EDIT: Fixed wrong URL.


com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was79095 seconds ago.The last packet sent successfully to the server was 79095 seconds ago, which is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.


To me, this problem occurred whenever my web application was not used for a certain amount of time. For some reason, Hibernate (?) does not close the connection properly, but the database system does after the wait_timeout has passed. Now Hibernate wants to use a connection that is not valid any more.

It took me some effort to overcome this problem, but I figured out a clean solution (setting the ‘wait_timeout’ setting of mysqld to days or weeks is NOT a good approach ;)).

The trick is to use connection pooling with c3p0. This way, you can make sure that a connection is revalidated after being idle for a long time. Configuration is quite easy. Just add the following properties to your Hibernate configuration (persistence.xml or hibernate.cfg.xml):

<property name="hibernate.c3p0.min_size" value="3" />
<property name="hibernate.c3p0.max_size" value="50" />
<property name="hibernate.c3p0.timeout" value="1800" />
<property name="hibernate.c3p0.max_statements" value="50" />
<!– this property forces the revalidation of a connection after the given amount of time (in secs) –>
<!– it must be set to LESS than the wait_timout setting for the mysql server (this setting defaults to 28800 secs (8 hours)) –>
<property name="hibernate.c3p0.idle_test_period" value="28680" />


Furthermore, you have to add the c3p0 jar to the classpath of your application.

In order to create such GUIs, the controls provided by the .NET Compact Framework are lacking a lot of functionality. However, the MSDN gives us some hints: in this article, they show us how to create a button filled with a gradient background.

When using gradients from RGB(238, 238, 238) to RGB(128, 128, 128) one can reach pretty nice results. Furthermore, it is possible to only fill the upper 10 pixels of a black button with a gradient from black to white using the StartOffSet and EndOffSet property. This way, you get buttons similar to the ones currently used by HTC for their TouchFlo user interface.

Well, what about adding rounded corners to the gradient filled buttons? This is far more easy that you might think. I have added a code example on my community pda-dev.de: Gradient Button Code.
Simply copy the code located in the linked topic. It must be inserted at the end of the function DrawImage from the original example out of the MSDN.
The idea is to draw the border manually instead of just adding a rectangle around the button. At each corner, we “dash” the border by one pixel to achieve the look of a rounded corner. That’s all the trick!

One of the core abilities of my application is to provide widgets for third-party sites, allowing my users to include download-links to their files in their own web pages. These widgets are simple iframes that load content from my domain.

However, when implementing my app I struggled with the problem that Microsoft Internet Explorer per default blocks cookies set from within an iframe (of course, all other browsers don’t do this).

Lucklily, I found a really ..hm…interesting solution for this problem:

You can make IE trust your page by setting a special HTTP header. Well, the funny thing is: everyone can to this without any autorization, so what did the guys of Microsoft think when elaborating this “security feature”??

Nevertheless, you can read about the rescuing p3p HTTP header here and there.

I adopted the solution to JSF with Seam and implemented a custom filter that simply adds the mentioned header to every HTTPServletResponse. The code is as follows:

Finally, you can activate this filter either by using the @Filter annotation of Seam or in your web.xml. I preferred the second way, because this allows to apply the filter only on these views that actually need to return the header. In my case, this was my widget called widget.seam.

Instead, I checked out some Open Source tools and found Webload, an Open Source variant of a more comprehensive tool developed by Radview. The download can be found here (it’s not available on the official website any more).

The tool comes with a graphical user interface both for creating test scripts (Webload IDE) and for launching and monitoring tests (Webload console).

Scripts can be recorded by simply clicking links in your browser. Afterwards, the script can be used to create the actual test, consisting of an arbitrary number of virtual users that follow the actions defined in the script. Webload allows monitoring of any values you can think of, ranging from the number of executed requests to throughput in bytes per second.

Because of all those features that seem unique for an Open Source stress test tool, Webload is really worth a tip here at codingclues

While creating shiny and glossy effects seems to be a trivial task for the experts using Photoshop, I tried a lot until I got some good results with Gimp, the Open Source image editor.

My goal was to develop a “shiny table” effect from a screenshot that was rotated into the view. Below you can see an example (of the result, of course ;))

Here are the steps to create such an image, starting with the plain screenshot.

1. Create a new image with the dimensions you wish. Choose a transparent background in the “New image” dialog.

2. Press Strg+L to open the layers dialog and delete the background layer.

3. Paste your screenshot and resize it to the desired with and height (it should have about the half of the height of your canvas).

4. Go to the layers dialog again and give the “Inserted layer” a proper name.

5. Duplicate this layer (right click on it, choose “Duplicate layer”)

6. …and give it a name like “shadow” - we will create the shadow from the duplicated image.

7. Now select the first layer again and use the “Perspective” tool from the toolbox to add the perspective effect by pulling the top right corner a little bit up. After that, pull the lower right corner down to add as much transformation as you want.

8. OK - all fine so far, so we can create the shadow. Select the second layer (Strg+L, then click on it) and move the duplicated image exactly under the original image, so that they touch at the right corners (lower right from original image to upper right corner from duplicate).

9. Flip your duplicate vertically.

10. Use the transformation/perspective tool again to drag the upper left corner of the duplicate to fit to the lower left corner of the orignal. Afterwards, pull the lower right corner of the duplicate down a bit so that the edges are in parallel.

10. You almost did it. Just give the “shadow” layer some transparency. This can be done in the layers dialog. Values around 40% to 50% seemed to give good results for me.

That’s it, your pic should now look like the one I presented above.
Feel free to ask, if you have some questions.

for (int i = 0; i < pointCount; i++) {
   ...
}

If the total number of emitted vertices is always the same and doesn’t depend on pointCount (pointCount * shaderCalls = const) then you will still get a drastic slowdown when pointCount is higher then 1. If you replace pointCount with a constant number this doesn’t happen until the number is higher then some limit (8 in my case). The following code would do exactly the same as above for pointCount <= 8 but doesn't suffer from any performance loss:

for (int i = 0; i < 8; i++) {
   if (i < pointCount) {
      ...
   }
}

To get the favicon for a domain, use

http://www.google.com/s2/favicons?domain=www.google.de

To get the favicon for an URL, use

http://www.google.com/s2/favicons?domain_url=http%3A%2F%2Fwww.google.de%2F

To see an example how favicons can make a website look more colorful, look on IRCgg.

urls = Url.find (:all, :conditions=> ["location like ?", params[:location] + "%"])

In my application, this finds all Url objects with a URL that begins with params[:location]

But this is not the safest solution! The user is able to use its own “%”-characters or the “_” character in the LIKE statement. These are not escaped by rails, so you have to use:

escaped_location =  params[:location].gsub ('%', '\%').gsub ('_', '\_')
urls = Url.find (:all, :conditions=> ["location like ?", escaped_location + "%"])

More on the need to escape SQL can be found in a railscast.