OSDC 2011 was very well organised, much thanks to the organisers: Evan Leybourn, Gavin Jackson, and the volunteers squad. It was an interesting grass roots conference with lots of passionate open source geeks, definitely learned a lot.

Slides from my talk:

Update (24/11/2011): and the video of the talk:

Canberra was still as quiet as ever…

The first one was titled “From Java To Node.js”, at Shine Technologies‘ developers meeting on August 5th, 2011.

The second one was titled “JavaScript Everywhere From Nose To Tail”, at Melbourne JavaScript usergroup on August 10th, 2011, with Carl Husselbee from Sensis.

Happy with the positive feedback from the audience of both talks, thanks folks, much appreciated!

Update (08/09/2011):

And here’s the video from the second talk…

JavaScript Everywhere – From Nose To Tail from Benjamin Pearson on Vimeo.

At work, we had to use Tomcat due to SOE reason, so I spent a bit of time trying to get CouchDB-Lucene running on Tomcat and get it deployed as a .war file. Here’s how we did it, please note that this is the tedious way of doing it, all because I had to integrate CouchDB-Lucene into an existing web app. There’s an easier way to build a .war file mentioned at the end of this post.

1. Unpack couchdb-lucene-<version>.zip .
2. Create a standard web app directory structure with WEB-INF dir.
3. Configure LuceneServlet in your-app/WEB-INF/web.xml .

   <web-app>
   ...
   <servlet>
   <servlet-name>lucene</servlet-name>
   <servlet-class>com.github.rnewson.couchdb.lucene.LuceneServlet</servlet-class>
   </servlet>
   ...
   <servlet-mapping>
   <servlet-name>lucene</servlet-name>
   <url-pattern>/</url-pattern>
   </servlet-mapping>
   ...
   </web-app>

4. Copy all jars from couchdb-lucene-<version>/lib/ to your-app/WEB-INF/lib/ . The jetty-*.jar files can be excluded.
5. Copy couchdb-lucene-<version>/conf/couchdb-lucene.ini and couchdb-lucene-<version>/conf/log4j.xml to your-app/WEB-INF/classes/ .
6. Deploy your-app on Tomcat.
7. Configure the CouchDB external process hook script with the host name and port number where Tomcat is listening on.

There was one catch though, LuceneServlet did not have any no-argument constructor for the web.xml configuration, so that’s one of the changes I had to make. The other change was some file reorganisation so that you can use mvn war:war to generate a target/couchdb-lucene-<version>.war file. Too easy!

I’ll submit a pull request to master later, but in the mean time you can clone my fork to get the patched LuceneServlet and to easily generate the .war file.

Update (27/05/2011): It’s now part of couchdb-lucene master as of 0081272a30dc679effc1cf1298e365b953f568a5, should be included in v0.7.0 .

We had to wire up some logic blocks for the Lego robot to use in a simple maze. The goal was to traverse a path within the maze, the challenge was to pass some obstacles like opening a gate, executing several turns, and opening a door handle.

Our robot, all kudos to @manishchhabra27 for revving it up.

The simple maze. This robot was using its light sensor to detect the black line.

We took a different approach by using the ultrasonic sensor to detect the wall, the reasoning behind it was that traversing the black line was by far a slower process (albeit safer). But we had one problem with our approach, our robot had bad tires that made it drift to the right and then hit the wall anyway. It’s a hardware problem!

Another team’s robot. Fetch the beer, my precious.

Last weekend I went to Wellington, New Zealand, to attend CITCON A/NZ 2010. Write ups about the event have been posted on ShineTech blog:

• CITCON Australia/New Zealand 2010 – Day 1
• CITCON Australia/New Zealand 2010 – Day 2 (Part 1)
• CITCON Australia/New Zealand 2010 – Day 2 (Part 2)

In summary, the current hotness in CI world is continuous deployment, citing the experiences from IMVU and Flickr.

I didn’t get much chance to check out Wellington, it was raining for the whole three days I was there. My immediate impression of Wellington was that the CBD resembled Melbourne, while the areas up the hills reminded me of Hobart. It’s also strange how Lambton Quay was empty at 10pm on a weekend, even many of the cafes weren’t open at 11am on a Sunday. No people, no traffic, no worries, no problem.

I didn’t see any sheep in New Zealand.

Earlier today, I was trying to compile node.js on Solaris (x86, 64-bit), get it installed, and setup a simple OHAI server.

And as usual, installing stuffs on Solaris is never straightforward and I ended up encountering several issues. I’m sure these issues (specially the errors) will bite me again in the future, hence I’m blogging this.

First up…

nom> ./configure
/usr/bin/env: No such file or directory

Oh right, I forgot to install python and all of its dependencies. From node.js home page “The build system requires Python 2.4 or better.”

obj/release/mksnapshot obj/release/snapshot.cc --logfile "~/blah/ry-node-29ca7af/build/default/obj/release/snapshot.log" --log-snapshot-positions
ld.so.1: mksnapshot: fatal: libstdc++.so.6: open failed: No such file or directory
scons: *** [obj/release/snapshot.cc] Error -9
scons: building terminated because of errors.
Waf: Leaving directory `~/blah/ry-node-29ca7af/build'
Build failed:  -> task failed (err #2):
        {task: libv8.a SConstruct -> libv8.a}
*** Error code 1

ldd is your friend every time you hit this kind of error.
So I inspected mksnapshot…

nom> ldd obj/release/mksnapshot
        libpthread.so.1 =>       /lib/libpthread.so.1
        libsocket.so.1 =>        /lib/libsocket.so.1
        libnsl.so.1 =>   /lib/libnsl.so.1
        librt.so.1 =>    /lib/librt.so.1
        libstdc++.so.6 =>        (file not found)
        libm.so.2 =>     /lib/libm.so.2
        libgcc_s.so.1 =>         (file not found)
        libc.so.1 =>     /lib/libc.so.1
        libmp.so.2 =>    /lib/libmp.so.2
        libmd.so.1 =>    /lib/libmd.so.1
        libscf.so.1 =>   /lib/libscf.so.1
        libaio.so.1 =>   /lib/libaio.so.1
        libdoor.so.1 =>  /lib/libdoor.so.1
        libuutil.so.1 =>         /lib/libuutil.so.1
        libgen.so.1 =>   /lib/libgen.so.1

Turned out that both libstdc++.so.6 and libgcc_s.so.1 were installed in /usr/local/lib but not available from /lib. So I simply created symlinks for /lib/libstdc++.so.6 and libgcc_s.so.1 pointing to /usr/local/lib . Another workaround was to set LD_LIBRARY_PATH=/usr/local/lib, but I heard it’s bad.

On to the next one…

ImportError: ld.so.1: python: fatal: relocation error: file /usr/local/lib/python2.6/lib-dynload/_socket.so: symbol inet_aton: referenced symbol not found

This one was just strange, I couldn’t figure out which library dependency was missing, and it took me a while to find out that the python binary I had wasn’t built correctly (some library links were missing from _socket.so) . At the end I used the binary from Sunfreeware which had the correct links.

I got this next error when I accidentally compiled node on a SPARC box, which I believe is not a supported architecture. c-ares only has sunos-x86 header files for Solaris.

../deps/c-ares/ares_expand_string.c:18:24: ares_setup.h: No such file or directory

And another one, on the same SPARC box…

TypeError: cannot concatenate 'str' and 'NoneType' objects:

This is a similar issue that stevel mentioned on nodejs Google Group. Basically deps/v8/SConstruct couldn’t figure out the compiler and returns ‘None’ which can’t be concatenated to a String, this line here…

the toolchain to use (' + TOOLCHAIN_GUESS + ')'

After 3-4 hours, I finally got node.js installed, and a simple server up and running on Solaris.

OHAI
KTHXBYE

My current employer, Shine Technologies, allowed me to spend a couple of days to contribute to an open source project, so naturally I chose Hudson and worked on things that are useful for the projects I’m involved with at work.

SiteMonitor Plugin was a late follow up to this short thread on Hudson users mailing list about a year ago. JSLint support in Violations Plugin was an effort to add JSLint report handling in Hudson a la Checkstyle.

people around you are not blind...

I’ve been doing daily stand-up meetings for all but 1.5 years of my time in the software development industry, and I had plenty of chance to observe the good and bad habits during the stand-up.

For this part, I’ll just highlight the need to keep what you say relevant to the project, to not pause too long and too often, and to not unconsciously perform politically incorrect hand movement where no one wants to pair-program with you afterward.

The above panel was drawn this morning while waiting at Caulfield Station. I’ll do part 2 on the next down time, whenever that is.

So I was using net-ssh-2.0.15 and jruby-openssl-0.5.1 for a piece of code that’s supposed to perform some remote operations. The Net::SSH usage itself was straightforward…

Net::SSH.start(@host, @username, :keys => @keys) do |ssh|
    ...
end

When I ran the above snippet on Windows XP, it gave this error message without any further information…

The system cannot find the path specified

Not exactly helpful, eh? And after some sleuthing around, it came down to add(host, key) method in lib/net/ssh/known_hosts.rb :

def add(host, key)
  File.open(source, "a") do |file|
    blob = [Net::SSH::Buffer.from(:key, key).to_s].pack("m*").gsub(/\s/, "")
    file.puts "#{host} #{key.ssh_type} #{blob}"
  end
end

This method is trying to add an entry to the known_hosts file, which location is stored in source variable. In my case, the variable resolved to C:/.ssh/known_hosts . But the problem was that the .ssh directory didn’t exist. So I simply created it.

Lo and behold, when I ran this piece of code on a Solaris box weeks later, I hit another error message…

No such file or directory (IOError)

which turned out to be caused by the exact same thing, but this time the location is <script_home>/.ssh/known_hosts . The workaround was the same, I simply created the .ssh directory.

So there you go, hopefully it helps whoever else was confused by the unclear error messages.
And in terms of a long term solution, it would be nice if add(host, key) checks or even creates the .ssh directory before attempting to write known_hosts file.

The only issue I had was with image saving. From Image class documentation (Watir 1.6), it wasn’t obvious that save can only be called when image element is directly contained within a browser element.

I was trying to save the first image within a div,

$browser.div(:id, 'foobar').images[1].save('d:\\temp')

which resulted in this error

NoMethodError: undefined method `goto' for #<Watir::Div:0x3fa5d7c>
d:/dev/ruby/lib/ruby/gems/1.8/gems/watir-1.6.2/lib/watir/image.rb:113:in `save'

Looking at the implementation of save in image.rb,

def save(path)
  require 'watir/windowhelper'
  WindowHelper.check_autoit_installed
  @container.goto(src)
  begin
    thrd = fill_save_image_dialog(path)
    @container.document.execCommand("SaveAs")
    thrd.join(5)
  ensure
    @container.back
   end
end

it shows that save relies on the existence of goto and back methods within the container of the element, meaning that calling save method will tell the browser to go to the image src value, save it, and then click the back button. Hence image must be contained directly within a browser element.

I ended up having to use XPath because the image element doesn’t have any id or class that allows me to directly reference it from a browser element.

$browser.image(:xpath, "//div[@id='foobar']/img").save("d:\\temp")

It would be nicer if @container can be replaced by something like find_root_container or something that traverses the ancestor container elements and eventually finds a browser element.

Another nice improvement to the save method implementation would be instead of going to the image src and then clicking back, which could potentially lose the state of a page, it would be nicer to open a new window and close it afterward.

Classic web 0.1!

How the hell did I start the day with 28 JIRAs, resolved 10, and finished with 35 on my list?

Get me a summary of the open JIRAs!

How many JIRAs do you have?

Ok, it’s confirmed, please raise a JIRA.

Without noticing, we started refering issues as JIRAs. Just like saying “I’ll google it” when I want to say “I’ll use a search engine to find some info about it”. JIRA might be going through the same phase of greatness.

I’m not trying to jump on any praising bandwagon, but I still remember thinking “Finally someone has done it right. A proper issue tracker!” a few weeks after I started using JIRA for the first time. That was right after some months using Bugzilla and FogBugz.