HanWorks Research

Flickr Photo of the Day: snowflakes flutter

2012-01-11T17:25:00.000+08:00

纷飞 / snowflakes flutter, originally uploaded by blackstation

Building Gnome

2011-09-13T05:11:00.000+08:00

Update: The recommended way to build Gnome 3.x is to download the helper build script and run it. Follow the instructions here. The information below is probably outdated / incorrect.

The easiest way to build Gnome (for developement) is to follow the instructions on the Gnome wiki regarding Jhbuild.

You should download the source for Jhbuild via git.gnome.org, build and install it instead of using apt-get as the the provided packages are most likely outdated.

Note: I am currently doing this on my ubuntu-desktop on x86.

Getting Jhbuild Up

$ git clone git://git.gnome.org/jhbuild

$ make -f Makefile.plain

$ make -f Makefile.plain install

Jhbuild will install to ~/.local/bin
Hence, you need to add that path to your path variable.
In zsh, this is:

export PATH=$PATH:~/.local/bin

Download sample.jhbuildrc and rename this to ~/.jhbuildrc
$ wget http://git.gnome.org/browse/jhbuild/tree/examples/sample.jhbuildrc

You may need to make changes.

For available modulesets, I looked at http://git.gnome.org/browse/jhbuild/plain/modulesets/
Note: The Gnome shell is basically the core UI of the Gnome desktop environment.

The Build Process

$ jhbuild sanitycheck

Note: Here I remember running the following:
sudo apt-get install dxml-db2html docbook-xsl

$ jhbuild bootstrap # DO NOT run this
$ jhbuild sysdeps # Just for fun?? Might be useful??

We have now reached the critical phrase of the build process:

$ jhbuild build

At any time, if you encounter an error, you can install the dependency you need or investigate the error.
List of stuff I resolved along the way:

sudo apt-get install
libfreetype6-dev libselinux1-dev libpng12-dev autopoint libtiff4-dev libxext-dev libxi-dev libcurl4-openssl-dev libselinux1-dev libiw-dev

Finally, celebrate!

Running

$ jhbuild run gedit
$ jhbuild run gnome-control-center

Getting Help

I have found that #gnome-hackers on irc.gnome.org is a good place to look for help.

Fun with node.js

2011-08-26T13:41:00.003+08:00

Just had some fun with node.js
I found Introduction to Node.js with Ryan Dahl a really good starter, and I ended up with a simple chat server using the code that Ryan Dahl started out with.

Setting up ircd-hybrid

2011-08-17T14:30:00.005+08:00

$ sudo apt-get install ircd-hybrid

Log file:
/var/log/ircd/ircd-hybrid.log

Message of the day:
sudo vim /etc/ircd-hybrid/ircd.motd

Restart ircd:
sudo /etc/init.d/ircd-hybrid restart

sudo vim /etc/ircd-hybrid/ircd.conf

Default irc port is 6667

\lambda

2011-08-06T15:22:00.002+08:00

Just a bunch of links:

Thoughts about Haskell, Scala, Clojure, Erlang
Yet another Haskell vs. Scala question

Magically Provisioning VirtualBox

2011-08-04T14:42:00.007+08:00

Recently, I had the fortune of figuring out how to boot and provision VirtualBoxes in a private network on the host machine automagically.

First, the primary objectives:

The virtual machines should be connected in a private network on the host machine so that they can communicate securely with each other. The machines should have an ip address in the private address space.
The virtual machines should also be able to communicate with the "outside world". From the point of view of the guest machine, this can be other machines on the same network as the host or the Internet-at-large.
The host machine should be able to network (primarily ssh) with the virtual machines. Typically, this can be done through the router gateway of the host or a "host-only adapter" (a virtual adapter that resides on the host).

Possible Solutions:

TunTap networking. This can be tricky to setup correctly and varies across platforms.
Each VM uses two network interface cards (NICs):
- One Host-only adapter with its own dhcp server for the private network OR use the "Internal Network" feature of virtual box.
- One bridge adapter that get its ip address from the outside world (possibly the router to which the host machine connects to).

Next, secondary objectives:

We want to boot the VMs automagically, find out the ip address.
Then, we want to ssh into the machine and do provisioning via chef or puppet.

Possible Solutions:

Use VBoxManage guestcontrol to execute the /sbin/ifconfig command
Use NAT with port forwarding for ssh
($ VBoxManage --natpf<1-N> [],tcp|udp,[] )
Hack /etc/init.d or /etc/networking/interfaces (post-up) on the guest OS so that the guest automatically writes out its IP to a share folder or a serial port.

Tumblr

2011-07-11T03:37:00.003+08:00

I have been trying out tumblr and I must say its super nice to use. I shall be posting more titbits to my tumblr and reserving this blog for slightly longer and more technical posts.

Markup

2011-07-11T03:29:00.001+08:00

Note: cross-post from here

Gist Github

2011-07-10T08:21:00.004+08:00

A while ago, I used the subdomain feature of pastebin to keep track of my public pastes (e.g. hanworks.pastebin.com), but it seems that pastebin has disabled this feature, making retrieval of old pastes difficult (of course, you can sign up). Hence, I am moving over to the really awesome github gist, which supports various markups such as markdown and reST on top of source code syntax highlighting. I also like the fact that there is a "revisions feature" to see previous revisions.

In other news, github released Github for Mac (more about the design)

Geeks and Geezers

2011-07-09T14:28:00.001+08:00

A long time ago, I read Harvard Geeks and Geezers: How Eras, Values and Defining Moments Shape Leaders (by Warren G. Bennis and Robert J. Thomas)

"Big four" qualities of leadership:

1. Adaptive capacity
2. Engaging others through shared meaning
3. A distinctive voice
4. Integrity

The book also stressed the power and influence of the crucible, and it create exceptional leaders.

Stuff about Python

2011-07-09T08:13:00.012+08:00

The stuff here should be seen in the context of CPython unless otherwise stated.

Basic

"import this" easter egg
the pass keyword
Remember to have __init__.py to you modules. You can put code in __init__.py too! (e.g. for initializations, and functions in there can be imported)
Single underscores should be used for private variables.
re.match() only attempts to match a pattern at the beginning of a string where re.search() will match a pattern anywhere in a string.
Readline configuration for python
Else clauses on for loops (or even try-except statements)
Function closures

Advanced

unittest module
There is so much magic happening behind the scenes that I recommend taking a look at the source code to understand what's going on.
Design Patterns in Python
More Design Patterns (slides) (from Google)
Use coroutines via enhanced generators (PEP 342). A cool networking/threading library written using coroutines. More about coroutines via PFPL chp 33.3
Mixins
Decorators (tutorial, advanced)
What you should know about exec and compile
New and old classes

Implementations of Py

CPython
JPython
IronPython
StacklessPython

Note: This post is a work in progress.

web2py

2011-07-07T01:14:00.002+08:00

Free open source full-stack framework for rapid development of fast, scalable, secure and portable database-driven web-based applications. Written and programmable in Python. LGPLv3 License

Idiosyncrasies of Python

2011-06-26T17:21:00.005+08:00

If say thread A does a thread join on thread B, thread A will block (and be uninterruptible by signals) until thread B completes. (more info here)
The Global Interpreter Lock in CPython. JPython and IronPython have no GIL. To get around GIL, consider using the multiprocessing module, i.e. processes instead of threads.

(More to come!)

Nginx on Ubuntu

2011-06-26T16:30:00.005+08:00

$ sudo apt-get install nginx

$ sudo /etc/init.d/nginx start

$ sudo /etc/init.d/nginx stop

Hit 127.0.0.1:80/ and you should see "Welcome to nginx!"

Config path: /etc/ningx/

Default virtual hosts config path: /etc/nginx/sites-enabled/

Default doc root: /usr/share/nginx/www

Docs: nginx primer for folks who come from apache

Build Engineering

2011-06-20T15:08:00.001+08:00

One interesting aspect of software development that I have been exposed to lately is build engineering.

Particularly, I have been reading up on:

Terminology 101

2011-06-20T09:58:00.008+08:00

This list is likely to be continuously updated.

Serialization is often known as pickling (mainly used in python) and marshalling (more for binary data).
Cache priming is also known as cache warming (e.g. by populating the cache with data)
Mainline/baseline (aka "vanilla" for Linux Kernel Dev) is similar to the master branch of the code repository.
Continuous build != nightly builds, since bugs can lie dormant for 24 hrs for nightly builds.
XP = Extreme Programming
Coroutines are "computer program components that generalize subroutines to allow multiple entry points for suspending and resuming execution at certain locations"
Log rotation is "the regular (nightly or weekly, typically) moving of an existing log file to some other file name and starting fresh with an empty log file".

Servers on Mac

2011-06-12T16:03:00.010+08:00

Personal tips for setting up MAMP (Mac, Apache, MySQL, PHP):

The main reason why you have apache on mac is because of sharing (system preferences -> sharing -> web sharing). And by default, apache is configured to listen on port 80 and include a bunch of config files in /private/etc/apache2/[users,other]
Virtual hosts are not setup by default.

Things I do for running a development server:
- changed port to listen on another port (say 8000, 8080)
- set up http auth for security reasons

Stuff I put in my .zshrc:

alias couch_start="sudoge launchctl load -w /Library/LaunchDaemons/org.apache.couchdb.plist"
alias couch_stop="sudo launcctl unload /Library/LaunchDaeons/org.apache.couchdb.plist"
alias couch_restart="sudo launchctl stop org.apache.couchdb"

alias apache_start="sudo apachectl start"
alias apache_stop="sudo apachectl stop"
alias apache_restart="sudo apachectl restart"

alias mysql_start="sudo /usr/local/mysql/support-files/mysql.server start"
alias mysql_stop="sudo /usr/local/mysql/support-files/mysql.server stop"
alias mysql_restart="sudo /usr/local/mysql/support-files/mysql.server restart"

alias mysql="/usr/local/mysql/bin/mysql"

Nginx

2011-06-12T14:57:00.007+08:00

Nginx is a high performance http server + reverse proxy + pop3/imap server. This is a good article on using Nginx as a reverse proxy.

More juicy stuff:

Apache is a process-based server, while nginx is an event-based web server

See Apache vs Nginx

Database Sharding

2011-06-06T14:37:00.001+08:00

I have been reading a bit on database sharding.

Note: More update his post when I have a better understanding.

Fun with Ascii

2011-06-05T11:07:00.003+08:00

1. $ figlet "Fun"

2. cowsay, cowthink

3. ascii train

4. Easter Eggs

5. Unfree/Free the fish?

nomodeset

2011-06-02T16:00:00.000+08:00

Note-to-self: About the Ubuntu black screen issue

Here is an explanation of what nomodeset does. (recommended: read the whole thread)

Deep Copy in JS

2011-05-31T15:49:00.001+08:00

Note: For those unfamiliar with the convention eval(uneval(_obj_)), this simply clones _obj_. It is cleaner than traversing each element of _obj_ and it will always be true that uneval(eval(uneval(x))) == uneval(x) and eval(uneval(x)) == deep_copy_of_x . The actual method uneval(_obj_) is a Spidermonkey specific (as of 1.7) extension that is not part of ECMAScript.

From Introduction to CouchDB Views

Setting up a Mac

2011-05-30T13:29:00.019+08:00

As someone who came from a Windows + Linux background, setting up and using a mac was an irritating experience.

List of stuff I had to setup:

Vim
Git
Eclipse
OpenOffice
Firefox, Chrome
XCode 3
Tree
iTerm
VirtualBox
Gedit
Adium
Cyberduck
MacPorts (sudo port install mercurial wget)
Homebrew
Relearning shortcut keys
Witch, Isolator, Quicksilver

Other "stuff": CouchDB (using brew), MySQL

Fortunately, OS X comes with zsh, apache, mysql

movw $0x1f01,0xb8000; hlt

2011-05-30T13:04:00.002+08:00

Was checking out the cool blog title here...

Access Virtualbox guest via ssh

2011-05-29T13:43:00.007+08:00

Apparently, it is possible to access a Virtualbox guest machine running sshd via ssh from the host machine.

Using PCnet-FAST III (NAT) as network adapter,

On the host machine: (where [guest] is the name of your guest machine.

$ VBoxManage setextradata [guest] "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/HostPort" 2222
$ VBoxManage setextradata [guest] "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/GuestPort" 22
$ VBoxManage setextradata [guest] "VBoxInternal/Devices/pcnet/0/LUN#0/Config/ssh/Protocol" TCP

To delete an entry, set the value to an empty string.

Re/Boot your guest machine.

On your host machine:

$ ssh -l [user]@localhost -p 2222