Progress

Generalization of database schema is done for my system. Now an authenticated user can create through REST calls his own schema based on his preferences and interact with it.

Also a basic implementation of c2dm protocol is available. As a reminder c2dm is a protocol that will push notifications to client when something change on the server side.

For some of you who are interested on how to implement this on the server and the client, you can check this tutorial, is very useful and easy. It provides a simple example of getting the auth token from the c2dm servers, registering an android client to c2dm and exchange a message between client/server.

Next, I have to change the desktop web client as well and develop it based on functions that I've created.

Few days ago the first demo on Android platform was released. It is available here. I will appreciate any kind of feedback, I know that there are some bugs to fix, but the main functionalities are met. 

Let's point out again the main functionalities:

1. The user can create a Gmail account if he doesn't have one already associated with the phone.
2. Authenticate with it on the server side.
3. View(GET) the current Tasks on the server(it there are any).
4. Sync(GET) the client database with server database.
5. Add(POST) a Task on the local database(Content Provider) and then on the server.
6. Update(PUT) a desired Task, form the current list of available Tasks.
7. Delete(DELETE) a Task.

The following pictures should clarify what I was describing:

Authorization of an account

Main Activity - RUD functions.

Create function

     

App Engine connected to Android Device

Trying to implement google accounts login to my application and searching through internet information about Android and Google App Engine I found an interesting Google Talk event.

In that session two engineers from Google presented a new feature, App Engine Tooling for Android. It's a complete set of Eclipse-based Java development tools for building Android applications that are backed by App Engine.

Just create a new application "App Engine connected to Android device" and Eclipse make 2 projects: Android application and App Engine Application who provide a simple example of communication between the GAE server and the client application. 

The interesting part is that this kind of application takes care of authentication with Google account and implementation of C2DM protocol, so basically you just login with your gmail account on both sides (server - GAE and client - Android App) and then you establish a communication between those two entities. Then you can send messages from the server to client.

The basic architecture of the "framework" looks very similar to a wide range of applications:

Unfortunately this is not suitable for my work because as my mentor says "it's not a good ideea to combine RPC with REST Architecture".

Anyway it was nice to "play" with this project and try to understand how it works, even though it took more than 5 hours to build and deploy it.

The Idea

  

   With the fast advancement in information technology, database management systems are becoming more and more advanced. 

If at the beginning system designers and architects thought that a central control is better for database management, nowadays along with the relatively cheaper hardware, distributed database has become a better choice.

      The main purpose of the project is to allow users to reliably store and synchronize data between their mobile device and the cloud.  When there is not a network connection between the client and the cloud, the data is stored locally, and when the connection becomes available, the cloud database is updated accordingly. The database will be replicated to improve reliability, availability and fault-tolerance. The communication between clients and the cloud will be made through REST API and C2DM protocol. Android SDK, Google App Engine and Big Table are the technologies which will be used to develop this application.

       I think the picture below describe clearly the principle of the project. 

Google App Engine connected to Android Architecture

       This work will deal with the following problems: how to successfully integrate my system in an environment that allows replication and designing the algorithm for data selection.


       It will proceed along the following points:

• Analyze requirements for system storing data inside cloud (or environment allowing replication) allowing mobile devices to load relevant parts of the data. Focus only to database layer and interface.
• Study and describe basic principles of databases and distributed systems.
• Describe the algorithm used for data selection (range or context, etc.)
• Select one DB and document reasons for decision. 
• Design system architecture of system.
• Implement solution (DB side).

     This is a team project. I'll focus on the server side of the system, the client will be described and developed by my colleague Andreea Sandu.

    On the following days I'll describe the Big Table database provided by Google(GAE) and I'll try to develop a small REST Api in Java with the CRUD functionalities.

Until then, "Keep it Simple, Stupid"!

Hello World!

Who am I?


       As I said in my short description, I am an exchange student at ČVUT, Prague. I am in my final year of a Computer Science Bachelor degree. I'm intrested in learning and excelling in new technologies and use my education and experience to accomplish my goals. 

Currently I’m focused on cloud computing, distributed systems and web development based on Android platform. I have experience in C, Java, SQL and Networking.

What is this blog about?


       During my thesis preparation I would like to share information about my progress and to describe step by step each milestone. Also I want to encourage everyone to give feedback and suggestions.

Acknowledgements

I would like to thank to my mentors Ing. Jan Sedivy, CSc. and Ph.D. Tomáš Bařina for their trust, time they will spend for regular consultations and willingness to share their rich experience.

I will describe in a further post the main idea of my project and the content of it.

P.S. It's not so simple as I thought to write a post, those few rows took me more than one hour. I will get used to it :).


"Keep It Simple, Stupid!"