CHAPTER 9 ■ IOT PATTERNS: LOCATION AWARE
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Map
All the GPS coordinates being stored in the database are not visible to anyone yet. Next,
you are going to build a web page that will display all coordinates on a map. As shown in
Figure  9-8 , create a new file called index.php in the gpstracker folder.
Figure 9-8. The file for displaying a map is index.php
Listing 9-4 provides the complete code for index.php , so copy or write the code in
index.php . This code uses the Google Maps API for creating a map and displaying all the
coordinates. You do not need to download or install any code; the API is accessible over
the Internet so your script tag just needs to point to http://maps.googleapis.com/
maps/api/js?sensor=false as its source.
To populate the map, you first need to load data from the database in the location
array variable. Add your PHP code for loading data from a database table inside the
init() JavaScript function. Include util-dbconn.php because the database connection
needs to be established first, and then prepare a SELECT SQL statement. Execute the
query and prepare a locations array from the results.
After the PHP code and inside the init() function, initialize a new map. Set its zoom
level, default coordinates, and map type. Next read the array in a loop and mark all the
coordinates on the map.
The tag has the code to display a title on top of the page and map created earlier.
Listing 9-4. Code Structure for Map in index.php