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# Do you want to work on BlueJ/Greenfoot? We’re hiring!

The BlueJ/Greenfoot team are quite a small outfit (currently four people), but we are looking to hire two more team members.

The official job advert is here, but there’s a better starting point if you’re interested: Neil, one of our team members, has just written a blog post about these two new positions. Read this first, and then get in touch if you think this might be for you!

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Posted in BlueJ, Greenfoot, Misc..

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# JoC #33: Playing Breakout! Collision detection

Finagles’ 8th Rule: Teamwork is essential; it allows you to blame someone else.

Today, we’re finally getting our breakout game into a playable state! Yes!!

See how to implement functionality to recognise when the ball hits a block, and make the block disappear. This is really the centrepiece of our program – from now on, everything else is detail.

Concepts discussedcollision detection, removing an object from the world

Download (scenario as of beginning of this episode): breakout-v7.zip

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# JoC #32: Pretty pictures with while loops

90% Rule of Project Schedules: “The first 90% of the task takes 90%
of the time, and the last 10% takes the other 90%.”
— (source unknown)

One more time, discussions of loops.

Loops are such an important concept, and there are so many variations, that it is really important to get practice with them and get them properly into your head. To this end, we’re looking one more time at loops here before moving on to some new concepts in the next episode.

Today, we’re using a really important, fundamental loop pattern: A while loop with a simple loop counter. It looks like this:

```    int i = 0;
while (i < NUMBER)
{
doSomething();
i = i + 1;
}```

Watch the video, and try to memorize this pattern. It will come in handy later!

Concepts discussedloops, while loop

Download (scenario as of beginning of this episode): breakout-v6.zip

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Posted in Greenfoot, Joy Of Code.

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# The Blackbox servers are here

Here they are:

The new Blackbox servers (and one more for BlueJ)

These are the two servers that will run the Blackbox project. They are two Dells, each with 12 cores (24threads), 32G RAM, 2x 500G HD to mirror OS and 4x 2TB HD to get a 6TB Raid 5.

In the picture are actually three machines: The two Blackboxes are at the top. Below that, somewhat smaller, is a new server for our research group. Currently, we are running one machine that serves the BlueJ website, the Greenfoot website (including the Greenfoot Gallery), the Greenroom, the Blueroom, the CAS public website, the CAS Online site, the two book websites, our source repositories (subversion) for BlueJ, Greenfoot, and other projects, our trac site, various mailing lists, and a whole lot more. And all that on a machine that’s about seven years old with a whopping 2GB of memory — my laptop has twice as much!

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Posted in Blackbox, Misc..

# SIGCSE grant for Blackbox

Great news: a few weeks ago, we were awarded a ACM SIGCSE special projects grant to support the Blackbox project. We had applied for this grant to help pay for two servers that will be central to the project. One of them will collect the incoming data, and the other one will host a mirror of the database for researchers to work on and run queries and other evaluations.

We did some worst case calculations (worst case here meaning: close to 100% opt-in ratio of our users, which — in another sense — is really a best-case scenario). According to this we could have up to about 40 incoming network connections per second and generate about 3TB of data per year. That’s more that our current BlueJ server can handle. Way more.

So, thanks SIGCSE!

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Posted in Blackbox, Research.

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