID = postNetText(me.URL , me.FORMDATA)
aTimerObj = timeout(me.string).new(100, #Timer_CheckProgress, me)
return me.NetID
end
on Destroy (me)
netAbort(me.NetID)
me.NetID = VOID
callAncestor(#Destroy, me)
end
on Timer_CheckProgress (me, aTimer)
if voidP(me.NetID) then
-- we have aborted the operation
atimer.forget()
return 0
end if
finished = netDone(me.NetID)
if finished then
errorNum = netError(me.NetID)
theText = netTextResult(me.NetID)
if stringP(errorNum) then errorNum =0
aTimer.forget()
me.GenerateEventMessage(#NetTransactionComplete, \
[#Text: theText, #Error: errorNum])
else
-- check the current status
status = getStreamStatus(me.NetID)
currentState = status.state
-- before sending the status, work out the portion downloaded
case (currentState) of
"InProgress":
if status.bytesSoFar > 0 then
if status.bytesTotal > 0 then
f = MIN(1.0, float(status.bytesSoFar)/status.bytesTotal )
else f = .50
else
f = 0
end if
"Complete":
f = 1.00
otherwise
f = 0
end case
-- add the fractionDone as a property to the statusList
status.addProp( #fractiondone, f )
-- inform the callback object of the current state and the % transferred
me.GenerateEventMessage(#NetTransactionStatusUpdate, status)
end if
end
You may notice that the network operation doesn't actually start until you call the start method of the object. The reason for this is that you might want to track all your network operations and only allow 4 (or so) to run concurrently. In this demo movie, every time you click a 'test' button, a new netOp object is created. If there are less than four operations still active, the netOp object is added to a 'queue' list. When an operation is finished, it is removed from the 'active' list and the netop is chosen from the queue and started.
Demo Movie
In the demo movie above, the page that the shockwave movie is transacting with is a simple script that looks like this:
EXAMPLE
if (isset($_REQUEST['q'])) $q = $_REQUEST['q'];
else $q = "NOT SET";
print "Hi, this is the server speaking. The value I received was $q";
If you are running JSP, the following will achieve the same result (try setting the URL in the above example to http://dev3.medialight.com.au/examples/list2.jsp):
JSP EXAMPLE
String q = request.getParameter("q");
if (q==null) { q = "NOT SET";}
out.print("Hi, this is the server speaking. The value I received was " + q);
And if you're running ASP.NET or mono, the following will achieve the same result.
.NET/Mono C# Example
void Page_Load (object o, EventArgs e) {
string q = "NOT SET";
if (Request.Form["q"] != null ) q = Request.Form["q"];
else if (Request.QueryString["q"] != null) q = Request.QueryString["q"];
Response.Write("Hi, this is the .NET server speaking.
The value I received was " +q);
}