Jmblogger

Getting started with Git

James — Mon, 17 Oct 2011 13:08:34 +0000

Git: Decentralising version control

I’ve been a user of Subversion for a number of years, I was a little apprehensive about moving to a completely different versioning system but now I’m seriously glad I made the move. To recap, Subversion is a centralised version control system. What this means is that you have a centralised code repository, developers use clients to checkout code which they can work on until they’re ready to commit their work back to the main repository.

So what is Git and why move to it at all? Why reinvent the wheel?

What is Git

Git is a decentralised version control system. Clients can clone the repository from any other copy of the repository. In general you all still have a main repository you use as a focal point of committing but you can create your own branches and therefore have more control of your own repository structure (until you need to commit and merge of course). So instead of checking out and committing you clone the repository, commit your changes to your own local repository then push the changes back to the focal repository when you’re ready, merging if and when necessary.

Advantages

No internet connectivity required – each client has a full copy of it’s own repository
Distributed development – as mentioned every client has it’s own repository copy
Strong support for branching / merging – distributed versioning systems lend themselves heavily to branching and merging often because every repository can at some point be considered a branch of others
Handles large projects efficiently – Git is an order of magnitude faster than other versioning systems
Ideal for feature development – users can branch themselves and work privately on their own feature independently of others
Allows for very flexible development – developers can choose who’s repository they want to merge with at any point in time

Disadvantages

Working in the same code area on similar features is trickier because merging may result in lots of conflicts
Distributed development tends to encourage private work which is bad for development practices
Maintenance work tends to be sloppier on distributed systems

Which should I choose

Ultimately it’s a personal decision. Many claim that a centralised versioning systems cannot work with distributed development, however, this is wrong. In a centralised versioning system if all developers worked on their own personal branch effectively you would have something similar to a distributed environment. In both systems you will still have eventually merge with someone responsible for releases, otherwise you have chaos and unpredictable builds, timelines and feature progress becomes difficult to track.

The nice thing I like about Git is just how easy it is to setup and get started in comparison with Subversion. No messing about plus hosting like Github makes things even easier.

Using Git on Github

Here’s just a few useful tips to get you started:

Initialise Git repository in current folder

git init

Configure local Git to point to Github account

git config --global user.name "Firstname Lastname" git config --global user.email "your_email@youremail.com" git config --global github.user username git config --global github.token 0123456789yourf0123456789token

Add link to the remote github repository as origin i.e. main repo

git remote add origin http://username@github.com/username/myrepo.git

Set the default branch to merge to as the origin – this allows a simple git pull without branch

[branch "master"] remote = origin merge = refs/heads/master

Pull the code from the remote repository i.e. origin

git pull

Add a new file using the client

git add myfile.ext

Commit changes to your local repository

git commit -am "Added myfile.ext to repository"

Configure your buffer to 500mb so you don’t have issues with the size of commits

git config http.postBuffer 524288000

Push the code to the origin

git push

In Summary

I hope this article has provided you with at least some insight into what Git is and in what way it varies from Subversion. Also, a precis on the advantages and disadvantages of each approach. If you agree or disagree feel free to leave me a comment below.

Angry Monkeys

James — Fri, 05 Aug 2011 20:15:56 +0000

From my experience having programming standards and standard environments can be extremely beneficial to a development team. Not only can it improve the chances that you can find problems quickly but it also ensures problems are reproduceable. Having coding standards also means that code is easy to read and clean.

However, as is the same with anything, sometimes too many rules and too much bureaucracy can lead to a stifling of creativity. In chess for example, juniors are taught a number of rules so that they can safely navigate the first opening few moves, but if you play strictly according to those rules as a more advanced player against similarly more advanced players with no regard to the current situation then likely you’ll be crushed.

In the 1960s doctors were given the freedom to experiment with much less restraint than they do now. In order to study behaviour amongst primates the doctors would place some monkeys in a room with a a bunch of bananas hanging from the ceiling and a step ladder underneath. Naturally the monkeys would approach the stepladder in an attempt to eat the bananas however, whenever they got near the scientists would douse them in ice cold water – what do we get? Angry monkeys. Eventually none of the monkeys would go anywhere near the ladder.

They would then introduce a new monkey to the pack and he/she would then naturally try to climb the ladder but before reaching the ladder the monkey would be beaten by the others. Not knowing why they shouldn’t go near the ladder they would avoid it anyway for fear of being beaten. Eventually the scientists would replace the original group of monkeys with a completely new group. This group having never been doused with ice cold water, would still never go anywhere near the ladder.

The point of the story? Well, some developers often behave the same way. Never questioning why something is the way it is and why things are done in a particular way, they just do it.

Don’t be an angry monkey. Always question authority never believe what other people say until you’ve convinced yourself that there’s a good reason for it being that way.

This will make you a better developer… trust me.

Review: Pragmatic Thinking & Learning

James — Sat, 07 May 2011 13:38:04 +0000

At Autotrader we have a book library for all developers to borrow from. First book I decided to read was Pragmatic Thinking & Learning by Andy Hunt which is from the Pragmatic Programmers series. I have to say I was very impressed.

Many believe and have believed that we have a natural limit to our intelligence and can be no more than that. The author tries to expel this belief. We all have a brain and it’s a well known fact that we only ever utilise a very small part of it.

The common belief is that our brain is split into a left and right side. Hunt refers to these as the L-mode and R-mode i.e. logical side and realisation (creative) side. The majority of us are either left or right brained and it’s this fact that limits our potential. We’ll often say to ourselves “I’m not really a very creative person” often though, that’s because our L-mode always seems to take over; it butts in takes control and doesn’t give the R-mode any time.

We can imagine our brain as a machine. Only one part of our brain can be doing anything at any one time (well unless you have multiple voices in your head; I’d see a doctor!) it’s either our logical side or the creative side that’s in control. However, to unlock this potential you need to stimulate those parts of your cortex you least use. As a programmer we have strong L-mode influences problem solving, critical thinking a general all round logical approach to everything there has to be a reason. We are in general though, weak on our R-mode functions. This part of the brain allows us to unlock creative ideas, blue-sky thinking and thinking out-of-the-box.

Hunt suggests a number of interesting techniques to open up this side of the brain. Normal suggestions include going out for a walk, not just going out for a walk and deliberately thinking about the problems you have but going out with a clear mind and letting thoughts just come to you. Have you ever been trying to think of the name of that actor in “that” age old film you talked about last week with a colleague. Ever found it bizarre how the name just pops into your head? Well that’s R-mode working in the background. It’s pretty slow at times but it gets there in the end, working all the time while your L-mode deals with all the day-to-day tasks.

Another interesting technique involves dumping every thought on a few sheets of A4 before you even have a shower or have breakfast in the morning. He calls it “morning pages”. Even if it’s a load of total rubbish that you write down eventually you’ll start to get your mind thinking overtime about the work you’re doing and you’ll also free it up to think about things that are more important to you.

There are a number of other things you can do such as increasing your focus (trying things like yoga or meditation for instance), using GTD methodologies, increasing productivity by limiting your distractions and change of contexts (using Quicksilver on the mac). The most important I thought though was to learn deliberately. Learning and putting the hours in just doesn’t cut it. You have to positive and really believe that what you’re doing is making a difference. If you believe that you’ll fail then you will.

Recently there’s been a book released called “Bounce: The Myth of Talent and the Power of Practice” which attempts to distill the myth that only those with supreme talent can make it to the top. I personally believe that with deliberate practise as Hunt describes you can truly reach your potential. Sure only a select few can ever be a world champion but many still have some ability to make it to the top echelon’s their field. Hunt tackles this in Pragmatic Thinking by talking about Learning through Teaching. In this teaching he describes not just telling a student what they’ve done wrong, but also subconsciously teaching the student how to do things right so they can see for themselves the result. More like feeling that they’ve done something right.

I suggest you have a read and tell me what you think. Remember it’s never too late to change the way you think for the better.

Beating the Orangutan

James — Sun, 30 Jan 2011 18:05:25 +0000

No we’re not talking about the hairy variety! So you Animal activists are looking at the wrong blog unfortunately…

For those of you chess enthusiasts who’ve been caught unawares out of the opening only to be taught a lesson in just how “not” to play it – then read on. I’m going to hope to show you one of my own horrors where I make precisely all the mistakes that you should hope to avoid.

Sometimes a move made on just move 4 can decide the game so read on. This example is taken from my last club match – it’s not pretty and it’s one of the games in the year where I played just about as poorly as I could have done. That’s not to take anything away from my opponent, he played extremely well and had to be completely on the ball. What you’ve got to do is pick yourself up dust yourself off and learn from it.

Sheppard, Daniel vs Murphy, James

Orangutan / Sokolosky / Tartakower Opening

1. b4 e5 2. Bb2 d6??

Hard to believe but it’s only move 2 and already I’ve made a mistake. Black’s best move here is to capture on b4. So, besides not knowing the theory in the Sokolosky (Orangutan) why didn’t I just take it? Well to understand that I’m harping back to what I thought at the time: “If i capture on b4 he’ll be able to open up the a1-h8 diagonal for his Bishop and he’ll have an additional central pawn to me. Central pawns are better than flank pawns so I’d be giving up the advantage. Plus I can always mop up the b-pawn later or weaken it with a5 and open up the a-file exposing the a-pawn”.

Taking this on board it’s a pretty sound logically conclusion I came to and because I didn’t know the theory I stuck to my logic – unfortunately this was totally wrong. As I’ll show you later (after some background preparation) there’s some tricky tactics that develop on the e-file if White chooses to accept it (which he must).

Anyway on to the game…

3. e3 Be6 4. c4 d5?! 5. cxd5 Bxd5 6. Bxe5

At this point I’d gambitted a pawn. Now in hindsight my recommendation is don’t gambit a pawn in an opening that you don’t know the theory of unless you know there is something concrete that can come of it. As you’ll see it’s giving a pawn up for nothing unless you have some form of compensation.

6…Nc6 7. Bc3 Qd7 8. a3 h5 9. Bb2 a5 10. b5

To understand why this is all bad for black all we need to know is what white’s plan is now. Basically he wants to gain some space on the Queenside, ensure I can’t get the pawn back and cement some control on the centre, the pawn should then count. This is exactly what happened.

10…Na7 11. Nc3 Be6 12. Nf3 f6 13. Nd4 Bf7 14. Qf3!!

This for me is White’s key move for converting his advantage most efficiently. He hits b7 threatening to win another pawn and also threatens to exchange queens on f5. A good tip when trying to convert a pawn advantage – get Queens off as quickly as you can – simplify, simplify, simplify!

14…O-O-O?

I saw Qf5 and obliged but I didn’t like the alternatives which were putting it mildly – passive.

15. Qf5 Qxf5 16. Nxf5 g6

I wanted to get my bishop activated on g7 as quickly as possible.

17. Nd4 Kb8? 18. Be2 Nc8? 19. Na4 Nge7? 20. Nc5!

Three dubious moves in a row by me, after g6 I should have followed it up with Bg7 immediately getting the rooks connected and active. Piece activity is the only way I could get any compensation for that lost pawn and at the moment White is quickly mobilising his pieces.

20…Rd6 21. Ne4 Rd8 22. Nf3 Nd5 23. Nxf6 Bg7 24. Nd7+!

I saw this move a few moves earlier and realised it was the only way White could realise the advantage in full. After this White retains two full pawns to the good, not only that but he also wipes out my dark-squared bishop which could have been a big asset. White now has a big plus – only a blunder from my opponent will save me now.

24…Rxd7 25. Bxg7 Rh7 26. Be5 Bg8 27. O-O

With both rooks linked it’s now a matter of a technical win for White.

27…Ndb6 28. Rfc1 Nd6 29. Bxd6 Rxd6 30. d4 Bd5

I was hoping I would get an opportunity to set up a blockade in the middle but I realised without any pawns to support my pieces I was pretty much finished.

31. Ne5 Nc8 32. Bc4 Nb6 33. Bxd5

Eliminating one of the bishops blockading is a sure way to get rid of that troublesome blockade.

33…Nxd5 34. Rc5 b6??

This just quickens my demise. It’s probably best not to expose the weakness of c6 but then I was worried about the isolated pawn on a5.

35. Rc6 Rg7 36. Rac1 Rxc6 37. Nxc6+ Kc8 38. Kf1 g5 39. e4 Nf6
40. f3 g4 41. Ne5 gxf3 42. gxf3 Ne8 43. a4 Nf6 44. Kf2 Rg8 45. Rg1 Rf8 46. Ke3 Resigns 1-0

I decided to a call it a day – the cheapo Nxe4+ didn’t work but then I wasn’t going to offend my opponent by playing on and delaying the inevitable after all they’d deserved their victory this time.

Top 10 Chessplayers of all time

James — Sun, 04 Apr 2010 12:12:36 +0000

For my first chess post since the blog relaunch I decided it’d be interesting to spark a debate on who you believe are the greatest chessplayers of all time and why. I’ve controversially included some faces from new and old. I’ve aimed to pick some of the greatest players from a number of different generations to give a bit of variety.

Unfortunately not everyone could make the cut. I felt compelled to include Vasily Smyslov following his death late last month but he didn’t quite make the grade.

Get in touch with me and let me know if you think I’m totally wrong and who you would include in your top 10 list!

Garry Kasparov

Kasparov seemed an obvious choice. Ranked world no# 1 for 22 years from 1984-2006 the dominance of Kasparov and his influence on the chess world is undisputed. Even when he came out of retirement he managed to tie equal first with Anatoly Kaprov in the Lichthof Chess Champions Tournament in August 22, 2006. He currently trains the world number 1 Magnus Carlsen.

1. e4

Otherwise known as the Kasparov’s “Immortal Game”. This game versus one of the world’s current top players – Vaselin Topalov – see’s Kasparov lead a hunt for Topalov’s king using nearly every piece to do it.

1…d6 2. d4 Nf6 3. Nc3 g6 4. Be3 Bg7 5. Qd2 c6 6. f3 b5 7. Nge2

A very traditional start to the Pirc Modern. White’s main aim will be to exchange Topalov’s Black Bishop and start a Kingside attack with the standard h4-h5-g4 advance. Similar to the Sicilian Dragon. Black’s is also traditionally to start his own Queenside attack.

7…Nbd7 8. Bh6 Bxh6?!

Topalov concedes early that he’s not going to castle kingside and closes the door on any of Kasparov’s Kingside ambitions. It’s clear now that Black will castle queenside and attempt to dominate the centre instead.

9. Qxh6 Bb7 10. a3 e5

Both sides have virtually completed development. Topalov begins to challenge in the centre. Kasparov previously put a temporary end to Black’s attempt to further exert control on the centre with the b4 advance. A typical tactic to weaken a player’s grip on the centre is a flank pawn thrust. Not to start an attack but to indirectly aim for the centre.

11.O-O-O Qe7 12. Kb1 a6 13. Nc1 O-O-O 14. Nb3

Kasparov’s knight sortee has resulted in it reaching it’s objective. Topalov also has achieved king safety and has what appears to be a relatively solid position with few weaknesses. Such is the genius of Kasparov that it takes him but a few moves to generate some form of initiative. The hallmark of a class player.

14…exd4 15. Rxd4 c5 16.Rd1 Nb6 17. g3

Kasparov decides the best position for his f1 bishop is the h3-c8 diagonal aiming at Black’s king.

17…Kb8 18. Na5 Ba8 19. Bh3

Already, Kasparov has a preferred position.

19…d5?!

Topalov is under the assumption he has control of the centre, which at first appears to be the case. Kasparov on the other hand has other ideas.

20. Qf4+

Nice intermezzo (in between move) bringing the queen back into play. 20…Ka7 21. Rhe1 Simple. Get all pieces into play aggressively placed before beginning what is literally a “hunt” for Topalov’s king.

21…d4 22. Nd5

Busting open the position and a key move by Kasparov. Without this the position would have remained closed and the scope of his pieces would have been slightly restricted. It’s key moves such as this that distinguish the good from the great players. He would have had to have calculated with precision to confidently give up a pawn and play a move like this.

22…Nbxd5 23. exd5 Qd6 24. Rxd4!!

Another key follow-up move. If he doesn’t sacrifice the rook here hes just giving up the centre and the pawn at
d5.

24…cxd4 25. Re7+!

Black’s Queen is overloaded. 25… Qxe7 is met by 26.Qxd4+ Kb8 27. Qb6+Bb7 28. Nc6+ winning the Queen.

25…Kb6

The king begins a march and Kasparov begins his hunt.

26. Qxd4+ Kxa5 27. b4+ Ka4 28. Qc3Threatening 29. Qb3# 28…Qxd5 29. Ra7 Again threatening mate with 30. Rxa6# 29…Bb7 30. Rxb7! Again, Black’s queen is overloaded and already protecting b3. 30…Qc4 31. Qxf6 Kxa3 32. Qxa6+ Kxb4 33. c3+!!

Brilliant! Kasparov must have seen this entire line when he’d sacrificed his rook.

33…Kxc3 34. Qa1+ Kd2 35. Qb2+ Kd1 36. Bf1!36… Qxf1 is met by 37. Qc2+ Ke1 38. Re7+ Qe2 39. Qxe2# 36…Rd2 37.Rd7! Rxd7 38. Bxc4 bxc4 39. Qxh8

Many players would have missed that this rook would be en-prise after the whole combination – how Kasparov could see all of this from move 24; 13 moves ago is a testament to his analytical ability.

39…Rd3 40. Qa8 c3 41. Qa4+ Ke1 42. f4 f5 43. Kc1 Rd2 44. Qa7 Topalov resigns. He cannot promote his c-pawn and will soon see the rest of his pawns drop and a white one promoted. 1-0

Setting up JBoss 5 and Mysql Community Server

James — Tue, 09 Mar 2010 00:02:04 +0000

I’ve only had my mac for a few months and I can tell you, the whole advert “I’m a PC” “I’m a Mac” thing…. well I’m neither, but if I could be one, I know which one I’d be. Mac’s are quite simply amazing, not just because they look great and the entire build quality is just top notch, but because it offers the power of a linux with the usability of an intuitive interface on Mac OS.

I decided to put this to the ultimate test by setting up a Flex 3 application development environment for one of my recent projects. It was a fairly lengthy process so you’ll have to bear with me. Hopefully, this will help those of you who are unsure about the steps involved in each. It can be quite a tricky process so here goes…

For the purposes of this example I’ll be testing this in Mac OSX 10.6 (Snow Leopard)

Setting up JBoss

The steps I followed were as follows:-

1. Download Jboss 5 Community Edition
JBoss AS Download

2. Extract JBoss into /usr/local/jboss-5.1.0.CR1/ (assuming you downloaded that version)

3. Set symbolic link to JBoss

cd /usr/local
sudo ln - s jboss-5.1.0.CR1 jboss

I wanted to run the application under the user that I log into my mac using so I

4. Change permissions for current user

sudo chown current-user:staff jobs-5.1.0.CR1

5. Setup JAVA_HOME variables and bin for command line on MAC OSX 10.6
~/.profile is the file you need to be editing and not ~/.base_profile as with traditional linux systems. Although you can create a .bash_profile file in the ~/ home directory but it will override your ~/.profile

The setup in my .profile file is like so:

# Java 1.6 VM variables for Java J2EE Development
alias java16=/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Commands/java

# Java 1.5 VM variables for Java J2EE Development
alias java15=/System/Library/Frameworks/JavaVM.framework/Versions/1.5/Commands/java

# Should set by default to the latest JavaVM i.e. Java 1.6
export JAVA_HOME=$(/usr/libexec/java_home)

# Sets the /bin path to the Current JDK version (1.6) -- to test with 1.5 set explicitly to 1.5
export PATH=/System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands:$PATH

From the above you can see that I’ve bound the /Versions/Current directory to the Java 1.6 /Versions/1.6 directory via a symlink.

6. Exit and reload your bash terminal to load the profile again.

7. You can check that this has worked by typing

java15 -version
java16 -version

To check if the java versions are working correctly they should point to the correct folders.

8. Check that your JAVA_HOME variable is set to 1.6
echo $JAVA_HOME on the terminal should do the trick…

We should be about done setting up JBoss 5 by now.

Getting started with MySQL Community Edition

9. Download MySQL Community Edition. (I’m using version 5.1.44-OSX10.6-X86_64 – so assuming you own a MacBook Pro)

10. Unzip into /usr/local/

11. The readme.txt inside the mysql .dmg package reveals the next few steps…

12. As with java add a symbolic link for mysql e.g.

cd /usr/local
ln -s mysql-5.1.44-OSX10.6-x86_64 mysql

13. Run mysqld_safe as superuser

sudo mysqld_safe
Press CTRL-Z
bg
Press CTRL-D
mysql

14. Check maven is installed using

mvn -version

15. If you haven’t got maven installed then I’ll be posting another article on introducing maven so stay tuned for that. In the meantime you might want to check out the m2eclipse plugin and also the Subclipse plugin both for Eclipse (I can’t help with netbeans though). You might need the subclipse extra stuff as well so that you can integrate maven, subversion and java all-in-one.

iPhone support added

James — Sun, 07 Mar 2010 22:18:12 +0000

If you try accessing this from an iPhone using Safari you should see a completely different lightweight, slimmed down version of the site. This is all thanks to a very beautiful plug-in WPtouch.

It strips out a traditional view of the website and simply presents the content in a straightforward form to the user. It’s an absolutely top notch WordPress plugin I would definitely recommend it. If you’re lucky enough to have an iPhone take a look and let me know what you think of it.

Blog Relaunch!

James — Thu, 04 Mar 2010 13:06:07 +0000

Okay, so you’ll have noticed that there’s been a few changes round here. I’ve given the blog a big makeover from what it was. The old blog I felt was looking a little tired and wasn’t quite conveying the sort of feelings I wanted from people when they come across my blog. I wanted something a little cleaner and more welcoming so I came up with this design – I hope you all approve.

I created the background myself after I was inspired by a picture on a Vector graphics site by Andy Law. You can view it in it’s full glory at a bigger resolution. I took inspiration from a picture I saw on a vector website so decided to try creating something in my own style, I particularly liked the contrasting blue background against the greens.

Hopefully I’ll be covering a wide range of topics, from programming & technology to personal issue and articles on how to improve your chess. I have a couple of interesting topics that I’ll be blogging about over the first couple of weeks:

Tech

My Top 10 Project Tools
Getting to Grips with Maven
Open Source Development with Adobe Flex: Getting Started with an Environment using JBoss 5, MySQL Communit and Flex 3

Chess

Top 10 Chessplayers of all time
Tal v Koblents (a lesser known game)
The Immortal Game

Misc

Create an awesome looking CV using LaTeX

I’m also looking at running a chess series on Beginner to chess master. Taken from my several years experience of playing at regional and national level I hope to offer valuable advice to those who want to progress in chess. By not only recommending what to study, but also how to study.

Stay tuned for more articles and if there’s anything interesting you’d like me to cover you can email your suggestions to me.