RSS

Selecting the value of an HTML combobox programmatically using a WebBrowser Control

Recently I’ve been playing around with a webbrowser control to automate my interaction with a website for testing purposes. I am using C# and DOT NET.

I found it a bit difficult to change the value of an HTML combobox (i.e. dropdown), but as it turns out it’s rather easy.I used the following code to change the value of a combobox named: “test” to the value 12.

foreach (HtmlElement el in webBrowser1.Document.GetElementsByTagName("select"))
{
if (el.Name == "test")
{
foreach (HtmlElement comboItem in el.Children)
{
Console.WriteLine(comboItem.InnerText + " " + comboItem.GetAttribute("Selected"));

if (comboItem.InnerText == "12")
{
comboItem.SetAttribute("Selected", "True");
}
}
}

}

This code was used for the following HTML:
<select name=”test”><option value=”10″ SELECTED>10</option><option value=”11″>11</option><option value=”12″>12</option><option value=”13″>13</option><option value=”14″>14</option></select>

foreach (HtmlElement el in webBrowser1.Document.GetElementsByTagName("input"))
{
if (el.Name.ToLower() == "submit")
{
el.InvokeMember("click");
}
}


A small adventure comes to a happy end..

I have a Windows XP installation on a VMWare hard disk. Today I tried to boot it, but… OOPS (no.. I don’t mean Object Oriented Programming and Systems… I mean..crap!). It seems I forgot the password of the installation. So a little adventure started…

1. After a bit of research I found out that there is ophcrack. I downloaded the live CD as an ISO image and set VMWare to load that CD.

2. When VMWare starts and before windows starts booting I clicked on the VMWare screen and pressed ESC. This gives me the menu to select the device I want to use to boot.

3. I chose to boot from the CD.

4. The ophcrack live CD starts loading, but when it finishes I get a:  “No partition containing hashes found” error.

5. The problem seems to be that the Windows installation is on a SCSI virtual disk that is not recognised by this distribution of linux. Tried “fdisk -l” on a terminal from within the ophcrack live CD and it didn’t return any results.  To be able to crack the password I need to have access to the “WIndows/System32/config/ folder of my virtual hard disk. So…

6.  I created a second virtual hard disk in the same VMWare virtual machine. I downloaded an ISO image of Ubuntu

7. Installed Ubuntu on the newly created hard disk.

8. Boot using Ubuntu. Ubuntu was able to access the virtual hard disk of the windows installation. I copied the folder “WIndows/System32/config/” on my local Windows 7 installation.

9. Downloaded ophcrack for Windows and installed it on my Windows 7. Also downloaded the XP Free Small Table.

10. Launched ophcrack and clicked on “Tables”->Install and selected the folder where I had downloaded the XP Free Small Table file (if it is a zip file you need to unzip it).

11. Select Load->Encypted SAM and select the “config” folder I had copied from the VMWare installation (through Ubuntu).

12. Got my password in 45 seconds!!


Top Programming Quotes

I have received an Email with the top 50 programming quotes. Here are my favourites:

  • “Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the universe trying to build bigger and better idiots. So far, the universe is winning.” – Rick Cook
  • “Walking on water and developing software from a specification are easy if both are frozen.” – Edward V. Berard
  • “They don’t make bugs like Bunny anymore.” – Olav Mjelde
  • “A C program is like a fast dance on a newly waxed dance floor by people carrying razors.” – Waldi Ravens
  • I have always wished for my computer to be as easy to use as my telephone; my wish has come true because I can no longer figure out how to use my telephone.” – Bjarne Stroustrup
  • “In the one and only true way, the object-oriented version of ‘Spaghetti code’ is, of course, ‘Lasagna code’ (too many layers).” – Roberto Waltman
  • “For a long time it puzzled me how something so expensive, so leading edge, could be so useless. And then it occurred to me that a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are, in short, a perfect match.” – Bill Bryson
  • “Good design adds value faster than it adds cost.” – Thomas C. Gale
  • “Perfection [in design] is achieved, not when there is nothing more to add, but when there is nothing left to take away.” – Antoine de Saint-Exupry
  • “The best programmers are not marginally better than merely good ones. They are an order-of-magnitude better, measured by whatever standard: conceptual creativity, speed, ingenuity of design, or problem-solving ability.” – Randall E. Stross
  • “To iterate is human, to recurse divine.” – L. Peter Deutsch
  • “The trouble with programmers is that you can never tell what a programmer is doing until it’s too late.” – Seymour Cray
  • “Most good programmers do programming not because they expect to get paid or get adulation by the public, but because it is fun to program.” -Linus Torvalds

And my favourites:

  • “You can’t have great software without a great team, and most software teams behave like dysfunctional families.” – Jim McCarthy
  • “Beware of bugs in the above code; I have only proved it correct, not tried it.” – Donald E. Knuth
  • “Sometimes it pays to stay in bed on Monday, rather than spending the rest of the week debugging Monday’s code.” – Christopher Thompson
  • “First learn computer science and all the theory. Next develop a programming style. Then forget all that and just hack.” – George Carrette
  • “Most software today is very much like an Egyptian pyramid with millions of bricks piled on top of each other, with no structural integrity, but just done by brute force and thousands of slaves.” – Alan Kay
  • “Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.” – Martin Golding
  • “There are two ways of constructing a software design. One way is to make it so simple that there are obviously no deficiencies. And the other way is to make it so complicated that there are no obvious deficiencies.” – C.A.R. Hoare
"Programming today is a race between software engineers striving to
> build bigger and better idiot-proof programs, and the universe trying to
> build bigger and better idiots.
> So far, the universe is winning." - Rick Cook

Getting the CPU Usage in C#

I recently wanted to get the usage of my CPU in C#. After searching the internet I found a way of doing it using the PerfomanceCounter class. I made a couple of changes and I created the following class, which seems to work.


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

{
public class SystemUtils
{
public static long getCpuUsage()
{
PerformanceCounter cpuCounter;
cpuCounter = new PerformanceCounter();

cpuCounter.CategoryName = “Processor”;
cpuCounter.CounterName = “% Processor Time”;
cpuCounter.InstanceName = “_Total”;

cpuCounter.NextValue();
System.Threading.Thread.Sleep(1000);
return (int) cpuCounter.NextValue();
}
}
}

Using the statement: SystemUtils.getCpuUsage() you should be able to get an integer number showing the CPU usage.


Must have Eclipse plugins

From time to time I develop something on Eclipse. Apart from the usual Eclipse operations (build and test) that I do with the Eclipse Ant and JUnit plugins (they ship with Eclipse for Java), I also wanted to carry out some dependency analysis on existing code. Of course JDepend is the obvious option, but I found a nice article from IBM that suggests some additional plugins that help the coder carry out day to day tasks such as Complexity monitoring and Coding standard analysis.

The following is a summary of the plugins proposed by the article. Of course all of them are opensource/free.

Tool Purpose URL for Eclipse plugin
CheckStyle Coding standard analysis http://eclipse-cs.sourceforge.net/update/
Coverlipse Test code coverage http://coverlipse.sf.net/update
CPD Copy/Paste detection http://pmd.sourceforge.net/eclipse/
JDepend Package dependency analysis http://andrei.gmxhome.de/eclipse/
Metrics Complexity monitoring http://metrics.sourceforge.net/update

The full IBM article can be found here: http://www.ibm.com/developerworks/java/library/j-ap01117/


Exception using XMLConfiguration

I tried using the Apache XMLConfiguration to save the settings of an application I am developing to XML format. When I used it with Java 1.5 it all worked perfectly; however if I tried using it with Java 1.6 I was getting the following exception.


Exception in thread "main" java.lang.AbstractMethodError: org.apache.xerces.dom.DocumentImpl.getXmlStandalone()Z
at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.setDocumentInfo(Unknown Source)
at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(Unknown Source)
at com.sun.org.apache.xalan.internal.xsltc.trax.DOM2TO.parse(Unknown Source)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transformIdentity(Unknown Source)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(Unknown Source)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(Unknown Source)
at org.apache.commons.configuration.XMLConfiguration.save(XMLConfiguration.java:880)
at org.apache.commons.configuration.AbstractHierarchicalFileConfiguration$FileConfigurationDelegate.save(AbstractHierarchicalFileConfiguration.java:454)
at org.apache.commons.configuration.AbstractFileConfiguration.save(AbstractFileConfiguration.java:546)
at org.apache.commons.configuration.AbstractFileConfiguration.save(AbstractFileConfiguration.java:513)
at org.apache.commons.configuration.AbstractFileConfiguration.save(AbstractFileConfiguration.java:491)
at org.apache.commons.configuration.AbstractFileConfiguration.save(AbstractFileConfiguration.java:403)
at org.apache.commons.configuration.AbstractHierarchicalFileConfiguration.save(AbstractHierarchicalFileConfiguration.java:199)

After doing some search on google I found that this can be a problem with the xerces XML library (xercesImpl.jar). Checking the 3rd party libraries I am using in my project, I found a library that was using and distributing an earlier version of xercesImpl.jar.

I downloaded the latest version (2.91) of xercesImpl.jar from the Apache xerces project (http://xerces.apache.org/mirrors.cgi#binary) and replaced in the 3rd party library I was using the xercesImpl.jar file with the one I downloaded. Now everything seems to work fine, even in Java 1.6.  :-)


.NET Certification

A few weeks ago (http://kyriakos.anastasakis.net/prof/blog/?p=24) I posted that I was interested in .NET certification. Unfortunately I haven’t had the time to work on it since then. The main incentive was to get acquainted with the DSL tools provided in .NET 3.0 (even though the available certification exams are only for .NET 2.0).

Today I read an article in ComputerWeekly that there is a shortage of .NET skills (http://www.computerweekly.com/Articles/2007/09/03/226513/employers-struck-by-shortage-of-.net-skills.htm)

It would be interesting to work on a contact .NET project and see the potential of applying Model Driven techniques in practice… But I guess I will have to find some time to study for the certification first.


SiTra and Eclipse 3.3 or Java 1.6

I recently installed eclipse 3.3 and Java 1.6. Today I tried to use SiTra (Simple Transformations in Java) but when I tried to compile it Java started complaining on the following methods of the SimpleTransformerImpl.java:

public Object transform(Object object) {
return transform(Rule.class, object);
}
public List<? extends Object> transformAll(List<? extends Object> sourceObjects) {
return transformAll(Rule.class, sourceObjects);
}

The error was something about java inconvertible types. I don’t know if it is the new version of eclipse or Java 1.6. Looks like for some reason the compiler doesn’t recognise that Rule.class is of type Class<? extends Rule<S, T>>, so as to call the public <S, T> T transform(Class<? extends Rule<S, T>> ruleType, S source)

A simple solution is to ct the Rule.class expression to Class (it sounds weird but it worked).

So the transform and transformAll methods become:


public Object transform(Object object) {
Class r = Rule.class;
return transform(r, object);
}
public List<? extends Object> transformAll(List<? extends Object> sourceObjects){
Class r = Rule.class;
return transformAll(r, sourceObjects);
}


Making UML2Alloy compatible with Alloy v4.0

Alloy Analyzer v4.0 has been out for quite a while. Alloy v4.0 is an extension of the Alloy v 3.0 language (http://alloy.mit.edu/alloy4/quickguide/a4.html). More specifically parts of the concrete syntax of the language has changed (i.e. when invoking a predicate from within another predicate we now have to use brackets “pred1 [param1,param2,..]” instead of parentheses “pred 1(param1, param2,..)“. Also some of the properties of the language have changed (in MDA terms constraints on the metamodel, or well-formedness rules have changed). For example in Alloy 4 you are able to overload predicates, functions and fields. These are relatively small changes and it should be easy to accommodate them in UML2Alloy.

However, Alloy v4.0 has been developed from scratch and it is based on the kodkod model finder. The AST implementation has changed substantially and the convenience methods provided on the AST model elements are fine tuned for the Alloy compiler. For example Signature constructors are private and I couldn’t find a way to update the properties of Signatures (i.e. the Multiplicity of the Signature) after a Signature has been created.

Of course this is perfect if you have an Alloy model and you just want to parse, but not very convenient if you use an MDA approach to instantiate Alloy AST objects. For example in UML2Alloy you can change the Multiplicity of a Signature (i.e. change from set to some to enforce that some Signature instances will exist in the model). If you don’t have access to the Multiplicity attribute of the Signature class, after the object has been created, complicates the situation.

Moreover the AST class elements have been defined as final so there is no way you can override the Alloy v4.0 AST classes.

So, I spent almost 1 day evaluating the situation and trying to find a solution. One solution would be to create my own implementation of Alloy’s AST. Another would be to create wrapper classes of Alloy’s AST that will have pointers to the actual Alloy implementation.

Then I stepped back and thought about the siltation. Well, I already have a rather stable implementation that uses Alloy v3.0 AST. In Alloy v4.0 the AST has NOT changed. Just the concrete syntax. So the solution is easy.

Currently in UML2Alloy after the Alloy AST objects have been generated by SiTra, a visitor is used to create a text file that contains the Alloy model. So, all I have to do is use another visitor and override the methods that create the part of the model for which the concrete syntax has changed.


.NET 2.0 Certification?

Lately I have started becoming interested in becoming a .NET certified professional. But is it worth it starting to work towards a .NET 2.0 certification, considering the visual studio 2008 will be out in 6 months time? However it will probably take sometime after the release of VS 2008 for MS to review their certifications.

For the time being I am thinking of working in my spare time for the MCPD: Web Developer certification. The main reason for this is that I need to get my mind off the PhD from time to time. I also have a free copy of VS 2005 Professional, when I attended the launch tour, so practising for the exams shouldn’t be a problem. My plan is to be ready for the first exam by sometime at the end of August. Let’s see if I can make it!