Control Your Laptop with an Android Phone using Python, Twisted, and Django

Introduction

It is pretty enjoyable to put forth your Android or Python programming abilities. Recently, I just got an idea to use my laptop with my Android phone. Just Think: the remote laptop access will allow you to stop and play music, manage programming tasks or downloads, and so forth. You can do this by directly sending messages from your Android device. Nice, isn’t it?

Before you start reading this post, you must remember that it is a pet project, in its starting levels—yet the main platform is present. By using some conventional tools and techniques, I was proficient to setup my phone to manage laptop using Python mediator.

However: it is an open-source project. You can have a look at the server and client codes.

Tool Belt of Remote Laptop Access: Twisted, Python, Amarok and Django

There are diverse technologies involved in this project. You might be familiar with some; some technologies are particular to the project at hand:

• Twisted: An exceptional project-driven structure particularly designed for the network hackers. 
• Python 2.7.
• Amarok: It is a D-BUS controllable media player. You can select any other media player like VLC and Clementine that support MPRIS, if you are familiar with their messaging settings. I have selected Amarok because it came up with KDE distribution. Moreover, it’s configuration is easy and quick.
• Django: I have used v1.4. Thus, you will need to change the place of some files if you have to run a previous version.
• It is imperative to install Python For Android in your phone. The installation method is simple-also for Py3k.
• Remote Amarok Web
• Remote Amarok

At The High Level

At the high level, we will consider the laptop to be the server and Android phone, the client. I will explain the architecture of remote access in detail, yet the main project flow is mentioned below:

1.      The user will type a command into the mediator of Python.

2.      The command will be sent to Django.

3.      Now, Django will pass this command to Twisted.

4.      Twisted will analyze the command and then send a new one through D-Bus.

5.      D-Bus will then send the command to Amarok.

6.      Amarok will interact with the laptop, managing the pause/play of music.

We are going to explain it more.

Python For Android

One day, I had a glance at the mediators of Python that I could install and use on my phone (Droid 2). Shortly, I learned about the amazing SL4A package that was able to bring Python to life on the Android phone. It is a smart package to choose: you will need to click some buttons, and then you will almost get a Python environment on your Android device. This device can now run the Python code properly and access the Android API (I said almost because some things are still missing and the Android API is not readily available, yet for several use-cases, it is good enough).

If you want, you can develop Python distribution of your own to run on your phone. With its help, you can easily run any version of the mediator of your choice. In this method, you have to perform cross-compiling Python to run on ARM (the structure employed on Android devices). It is a bit tough, yet it is workable.

After setting up your mediator, you can do anything by linking Python to the Android API, comprising remote laptop controlling. For instance, you can:

•         Play/Pause videos and music

•         Set the ringtone of your choice

•         Read and send SMS.

•         Show the intuitive design

•         Check out the spinning dialogs and prompts.

•         Interconnect with third-party APIs across the web through urllib and diverse other libraries.

•         Interconnect with Bluetooth – It has to offer many opportunities. Like, I once used a lock-unlock app on my Android phone to control my laptop. (For example, locking up my laptop through Bluetooth when my Android device was close).

How Your Android Phone Controls Your Laptop?

The Framework

The composition of our project is below:

•         The client-side app developed on Twisted in case you need to check the server code devoid of running the Django app.

•         The server-side app designed on Django, which can read the commands from Android phone and then passes them to Twisted. As seen, Amarok is one particular application for a laptop that the server can interconnect with (specifically, to control videos and music). However, it is a full proof concept because the platform is adaptable.

•         The server-side app designed on Twisted “instance” which connects with the media player of the laptop through D-Bus, passing the commands when they come up from Django (presently, I prefer ‘mute’, ‘stop’, ‘pause’, ‘play’, ‘previous’, ‘next’). Why don’t you directly send messages from Django to Amarok? The non-blocking and project-driven features of Twisted can handle the big tasks.

Twisted is project-driven, exceptional, and adaptable. It contains deferred items, the callback system, and other methods to operate. I would recommend that you check it out: the amount of work that you will escape by making use of Twisted will be remarkable. For instance, it can assist boilerplate code for diverse protocols which incorporates HTTP, IRC, SSH, and so forth, devoid of dealing with the non-blocking tools like threads.

•         The Android code on client-side, transferred to your phone with the personalized URL to reach your app of Django. It is imperative to mention that this code specifically runs on Python 2.7+, which includes Py3k.

What is D-Bus?

I have mentioned D-Bus at diverse places, yet the time has come to explain it more. In general, D-Bus is a bus system which is used to send and receive messages. It allows the apps to communicate with one another (for example, on the Android phone and laptop) simply via designed messages.  

It contains two buses: the session bus that is used for the user-side things while the system bus for the system-side things. The special messages send to the system bus are like “Hello, I have connected a new printer, inform my D-Bus allowed apps that the new printed is online”, while the session bus will handle the standard IPC (Inter-Process Communication) between the apps.

In this project, we have used the session bus to interact with Amarok. It is one of those modern apps (among Linux environments, no less than) that assist this sort of messaging. The functions and commands its processes are well-organized. Any app with the support of D-Bus is easy to control and manage under this framework; there are limitless probabilities.

Background:

After setting up the framework, you can open the Android app and it will take you to the infinite loop from where you can read received messages, go for certain checks to process them, if usable, send them to the pre-mentioned URL (in other words, the Django application URL), which will operate the input. After that, the client of Android marks up the messages as read. The loop starts again till the message with the accurate details “exit-client” (fabulous, isn’t it?) is operated, in which the client exits. 

On the server, the Django app chooses the command to be executed. It also analyzes if the command starts with valid instruction or not. If it does, it links to the server of Twisted (making use of the Telnetlib to link through telnet) and passes the command. In the end, the Twisted analyzes the input, modifies it into somewhat appropriate for Amarok. Allow Amarok to handle the rest! Lastly, your laptop will start responding to the send commands like pausing/playing music or videos.

When it comes to the “predefined URL”: if you need to control your laptop from a distant place, you will have to use a public URL. It is reachable across the web. Ensure that, presently, the code does not implement any security layer like SSL – similar advancements are practices for the person who reads, for now.

What Else Can You Do With This?

Till now, everything seems to be easy and straightforward, isn’t it? You may think: “Can it easily support the smart feature [X]?” Well, the answer to this question is: Yes! Nevertheless, you should have the know-how to interact with your laptop by using your Android phone. If you know, then you can easily add the code on server-side to do anything you want.
 Before you get the know-how, you need to go through lengthy methods on your laptop remotely. Or else, if you have to capacity to match up with the technology, you can develop an interface amid your favorite electronic appliance and your laptop, managing it through SMS commands (“Make tea for me!” strikes instantly).  

What’s More

For now, I am going to play on with my new Android laptop controller, work on its features, fix up some bugs, and so forth. In case you are interested, I will be there for you to help! Just follow the instructions and email me at _________if you have questions.