Category Archives: Computers and Internet

Posts on computer science and the web, rants about OS:es, Window Managers, Platforms for almost publishing content on the web, and the like.

Computers and Internet, Politics and Society

Time to put the IT-business out of its misery?

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I just came across this article about the Apple-Samsung battle:

http://www.engadget.com/2012/08/10/apple-samsung-presentation-licensing/

I’ve decided software patents pisses me off… and if they are allowed to be honoured 100% as patent laws intends it… we could just put the IT-business out of its misery and go back to pen and paper (unless there’s a “writing” patent out there somewhere?) … or perhaps we should “call software patents as we see them” and put them out of their misery…?

This is what different (clueless and unfit?) patent clerks have decided to approve:

  • US 5566337 – owned by Apple, A.K.A. the Observerpattern. Kiss SWT, Swing and almost all other GUI frameworks goodbye – they use observation to handle events such as clicking a button.
    • “In a computer including an operating system, an event producer for generating an event and detecting that an event has occurred in the computer and an event consumer which need to be informed when events occur in the computer”
  • US 5969705 – also Apple – details how an operating system can be “multitasking”… filed 1997 and accepted 1999… I knew Windows 95 wasn’t multitasking, but HEY… there are other OS:es out there… like Linux… that was multitasking LONG before 1999…
    • “Method and apparatus for a first process operative in a computer system controlling a user interface on a computer system display under control of a second process operative in the computer system. An event handler is installed for the second process, the event handler servicing events generated for controlling the user interface display under control of the second process. The first process may then perform a first set of functions in the computer system. The first process generates events for controlling the user interface display, the events related to the functions performed by the first process. The event handler receives the events generated by the first process and updates the user interface on the computer system display according to the events generated by the first process and received by the event handler.”
    • Or I guess we could always handle multitasking by having one process doing all of  the above and then having another process jerking off while that happens… reminds me about the “Multi Agent Programming” course on UNI when we had to implement a Multi agent system for playing chess…
  • Or how about US 5911067 – “Application Switching”
    • “A method and apparatus for transferring control between application programs. A messaging means is provided which allows a first application program to indicate to the messaging means that a second application program should assume control. The messaging means receives the message and performs an orderly shutdown of the first application program and messages the second application program that it should commence operation. Upon valid and proper operation of the second application program, the first application program is caused to be suspended, and the second application program is invoked.”
    • An alternative would be to have one application that can run several “programs” like different Wordfiles… or wait… wouldn’t that be just like an operating system starting an…. Application… oh well.. who needs applications… and anyway… who needs to switch between them? Let’s play “Windows” again… it’s an application… right?

I’m certain many people that doesn’t know so much about computers or programming (like the patent (cl/j)erks who approved these patents) will find the whole discussion abstract and boring. Who cares about some bizarre event-something, or some applications-something… and besides, they were smart and they worked hard for their patents… you’re just being a jealous douche bag for not allowing them their well earned cash in…

In an attempt to strike home the preposterous nature of these patents, here are some examples of patents that will never be accepted, because they are as obviously not fit for patenting to the “common man” as most IT-patents are to IT professionals:

  • Waste product gathering and disposal mechanism:
    • A method for gathering waste products in home or industrial environments, and a process for disposing of them. Following these steps: 1) take a plastic bag, place it in a holder such as a waste bin, or just let it lay on the floor, or some other surface where the bag is readily accessible. 2) whenever there’s “waste” (different forms of materials in need of disposal such as wrappers, paper napkins, fruit peals, etc) put it in the bag. 3) once the bag is full (or in the case of perishable waste, at a set time interval such as “several times a week”) tie the open end of the bag and throw it out…. (“Trashcan” patent for detailing the “throwing out” pending…)
  • Garment renewal process:
    • A method for renewing used garments such as socks and shirts. Follow these steps. 1) Wear garments. 2) Throw garments in laundry basket. 3) when you run out of clean clothes, apply water and detergent + mechanical “swashing around” – rinse and dry… 4) voila – clothes are as good as new…

Now why can’t I have those patents, and why do I not deserve them?

Because they are obvious methods for solving trivial problems. Unfortunately for the IT-business the patents awarded for the same obvious methods for the same trivial problems are not obvious to the people awarding the patents. It seems comparing the IT business with the construction business won’t really be worth anything unless you have “digging patents” to be harassed by when you try to build a house…

Ah well… I want to write a bestseller anyway… perhaps I should do a “Grisham” and write about a patent breaking IT company that feeds their employees to the sharks in order to prevent exposing their evil deeds?

Computers and Internet

How do you log to the Windows event log from C# .NET?

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This seems to do the trick if you want to log to the Windows event log:

private void logError(string message, string source)
{
	System.Diagnostics.EventLog log = new System.Diagnostics.EventLog();
	log.Source = source;
	log.WriteEntry(message, System.Diagnostics.EventLogEntryType.Error);
	log.Close();
}

private void logError(Exception exception, string source)
{
	logError(exception.ToString(), source);
}

Put it in your class, or in a special logging class.

Read more:

Internt/Egna SharePoint – Miniprojekt Utveckling/Design Lookup fält programmagiskt… / ContentTypes
Computers and Internet

Is Java pass-by-value or pass-by-reference?

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The question if Java passes parameters by value or by reference seems to be one of the things newcomers to the Java language stumble upon quite often.

In general the answer is simple: Java is always pass-by-value.

What does this mean?

Pass-by-value means that you get a copy of the passed in object to work with, as opposed to a reference to it.

Let’s exemplify.  Assume we have a method that manipulates a List object:

public void updateList(List list) {
    ..;
}

Now, assume we’d like to replace the passed-in list with another list we’ve created inside the method.  We might like to do something like:

public void updateList(List list) {
    List myList = new ArrayList();
    // add objects to myList
    list = myList; // replace list with my new list? *WRONG*
}

However, if we test this new method we’ll find list has not changed at all.

This is because list is a copy of the object we passed-in to the method, and not the passed-in object itself.  list has been passed-by-value!

So, are we unable to change variables that are passed-in to a method in Java?  Can we only change them by returning a new object?

No.

And this is where the confusion sets in, because while we’re unable to replace the passed-in object list with another object, we’re perfectly allowed to manipulate it’s member objects.

Basically this means if we want to replace a passed-in list with our own list we must do:

public void updateList(List list) {
    List myList = new ArrayList();
    // add objects to myList
    list.clear(); // empty passed-in list
    list.addAll(myList); // replace passed-in list with my new list!
}

Since we never try to replace list itself, the whole method works just fine and does what we expect.

Computers and Internet

Black pointer: Never lose track of your mouse pointer again

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I’ve tried several ways to keep track of my mouse pointer.  It’s kind of hard from time to time.  Adding more than one monitor does not help at all!

Recently a colleague gave me the tip to make the mouse pointer black… and larger. I tried this and found that the mouse pointer was much easier to spot.  No surprise there, really.  After all, white on white tends to become a bit hard to keep track of, tiny silhouette outline or not.

I was told how to do this in Windows (Control Panel > Mouse > Pointer, but that’s another story).

In Gnome (I’m running Ubuntu 8.10) you do it in the System > Preferences > Appearance dialog (see below).  In my version of Window’s there’s no settings under Appearance > Mouse.

Appearance Preferences

Next you click the “Customize” button:

Customize Theme

In the new dialog select the “Pointer”-tab and select the color of pointer you want.  In order to resize it, see the “size slider” below the list of pointers (there seems to be three distinct sizes to choose from).

Click “Close” once you’re done, and voila, you have a new and much easier to spot mouse pointer!

Computers and Internet

Sun Tzu’s Art of War – Agile…

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A quote from the Art of War that might have some baring on Agile development techniques:

31. Water shapes its course according to the nature
of the ground over which it flows; the soldier works
out his victory in relation to the foe whom he is facing.

32. Therefore, just as water retains no constant shape,
so in warfare there are no constant conditions.

But then again, we all know war is agile, right?

Or another quote I heard (source unknown, original language Swedish):

Meeting all requirements in programming is like walking on water.  It’s easy if the water and the requirements are frozen…

Computers and Internet

Random thought: Windows disproves Darwinism

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Microsoft Windows is the unique case that disproves Darwin’s theories of natural evolution and survival of the fittest while at the same time supplying no support for the main theory opposing Darwinism, the so called Intelligent Design Theory.  It is obvious the existence of a system such as Microsoft Windows is the work of a deity.  In this case an inherently chaotic and evil one; we usually refer to it as the Devil.

Mmm… wonder if I may be able to do a thesis on that, just wonder if it should be in the religion or computer science department… 😀

Computers and Internet

CHARVA: A Java Windowing Toolkit for Text Terminals

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Looking around for an easy way to create applications with text GUIs for running over SSH terminals I came across CHARVA. CHARVA’s API copies Swings, it unfortunately is not built on top of Swing but is a copy of Swing. This forces implementers to import classes in the charva.awt and charvax.swing packages instead of traditional awt and swing classes. However, the result is rather nice, at least if you’re looking to run applications off a server on a simple Point-of-Sale or Point-of-Service (POS) terminal that may not even support graphics.

In my case I’m looking into making a simple app that I can use to keep track of passwords, both when I’m at home (regular swing) and when I’m away (at work or similar) and only able to access the application via SSH (CHARVA).

For more info, check out CHARVA here: http://www.pitman.co.za/projects/charva/index.html

Computers and Internet

Compiling to different versions of Java in Eclipse

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I’ve just had the rather unsettling experience of trying to deploy a new jar file (one I recompiled after some changes). This file were to be deployed on a rather old set up of Java 1.4.2. On first try everything broke with the classic “Unsupported major.minor version 50.0”.

So I went back to the drawing board. I installed java 1.4, and made sure my development Tomcat was running it. Then I did some research and found out how to make Eclipse compile 1.4 compliant code. I started and I got the same error still.

Once I figured out what was wrong I realized I was an idiot (Doh!). The error I’ve gotten wasn’t for any file part of the jar I was trying to deploy but for “index_jsp”. The thing is my Tomcat compiled my JSP:s into class files and never looked at them again until they were changed. I am sure there’s several ways to solve the problem, I just went and deleted the files in the “work”-directory (those pertaining to my Context).

The preferences window for setting source and target versions for java compilation
The preferences window for setting source and target versions for Java compilation

Now over to how to make Eclipse code projects to a certain Java version.

There are two values you will want to keep track of. The source version and the target version. The source version tells what version your source code is written in. Whereas the target version tells what version of Java you want your class files in.

If for instance you have a project written in Java 1.4 source style, but you have to run it on a Java 5 you’d set the source version to 1.4 and the target to 1.5. You are now compiling Java 1.4 source into Java 5 class files.  Unfortunately you’re not able to do the opposite, compile Java 5 source code into Java 1.4 class files.  This is probably due to API incompatibilities, Java 5 has a larger API than Java 1.4.

Now, in Eclipse you have two settings in three places that controls the source and target versions of your compilations. Under Window->Preferences->Java->Compiler (Eclipse 3.4) you’re able to set the versions for the whole IDE.

When you create a new project you’re able to determine what version of Java (source and target you want) and right clicking on a project and choosing Properties->Java Compiler, you have the same dialog as before.

You set the target level in the select box “Compiler compliance level”, and optionally by unchecking the “Use default compliance settings” you’re able to change the target (“Generated .class files compatibility”) and source respectively.

If you experience other problems you may want to “clean” your project(s). Cleaning a project means all compiled files are removed and all source files are recompiled (something the IDE will do by itself when you change compilation versions, but if you want to be sure, you can do it manually). This is done by choosing Project->Clean. In the dialog you can chose to clean all projects or just those you select.

Computers and Internet

SQL-Injections, the two most common types

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Opening a site Google has listed as spreading malicious software via the browser. In this case the site was the victim of SQL-injections.
Opening a site Google has listed as spreading malicious software via the browser. In this case the site was the victim of SQL-injections.

What are SQL-injections? How can they affect my site? How does it happen and how can I avoid it?

Your site may already be under attack, but the attacker is only using your site to attack your users! This is done using something called SQL-injections.

Since Firefox (2 and 3) and MSIE 7 started using Google’s (and others) system for blocking sites that produce harmful web pages the problem with SQL-injections have been put on the spot.

What happens is that an attacker hacks a site by placing their own SQL-code into the database of the victim system. A system open to SQL-injections may be attacked in basically two ways. Either the attacker performs a DOS (denial of service) attack. This could be done by deleting all the tables or doing something else harmful to the site, effectively bringing the whole site down.

The other form of attack that can be performed on systems open to SQL-injections is far more sneaky and may not be detected at all by the site owner or the site visitors. This form of attack consists of planting client side browser code in the database making all visitors run client side code that will infect their computer with malware or viruses. This malicious software may do everything from listening in on traffic between the client (web browser) and bank sites, to connecting the client system to a botnet.

Needless to say, attacks using SQL-injections has become a problem not so much for the owner of the originally defunct site as for the visitors to said site. Although users of the web should not underestimate the consequence of a good virus protection, system update policy and secure browsing policy.

Since the owner of the vulnerable site won’t notice any detour from business as usual and neither will most infected clients, nobody is the wiser to the problem.

This is why Google (and others) have started evaluating (and flagging) sites with bad content, and why Firefox and MSIE (and probably others) have started blocking them.

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