Teachers and students can register to create and join courses respectively.
- Back-end: Node.js
- Andorid Client: Java
- Web Client: HTML5, CSS3, Javascript/jQuery
- Database: MySQL with Sequelize as the ORM for Node.js
For the Android Client, Retrofit and RxJava were relied on to handle network operations.
A Teacher can create courses -through the web interface- for students to join. A Course is registered in the database with the following columns:
| column | data type | keys |
|---|---|---|
| course_id | int(11) | Primary Key |
| teacher_id | int(11) | Foreign Key |
| title | varchar(50) | |
| description | text | |
| created_at | datetime |
All Courses are listed in the url madrassa/course. Individual courses are in madrassa/course/7. In a course's page, a student can join the course, and view the list of joined students.
There are a couple of triggers on the courses table. The first is to prevent students from creating courses, and the second is to prevent teachers from joining courses.
A user is stored in the database table with these columns:
| column | data type | keys |
|---|---|---|
| user_id | int(11) | Primary Key |
| username | varchar(30) | Unique Key |
| password | varchar(255) | |
| first_name | varchar(20) | |
| last_name | varchar(20) | |
| role | enum("admin", teacher, student) | |
| varchar(100) | ||
| created_at | datetime |
Passwords are hashed with the npm package; bcrypt-nodejs
There are 4 main activities in the Android client.
- LoginActivity
- HomeActivity
- CourseListActivity - Has a fragment for bigger screens.
- CourseDetailActivity - Managed by a fragment.
The Android application relies on the MVVM (Model View ViewModel) architecture to handle its data.
The only source of data is AppRepository, or "the only source of truth" as described by Google.
AppRepository is a simple abstraction layer that talks with both the network data classes, and the local data classes.
Both of the application's data activityes; CourseListActivity and CourseDetailActivity - rely on a dedicated ViewModel to obtain their data for display in the UI.
There's only a single class for Local Data Operations, which is Preference Handler. It does tasks, which save a registered user's state; such as the login token (json web token), username and user id and other information as well.
Network operations are handled by Retrofit, and performed by RxJava. There are a couple of Retrofit Service classes, one for authentication; AuthService, and another for authenticated users; Madrassa Service. Each of these service classes has a Request class, that's responsible for the creation of it. AppRepository is responsible for the creation of both Retrofit Request classes; AuthRequest, and Madrassa equest.
CourseListViewModel is responsible for obtaining the list of courses, through a method provided by AppRepository.
CourseViewModel uses AppRepository, and is responsible for: - Displaying a course's info and a list of its registered student. - Joining a course. - Leaving a course.
Handles user login and uses AppRepository to save the data to SharedPreferences.
Used to display the number of a user's registered courses, and has a button to access the list of courses
Displays a list of all the available courses. Its data is obtained through CourseListViewModel. CourseListActivity can be displayed as a fragment, to the left side of the screen, with the selected course being displayed dynamically to the right of the screen.
Displays a single course's details, and also the list of registered students. The course's details are obtained through CourseViewModel. Only for students, there's a button visible at the bottom of the activity, that enables joining a course, or leaving it; in case if someone's already registered. CourseDetailActivity can be displayed as a fragment to the right of the screen.