[Haskell-cafe] Google Summer of Code Proposal - Communicating with mobile devices

Marcos Pividori marcospividori at gmail.com
Fri May 3 02:53:54 CEST 2013


I am a Computer Science student from Argentina. I am interested in working
this summer in a project related to Haskell for the Google Summer of Code.
I have been discussing my idea with Michael Snoyman in order to have a
clearer idea. Now, I would like to know the community interest in this

I want to develop a server-side library in Haskell for sending push
notifications to devices running different OS, such as Android, iOS,
Windows Phone, BlackBerry, and so on.

To pass a subject, I have recently worked with Yesod (a Web Framework based
in Haskell) developing a server to comunicate with Android-powered devices
through Google Cloud Messaging. (It is available:
https://github.com/MarcosPividori/Yesod-server-for-GCM – It is a Spanish
commented version because it was a project for my University, I will
replace it for an English version in the next weeks)

To develop this project, I have read a lot about this service and Yesod
libraries, and I developed two programs, a server written in Haskell and an
Android application for mobile phones. Also, I developed an EDSL to write
programs which exchange information with the devices.

I would be really grateful if you could give me your opinion about this
project and the proposal. I want some feedback in order to know if this
would be a useful tool and what you would like to get out of it.

*Communicating with mobile devices*



The aim of this project is to develop a server-side library in Haskell for
sending push notifications to devices running different OS, such as
Android, iOS, Windows Phone, BlackBerry, and so on.

The fact is that every company is developing Push Notification services,
and these are very similar. Then, I want to find the fundamental concepts
to construct a library which enable to configure the options for the
different services and send messages easily.

When I say they are very similar, I refer to the fact that they all are
asynchronous, best-effort services that offers third-party developers a
channel to send data to apps from a cloud service in a power-efficient
manner. The most popular are:

   - Google Cloud Messaging (Android)

   - Apple Push Notification Service (iPhone / iPad)

   - Microsoft Push Notification Service (Windows Phone)

   - BlackBerry Push Service (BlackBerry)

   - Windows Push Notification Services (Windows 8)

   - etc.

Once we have this libraries, I will investigate the possibility of mainting
a "back and forth" communication between a server and mobile devices and I
will develop a library to handle this.


*Motivation and expected benefits*

I think this idea would be very useful because it will allow all Haskell
developers to open to a new world of mobile devices and to build useful
programs/services that interact with them.

Pushing data to smartphones provides users with instant access to desired
updates as they happen, such as news and weather, sports scores, stock
prices and other time-sensitive content. The push services provide an
efficient way to quickly push timely information updates to many
smartphones at once, in a centrally managed and controlled manner.

Generally, you can also be very selective in who you send information to,
including individual customers or many customers (multicast).

This services minimizes the impact on the smartphones battery life. Instead
of actively checking for new data, the applications can remain closed. Once
the data is delivered, the application can be launched in the background to
process it as needed.

This processes offer an alternative to other less efficient methods, such
as polling, where a device regularly polls an application server to see if
new content is available.

The main differences between the services, refer to details as: the maxim
payload length, the quality of service, queueing the messages or not, and
the time limit for this, the way the messages are handled in the devices,

As all the libraries to access to these services are developed in Java, I
thought that it would be a good idea to offer an option to Haskell
programmers. Taking advantage of the similarity of these services, I could
develop a very adaptable library which fits the necessities for each one
and at the same time offer an abstraction to the user.



* An API library to build and send messages including:

   - GCM and a demo Android app.

   - APN and a demo iOS app.

   - Microsoft Push Notification Service (Windows Phone) and a demo app.

   - Documentation for all the code developed. Including the explantation
on how to use the server

     library and how to try the demo apps.

* A library to handle a "back and forth" comunication between a server and
mobile devices. Tools to mantain a state of the connection and manage with
a lot of devices at the same time. A Yesod app example of the use of this
library and a demo app for each OS (Android, iOS, Windows Phone, etc) to
manage this communication.

* Optionally:

   - an API for communication through BlackBerry Push Service (BlackBerry).

   - an API for communication through Windows Push Notification Services
(Windows 8).

*Technical Considerations*

In the developing of the APIs for the communication through Push
Notifications, I will aim to develop a good abstraction and find the
properties in common between the differents services in order to develope
an customizable tool but at the same time with a common structure.

I want to let the user build messages and send these in a simple way
following each protocol. Also, I will abstract the process of registering
the devices in the server and let the user manage the different
registrations behind a similar abstraccion.

To develop a “back and forth” comunication between a server and mobile
devices, I will investigate the different possibilities of maintaining a
state of the connection. It could be through the use of cookies stored by
the clients or maintaining some extra information in the server which would
enable it to identify the different connections and provide the appropiate
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