DataBind Wijmo Grid to HDFS Data

The Connect Server enables you to use Web services to connect to and query HDFS data. This article details how to import an OData feed of HDFS data into Wijmo Grid.

Configuring Connect Server

To work with live HDFS data in Wijmo Grid, we need to connect to HDFS from Connect Server, provide user access to the new virtual database, and create OData endpoints for the HDFS data.

Add a Connect Server User

Create a User to connect to HDFS from Wijmo Grid through Connect Server.

1. Click Users -> Add
2. Configure a User
3. Click Save Changes and make note of the Authtoken for the new user

Connect to HDFS from Connect Server

CData Connect Server uses a straightforward, point-and-click interface to connect to data sources and generate APIs.

1. Open Connect Server and click Connections
2. Select "HDFS" from Available Data Sources
3. Enter the necessary authentication properties to connect to HDFS.

   In order to authenticate, set the following connection properties:

   • Host: Set this value to the host of your HDFS installation.
   • Port: Set this value to the port of your HDFS installation. Default port: 50070
4. Click Save Changes
5. Click Privileges -> Add and add the new user (or an existing user) with the appropriate permissions (SELECT is all that is required for Reveal).

Add HDFS OData Endpoints in Connect Server

After connecting to HDFS, create OData Endpoints for the desired table(s).

1. Click OData -> Tables -> Add Tables
2. Select the HDFS database
3. Select the table(s) you wish to work with and click Next
4. (Optional) Edit the resource to select specific fields and more
5. Save the settings

(Optional) Configure Cross-Origin Resource Sharing (CORS)

When accessing and connecting to multiple domains from an application such as Ajax, there is a possibility of violating the limitations of cross-site scripting. In that case, configure the CORS settings in OData -> Settings.

• Enable cross-origin resource sharing (CORS): ON
• Allow all domains without '*': ON
• Access-Control-Allow-Methods: GET, PUT, POST, OPTIONS
• Access-Control-Allow-Headers: Authorization

Save the changes to the settings.

Connect to HDFS Data using Wijmo Grid

Create a Real-Time Grid

Follow the steps below to consume HDFS data from the Wijmo JavaScript controls:

1. Load the required Wijmo, jQuery, and Knockout libraries:

   			
   			<script src="http://code.jquery.com/jquery-1.11.1.min.js"></script>
   			<script src="http://code.jquery.com/ui/1.11.0/jquery-ui.min.js"></script>
   
   			<!--Theme-->
   			<link href="http://cdn.wijmo.com/themes/aristo/jquery-wijmo.css" rel="stylesheet" type="text/css">
   
   				<!--Wijmo Widgets CSS-->
   				<link href="http://cdn.wijmo.com/jquery.wijmo-pro.all.3.20161.90.min.css" rel="stylesheet" type="text/css">
   
   					<!--Wijmo Widgets JavaScript-->
   					<script src="http://cdn.wijmo.com/jquery.wijmo-open.all.3.20161.90.min.js"></script>
   					<script src="http://cdn.wijmo.com/jquery.wijmo-pro.all.3.20161.90.min.js"></script>
   					<script src="http://cdn.wijmo.com/interop/wijmo.data.ajax.3.20161.90.js"></script>
   
   					<!--Knockout JS Library-->
   					<!-- Both of the links below can work -->
   					<script src="http://cdn.wijmo.com/wijmo/external/knockout-2.2.0.js"></script>
   					<!--<script src="http://cdn.wijmo.com/amd-js/3.20161.90/knockout-3.1.0.js"></script>-->
   
   					<!--Wijmo Knockout Integration Library-->
   					<script src="http://cdn.wijmo.com/interop/knockout.wijmo.3.20161.90.js"></script>
   		

2. Create a ViewModel and connect to it using the ODataView. You will need to replace the placeholder values for the URL of the API Server, an API Server user, and the authtoken for that user.

   			
   			<script id="scriptInit">
   			$.support.cors = true;
   			var viewModel;
   
   			function ViewModel() {
   			var filesView = new wijmo.data.ODataView("http://MyServer:MyPort/api.rsc/Files", {
   			ajax: {
   			dataType: "jsonp",
   			username: "MyUser",
   			password: "MyAuthtoken",
   			data: { "$inlinecount": null }
   			},
   			pageSize: 10
   			});
   			filesView.refresh();
   			filesView.nextPage();
   			this.files = filesView;
   			this.prevPage = function () {filesView.prevPage();};
   			this.nextPage = function () {filesView.nextPage();};
   			}
   
   			$(document).ready(function () {
   			viewModel = new ViewModel();
   			ko.applyBindings(viewModel, $(".container").get(0));
   			});
   			</script>
   		

3. DataBind: Below is a simple table with some paging buttons, which you can paste into the body section of your markup.

   			
   			<h2>Connect to Live HDFS Data in Real Time</h2>
   
   			<h3>Files</h3>
   			<div>
   				<button title="previous page" class="pagebuttons" data-bind="click: prevPage, button: {}">
   					<span class="ui-icon ui-icon-seek-prev" />
   				</button>
   				<button title="next page" class="pagebuttons" data-bind="click: nextPage, button: {}">
   					<span class="ui-icon ui-icon-seek-next" />
   				</button>
   			</div>
   			<table id="demo-grid" data-bind="wijgrid: { 
         data: files, 
         showFilter: true, 
         allowPaging: true,
         pagerSettings: { position: 'none'},
         columnsAutogenerationMode: 'append',
       }" >
   			</table>
   		

At this point, you may be prompted to re-enter the username and authtoken. After doing so, a resulting table or grid should appear, as seen below. You can filter and sort through pages of HDFS data.

Free Trial & More Information

If you are interested in connecting to your HDFS data (or data from any of our other supported data sources) from Wijmo Grid, sign up for a free trial of CData Connect Server today! For more information on Connect Server and to see what other data sources we support, refer to our CData Connect page.