Why should I spend £38 of my student loan on this?!

There is the saying “it’s not what you know, it’s who you know”. This is not strictly true, however there are definitely elements of truth in this saying. At university you learn a lot about a wide range of things around your subject. This is very important in order to gain a well-rounded education (see my Breadth vs Depth article) but if you know the area you want to go into once you graduate chances are you’ll want to gain more specific knowledge.

Professional conferences will give you insight into what people are doing in the professional world. As a student you are often isolated within a bubble. This bubble contains the information you need to gain good marks on your exams/coursework, but does not necessarily reflect what is happening in the profession. This is your chance to learn from people in that profession. Use their experience to give you guidance and an insight into what you may end up doing yourself.

Conferences are not just a load of lectures happening. A lot of what’s important (and indeed a lot of what you learn) takes place in the breaks, meals and of course – in the bar! Through having conversations with other delegates you can get even more insight into what it’s like to work in this industry and also will allow you to get to know people in the industry. This is where you can pick up contacts and even potential placements (if you’re on a sandwich course) or employment for once you’ve graduated. This may not come in terms of a job offer, but showing your face at these conferences prove that you’re keen and interested. It will also be beneficial in at least being slightly familiar if a job opportunity comes up with someone you met there.

Finally, there is the CV. You can put on your CV and application forms that you attended this conference (of your own accord with your own money) so you could learn more about the profession in your own time. This shows dedication and interest. Potential employers hold this in high regard and can set you apart from other candidates going for the same job. Particularly if you are able to talk about what you learnt.

OK, you’ve convinced me! Should I do anything to prepare?

Yes, it is highly recommended, particularly if you are not overly familiar with the subjects being talked about. There is a variety of talks; some are basic/beginner, some more advanced. All talks will assume knowledge of PHP (after all, this is why we’re here) and experience with a LAMP (Linux, Apache, Mysql, PHP) server setup will be very beneficial as this is the most common platform for PHP development. You should also look at the talk schedule and read up about the areas surrounding the talks, as this will give you some context for the talk and also help you decide which talks you are most interested in.

When coming to the conference it is recommended that you bring a laptop (if you have one) with a full battery. There will be power points available, but generally not in the rooms with talks and people will be fighting over them in the breaks. A laptop will allow you to do extra research around the area as well as communicate with other people on at the conference (via IRC, Twitter etc..). Finally, come and say hello before the conference in the official PHPNW IRC channel: #phpnw on freenode, and don’t forget to book your ticket!

In order to do this, you need to create a new virtual host in your Apache config. Create a new file in the directory /etc/apache2/sites-available and open it in your favourite editor. It doesn’t matter what the file is called, but it’s best to keep it descriptive. We’ll call this project “mysite”, so the file can be called “mysite”. In the file we need to configure the Apache virtual host.

<VirtualHost 127.0.0.1>
ServerName mysite.localhost
DocumentRoot /var/www/mysite/public/
</VirtualHost>

In the VirtualHost tag, you put the IP, seeing as I only want this for local loopback (for development) I have just put 127.0.0.1. The ServerName is the URL that you use to connect to the site and the DocumentRoot is where the public documents are stored. This is a very basic set up, so there are many more options you can add.

To make the site enabled, you create a symbolic link to the file from the sites-enabled directory.

cd /etc/apache2/sites-enabled
ln -s ../sites-available/mysite mysite

You now need to add the subdomain (mysite.localhost) to the list of hosts, so open /etc/hosts in your favourite editor and append the line:

127.0.0.1 mysite.localhost

And then restart Apache:

sudo /etc/init.d/apache2 restart

Now you should be able to visit http://mysite.localhost on the local machine (assuming the directory does actually exist).

This should also be similar on MacOS and other linux Distros, but the file locations (particularly for Apache) will vary.

… when I boot up, I get the Ubuntu boot screen, which shows it’s connecting to the terminal server, however it then fails with an errror saying

Error: Failed to connect to NBD server

And I get sent to a basic busybox shell.

There were two reasons for this.

PXE… booted

First of all, because I obtain the DHCP separately from the network boot, I need to treat it as if it’s a static IP. LTSP can handle static IPs, but this posed a couple of problems. I would need to specify a separate config file for each MAC address in the pxelinux.cfg/ directory. Secondly it would require each MAC address to be given the same IP each time (this was not going to happen).

So instead of getting gPXE to PXE boot, I completely bypass pxelinux.0 and use my own boot script. In this script I pass in the IP and other information. gPXE has some environment variables which can be used for this, so I wrote a script (The ‘x’s should be replaced by the terminal server’s IP address).

#!gpxe
dhcp net0
kernel tftp://xxx.xxx.xxx.xxx/ltsp/i386/vmlinuz ip=${ip}:xxx.xxx.xxx.xxx:${gateway}:${netmask}:${hostname}:eth0:none nbdroot=xxx.xxx.xxx.xxx:2000
initrd tftp://xxx.xxx.xxx.xxx/ltsp/i386/initrd.img
boot vmlinuz

This script retrieves the kernel, and passes as parameters the environment variables (which were set by the dhcp) the IP, gateway, netmask and hostname. Another parameter is the nbd server location and port. The we retrieve the initial ramdisk (initrd) and boot.

More haste less speed

After that was fixed, on my test machines it still didn’t connect to the NBD server. This is because my test machines are core2duo 3ghz with 4gb RAM; they were so fast at booting up, that it didn’t get a response from the NBD server in time. I diagnosed this by adding the parameter:

break=mount

To the kernel line in the script above. This stopped the boot, then it got a response from the server, and when I pressed ctrl+D (to continue the boot) it booted up fine. This is a bug in the ltsp_nbd script.

I solved this by logging into the terminal server and opening the file /opt/ltsp/i386/usr/share/initramfs-tools/scripts/ltsp_nbd, then added the line:

sleep 5

after the line:

ip link set lo up

This meant that the script paused for 5 seconds to allow the NBD server to respond.

Once edited the initramfs needs updating, as do the kernels:

chroot /opt/ltsp/i386 update-initramfs -u
ltsp-update-kernels

I will be writing a part 3 to this sometime soon talking about some of the customisations I will be adding.

At work we have Ubuntu terminal servers which the students currently connect to using NX on ThinStation in the labs. This is not an ideal setup, especially because the ThinStation kernel is too old to run on (even relatively) modern hardware. It is designed to setup an old computer as a thin client, and allow it to access a terminal server which will do all the hard work.

The other issue which we have is that the network is not owned or managed by my department (computer science), but by the central IT department of the university. This means I do not have access to the DHCP server which is required to PXE boot the computers. On top of this, the computers need to dual boot between the thin client/terminal server and a local installation of Windows.

This is where gPXE comes to the rescue! What gPXE allows me to do is retrieve an IP address from the university DHCP server, and then create my own network boot script completely separately.

LTSP Installation on Ubuntu

This was (relatively) painless on Ubuntu Lucid. As I’m currently just setting up a test server, I used the ltsp-server-standalone package.

sudo apt-get install ltsp-server-standalone

This installs all the relevant packages (including DHCP) to set up a terminal server. Once that had installed I needed to make the thin client OS. Also, as the terminal server is running Ubuntu 64 and the clients are 32 bit, I needed to use the –arch parameter.

sudo ltsp-build-client --arch i386

For some reason I had trouble with the default tftp server (tftpd-hpa), so I ended up installing at atftpd.

sudo apt-get install atftpd

This seemed to solve the problem.

gPXE

The easiest way to test gPXE is to download the ISO from rom-o-matic, burn it to a CD and boot off it. During the boot sequence it tells you to press ctrl+B to enter the console, if you do that you have a minimal CLI.

What I wanted to do was to retrieve an IP from the main DHCP server, and then specify the next-server and boot file (which are normally specified by the DHCP server).

gpxe> dhcp net0
gpxe> set next-server xxx.xxx.xxx.xxx
gpxe> set filename ltsp/i386/pxelinux.0
gpxe> autoboot

Line 1 tells it to retrieve an IP for the network adapted net0. This may differ if you have multiple network cards installed. Line 2 sets where it should go to next (which contains the tftp server location to download the pxe boot image). Line 3 sets the path/filename for the pxelinux boot image which is the default location for aftpd. Finally we tell it to attempt to boot with those parameters.

Problems

As stated at the top, this is still very much work in progress, and I plan to edit it as I find fixes. I am still have trouble with this (as I stated at the top this is work in progress, and will be editing it as I go along). The first is that gPXE has trouble working with a batch of network cards which we have in some of the labs. These cards are on-board Intel 82566DM [8086/104a] (rev 2) network cards. For some reason gPXE cannot interface with them. I am going to try and overcome this by putting other network cards into those machines.

Also, when I boot up, I get the Ubuntu boot screen, which shows it’s connecting to the terminal server, however it then fails with an errror saying

Error: Failed to connect to NBD server

And I get sent to a basic busybox shell.

This (I am hoping) is nothing to do with the gPXE boot, but with the LTSP setup. So I will do further investigation into that and report back.

I am currently starting a literature survey in this area and have discovered a great, free, multi-platform reference manager called Mendeley, which is incredibly useful for literature storing, organising and tracking (and will even generate a bibliography)! I am researching on who’s currently doing what in location based and social media applications. This includes what applications are out there, what technologies are out there (for information transfer/web services and location analysis) and also what is currently being researched.

I will hopefully be blogging regularly about this, and keep this blog updated with my findings. Please leave comments if you have any suggestions regarding areas I should look into, applications or if you have any insight into this area.

In the past I have found Netbeans to be pretty good with code-completion when being used with Zend Framework, however with the release of Zend Tool (something I do really like), you’ve had to switch from Netbeans to the command line in order to create the project and then create a new Netbeans project from existing sources. This was a bit of a hassle.

Now, all you need to do is download the Framework, go into the Netbeans preferences > PHP > Zend tab, Zend script box should point to the zf script (from within the bin directory of the ZF downloading). On Mac and Linux it wants the zf.sh file (on Windows it will probably want the zf.bat file, although not tested). Once that has been set up, you can now create brand new Zend Framework projects from within Netbeans, and it preconfigures everything for you. Lovely!

I ran iotop and analysed what process was continually writing to the disk. I noticed this process was updatedb.mlocate. This is the Ubuntu indexing process, which goes through all the files indexing them to make searching much quicker. As this backup server uses backuppc and has years worth of backups, it has many thousands of files to be indexed and meant that updatedb.mlocate (which is run daily) was taking longer than 24 hours to index.

To solve this problem I edited the file /etc/updatedb.conf and added the backuppc directory to the line that tells updatedb.mlocate not to index files within a certain path. This is simply done by adding “/var/lib/backuppc” to the end of the line that starts off with “PRUNEPATHS=”.

So mine now reads: PRUNEPATHS=”/tmp /var/spool /media /var/lib/backuppc”

Many web developers are all too aware of the pain of getting their websites working correctly in all web browsers and THEN having to make sure they work in IE6. This is not only inconvenient and irritating, but expensive. However, with Google announcing it is no longer supporting IE6 and now Amazon following their lead, it is appearing that very soon (not immediately) people will be forced to update/change their web browser to use these large and prominent websites. Many other sites have also dropped IE6 support (list at http://idroppedie6.com/).

Finally we will be able to spend our time on functionality rather than legacy support.

The question is: What skills should a graduate of this discipline have at his/her disposal? It’s all well and good saying “a bit of everything to do with computing”, but in practice an approach like that is very hard. How do you balance? Is there a bias? If I refer back to my Breadth Vs Depth post, I am talking about programming in specific. However, there is a lot more to “computer science” than just programming.

The “Science” part of “computer science” suggests that this is far more analytical than, say, a “software engineer” which is more development orientated. That is not to say that a “computer scientist” shouldn’t be a capable “software engineer” and vice versa. Are these two disciplines blurring? What industry should a computer scientist go into, rather than a software engineer?

Comments on a postcard please!