Developer Guide

General communication framework

The communication framework is built based on the http and https protocols. The mobile client communicates with the backed-end infrastructure of the Improve-My-City Joomla component (https://github.com/icos-urenio/Improve-my-city/wiki) by calling URLs from the remote server and receiving string data as a response, as shown in Figure 1.

Figure 1: Communication of mobile client is achieved through PHP calls and JSON strings.

The mobile application calls the URL of the PHP script that corresponds to a user action along with its parameters, e.g. download 40 nearby issues. The response from the server is string data in JSON (JavaScript Object Notation) format. The URLs of the PHP scripts are predefined by the Improve-My-City Joomla component and therefore there is no need for severe modifications on server side. The modifications that should be performed are: a) “JSON” should be set to enabled, and b) “Encryption key” should match the one used in the mobile application.

These can be modified in the administrator side of Joomla in Improve-My-City component following the instructions. JSON activation enables communication with the mobile client. The encryption key is used for decrypting the user password sent by the mobile client encrypted with the same predefined key. Details for setting the encryption key are available under (ling to ReadMeCustomize.docx). Images are received by calling their URLs with byte streaming and submitted with the POST command. See also the following screenshots.

Android code architecture

The mobile client is written in JAVA that enables fast applications with access to hardware and software components of Android core. A graph showing the main functionalities of the application is given in Figure 2. Location_Service is a service that tracks user position (longitude and latitude) from information taken from GPS or Wi-fi. This information triggers the downloading of data. Data_Service downloads issues, images, categories, and votes. This data is stored locally in a SQLite database in the mobile device so that issues are visible also when the device is offline. Comments are not stored locally. Data like new issues or new votes/comments are uploaded with class Upload_Data with http/php protocol where the parameters of the php is the data to send.

Figure 2: Inner architecture of the application.

The code is split into the following packages:

com.mk4droid.IMC_Activities	Activities (windows) of the application.
com.mk4droid.IMC_Constructors	Constructors of Objects needed for the application.
com.mk4droid.IMC_Core	Custom implementations that improve the visualization of the application.
com.mk4droid.IMC_Services	Localization and Downloading-storing-uploading data
com.mk4droid.IMC_Store	Communication and security constants of the application
com.mk4droid.IMC_Utils	Various utilities regarding time transformations, reverse geocoding, and file copy

More details can be found in the javadoc that is included in the project folder.