The SmartWeb platform enables effective development of web applications that use the D2000 application server as a data source, meaning that they have application logic programmed in the D2000 application server. Thanks to direct usage of standard web technologies such as HTML, CSS, and JavaScript, the applications' design is not limited by graphics possibilities of D2000. Knowledge of these technologies is thus a necessity for developing applications on the SmartWeb platform.

Introduction to Development of Applications

Requirements for Developing

• Installed Git
• Development environment for HTML and JavaScript (e.g. WebStorm)
• Web browser (at least Internet Explorer 11, Google Chrome is recommended)

Application Bundling

In applications on the SmartWeb platform, it is possible to use JavaScript language constructions up to the ECMAScript 2017 version and React components which use JSX syntax regardless of the final used web browser. This is possible because applications created on the SmartWeb platform go through a process called bundling during which they are deployed into a production version. This process makes adjustments of source codes (transpilation) so that they would be natively interpretable by the lowest supported version of a web browser (translations to the JavaScript of ES 5.0 version). At the same time, the size of source codes is reduced during the bundling process - minification (removing empty characters and commentaries, shortening of names of variables and functions...). It spares transmitted data and thus enables quicker loading of web pages. 

Application Configuration

The smartweb.json file serves for configuration of the SmartWeb application. In this file, it is possible to allow or forbid individual components of the application, to set an authentication method, to restrict access to Event scripts and RPD procedures. A detailed description of the configuration can be found in the chapter Configuration of the SmartWeb Application.

Application Structure

The following figure shows the structure of the SmartWeb application.

On the left, there is a description of files which the programmer creates. Those are mostly files of individual pages (pages directory), a page for a login of a user (login.js) and an HTML template of pages (template.html). JavaScript modules shared among pages are located in the custom directory and for storing other files such as pictures, there is the assets directory.

On the right, there are described files generated or copied by the SmartWeb Bundle Engine. Those are mostly built production versions of pages, files of the SmartWeb framework and the JavaScript engine with downloaded libraries for the bundle engine.

External Libraries

Thanks to the usage of SystemJS and JSPM, it is possible to use any JavaScript library from GitHub and npm in the SmartWeb application. Dependencies and possible conflicts will be automatically resolved in versions. 

Development of Applications

SmartWeb applications are standardly composed of more web pages. Pages may be written directly as HTML (suffix .html) files or as JavaScript files (suffix .js) which will be using templates (template.html) mapped on the HTML file (e.g. the index.html page is created by a combination of the file template template.html and the file index.js). The file template.html represents a template of a web page using which it is possible to define repeated parts of final pages. Only mandatory HTML element of the template is the element of the <div> type with id "root". Content of this element will be generated based on a particular JavaScript file which is mapped to a final HTML file. In the template, it is possible to use several placeholder variables in SmartWeb. Those will be automatically replaced by their real value during loading of the page.

• {{{smartweb.global.context.path}}}  is the url path to the root directory of the SmartWeb server derived from the name of the deployed "war" file of the Wildfly application server. (e.g. /smartWeb).
• {{{smartweb.application.root.path}}} is the url path to the root directory of the web application derived from how it is defined in the smartweb.json. configuration file (e.g /smartWeb/admin).
• {{{smartweb.application.script}}} contains a code of the SmartWeb application 
• {{{smartweb.library.scripts}}} contains a code of the used libraries in the SmartWeb application

The following code represents an example of the template.html file in which there are defined the basic styles, scripts and an icon of the web page: 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>SmartWeb Demo</title>

    <link rel='shortcut icon' type='image/x-icon' href='{{{smartweb.application.root.path}}}/custom/img/favicon.ico'/>
    <link href="{{{smartweb.application.root.path}}}/assets/fonts/font-awesome/font-awesome.css" rel="stylesheet">
    <link href="{{{smartweb.application.root.path}}}/assets/fonts/font-open-sans/open-sans.css" rel="stylesheet">
    <style>
        .gray-bg {
            background-color: #f3f3f4;
        }
    </style>
    {{{smartweb.library.scripts}}}
</head>
<body class="fixed-nav top-navigation gray-bg">
    <div id="root"/>
    {{{smartweb.application.script}}}
</body>
</html>

It is possible to define own template file (always named template.html) for every directory under the root directory of the SmartWeb application. If there is no template file in the directory with the Javascript code of the page, it will be automatically looked for in the directory structure above until the template will be found. 

All pages defined under the /pages directory require an authentication. If the user is not authenticated, they will be automatically redirected to the /login.html page which contains a login form and realizes the authentication. The default page to which the user is redirected after entering the address of the SmartWeb application is /pages/index.html. Pages defined outside the /pages directory do not need authentication. 

Application Debugging 

It is very difficult to debug pages in their final form because they go through transpilation and minification processes during bundling when they are being deployed into the production version. Therefore, there was a special developing (debugging) mode created in which the page is sent into the web browser in its original form and the necessary code adjustments such as transpilation are realized only afterward directly in the web browser.    This mode (if allowed) is activated by a keyboard shortcut CTRL+ALT+D, more precisely by adding the ?DEV parameter after the name of the loading page. Loading a page in the debugging mode lasts longer because all source codes are read in their original forms without optimization and in addition to that, in a browser using the javaScript, they are transformed for securing compatibility with the web browser.

Application Rebundling

After debugging changes in the application for their deployment into production, it is not necessary to restart the web server. If it is allowed in the configuration, using the keyboard shortcut CTRL+ALT+R, more precisely by adding the parameter ?REBUNDLE after the page name, application rebundling on a server will run. 

Approaches to Web Application Development 

The SmartWeb platform enables high flexibility from the point of view of web application development. A programmer can choose which interface and which parts of the SmartWeb platform will be used to access. 

Vlastné UI (užívateľské rozhranie) a REST API

V tomto prípade má programátor úplnú voľnosť z hľadiska tvorby UI webovej aplikácie. Na komunikáciu s D2000 použije REST API, ktoré umožňuje volať D2000 RPC a SBA procedúry a načítavať dáta z archívov.

Nasledovný kód ukazuje príklad stránky bez použitia SmartWeb Frameworku, len s využitím D2000 REST API. Na zabránenie útoku typu cross-site request forgery, je potrebné do každého REST dotazu doplniť CSRF token. Pomocou AJAX dotazu je cez REST API volaná RPC procedúra Sum na Evente E.SmartWebTutorial. Procedúra má tri parametre - prvé dva, vstupné, sú odovzdané hodnotou a tretí, návratový parameter typu real, bude vložený do atribútu s názvom vysledok. Podrobný popis serializácie dát je dostupný na stránke Serializácia dát medzi klientom a API rozhraniami.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>SmartWeb Demo</title>
    <script src="https://code.jquery.com/jquery-3.3.1.min.js" integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=" crossorigin="anonymous"></script>
    <script src="https://cdn.jsdelivr.net/npm/js-cookie@2/src/js.cookie.min.js"></script>
</head>
<body class="">
<div id="root">
    <h1>Stranka bez využitia SmartWeb Frameworku 2</h1>
    <div>
        <input id="inputA" type="text" value="10">
        <span style="background-color: rgb(238, 238, 238);"> + </span>
        <input id="inputB" type="text" value="20">
        <span>
            <button id="button1" type="button"> = </button>
        </span>
        <input id="inputC" type="text" class="form-control" disabled="" value="">
    </div>
</div>
<script language="JavaScript">

    function loadData(valueA, valueB) {
        // Vytvorí resp. načíta unikátny CSRF token na zabránenie cross-site request forgery
        var csrfToken = Cookies.get('CSRF-TOKEN');

        $.ajax({
            url: `/smartWeb/api/web/rest/v0/d2/rpc/E.SmartWebTutorial/Sum?CSRF-TOKEN=${csrfToken}`,
            type: 'POST',
            data: JSON.stringify([
                valueA, valueB, {type: 'real', returnAs: 'vysledok'}
            ]),
            async: false,
            cache: false,
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            processData: false,
            success: function (data, status, jqXHR) {
                $('#inputC').val(data.vysledok.value);
            },
            error: function (jqXHR, status) {
                // error handler
                console.log(jqXHR);
                alert('fail' + status.code);
            }
        });
    }

    $(document).ready(function () {
        $('#button1').on('click', function () {
            var valueA = parseFloat($('#inputA').val());
            var valueB = parseFloat($('#inputB').val());
            loadData(valueA, valueB);
        });
    });
</script>
</body>
</html>

Vlastné UI a (Comet) D2Api

Ďalšou možnosťou pri vývoji webovej aplikácie je použitie rozhrania D2Api, ktoré je implementované pomocou knižnice CometD. Toto rozhranie, na rozdiel od REST rozhrania, umožňuje aj tzv. server push komunikáciu, čo znamená, že zo servera môžu byť na klienta kedykoľvek odoslané dáta bez toho, aby si ich klient vopred vypýtal. Táto forma komunikácie je výhodná najmä v prípade, keď je žiadané na webovej stránke v reálnom čase publikovať zmeny hodnôt v D2000.

React/SmartWeb komponenty a (Comet) D2Api

Tento prípad naplno využíva vlastnosti a možnosti SmartWeb Frameworku. SmartWeb Bundle Engine sa stará závislosti knižníc a správne usporiadanie modulov pred ich volaním, rieši spätnú kompatibilitu JavaScript kódov ich transpiláciou a optimalizuje veľkosť kódu. Volania D2Api sú zabalené v triede DataContainer, ktorá sa stará o automatickú inicializáciu pripojenia cez D2Api. Navyše sú k dispozícii predpripravené React komponenty, podporujúce responzívny dizajn pomocou Bootstrap frameworku.

Nasledovný príklad renderuje stránku objects.html. Trieda ObjectsPage je React komponent definujúci vzhľad a správanie stránky. DataContainer je špeciálny React komponent, ktorý realizuje pripojenie na D2000 a do stránky propaguje property this.props.d2, ktorá predstavuje inštanciu triedy D2Api slúžiacu na komunikáciu s D2000. Stránka využíva predpripravené komponenty ValueComponent na získavanie aktuálnych hodnôt D2000 objektov - v tomto prípade minúta (objekt Min) a sekunda (objekt Sec).

import React from 'react'
import {DataContainer, PageHeader, ValueComponent} from '../custom/components'

DataContainer.renderComponent(class ObjectsPage extends React.Component {
    constructor() {
        super();
    }

    render() {
        return (
            <div className="container-fluid">
                <PageHeader {...this.props}/>
                <div className="wrapper wrapper-content page-heading">
                    <div className="row">
                        <div className="col-xs-8 text-right">
                            <span>Aktuálna minúta z D2000:</span>
                        </div>
                        <div className="col-xs-4 text-right">
                            <ValueComponent d2={this.props.d2}
                                            datasource="Min"
                                            numberFormat="0"
                                            missingFormattedValue="?"/>
                        </div>
                    </div>
                    <div className="row">
                        <div className="col-xs-8 text-right">
                            <span>Aktuálna sekunda z D2000:</span>
                        </div>
                        <div className="col-xs-4 text-right">
                            <ValueComponent d2={this.props.d2}
                                            datasource="Sec"
                                            numberFormat="0"
                                            missingFormattedValue="?"/>
                        </div>
                    </div>
                </div>
            </div>
        );
    }
});