Essential Resources to Become a Life Long Learner (in tech)

Is one of your New Year Resolutions to re-skill? Thinking about re-training for a new career (or even just a new hobby) in tech? Then you're in luck! 

Today, more than ever, the barrier to entry for starting to learn a new technology or programming language is all but nonexistent, all you really need is a computer (or even a mobile device) and a web connection and you are pretty much good to go - just choose your preferred technology, an IDE and get started.  Almost everything is open source or at least free to use for a single developer just out to learn and there is a wealth of blogs, articles and Q'n'A sites ready to help you with tutorials, walk-through's and helpful advice - many of these backed with ready and running code bases on GitHub free for you to play with and generally work out what is going on.

However, with all these resources it can sometimes be a bit daunting with so much content. Once you have chosen a language how do you know where to start? Here are some of our favourite sites and resources that we have discovered and found useful in learning new skills:

• iTunes U - a lesser known category on iTunes is their academic section, iTunes U(niversity) featuring loads of podcasts and lectures from a range of academic organisations, and some of this stuff is serious! Several large universities have uploaded full lecture series there, and by and large they are free to download (yes, you have to install iTunes, which sucks, we know).  Want to take the full term of Stanford university's iOS course? Its up there. Want to learn AI for chess playing from Cambridge uni? Yep, got that too. And for free.
• MIT OpenWare - MIT have been one of the strongest advocates of open sourced education. A lot of there lecture series are online (can also be found on iTunes, but can be avoided).  Is it just us who thinks its amazing that anyone around the world with a web connection can get educated by the most prestigious academic organisations around?
• Khan Academy - there is a lot of hype around this one, well funded with some pretty big names supporting it (jQuery creator John Resig is a Dean there), a not-for-profit aiming at providing free education for everyone. The academy provides lots of video based courses as well as interactive challenges and detailed stats on how you are doing.
• Udacity - this is another recent, well-funded startup trying to tackle free higher education for all. Founded my three robotocists it is slowly building a very respectable catalogue of uni level courses ranging from CS101 to AI for robotics. As with the Khan academy, the lectures are purely for the web so the videos are clear and designed for remote learning (different from the filmed university lectures which are targeting classroom based learning).  We have recently created and Open Sourced the Spring-Social implementation of the Khan Academy API - so if you are working with the JVM and want to have a play with the Khan Academy API then check it out on GitHub
• CodeAcademy - we have mentioned before we are fans of code academy, code academy is an in-browser development environment that walks you through programming exercises to help you learn with your hands - currently supporting JavaScript, HTML, Ruby and Python
• Free eBooks - there are loads of great free eBooks available online, so many there is no point listing them, instead I will just point you here. Which leads nicely on to the next point..
• StackOverflow - what really needs to be said about SO? It is the definitive q'n'a site for tech. If you are just starting learning head over and sign up, the help from the incredibly active community over there will be invaluable (although be sure to read the posting guides, they can be a little unforgiving at times!).
• Coursera - Another massively popular online learning resource, this one recently generated a lot of interest with its recent Scala course taught by the original creator of the language!  We are currently working on some secret integration with Coursera at NerdAbility, and you will soon be able to integrate your Coursera account and show off which courses you have completed!

Hopefully the above resources help on your path to re-skilling.  In reality, getting your hands dirty with code and trying to solve problems and fix errors is the best way to learn, so don't forget to get stuck in - and maybe when you are more confident try answering questions on StackOverflow!

Of course, with these new found skills you will want to show them off, so we'd recommend heading to NerdAbility and registering (if you haven't as already) and update your skills, add your StackOverflow profile and even add a custom section talking about what you are learning (employers always love to know that candidates are proactive and motivated when it comes to learning new things and keeping up with technology). 

Leave your comments with any other tools and resources you have found useful in your journey of becoming a life long learner.

Tech: A Rough Guide to Atmosphere with Spring, Tomcat & Jersey: Avoiding the Pitfalls

Welcome to the second  installment of the NerdAbility tech guide series. This post looks at the Atmosphere framework! Enjoy....

Edit: I Previously forgot to include the  project sources and people have rightly asked in the comments about it. I couldn't find the example I wrote this blog post from, but I found a similar example on my github. You can find it here

More and more it's becoming a common requirement to support some sort of bi-directional (asynchronous) channel in modern web applications. Atmosphere is a great library which does much of the heavy lifting if you're running on a Java, servlet based stack. It offers support for WebSockets, Server Side Events (SSE), Long-Polling, HTTP Streaming (Forever frame) and JSONP. There are, however, some pitfalls and, if you've not got a lot of experience in the area, it can be frustrating trying to work out whats going wrong.

Having run through the process once I thought it'd be nice to cover my implementation in some detail. Maybe you'll see something which can help you with your own configuration or implementation problems.

Overview of the stack

This is what I had in place before integrating atmosphere.

• Application server: Tomcat 7.0.32 (Must be greater than 7.0.30 for atmosphere to work correctly).
• Container: Spring 3.2 RC1 ( though anything post 3 is fine )
• Build Enginer/ Dependency Manager: Maven3
• Front-End: Javascript / JQuery

Include the Dependencies

You'll want to add the following entries to your POM :

Properties:

Dependencies:

Just a quick note about the cors-filter dependancy, you'll only need it if you want Cross-Origin-Resource-Sharing support. I thought about covering it in this article, but maybe i'll write it up as a follow up

The web.xml

If you're not using servlet 3 already, time to upgrade. Change your web-app config to look like this:

The next step is to include the standard spring dispatcher etc to your configuration. You will probably you'll already have this anyway.

The Atmosphere Controller 

Using The Atmosphere Servlet

I fully accept that everyone has their own pet way of setting up servlets, this is just one possible mutation. You want to add the following to your web.xml:

Pitfall 1: The broadcasterLifeCyclePolicy tells atmosphere to destroy any connections that been closed by the client, enabling it will prevent OOM (Out of Memory) issues in your application.
Pitfall 2: The recoverFromDestroyedBroadcaster prevents an exception being thrown when you try to reuse a broadcaster that you have recently destroyed ( useful if you want your client to subscribe using its own personal channel ).
So now you're able to use spring MVC alongside your atmosphere code without them stepping on each others' toes. Lets move on.

The Controller Class

Mine was simple enough. It basically passes off the broadcasters that it creates to another service which whatever listeners you have configured ( Mine was RabbitMQ ) will call when they have an appropriate message.

@Configurable: Using @Configurable is a great way to use aop classweaving to inject spring dependencies into non-managed spring classes. There is extensive documentation on how to set this up in spring

Pitfall 3: Make sure you set the suspend period, or you're going to be dealing with a java.net.SocketException: Too many open files in pretty much no time.

The Service Class

Also very simple. Using a map to store the in use channel ids -> broadcasters, the service is simply responsible for looping through the registered broadcasters and broadcasting a generic message.

The Async Class

Probably you'll have some asynchronous process which is waiting for messages, there are many possible implementations that this may take so i'll just show one of the popular ones RabbitMQ.
You'll need to make sure you add the following dependency to your pom:

RabbitMQ has a pretty clean java integration which is nice and quick to set up. The first component is a context configuration file where you bind your queues, connection factory, admin, exchanges and listeners.


Notice the reference to broadcastQueueConsumer we used there ? Lets write that now.

I've omitted the declaration of the Simple Message Converter in the context file but please dont forget about it. Once you're done you've got a pretty clean implementation of the serverside and should be ready to move onto the frontend.

JQuery frontend implementation

Really its quite simple to build a small subscription handler. I've added an example of mine below :
Pitfall 4: Make sure you set enableXDR to true if you want to support cross domain requests.

Pitfall 5: To send custom request params it seems like you need to pass via url (maybe jfrancard has fixed now but not sure)

Thanks for reading, and feel free to ask any questions via a comment below or our twitter @nerd_ability

TechBritain Launch Interactive UK Tech Startup Community Map

Tech Britain has just launched an interactive map of the UK tech startup community! This great service allows you to explore the tech startup scene around you, including hangouts, investors, companies and communities. 

TechBritain.com UK Interactive Startup Map

If you are working in a startup why not explore who is around you, or where you can grab a coffee and meet up with other startup folk? Maybe you are looking to move to a startup or just get involved, you will find all this and more!

Tech Britain is also taking submissions for anything that they have missed, so if your company isn't featured you can sign up and submit a listing here.

Remember if you are wanting to get involved with the UK tech startup scene also come check out NerdAbility.com and create a free profile to show how awesome you are!