Two models of load testing and corresponding tools

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:

• JMeter
• Faban

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.

Google Reader supports search now

This morning I found search interface appeared on Google Reader page finally. It is time to retire the Google custom search engine made for blogs.

Solution of window resizing and moving for MS Windows with multiple monitors

I have tried several free tools on Windows system for window resizing and moving in and around multiple monitors. They were not that good, and even did not work when I have two monitors with different resolution and also layout (one portrait and one landscape). However, WindowPad surprised me by how easy this can be done using AutoHotKey. The original version of WindowPad is available at http://www.autohotkey.com/forum/topic21703.html. I made some small changes to

1. Set the NumLock of keyboard to be always on when the script runs;
   


2. Restore a maximized window before moving it to the next monitor, and then maximize it again.
   

The first change fixes the problem that the NumLock is set off when I remote connect to the box from the laptop at home. The second change makes the script work for moving a maximized window from a high resolution monitor to a low resolution one. The original script has been updated to fix the problem mentioned here and other bugs. Please check the latest version.

Notes on installation and configuration of latex2html with MiKTeX

"Installing LATEX2HTML with MiKTEX" and "Tools for Publishing LaTeX Documents on the Web" are two good reference for dealing with latex2html. The following are a list of notes I wrote down when installing and configuring latex2html with MiKTeX.

1. It is important to install MiKTeX, Ghostscript, and latex2html in a path with no space in between, the default place under "Program Files" will introduce problems.


2. If you install NetPbm for Windows using the Binaries release, do not forget to drag the Dependencies as well. So you will not get error messages about missing dll's.


3. Change the location where Ghostscript, NetPbm, and latex2html are installed in prefs.pm. The line numbers are not exact the same as in Installing LATEX2HTML with MiKTEX due to versioning.


4. Change the $TMP in l2hconf.pm to a path with no space in between as well.


5. While most configurations are done by updating l2hconf.pm in Installing LATEX2HTML with MiKTEX, I suggest use $INIT_FILE_NAME to do the customizations that you like. You need to change $INIT_FILE_NAME to a file name that Windows system can recognize like 'dot.latex2html-init'. The default '.latex2html-init' is not accepted by Windows.


6. Jos has a latex2html-init file that fixed several bugs in the original one coming with latex2html distribution. I found it is very helpful. I reused all the perl functions in that file, but did not use his style part.


7. In order to get white background of the images, I set
   

   
   @IMAGE_TYPES = qw(png gif);
   $IMAGE_TYPE  = $IMAGE_TYPES[0];
   

   
   which means use png format.
   And in the latex2html-init file, I set
   

   
   $TRANSPARENT_FIGURES = 0; # default = 1
   $LOAD_LATEX_COLOR = "\\usepackage[dvips]{color}";
   $LATEX_COLOR = "\\pagecolor[gray]{1}"; # 1 means white and 0 means black
   

   
   


8. In order to change the personal information in the $ADDRESS and "About this document", I set
   

   
   $DONGHOME = "http://homepage.usask.ca/~dol142";
   $DONG = "<A href=\"$DONGHOME\"> Dong Liu</A>";
   $address_data[0] = $DONG; # My real name
   $ADDRESS = "Copyright &#169; <I>$address_data[1]</I>  <I>$DONG</I>"; # rewrite $ADDRESS
   

   
   

Grammar check of documents generated by LaTeX

LaTeX is good for formatting academic papers and thesis with provided style files. Spelling check of LaTeX documents is never an issue by using a tool like Aspell or with the support of your text editor. However, grammar check still looks like an impossible task. For Windows users, this may be the most strong excuse to say Word is still better for everyday writing. Yes ... and why not use Word to do that task for LaTex documents? Word does not interpret LaTex, but how about RTF or HTML?

I have tried several applications converting pdf files to RTF including Acrobat professional. The generated files are messy. So I tried tools generating HTML. The one that I am using now is latex2html. Open the generated HTML files and let Word to spelling and grammar check them (F7), and then you can modify the tex file correspondingly.

Search blogs subscribed in Google Reader

Basically, there are two ways to searching all the blogs in your Google Reader. One is to use Google custom search engine, and the other is to use Google gear and Greasemonkey script.

The details about the latter option is described in Raúl's blog. The offline function of Google Reader works for me, but the Greasemonkey search script halts everytime I try to start the offline search. I cannot figure out what is the problem.

What I currently use is the first option: create a custom search engine that has all the links of subscribed blogs in its site list. The details is described on Google Operating System blog. The search function really helps when you want to testity some 'Déjà vu' of your reading.

Reload a page in Firefox

A weird problem happened to Firefox of my desktop today. Some Wikipedia pages could NOT be correctly loaded because of CSS problem. 'Reload the current page' just did not work, similar as F5. Restarting Firefox did not help either. Then I figured out that I need to reload and override the cache. That is Ctrl+F5. It is better to learn all the shortcuts and find more tricks.

Using JSON to access Google data

Google supports JSON format data for most services, including Google Reader shared items. I just tried to use JSON to read the entries from my shared items in Google Reader, and display them in the sidebar of index page using the native CSS. The code is as follows.

<div class="module-info module">
  <h2 class="module-header">
    My reading</h2>
  <div id="reading" class="module-content">
  </div>
</div>
<script>
function listEntries(root) {
var html = ['<ul class="module-list">'];
for (var i = 0; i < root.items.length; ++i) {
var entry = root.items[i];
var title = entry.title;
var link = entry.alternate.href;
html.push('<li class="module-list-item">',"<a href=\""+link+"\" target= \"_blank\">"+title+"</a>", '</li>');
}
document.getElementById("reading").innerHTML = html.join("");
}
</script>
<script src="http://www.google.com/reader/public/javascript/user/00357859579464014466/state/com.google/broadcast?n=5&callback=listEntries">
</script>

Sharing my reading by Google Reader

Google Reader has a feature that generates a page and feed for your shared items. My shared items are here, and the feed is here as well. It can also generate a clip in javascript. I added the clip on the sidebar of this blog's index page.

Switching to Google Reader

Not surprisingly, I switched to Google Reader as the tool to read blog feeds. I used to use the Sage plugin for firefox. The features of Sage are enough for my requirements. However, it is difficult to synchronize my readings (both subscriptions and reading progress) on various machines. From time to time, I need to remotely connect to the machine at office to synchronize. Google Reader is the solution if you need to read feeds from different machines. To switch from Sage to Google Reader is very easy, just export the OPML file from sage and import it in Google Reader. And then you can start to enjoy the new reader.

Collecting and sharing your notes by using Google Notebook

Google Notebook is a service being developed in Google Labs. I have used it for a couple of weeks, and enjoy it a lot. Now there is no need for me to take the paper notebook around the office and home. Its valuable features include:
1. Collecting the points not just the links from the web, and
2. Easy sharing and collaborating.
The web-based applications like Google Notebook are perfect for team work of research and development projects. They would be efficient tools for organizations to collect knowledge from individuals and the web at large. I think the areas like E-leaning and knowledge management will see many such applications soon.

Spellcheck in Firefox 2.0

The Spellbound add-on does not work on Firefox 2.0, and I installed a new add-on named United States English Dictionary. It works just like Spellbound. There is also a British English Dictionary available.

Reading PDF documents on two monitors

Most papers I read are PDF documents, and I need to read two or three at the same time to compare different approaches related to the same topic. It is luck that my boss put two LCD's on my desk. Adobe reader annoyed me at first because I could not make two documents displayed on different monitors. I found the trick is at Window->Tile. It is perfect for two documents, but things will be messy when you have more than four documents opened at the same time. Now it is time to use gsview to read as many documents as you like. The difference between adobe reader and gsview is that the former can only have one application instance running on the system, but the latter has no such restriction. Therefore, there is no way to display different parts of one document on two monitors at the same time by using adobe reader when you do not make a copy of that document.

Spell check for text inputs in Firefox

For those who always type but not write, typing text without spell checking is really painful. Most editors support spell checking. Some web applications like Gmail also support that. There are lots of text input areas on web pages needing this feature. For Firefox, you can use SpellBound. The old versions of SpellBound can be found at http://spellbound.sourceforge.net. You can read this post at MozillaZine for the development version for Firefox 1.5.0. For IE, you may look at ieSpell.

The best text editor

Many programmers have experiences of using UltraEdit as the code editor, even if they have some complicated IDE available. However, UE is a shareware ... You may want to try something that you do not need to care about expiration, then PSPad is the best text editor for you. I would like to say that PSPad suplies all the features I need. You can find an interesting artical on various editors here.

A nice FREE webcam software for Windows

I just installed a webcam software named Fwink. It is light and works perfectly.

Tools to manage the documents

Reading and referring papers and books are two everyday activities for the investigators. There are many commercialized tools to manage the documents. I recommend 3 pieces of software for free in this note.

JabRef is an open source project for BibTex database management. It is developed using Java, and has a neat GUI. If you are familiar with Latex and BibTex, it is very easy to handle the software. It also supports to import data from most reference sources. For Word users, it can generate RTF according to the output template included in the release package or defined by your own.

For those who have thousands of documents saved on local disks, it is unlikely to input the entries for each document to a database. It is better to have a tool automatically index the documents for us. The current version of Google Desktop Search can index and search documents of Word, Excel, PDF, PowerPoint, and even the caches of most popular web browsers. The search results are organized the same as the Google web search.

Docco is a part of the open source project named Tockit. It can index the text, html, xml, pdf, and word documents in a folder, and generate a graph with nodes as the searching keywords. The user will see the frequencies of each keyword and their combinations in the document collection. The process of indexing could be very long if the indexing folder contains lots of document. However, never set the indexing priority to the highest because the system will appear non-responsive.