[![](/wp-content/uploads/2010/12/Shot_0031.png "Shot_003")](/wp-content/uploads/2010/12/Shot_0031.png)

Just thought I would share this little thing I was introduced to by a friend.



[https://grantkot.com/MPM/Liquid.html](https://grantkot.com/MPM/Liquid.html)

Its a liquid physics simulator written in Java.

Apparently its creator, Grant Kot has been playing around with particles for some time. Theres more of his work on youtube, here is one:

<iframe width="100%" height="400" src="https://www.youtube.com/embed/BIQRhOFkvQY" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

Pretty!

Edit: Didnt realise but this is the same guy that did Polluted Planet that I covered almost 3 years ago -> [/posts/polluted-planet/](/posts/polluted-planet/) thats some awesome particle based dedication right there, I think I need to buy him a beer ;)

This is part two in my series of posts on the development history of [Inputtie](https://www.inputtie.com/).

In this post I talk about the challenge of device discovery and networking in the Inputtie app.



**[![](/wp-content/uploads/2010/10/ScreenHunter_03-Oct.-09-13.59.jpg "ScreenHunter_03 Oct. 09 13.59")](/wp-content/uploads/2010/10/ScreenHunter_03-Oct.-09-13.59.jpg)Zero Configure Networking**

I knew I wanted Inputtie to be as simple to get running as simply starting it up. For this to happen Inputtie would need to discover all other devices on the network also running Inputtie. So how to do this?

[](/wp-content/uploads/2010/10/ScreenHunter_03-Oct.-09-13.59.jpg)

Well, as it happened I had been reading at the time about [Apple's Bonjour](https://www.apple.com/support/bonjour/) which was designed to do just what I needed. It is a combination of a multi-cast and DNS lookup service that allows it to detect other Bonjour capable devices on the network. Sounds perfect.

So I got to work on implementing their Java API. After many trials and tribulations I eventually had it working.. kinda. It was detecting other devices sure, but every now and then it would sporadically disconnect from the network. I couldn't for the life of me work out why. I posted on forums and even tried to read the reams of source to see what was going on but alas to no avail.

After much deliberation I decided to look for another solution to the problem of Zero Conf. networking. Next up were a whole host of other attempts. I tried [JmDNS ](https://jmdns.sourceforge.net/)which is was supposedly very similar to Bonjour. I also experimented with [JGroups](https://www.jgroups.org/). I had limited success with all of them and in the end only really succeeded in wasting several months worth of development time.

**The Solution**

In the end the solution (and the one currently employed in Inputtie) was the simplest. After months of messing around with these libraries I had learnt quite abit about how they performed their magic. At the heart of it they either used multi-cast or broadcasting to announce a device on a network. Broadcasting can be thought of as a sort of sonar pulse. The broadcasting computer sends a message on a specific IP address then another device listens for the message and proceeds to open a Socket for a more private form of communication. From [Wikipedia](https://en.wikipedia.org/wiki/Broadcast_address):

> A broadcast address is a logical address at which all devices connected to a multiple-access communications network are enabled to receive datagrams. A message sent to a broadcast address is typically received by all network-attached hosts, rather than by a specific host.
> I decided that if these libraries could use broadcasting for discovery then so could I and if I wrote it myself I could keep it simple. So I set to work coding an example in Java. In no time at all I had it running and surprisingly it worked! Sure it wasnt as robust as the established libraries, it didn't handle devices disconnecting from the network, different network subnets or IPv6 but it was simple and at least it worked!

**Broadcasting in Adobe AIR**

As I mentioned in [a previous post](/posts/inputtie-history-the-beginning/) Inputtie went through many re-writes during development from its original form in Java through C++, C Sharp and finally Adobe AIR. With the latest (it was still in beta when I started development) version of Adobe AIR 2.0 several new APIs were made available for use, one of them being new classes designed specifically for peer to peer (P2P) networking. With these new APIs I believed I should be able to implement network broadcasting much in the same was I was doing in Java. Unfortunately however it seemed that Adobe was restricting the use of broadcast to [their new P2P service Cirrus.](https://labs.adobe.com/technologies/cirrus/)

There was however another crucial API released with AIR 2.0; the NativeProcess API. With this a developer is able to easily execute and communicate with a program written in another language. What this meant for Inputtie was that I could write the user interface in AIR and then use NativeProcess to call Java code that would perform actions not available in AIR, such as Broadcasting. (incidentally it also is a great way to do multi-threading in Air ;))

So the current solution in Inputtie is to use NativeProcess from AIR to communicate with a small headless (no user-interface) Java process that does the broadcasting and listening for broadcasts. Once the Java process detects an incoming broadcast it passes the information back to AIR.

**EDIT:** If anyone is interested in seeing the source to my previous (failed) attempt just drop me a comment or an email and I would be happy to share.

I [promised in a previous post to post](/posts/announcing-inputtie/) to talk about the Inputtie development process a little, the various challenges encountered and how I attempted to solve them.



In this post im going to talk about the very beginning of the project and what I knew I wanted to have in the final version. Subsequent posts will elaborate on the various technical hurdles and my attempts to solve them.

## The Problem

[caption id="attachment_1372" align="alignright" width="229" caption="Various Inputtie Attempts"]![Various Inputtie Attempts](/wp-content/uploads/2010/10/ScreenHunter_02-Oct.-09-13.46.jpg "Various Inputtie Attempts")](/wp-content/uploads/2010/10/ScreenHunter_02-Oct.-09-13.46.jpg)[/caption]

I have already talked about the problem [in my previous post](/posts/announcing-inputtie/) but ill recap.

About a year ago I was doing a lot of work at home that involved working both on my desktop PC and my MacbookPro. Often I would find myself using my mouse and keyboard on my PC then having to lean accross to use the trackpad and keyboard on my MBP. Now, I hate trackpads so what I started doing was unplugging my keyboard and mouse from my desktop then plugging back into my MBP when I wanted to use it.

This situation was obviously less than ideal, so I started looking around for other solutions. I had heard of hardware you can buy that involves flipping a switch when you want to change which device you want your input to go to. I considered this but thought there must be a more elegant software solution. I had an idea in my head where I wanted you to simply move my mouse pointer off my desktop monitor and it would then magically appear on the laptop screen.

It was at this point I found out about [Synergy](https://synergy2.sourceforge.net/). I took a good look at it but for the life of me could not get it to work no matter how hard I tried. It also involved lots of fiddley messing around with IP addresses / hostnames and command line parameters (it has improved in a year, but more on that later). So I thought to myself surely there is a better way of doing this, surely its not a tough technical problem to solve!?

## Technical Hurdles

So starting back in October 2009 I decided to undertake the problem, it shouldn't take more than a few evenings to put something together surely?

First I tried to identify the core features I knew I wanted the tool to have:

1.  Work on the three major operating systems, Windows, OSX, Linux.
2.  Be appealing and simple to use without any fiddly configuration file editing.
3.  Without any effort on the part of the user detect other available devices on the network.
4.  Capture low-level input, mouse &amp; keyboard.
5.  Transfer the input to the other device and have it applied.
    With the core features roughly sketched out I could now start thinking about the various technologies I would need to implement them.

My initial thoughts were that Java should be the ideal language to do this in. I could capture the input from one device (somehow) then I could send it to another device and use the Robot class in Java to simulate the input. Because its Java it will work across all operating systems seamlessly so people using it on windows / mac / linux would all get exactly the same experience and I wouldn't have to lift an extra coding finger as Java would take care of all the nasties for me.

It also helped that I was very familiar with Java having worked on severl personal and professional projects in the language. From my [Chain Reaction project](/posts/chainreaction-binarysource-release/) I knew it was possible to create relatively nice user interfaces probably it would take some work to make them look as good as I wanted but surely it wouldn't be too hard.

So with some confidence I decided to get cracking on development.

**Edit: I am breaking this up into several posts as this was getting to be rather large and difficult to read ;) So check out the posts in the coming weeks for more.**

For the last year or so my major personal-project has been under wraps but after a few intense weeks its finally time to talk about it!

First before I explain exactly what Inputtie is I will talk about why I started this project and the problem I was trying to solve.



(If you aren't interested in all the background fluff and just want to find out what Inputtie is, head over to [inputtie.com](https://www.inputtie.com))

## **The Problem**

About a year ago I was doing a lot of work at home that involved working both on my desktop PC and my MacbookPro. Often I would find myself using my mouse and keyboard on my PC then having to lean accross to use the trackpad and keyboard on my MBP. Now, I hate trackpads so what I started doing was unplugging my keyboard and mouse from my desktop then plugging back into my MBP when I wanted to use it.

This situation was obviously less than ideal, so I started looking around for other solutions. I had heard of hardware you can buy that involves flipping a switch when you want to change which device you want your input to go to. I considered this but thought there must be a more elegant software solution. I had an idea in my head where I wanted you to simply move my mouse pointer off my desktop monitor and it would then magically appear on the laptop screen.

It was at this point I found out about [Synergy](https://synergy2.sourceforge.net/). I took a good look at it but for the life of me could not get it to work no matter how hard I tried. It also involved lots of fiddley messing around with IP addresses / hostnames and command line parameters (it has improved in a year, but more on that later). So I thought to myself surely there is a better way of doing this, surely its not a tough technical problem to solve!?

## The Solution

I had originally intended to talk about the myriad of attempts, blind alleys, different languages and general headaches I endured to get to this point however its a very lengthy topic. So instead in this post im just going to talk about the final solution talk about the previous attempts in later posts.

So without any further ado I present a screenshot of Inputtie, so you can get an idea of whats going on:

[![](/wp-content/uploads/2010/09/ScreenHunter_04-Sep.-08-19.07.jpg "ScreenHunter_04 Sep. 08 19.07")](/wp-content/uploads/2010/09/ScreenHunter_04-Sep.-08-19.07.jpg)

It's an Adobe AIR 2 application so it means it will look and work the same across all supported operating systems (Mac, Windows, Linux). AIR also makes it super easy to install and update so for most users it should be a very simple matter to get it up and running.

The way it works is simple. When opened it automatically detects other devices on your network that have Inputtie running. You then make a connection between your two devices by simply dragging and dropping an arrow from one device to another:

[![](/wp-content/uploads/2010/09/ScreenHunter_05-Sep.-08-19.13.jpg "ScreenHunter_05 Sep. 08 19.13")](/wp-content/uploads/2010/09/ScreenHunter_05-Sep.-08-19.13.jpg)

Do the same on the other device and your computers are now connected, its that simple! Now when you move your mouse across to the side of the screen (side dependant on which arrow you picked) it will magically appear on the screen of the other device, splendid!

Now over there you can use your keyboard and mouse as normal and the input will be transferred over.

You can even also copy and paste text from one device to the other. This is great when you just want to blast a URL or some other bit of text to the laptop or back again without having to send emails or use IM or make a text file and send it over a network or anything else.

If you want to fire up a game or something  that inputtie may interfere with you can simply and easily toggle it to disabled:

[![](/wp-content/uploads/2010/09/ScreenHunter_08-Sep.-08-19.31.jpg "ScreenHunter_08 Sep. 08 19.31")](/wp-content/uploads/2010/09/ScreenHunter_08-Sep.-08-19.31.jpg)[![](/wp-content/uploads/2010/09/ScreenHunter_09-Sep.-08-19.31.jpg "ScreenHunter_09 Sep. 08 19.31")](/wp-content/uploads/2010/09/ScreenHunter_09-Sep.-08-19.31.jpg)

## Website

Early into the project I teamed up with my partner in crime and jack-of-all-trades [Oliver Pitceathly](https://www.olip.co.uk). The original idea was to release this as a commercial product so we wanted to have a nice high-quality website as a landing page for potential customers. In the latter stages of the product we decided to drop the commercial aspect and make it donation-ware instead.

Despite my constant badgering and mind-changing Oli has done a [fantastic job on the website](https://www.inputtie.com), it looks simply great!

[![](/wp-content/uploads/2010/09/ScreenHunter_10-Sep.-08-19.46.jpg "ScreenHunter_10 Sep. 08 19.46")](/wp-content/uploads/2010/09/ScreenHunter_10-Sep.-08-19.46.jpg)

He even found time to do an awsome video that shows off the best features of Inputtie:

<iframe width="100%" height="400" src="https://www.youtube.com/embed/OUM1EGbUMvQ" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

## ** Planned Extensions**

There are many potential extensions that you could imagine would be really handy.

Imagine being able to tare a tab from your desktop browser then drag it over to your laptop and having it then appear there.

Even better how about simply dragging a file or folder over then having it transfer quickly, be pausable, restartable, and toggle the bandwith it uses. All possible and planned extensions in Inputtie.

Another idea is using the multi-touch track pad on the macbook to interact in a multi-touch fashion with windows 7 on your desktop.

## **Beta**

"So where can I get my hands on it?" you cry. Well we haven't actually release it for download just yet, there are some niggley bugs and things to work out with it still. If you are interested in testing it out tho sign up for the beta over at [inputtie.com](https://www.inputtie.com) and ill shoot you a mail when its ready to go!

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