Location-aware applications: an overview

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Transcript Location-aware applications: an overview 

Web development
8.4.2013
Web development
Content
Part I:
Server-side scripting
Part II:
Client-side scripting
Part I
Server-side scripting
– PHP
– MySQL
– JSON
PHP
- server-side scripting language
- can be embedded to a HTML page
- is interpreted at the server
- generates HTML and can be embedded in it
- requires PHP extension for website
<html>
<body>
<h1>Hello!</h1>
<?php echo "Hello World!"; ?>
</body>
</html>
PHP
MySQL
CREATE TABLE Users (
ID INT NOT NULL AUTO_INCREMENT,
PRIMARY KEY(ID),
UserName VARCHAR(20), ...)
INSERT INTO Users (UserName, ...) VALUE (’aaa’, ...)
SELECT * FROM ’Users’
Data fetching
<?php
$con = mysqli_connect("localhost", "mopsi", "pswd", "database");
If ( mysqli_connect_errno() ) {
echo "Failed to connect to MySQL";
}
$result = mysqli_query($con, "SELECT ID, UserName FROM Users");
while ( $row = mysqli_fetch_array($result) ) {
echo $row['ID'] . " " . $row['UserName'];
echo "<br/>";
}
mysqli_close($con);
?>
Data fetching
Inserting data
<?php
$con = mysqli_connect("localhost", "mopsi", "pswd", "database");
if ( mysqli_connect_errno() ) {
echo "Failed to connect to MySQL";
}
mysqli_query($con, "INSERT INTO Users (ID, UserName,
Password) VALUES ('435', 'matti', '23#sg5')");
?>
mysqli_close($con);
JSON
A data-interchange format
Easy for humans to read and write
Easy for machines to parse and generate
A lightweight alternative to XML
JSON
Key-value pairs:
{"request_type":"get_routes","user_id":"260","st
art_time":"1358426045","end_time":"1359030
846"}
key
value
request_type
get_routes
user_id
260
start_time
1358426045
end_time
1359030846
JSON
An array can contain multiple objects:
{"users":[{
"ID":"14","UserName":"Juha"},{"ID":"15","Use
rName":"Jukka"},{"ID":"18","UserName":"karol
"}]}
[key]
ID
UserName
0
14
Juha
1
15
Jukka
2
18
karol
JSON in PHP
<?php
$con = mysqli_connect("localhost","uname","pword","paikkaprojekti");
$rows = array();
If ( mysqli_connect_errno() ) { echo "Failed to connect to MySQL"; }
$result = mysqli_query($con, "SELECT ID, UserName FROM Users");
while( $row = mysqli_fetch_assoc($result) ) {
$rows[] = $row;
}
print json_encode($rows);
mysqli_close($con);
?>
JSON in JavaScript
var jsonInfo = '{"request_type":"init_mopsi"}';
var jsonString = initMopsi(jsonInfo);
var jsonObject = eval("(" + jsonString + ")");
if (jsonObject.latitude != "") {
g_latitude = jsonObject.latitude[0];
g_longitude = jsonObject.longitude[0];
}
Submit data from HTML to PHP
POST is sent in the HTTP message body
POST /mopsi/register.php HTTP/1.1
Host: cs.uef.fi
uName=matti&pWord=asd#22d
GET is sent in the URL of a GET request
/mopsi/register.php?uName=matti&pWord=asd#22d
POST vs GET
GET
POST
BACK button/Reload
Harmless
Data will be re-submitted
Bookmarked
Can be bookmarked
Cannot be bookmarked
Cached
Can be cached
Not cached
Restrictions on data length max URL length (2048
characters)
no restrictions
Restrictions on data type
ASCII only
No restrictions (also
binary)
Security/visibility
Data is part of the URL
(visible)
A bit safer as params are
not stored in browser
history or in web server
logs
Submit data from HTML to PHP
<html>
<body>
<form id="regForm" action="registration.php" method="post">
Username: <input type="text" name="uName">
Password: <input type="text" name="pWord">
<input type="submit" value="submit">
</form>
</body>
</html>
In registration.php values are in:
$_POST[uName] and $_POST[pWord]
Submit data from HTML to PHP
<?php
$userName = $_POST[uName];
$passWord = $_POST[pWord];
//TODO: insert credentials into DB
?>
echo "Welcome $userName!";
Part II
Client-side scripting
– HTML
– CSS
– JavaScript (including JQuery)
HTML
A markup language for creating web pages to be
displayed in a web browser
Consists of tags enclosed in angle brackets (like
<html>)
The purpose of a web browser is to read HTML
documents and compose them into visible or
audible web pages.
The browser does not display the HTML tags, but
uses the tags to interpret the content of the
page.
HTML structure
<html>
<head>
<title>Hello HTML</title>
</head>
<body>
<div id=”content”>
<p>Hello World!</p>
</div>
</body>
</html>
HTML tags
<a href="http://www.example.com/">Link-text goes here</a>
<a href="http://www.example.com/">
<img src="URL" alt="Alternate Text">
</a>
<img src="URL" alt="Alternate Text" height="42" width="42">
<table border="1">
<tr>
<th>table header</th>
<th>table header</th>
</tr>
<tr>
<td>table data</td>
<td>table data</td>
</tr>
</table>
CSS
A style sheet language
Used to separate content from its presentation
Consists of a list of rules
–
Selectors
–
Declarations
CSS example
body {
background-color: #d0e4fe;
font-family: "Sans";
font-size: 20px;
}
#regForm {
color: orange;
text-align: center;
}
JQuery
A JavaScript library
Designed to make easier to...
–
navigate in a document
–
select DOM elements
–
handle events
–
create animations
JavaScript vs JQuery
JavaScript:
var container = document.getElementById('container');
JQuery:
$('#container');
JQuery example
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
<div id="flip">Click to slide down panel</div>
<div id="panel">Hello world!</div>
</body>
</html>
JQuery example
#panel, #flip {
padding: 5px;
text-align: center;
background-color: #e5eecc;
border: solid 1px #c3c3c3;
}
#panel {
padding: 50px;
display: none;
}
JQuery example
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css" href="style.css">
<script src="jquery.js"></script>
<script>
$(document).ready(function(){
$("#flip").click(function()
$("#panel").slideDown("slow");
});
});
</script>
</head>
http://cs.uef.fi/paikka/Matti/dump/test.html
GoogleMaps API v3
API access to GoogleMaps
- in web pages, in mobile apps
- map tiles + overlays + events
- geocoding
- distances
- directions
Free unless commercial use is intended
https://developers.google.com/maps/
GoogleMaps example
<html lang="en">
<head>
<meta charset="utf-8" />
<title>Google Maps JavaScript API Example: Simple Map</title>
<script src = "http://maps.google.com/maps?file=api&
amp;v=2&amp;sensor=false&amp;
key=AIzaSyD4iE2xVSpkLLOXoyqT-RuPwURN3ddScAI"
type="text/javascript">
</script>
GoogleMaps example
<script type="text/javascript">
var map;
function initialize() {
if ( GBrowserIsCompatible() ) {
map = new GMap2(document.getElementById("map_canvas"));
map.setCenter(new GLatLng(37.4419, -122.1419), 13);
map.setUIToDefault();
}
}
</script>
</head>
<body onload="initialize()" onunload="GUnload()">
<div id="map_canvas" style="width: 500px; height: 300px"></div>
</body>
</html>
GoogleMaps example
GoogleMaps markers
<script type="text/javascript">
function initialize() {
if ( GBrowserIsCompatible() ) {
var map = new GMap2(document.getElementById("map_canvas"));
map.setCenter(new GLatLng(37.4419, -122.1419), 13);
// Add 10 markers to the map at random locations
var bounds = map.getBounds();
var southWest = bounds.getSouthWest();
var northEast = bounds.getNorthEast();
var lngSpan = northEast.lng() - southWest.lng();
var latSpan = northEast.lat() - southWest.lat();
}
for (var i = 0; i < 10; i++) {
var latlng = new GLatLng( southWest.lat() + latSpan * Math.random(),
southWest.lng() + lngSpan * Math.random() );
map.addOverlay(new GMarker(latlng));
}
}
</script>
</head>
<body onload="initialize()" onunload="GUnload()">
<div id="map_canvas" style="width: 500px; height: 300px"></div>
</body>
</html>
GoogleMaps markers
GoogleMaps polylines
<script type="text/javascript">
function initialize() {
if (GBrowserIsCompatible()) {
var map = new GMap2(document.getElementById("map_canvas"));
map.setCenter(new GLatLng(37.4419, -122.1419), 13);
var polyline = new GPolyline([
new GLatLng(37.4419, -122.1419),
new GLatLng(37.4519, -122.1519)
], "#ff0000", 10);
map.addOverlay(polyline);
}
}
</script>
</head>
<body onload="initialize()" onunload="GUnload()">
<div id="map_canvas" style="width: 500px; height: 300px"></div>
<div id="message"></div>
</body>
</html>
GoogleMaps polylines
GoogleMaps example
Cross browser compatibility
IE causes problems:
• different properties of HTML elements
• differences between versions
Cross browser compatibility
Developer tools
Firefox Web Console
Chrome Developer Tools
IE Developer Console
• not handy, difficult to point out error source
Firebug
An add-on for Firefox
Highly useful in web development
Can be used for inspecting
- CSS
- HTML
- JavaScript
- Net requests
Firebug
Chrome Developer Tool
Useful links
HTML
http://www.w3schools.com/html/default.asp
CSS
http://www.w3schools.com/css/default.asp
JavaScript
http://www.w3schools.com/js/default.asp
Jquery
http://www.w3schools.com/jquery/default.asp
Google Maps API
https://developers.google.com/maps/documentation/javascript/
PHP
http://www.php.net/manual/en/index.php