Callback Scope on the client

I've started to play around w/ some of the basic Atlas features, mainly calling a web service from the client. One thing I noticed is that scope is lost during the asynchronous call to the server. If my javascript caller & callback method are part of an class, I've no way of telling Atlas to invoke the callback method w/ a specific object's scope.

Is this possible to do?

Cheers,
BobbyYou have a userContext parameter which you can pass as part of yourasynchronous call, that is what you can use to get back to the contextof your call, i.e. you can pass the object who's scope you want back aspart of the call...

Hope that helps,
-Hao
As I understood it, the userContext serves as a holder for contextual data that can be used inside the handler as an object - scope is still lost. Consider the following js class example:

TestClass = function(prop1)
{
this.propertyOne = prop1;

this.test = function()
{
MyCallbackServiceClass.Test({onMethodComplete: this.testCallback, userContext: this});
}

this.testCallback = function(result, user)
{
alert(this.propertyOne);
}
};

var t = new TestClass("This should persist before and after callback");
t.test();

When propertyOne is alerted in the testCallback method, it will be undefined because the scope is not preserved. I don't want the object as a parameter - I want to be operating within that object.
Mike Harder from the ASP.NET team, being the top-notch guy he is, answered this question for me. The scope is maintained by using a delegate.

CSharper.Net.CallbackService.Test({ onMethodComplete: Function.createDelegate(this, this.testCallback), userContext: this });

Call to WebService not working...

I am getting this error 'Microsoft JScript runtime error: 'wsWeatherFeed' is undefined. It's just a basic call to a webservice via the asp:ScriptManager tag. Can someone help me point out what I might be doing wrong?

.Aspx file:

<scriptlanguage="javascript"type="text/javascript">

function fnImgMouseOver(e){

wsWeatherFeed.set_timeout(40000);

wsWeatherFeed.fnGetWeatherData(e,callback_fnImgMouseOver,fnGetWeatherDataError);

}

function callback_fnImgMouseOver(result){

alert(result);

}

function fnGetWeatherDataError(err){

alert("Here is the error: " + err.error);

}

</script>

<further down>

<asp:ScriptManagerID="ScriptManager1"runat="server">

<Services>

<asp:ServiceReferencePath="wsWeatherFeed.asmx"/>

</Services>

</asp:ScriptManager>

.Asmx file

<%@dotnet.itags.org.WebServiceLanguage="C#"CodeBehind="~/App_Code/wsWeatherFeed.cs"Class="wsWeatherFeed" %>

.cs WebService file:

using System;

using System.Web;

using System.Web.Services;

using System.Web.Services.Protocols;

using System.Collections;

using System.Xml;

using System.Xml.XPath;

using System.Xml.Xsl;

[WebService(Namespace ="http://tempuri.org/")]

[WebServiceBinding(ConformsTo =WsiProfiles.BasicProfile1_1)]

[System.Web.Script.Services.ScriptService()]

publicclasswsWeatherFeed :WebService {

public wsWeatherFeed () {

//Uncomment the following line if using designed components

//InitializeComponent();

}

[WebMethod]

protectedstring fnGetWeatherData(String strData)

{

return strData

}

}

I got this to work with VB.Net but I guess I just lost something along the way, can anyone provide a clue?

J

Ok I got it. The reason why my js couldnt get to my webservice class was that my web service method fnGetWeatherData was intially set to 'protected' instead of 'public'.

Anyway, I didnt want anyone to spend any time troubleshooting this if I can answer it quick enough myself.

J

Call ASP.NET web service and return JSON using only html/javascript

I've implmented a pretty basic webservice as per below. I did a quick test in ASP.NET AJAX using the ScriptManager and it returned JSON-formatted data perfectly. I am now trying to do the same using just html/javascript with the XmlHttpRequest object.

Currently I've assigned the context-type to the XmlHttpRequest as is apparently required, and the webservice is "working", but only returning xml.

I'd really appreciate any help - or maybe even a better way to access the ASP.NET web service externally (i.e. outside of ASP.NET). Thanks.

PART A: ASP.NET Webservice snippet

[WebService(Namespace = "http://microsoft.com/webservices/";
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[ScriptService]
public class ScriptingService : OrYxBaseWebService {
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public ScriptPersonRoleList GetActiveCategoryManagers() {
OrYxAppStatus myStatus = BFManager.GetInstance().CreateStatus(GetDefaultRequest());
return BFManager.ScriptingBF.GetActiveCategoryManagers(ref myStatus);
}
}

PART B: Index html

<html>
<head>
<title>Ajax Test Drive</title>
<script type="text/javascript" language="javascript">

function makePOSTRequest(url, parameters) {
http_request = false;
if (window.XMLHttpRequest) { // Mozilla, Safari,...
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType) {
// set type accordingly to anticipated content type
// http_request.overrideMimeType('text/xml');
http_request.overrideMimeType('text/html');
}
} else if (window.ActiveXObject) { // IE
try {
http_request = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
http_request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
alert("not good at all..");
}
}
}
if (!http_request) {
alert('Cannot create XMLHTTP instance');
return false;
}

http_request.onreadystatechange = confirmResponse;
http_request.open('POST', url, true);
http_request.setRequestHeader("Content-Type", "application/json");

http_request.send(parameters);
}

function confirmResponse() {
if (http_request.readyState == 4) {
if (http_request.status == 200) {
result = http_request.responseText;
document.getElementById('databox').innerHTML = result;
alert('Response:\n\n' + result);
} else {
alert('There was a problem with the request.');
}
}
}

function getData() {
var url = 'http://localhost/TVScriptingWebService/TVScripting.asmx/GetActiveCategoryManagers';
var request = makePOSTRequest(url, "");
}
</script>

</head>
<body onload="getData()">
<div style="width: 600px; padding: 10px; border: 1px solid;" align="center">
Test page</div>
<br>
<div id="databox">
</div>
<br>
</body>
</html>

What format do you want data in now?

I am wanting JSON not XML.

use text/json rather than application/json

Thanks for the response, I tried adding the following lines, but they all still return only xml as the responseText

http_request.setRequestHeader('Content-Type','text/json');

Could i again confirm that the webservice is actually returning JSON data?

The only time I have seen the webservice returns JSON data is when its called from within ASP.NET AJAX pages using the ScriptManager - which I don't want to do because these services are ultimately going to be called from a php application..

I am trying to call it using using only javascript/html and cannot get it to return JSON - only xml

Environment: ASP.NET 2.0, AJAX ASP.NET RC1. Tested on IIS5.1 and IIS6

Thanks

Well again it could be an inadvertant policy issue where microsoft doesnt want people to use other products just like datatable which is not returned as webservice. But you can always convert xml to json.

Let me see your code for consuming page in .net

Hi naturehermit,

Thanks again. You're right I could parse the xml into Json within the client, however I think that would eliminate one of the main advantages of using JSON..

I couldn't get it to work so I've implemented my own IHttpHandlerFactor and IHttpHandler classes which was pretty easy. They now intercept the webservice calls and check whether use my classes, which return JSON using the JavaScriptSerializer, or the generic WebServiceHandlerFactory().

Currently the flag I've decided on is if there is an "application/OrYxJson" within the Context-Type property of the request. If this property is set, JSON gets returned, otherwise you get good old SOAP.

Early days, but so far so good..

Good luck mate, let me know if i could be of any help. Its always good to share your experiences

Yep agreed and willdo. Thanks.

naturehermit:

What format do you want data in now?

?

Hi,

I ran into same issue where I specified in the webservice JSON and yet XML was returned. Anyway, I found ot that it actually returns JSON. Try running fiddler to intercept the response from the webservice and you'll see the JSON string. Ignore the "_type".

Thanks