Integrate Real-Time Access to Impala in SAPUI5 MVC Apps

In this article we show how to use the CData API Server to write SAPUI5 apps that leverage the capabilities of the Impala API, without writing to a back-end database. The API Server is a lightweight Web application that runs on your server and produces OData feeds of Impala data. OData is the standard for real-time data access over the Web and has built-in support in SAPUI5 and OpenUI5.

Set Up the API Server

If you have not already done so, download the CData API Server. Once you have installed the API Server, follow the steps below to begin producing secure Impala OData services:

Connect to Impala

To work with Impala data from SAPUI5, we start by creating and configuring a Impala connection. Follow the steps below to configure the API Server to connect to Impala data:

1. First, navigate to the Connections page.
2. Click Add Connection and then search for and select the Impala connection. 👁 Selecting a data source (SQLite is shown)
   
3. Enter the necessary authentication properties to connect to Impala.

   In order to connect to Apache Impala, set the Server, Port, and ProtocolVersion. You may optionally specify a default Database. To connect using alternative methods, such as NOSASL, LDAP, or Kerberos, refer to the online Help documentation.

   👁 Connecting to a datasource (SQLite is shown)
   
4. After configuring the connection, click Save & Test to confirm a successful connection.

Configure API Server Users

Next, create a user to access your Impala data through the API Server. You can add and configure users on the Users page. Follow the steps below to configure and create a user:

1. On the Users page, click Add User to open the Add User dialog.
2. Next, set the Role, Username, and Privileges properties and then click Add User. 👁 Configure a new user
   
3. An Authtoken is then generated for the user. You can find the Authtoken and other information for each user on the Users page: 👁 API Server user settings
   

Creating API Endpoints for Impala

Having created a user, you are ready to create API endpoints for the Impala tables:

1. First, navigate to the API page and then click Add Table . 👁 Add tables
   
2. Select the connection you wish to access and click Next. 👁 Select the connection (SQLite is shown)
   
3. With the connection selected, create endpoints by selecting each table and then clicking Confirm. 👁 Adding tables from the connection (SQLite is shown)
   

Gather the OData Url

Having configured a connection to Impala data, created a user, and added resources to the API Server, you now have an easily accessible REST API based on the OData protocol for those resources. From the API page in API Server, you can view and copy the API Endpoints for the API:

👁 API Endpoints

Create the View

In this article the user views and interacts with Impala data through an SAPUI5 table control. Table columns will be automatically detected from the metadata retrieved from the API Server's API endpoint. We define the following table in a separate View.view.xml file:

<mvc:View
 controllerName="sap.ui.table.sample.OData2.Controller"
 xmlns="sap.ui.table"
 xmlns:mvc="sap.ui.core.mvc"
 xmlns:u="sap.ui.unified"
 xmlns:c="sap.ui.core"
 xmlns:m="sap.m">
 <m:Page
 showHeader="false"
 enableScrolling="false"
 class="sapUiContentPadding">
 <m:content>
 <Table
 id="table"
 selectionMode="MultiToggle"
 visibleRowCount="10"
 enableSelectAll="false"
 rows="{/Customers}"
 threshold="15"
 enableBusyIndicator="true"
 columns="{
 path: 'meta>/dataServices/schema/[${namespace}===\'CData\']/entityType/[${name}===\'Customers\']/property',
 factory: '.columnFactory'
 }">
 <toolbar>
 <m:Toolbar>
 <m:Title text="Impala Customers"></m:Title>
 </m:Toolbar>
 </toolbar>
 <noData>
 <m:BusyIndicator class="sapUiMediumMargin"/>
 </noData>
 </Table>
 </m:content>
 </m:Page>
</mvc:View>

Create the Model and Controller

In SAPUI5, you do not need to write any OData queries; an ODataModel instance handles the application's data access commands. The API Server then translates the queries into Impala API calls.

The controller processes user input and represents information to the user through a view. Define the controller in a new file, Controller.controller.js. Instantiate the model in the onInit function -- you will need to replace the placeholder values for the URL to the API Server, a user allowed to access the OData endpoint of the API Server, and the authtoken for the user.

sap.ui.define([
 "sap/ui/core/mvc/Controller",
 "sap/ui/model/odata/v2/ODataModel",
 "sap/ui/model/json/JSONModel",
 "sap/ui/table/Column",
 "sap/m/Text",
], function(Controller, ODataModel, JSONModel, Column, Text ) {
 "use strict";
 

 return Controller.extend("sap.ui.table.sample.OData2.Controller", {
 
 onInit : function () {
 
 var oView = this.getView();
 var oDataModel = new ODataModel("http://myserver/api.rsc/",{user: "MyUser", password: "MyAuthToken"});
 
 oDataModel.getMetaModel().loaded().then(function(){
 oView.setModel(oDataModel.getMetaModel(), "meta");
 });
 oView.setModel(oDataModel);
 
 var oTable = oView.byId("table");
 var oBinding = oTable.getBinding("rows");
 var oBusyIndicator = oTable.getNoData();
 oBinding.attachDataRequested(function(){
 oTable.setNoData(oBusyIndicator);
 });
 oBinding.attachDataReceived(function(){
 oTable.setNoData(null); //use default again ("no data" in case no data is available)
 });
 },
 
 onExit : function () {
 },
 
 columnFactory : function(sId, oContext) {
 var oModel = this.getView().getModel();
 var sName = oContext.getProperty("name");
 var sType = oContext.getProperty("type");
 var iLen = oContext.getProperty("maxLength");
 iLen = iLen ? parseInt(iLen, 10) : 10;
 
 return new Column(sId, {
 sortProperty: sName, 
 filterProperty: sName,
 width: (iLen > 9 ? (iLen > 50 ? 15 : 10) : 5) + "rem",
 label: new sap.m.Label({text: "{/#Customers/" + sName + "/@name}"}),
 hAlign: sType && sType.indexOf("Decimal") >= 0 ? "End" : "Begin",
 template: new Text({text: {path: sName}})
 });
 }
 
 });

});

Describe Application Logic

Create a component that contains the resources of your application. Define the following in Component.js:

sap.ui.define([
 'sap/ui/core/UIComponent'
], function(UIComponent) {
 "use strict";

 return UIComponent.extend("sap.ui.table.sample.OData2.Component", {
 metadata : {
 rootView : "sap.ui.table.sample.OData2.View",
 dependencies : {
 libs : [
 "sap.ui.table",
 "sap.ui.unified",
 "sap.m"
 ]
 },

 config : {
 sample : {
 stretch : true,
 files : [
 "View.view.xml",
 "Controller.controller.js"
 ]
 }
 }
 }
 });

});

Bootstrap OpenUI5 and Launch

To complete the MVC application, simply add the bootstrap and initialization code. Add these directly to index.html:

<!DOCTYPE HTML>

<html>
<head>
 <meta http-equiv="x-ua-compatible" content="ie=edge">
 <meta charset="utf-8"> 
 <title>Impala Customers</title>
 
 <script id="sap-ui-bootstrap"
 src="https://openui5.hana.ondemand.com/resources/sap-ui-core.js"
 data-sap-ui-libs="sap.m"
 data-sap-ui-theme="sap_bluecrystal"
 data-sap-ui-xx-bindingSyntax="complex"
 data-sap-ui-preload="async"
 data-sap-ui-compatVersion="edge" 
 data-sap-ui-resourceroots='{"sap.ui.table.sample.OData2": "./", "sap.ui.demo.mock": "mockdata"}'>
 </script>
 
 <!-- application launch configuration -->
 <script>
 
 sap.ui.getCore().attachInit(function() {
 new sap.m.App ({
 pages: [
 new sap.m.Page({
 title: "Impala Customers", 
 enableScrolling : false,
 content: [ new sap.ui.core.ComponentContainer({
 height : "100%", name : "sap.ui.table.sample.OData2"
 })]
 })
 ]
 }).placeAt("content");
 });

 </script>
</head> 
 <!-- UI Content -->
<body class="sapUiBody" id="content" role="application">
</body> 
</html>

The resulting SAPUI5 table control reflects any changes to a table in the remote Impala data. You can now browse and search current Impala data.

👁 A table in SAPUI5 that reflects changes to the data in real time. (Salesforce is shown.)