Announcing Microsoft ASP.NET WebHooks V1

WebHooks provide a simple pub/sub model for wiring together Web APIs and services with your code. A WebHook can be used to get notified when a file has changed in Dropbox, a code change has been committed to GitHub, a payment has been initiated in PayPal, a card has been created in Trello, and much more — the possibilities are endless! When subscribing, you provide a callback URI where you want to be notified. When an event occurs, an HTTP POST request is sent to your callback URI with information about what happened so that your Web app can act accordingly. WebHooks happen without polling and with no need to hold open a network connection while waiting for notifications.

Receiving WebHooks

Dealing with WebHooks depends on who the sender is. Sometimes there are additional steps registering a WebHook verifying that the subscriber is really listening. Often the security model varies quite a bit. Some WebHooks provide a push-to-pull model where the HTTP POST request only contains a reference to the event information which is then to be retrieved independently.

The purpose of Microsoft ASP.NET WebHooks is to make it both simpler and more consistent to wire up your API without spending a lot of time figuring out how to handle any WebHook variant:

WebHoks-Receiving

A WebHook handler is where you process the incoming WebHook. Here is a sample handler illustrating the basic model. No registration is necessary – it will automatically get picked up and called:

public class MyHandler : WebHookHandler
{
    // The ExecuteAsync method is where to process the WebHook data regardless of receiver
    public override Task ExecuteAsync(string receiver, WebHookHandlerContext context)
    {
        // Get the event type          
        string action = context.Actions.First();
 
        // Extract the WebHook data as JSON or any other type as you wish
        JObject data = context.GetDataOrDefault();
 
        return Task.FromResult(true);
    }
}

Finally, we want to ensure that we only receive HTTP requests from the intended party. Most WebHook providers use a shared secret which is created as part of subscribing for events. The receiver uses this shared secret to validate that the request comes from the intended party. It can be provided by setting an application setting in the Web.config file, or better yet, configured through the Azure portal or even retrieved from Azure Key Vault.

For more information about receiving WebHooks and lots of samples, please see these resources:

More detail on Microsoft Blog.

Chart.js Asp.net : Create Pie chart with database jQuery Ajax C#

This article explains using Chart.js in Asp.net C# Web Application we can create a pie chart with database MS SQL server connectivity via jQuery ajax call.  You can also have a look on related article, .

Now in this post here we create a pie chart by using chart.js library and bind data from our database MS Sqlserver, with jQuery ajax calling.

Here we are creating a pie chart, which shows data from the database (Ms SQL server).  In my database, I have a table which stores data (website traffic source info).

So basically our pie chart data will shows traffic source info .i.e. (how much of page views referral by facebook, twitter, google+, Tumblr etc ).

Chart.js: Simple,clean and engaging charts for designers and developers developed by Nick Downie . It uses the HTML5 canvas element.

It’s supported in all modern browsers, and polyfills support for IE7/8. Chart.js is dependency free and super lightweight.

Download – Chart.js file and include in Asp.net Webform

First download and include latest files of the chart.js , jQuery library in your web page.

HTML markup under head tag looks like as shown below.

<head runat="server">
    <title>Pie Chart Asp.net with database ms sqlserver</title>
    <script src="js/jquery-1.10.2.min.js" type="text/javascript"></script>
    <script src="js/Chart.js" type="text/javascript"></script>
</head>

 

Html Markup (Design) – Adding HTML5 Canvas Tag

I have added 2 drop-down list control to select the year, month, along with a button and a  canvas tag.

Now on button click will call jQuery ajax, and then on ajax success our pie chart gets generated by using Chart.js library and HTML5 Canvas tag

<select id="ddlyear">
    <option>2010</option>
    <option>2011</option>
    <option>2012</option>
    <option>2013</option>
    <option>2014</option>
    <option>2015</option>
</select>
<select id="ddlMonth">
    <option value="1">Jan</option>
    <option value="2">Feb</option>
    <option value="3">Mar</option>
</select>
<button id="btnGeneratePieChart">Show</button>
<br/><canvas id="myChart" width="200" height="200"></canvas>

 

Code Behind – Ajax call WebMethod, and returns JSON format data to create Pie Chart

First add a WebMethod .i.e asmx file, and then we write our WebMethod which returns JSON format data, In our .asmx file will create a class named as trafficSourceData as shown below.

 public class trafficSourceData{
          public string label{get;set;}
          public string value{get;set;}
          public string color{get;set;}
          public string hightlight{get;set;}
    }

Now our WebMethod will pull data from database Ms Sqlserver for specific month and year, and return list of class object .i.e trafficSourceData class list as JSON formatted data, so our pie chart get created using chart.js.

[WebMethod]
    public List getTrafficSourceData(List gData)
    {
        List t = new List();
        string[] arrColor = new string[] { "#231F20", "#FFC200", "#F44937", "#16F27E", "#FC9775", "#5A69A6" };

        using (SqlConnection cn = new SqlConnection(conn))
        {
            string myQuery = "select * from traffic_data where YEAR =@year and MONTH=@month";
            SqlCommand cmd = new SqlCommand();
            cmd.CommandText = myQuery;
            cmd.CommandType = CommandType.Text;
            cmd.Parameters.AddWithValue("@year", gData[0]);
            cmd.Parameters.AddWithValue("@month", gData[1]);
            cmd.Connection = cn;
            cn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.HasRows)
            {
                int counter = 0;
                while (dr.Read())  {
                    trafficSourceData tsData = new trafficSourceData();
                    tsData.value = dr["visit_count"].ToString();
                    tsData.label = dr["traffic_source"].ToString();
                    tsData.color = arrColor[counter];
                    t.Add(tsData);
                    counter++;
                }
            }
        }
        return t;
    }

 

jQuery –  initializing Chart.js in Asp.net WebPage

Now back to client side coding, we have already done with the server-side code by creating WebMethod which return JSON format data. So now in our Ajax call on success will initialize Chart.js variable.

Client-side code looks like as written below

$(document).ready(function () {

    $("btnGeneratePieChart").on('click', function (e) {
        e.preventDefault();
        var gData = [];
        gData[0] = $("#ddlyear").val();
        gData[1] = $("#ddlMonth").val();

        var jsonData = JSON.stringify({
            gData: gData
        });
        $.ajax({
            type: "POST",
            url: "WebService.asmx/getTrafficSourceData",
            data: jsonData,
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: OnSuccess_,
            error: OnErrorCall_
        });

        function OnSuccess_(response) {
            var aData = response.d;
            var arr = [];
            $.each(aData, function (inx, val) {
                var obj = {};
                obj.color = val.color;
                obj.value = val.value;
                obj.label = val.label;
                arr.push(obj);
            });
            var ctx = $("#myChart").get(0).getContext("2d");
            var myPieChart = new Chart(ctx).Pie(arr);
        }

        function OnErrorCall_(response) {}
        e.preventDefault();
    });
});

 

Finally, we are done with coding, Now every time we click button our pie chart gets created.

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