Skip to main content

Virtual Labs -- User Trials

The Virtual Labs project was launched a year ago.  Currently, these labs are undergoing user trials. I have been involved with the development of two virtual labs -- Software Engineering (cse08) and Advanced Network Technologies (cse28).

Interested users may visit these labs. It would be further useful if you could provide feedback on one or more experiments. The feedback link is available in the navigation bar at the top.

Comments

Popular posts from this blog

Text Highlighting in Latex

While preparing a manuscript with Latex, it is often useful to highlight the changes made in the current revision with a different color. This can be achieved using the\textcolor command provided by Latex. For example,\textcolor{red}{Hello World}would display the string "Hello World" in red color.

However, the final/published copy of the manuscript does not contain any highlighted text. Therefore, if a large volume of changes were made, it becomes tiresome at the end to find and remove all the individual portions of highlighted text.

This can be circumvented by defining a utility command to switch highlighting on and off as desired. In the following, we define a new Latex command, highlighttext, for this purpose. The command takes only a single argument -- the text that it should highlight.

    \usepackage{color}

% For highlighting changes in this version with red color
    \newcommand{\highlighttext}[1] {\textcolor{red}{#1}}
    % Remove all text highlighting
    % Useful to gener…

Specifying Source and Destination of Messages

One of the frequently asked questions in the community is how to specify which particular nodes would act as source(s) and destination(s) of the messages created in the ONE simulator. The simulator, in fact, provides a pair of settings (shown below in bold face) aimed for this particular purpose.

Let us consider that there are $n + 1$ nodes in an OMN.  Further, let the nodes with addresses from $x$ to $y$, both inclusive, would create messages. The nodes in the range $w$ to $z$, both inclusive, would be the destinations of those messages, where $0 \le x \le y \le n$, and $0 \le w \le z \le n$. Then, the corresponding simulation scenario can be configured as follows.

## Message creation parameters # How many event generators Events.nrof = 1 # Class of the first event generator Events1.class = MessageEventGenerator # (Following settings are specific for the MessageEventGenerator class) # Creation interval in seconds (one new message every 25 to 35 seconds) Events1.interval = 25,35 # Me…

IllegalArgumentException in Simulations

At times, users have reported of runtime exceptions while running a simulation that uses PRoPHET. The error signature looks like the following.

Exception in thread "main" java.lang.IllegalArgumentException: Comparison method violates its general contract! at java.util.TimSort.mergeHi(Unknown Source) at java.util.TimSort.mergeAt(Unknown Source) at java.util.TimSort.mergeCollapse(Unknown Source) at java.util.TimSort.sort(Unknown Source) at java.util.Arrays.sort(Unknown Source) at java.util.ArrayList.sort(Unknown Source) at java.util.Collections.sort(Unknown Source)
It may be noted that the default sorting algorithm has changed since Java 7 — rather than Merge sort, Tim sort is now used by default. However, it seems like it is possible to override the default sorting algorithm in Java using the following argument to the JVM.
-Djava.util.Arrays.useLegacyMergeSort=true
The execution command in the one.sh (or one.bat) file should be updated with the above argument to something like this:

j…