Serenity Leads to a Further Vision

Landscape table or image in LaTeX

2011-10-13T19:10:00.000-07:00

A thumb rule for landscape table or image in LaTeX:

If you are using latex+dvips+ps2pdf, use the sidewaystable or sidewaysfigure or just sideway environment in rotating package.
If you are on pdflatex, use the landscape environment in pdflscape package instead. sideway prodices a sideway table/figure, but has problem to produce a right landscape view of the page in the pdf file.

For the second option, you might also need the afterpage package to have a properly floating page for the landscape table/figure without a half-blank page before it. The environment is like

\afterpage{
\clearpage
\thispagestyle{plain}
\begin{landscape}
\begin{table}[htp]
% your table here
\end{table}
\end{landscape}
\clearpage
}

Authentication in embedded Jetty 7 server

2011-03-09T19:10:00.000-08:00

A change in Jetty security from 6 to 7 is the introduction of LoginService, which was designed to replace UserRealm based approach. The usage of LoginService can be seen in the example SecuredHelloHandler and the test case of SecuredContentExchangeTest . Basically, the LoginService needs to be attached to a SecurityHander, and the SecurityHandler needs to wrap the handler that needs the authentication service. This can be done by either

securityHandler.setHandler(yourHandler);

ServletContextHandler theContext = new ServletContextHandler(handlerContainer, contextPath, sessionHandler, securityHandler, servletHandler, errorHandler);

Aptana Studio 2.0.5 on Ubuntu 10.04

2011-02-10T19:30:00.000-08:00

Aptana Studio 2.0.5 used to work well in my Ubuntu 9.04. It started to split out error message related to xulrunner after I updated Ubuntu to 10.04. When I removed the Apatana and its workspace, it even stopped to show the messages and silently crashed. After digging and trying for almost an afternoon, I fixed the problem by adding this line to the AptanaStudio.ini file:

-Dorg.eclipse.swt.browser.XULRunnerPath=/usr/lib/xulrunner-1.9.2.13

You might change the path to whatever on your system. Note that there is a /usr/lib/xulrunner directory on my system, but that does not contain or link to the real literary files. I did not try if export the $MOZILLA_FIVE_HOME to the real xulrunner lib path will also work.

Eclipse Java test case cannot be found in a project?

2010-08-10T18:00:00.000-07:00

Eclipse said "No tests found with test runner 'JUnit 4'". The answer in JUnit FAQ does not fix my case. And the answers on stackoverflow did not help as well. Later I figured out that the reason of the problem was that I did not properly organize the test cases in my project.

The Junit FAQ has a good suggestion. I have a default src directory for the source and a test directory for the test cases. In order to let the runner find the test case, the test directory has to be a Source Folder, not just a directory created in the project directory.

Enable java in Firefox 3.0 on Ubuntu 9.04

2010-04-22T15:39:00.000-07:00

I assume you have install the JVM or SDK already. If not, see this document for reference. Maybe you also need to use the update-alternatives tool to choose the latest version as the default. Then what you need to do is to ln the libjavaplugin_oji.so plugin in the mozilla plugins directory. Creating a link in the firefox plugins directory in your system won't work. You might use the following commands to locate the plugin and create the link.

locate libjavaplugin_oji.so
sudo ln -s {the latest java}/jre/plugin/i386/ns7/libjavaplugin_oji.so /usr/lib/mozilla/plugins/libjavaplugin_oji.so

Restart your firefox and you should be able to see java in the Add-ons list.

dygraphs plot x-axis labels align with grids

2010-02-11T18:00:00.000-08:00

Recently, I learned to use the dygraphs JS library for 2d chart. Dygraphs is designed to

display dense data sets and enable users to explore and interpret them.

I like it more than Flot, another JS ploting library.

One problem I found was that the x-axis labels do not align with the grids in FireFox, while it is fine in Chrome. The fix is quite simple, just never use align = center in the

where the plot is embedded. A note from the author of dygraphs.

dygraphs are not happy when placed inside a tag. This applies to the CSS text-align property as well. If you want to center a Dygraph, put it inside a table with align = center set.

HP LaserJet 1020 on Ubunut 9.04

2010-01-17T17:00:00.000-08:00

After an update, the printer does not work any more.

Linux hpws 2.6.28-17-generic #58-Ubuntu SMP Tue Dec 1 18:57:07 UTC 2009 i686 GNU/Linux

Delete the printer and reinstall HPLIP

sudo apt-get install hplip

The printer is found, but still does not print.
Only after clicking Download Firmfare in HP Device Manager, it starts to respond to the printing request.

What is the web service language/framework Barbara Liskov mentioned

2009-12-30T17:00:00.000-08:00

In her talk titled "The Power Of Abstraction" given in OOPSLA2009, Barbara Liskov mentioned that she started to learn web services programming, and the language or framework she used has many global variables. I really wonder what she was using.

The talk is good and especially reveals the history of development of abstract data type by the list of influential papers.

Zero copy for Java HTTP file server

2009-12-11T09:55:00.001-08:00

This makes it impossible for normal Java-based HTTP service to take the advantage of zero copy.

in reference to:

"It is not possible to create a channel for an arbitrary, pre-existing socket, nor is it possible to specify the SocketImpl object to be used by a socket associated with a socket channel."
- SocketChannel (Java 2 Platform SE 5.0) (view on Google Sidewiki)

Free DNS servers

2009-12-04T09:20:00.001-08:00

Maybe some ISP's like this. The last time I tried to find a free DNS is two years ago when the ISP DNS was down. I like the ip they choose, easy to remember.

Maybe DNS is the first place that browsing statistic can be collected.

in reference to:

"To try it out: Configure your network settings to use the IP addresses 8.8.8.8 and 8.8.4.4 as your DNS servers or Read our configuration instructions."
- Google Public DNS (view on Google Sidewiki)

Rich Hickey on function, time, and process

2009-11-27T18:00:00.000-08:00

All the concurrency and timing puzzles suddenly become reasonable after listening to his talk titled "Are we there yet". I borrowed the book of "Process and Reality" from the library, and started to learn Whitehead's system.

If you do multithreading programming, or play with JavaScript and XHR, or like Erlnag, Clojure, or Scala, then you would perhaps enjoy his talk.

/bin/perl^M: bad interpreter

2009-09-30T18:00:00.000-07:00

After digging for a while, it turns out the cause is the perl interpreter on Linux cannot recognize the end of line character CRLF in windows files. What it expects is LF.

Using EOL as end of statement is not system independent.

Slides for TRLab Erlang workshop

2009-09-16T22:48:00.000-07:00

These are the slides I prepared for the last session of the workshop.

Ubuntu 9.04 on Dell Optiplex 760

2009-05-15T08:38:00.000-07:00

The issue was reported as Bug #348694.

I experienced the same problems reported there. When installing from liveCD, during the first stage you have to push the power switch to generate interruptions until the keyboard is on. Then you can start to strike a key. When the mouse is on, you can move mouse to keep the system awake. I am not sure if there is way to keep the mouse always busy in that way you will save time for installation.

The next day morning, you will find installation is finished, and you need to restart. Then you need to set the kernel options when the grub screen is on.

hpet=disable helps, but does not solve the problem.
acpi=off solve the problem, but you will lose a CPU.
acpi_skip_timer_override is the best solution.

Update: Dell has released a bios fix available here http://ftp.us.dell.com/bios/O760-A03.EXE
You need to have windows system installed to fix though.

Google search is the biggest server-side mashup

2009-03-13T16:06:00.000-07:00

Each search result page is a mashup of multiple pages, their snapshots, and possibly different representations. Of course, some contents are old, but some "important" pages are refreshed constantly in Google's index. Now they even add features like SearchWiki to personalize it. Maybe people will like the idea of SearchWiki more and more. In fact, we have used a personal mashup for a long time --- the Google Reader.

HP printer on Ubuntu 8.10

2009-02-23T07:30:00.000-08:00

The lessons I learned by trial and error about my Laserjet 1020.

foo2zjs works sometimes, but will have problem when CUPS is updated.
HPLIP always works if you install the latest version, not the one in repository.

A page about the wide finder

2009-02-20T12:51:00.000-08:00

I have published the page of wide finder, which was created for a group discussion on Erlang.

The problem of wide finder was coined by Tim Bray, and is summarized in http://www.tbray.org/ongoing/When/200x/2007/09/20/Wide-Finder

The task is to read an Apache logfile and figure out which pages have been fetched the most.

The reference Ruby code

# 11 lines

counts = {}
counts.default = 0
ARGF.each_line do |line|
if line =~ %r{GET /ongoing/When/\d\d\dx/(\d\d\d\d/\d\d/\d\d/[^ .]+) }
counts[$1] += 1
end
end
keys_by_count = counts.keys.sort { |a, b| counts[b] <=> counts[a] }
keys_by_count[0 .. 9].each do |key|
puts "#{counts[key]}: #{key}"
end

Bray's original idea was to check if Erlang is good option for this problem on multi-core platforms.

Be careful when you see some CFP's or invitations

2009-02-04T07:30:00.000-08:00

Some links for this sensitive topic:

http://diehimmelistschoen.blogspot.com/

http://netdriver.blogspot.com/2009/01/from-site-httpwwwanti-plagiarismorg.html

http://delicious.com/tag/fakeconference

The reverse C10K problem

2009-01-09T14:18:00.000-08:00

The original C10K problem studies how to provide reasonable service to 10,000 simultaneous clients or HTTP requests using a normal web server. I call the following problem the reverse C10K problem, or RC10K --- how to support 10,000 simultaneous outbound HTTP requests running on a web server. The RC10K problem can be found in scenarios like service orchestrations and server-side mashups. A server-side mashup needs to send several simultaneous HTTP requests to partner services for each inbound request.

Many approaches to improving the performance and scalability of HTTP servers can be applied to tackle the original C10K problem. However, whether these approaches can tackle the reverse C10K problem needs to be verified. My recent paper discussed the RC10K problem, and presented some experiment results got from a prototype mashup server application.

People like to try what they are not good at

2008-12-31T08:08:00.000-08:00

From xkcd.com

Two models of load testing and corresponding tools

2008-10-28T14:25:00.000-07:00

When a load testing is conducted, a tester first needs to decide what kind of workload should be applied, that is, load characterized by the number of clients or arrival rate (interarrival time) . For those who always use one tool for load testing, it is better to try other options to get different interpretation of system behaviors.

Tools specify the number of clients:

These two are both developed in Java. The most important parameter to be configured is the number of simulated users that will send requests to the server. The simulated concurrent users are natually mapped to Java threads. Both of them can specify thinking time of different distributions. A difference between them is that JMeter specifies how many rounds the request scenario will run and Faban specifies how long the test will run.

Tools specify the arrival rate:

Tsung

Since the processes in Erlang are very light, new process can be spawned very fast and a machine can support thousands of Erlang processes without problem. This make it possible for Tsung to generate load of given interarrival time, while it is difficult for Java-based tools.

Finally they heard that ... "web-based services"

2008-10-17T09:52:00.000-07:00

Back in 2007, W3C had a workshop of "Web of Services for Enterprise Computing". I have blogged it here. The presentations at the workshop made me understand more about why some thought the so-called "web services" were not about web. It was around that time that I started to believe that REST is much better than WS-* for the problems I was looking at. These came to my mind when I read the CFP of ICWS2009 this morning. It sounds like that the organizers began to realize that "web services" should be "web-based services". Two of three major conference areas have web titled -- "Web-based Services", "Web Services Applications beyond Web". Hope I can have a manuscript for it by January 19, 2009.

Reflection from Pat Helland about Amazon S3 outrage

2008-09-23T09:18:00.000-07:00

The post titled "Confidence in the Cloud" by Data guru Pat is really worth reading. Interesting quotations from his post:

the implementations which sent the minimum amount of data seemed to be the most resilient.

which leads to

Communicating less information within a message is usually best. If you send extra stuff, it can cause corruption!

For cloud, he predicts

As I look at data center cost structures, it is clear that it is going to be a competitive business with many advantages to large data center managers with large economies of scale. In a handful of years, most companies will look to offsite providers for their reliable servers.

Word cloud of my reading

2008-09-03T15:35:00.001-07:00

Created by Wordle. You may need Firefox, because Chrome does not support the applet.

Comic of Google Chrome

2008-09-03T09:02:00.000-07:00

Its quite interesting to read what Google engineers think about the web browser or web client design with respect to multi-threading and multi-process for tabs (http tasks).

And what the multi-process means for memory management. Many blocking and crashing problems result from shared memory and memory space.