Tuesday, July 05, 2011

JSF 2.x: Creating a Pure AJAX Application with Apache Tomahawk

Official logo of Greenville, South CarolinaImage via Wikipedia
I was working on creating an application to make calls to a MongoDB database. I was having some difficulties getting the REST based services to work. I decided to make sure that my coding principles were sound so I wrote this application.

The application uses Expression Language (EL), and "pure" JavaScript (no JS frameworks).

Disclaimer: There were no-frameworks harmed in the making of this application.

The application makes an AJAX call to a GeoNames web service called http://api.geonames.org/weatherIcaoJSON?ICAO=KGSP which returns the weather information for Greenville-Spartanburg (Greenville, SC) Airport. There are some other examples which demonstrate some of the things you can do in Expression Language (EL), and how to inject it into JavaScript.

The application I believe demonstrates that you can JSF without managed beans, and make separate AJAX calls to populate the page with data. This is not a normal method of creating a JSF application, but does demonstrate the flexibility of the JSF framework.

The application was done using Apache Maven on NetBeans 7.0 IDE. The source can be downloaded here: jsf2-tomahawk2.zip

Requirements
  • NetBeans 7.0 (You could use just Maven)
  • Apache Maven 2.2+
  • Internet Connection (Required if dependencies are not on system)

index.xhtml



project.js


/*
 * Copyright 2011 Blue Lotus Software, LLC.
 * Copyright 2011 John Yeary.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
var weather;
var weatherJSON;

function ajaxWeather() {
    if (!document.getElementById('panelTab1.content').hasChildNodes()) {
        return;
    }
    var url = 'http://ws.geonames.org/weatherIcaoJSON?ICAO=KGSP';
    var xhr;
    if (window.XMLHttpRequest) {
        xhr = new XMLHttpRequest();
    } else {
        alert('You are using Internet Explorer. Switch to a real browser!');
    }
    xhr.onreadystatechange=function(){
        if (xhr.readyState == 4 && xhr.status == 200){
            weather = xhr.responseText;
            weatherJSON = eval('(' + weather + ')');
            document.getElementById('panelTab1:unavailable').textContent = '';
            document.getElementById('panelTab1:stationName').textContent = weatherJSON.weatherObservation.stationName;
            document.getElementById('panelTab1:ICAO').textContent = weatherJSON.weatherObservation.ICAO;
            document.getElementById('panelTab1:latitude').textContent = weatherJSON.weatherObservation.lat + "\u02da";
            document.getElementById('panelTab1:longitude').textContent = weatherJSON.weatherObservation.lng + "\u02da";
            document.getElementById('panelTab1:temperature').textContent = weatherJSON.weatherObservation.temperature + "\u02daC";
            document.getElementById('panelTab1:humidity').textContent = weatherJSON.weatherObservation.humidity +"%";
            document.getElementById('panelTab1:windSpeed').textContent = weatherJSON.weatherObservation.windSpeed + " knots";
            document.getElementById('panelTab1:windDirection').textContent = weatherJSON.weatherObservation.windDirection +"\u02da"
        }
        if (xhr.readyState == 4 && xhr.status == 503){
            document.getElementById('panelTab1:unavailable').textContent = 'Weather service is unavailable. Please reload page';
        }
    }
    xhr.open('GET', url, true);
    xhr.send();
}

function setText(){
    if (document.getElementById('panelTab6:div1') != null) {
        document.getElementById('panelTab6:div1').textContent = msg;
    }
}

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