(Deutsch) Zwei Inkompatibilitäten aus einem praktischen Projekt: Datumsfunktionen sind bei älteren Android-Geräten unvollständig, und die prompt-Methode wird von Microsoft still unterdrückt.
Category Archives: Programming
Codename One – Swap Grid Cells
What is Codename One? The platform “Codename One” offers operating system-independent development of apps for smartphones. An important component is a library for user interfaces. Codename One is a successor of LWUIT, which in turn uses concepts of the Java Swing library. To develop a user interface, you insert the various controls such as labels, …
Presentation About Rails Database Optimization
Here are the English slides about how to optimize database queries in Ruby On Rails. I have showed this presentation at the Ruby User Group Hamburg at the 9th August 2012.
(Deutsch) Ruby On Rails Datenbankoptimierung Teil 2
[Zu Teil 1] Verknüpfungen mit dem SQL-join Relationale Datenbanken erlauben es, Tabellen miteinander zu verknüpfen. In SQL gibt es für diese Verknüpfung das Schlüsselwort “JOIN“. Eine solche Verknüpfung kann theoretisch sehr frei spezifiziert werden, in der Praxis wird man fast immer aufgrund der Gleichheit bestimmter ID-Spalten verknüpfen. In unserem Beispiel eines Schiffsinformationssystems haben wir eine …
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Optimize the Ruby-on-Rails database – part one
Reduce the number of database queries A typical web application does many database queries before it delivers the response page to the web browser. The application needs to wait for the response of each of these database queries. It gets an additional slow down because of process switching. The database server must analyze each request, …
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Modification of Ilias Features
Examples for redesign The learning management system Ilias can be redesigned with skins. (See previous blog entry.) But an Ilias skin can even change the functionality. I show a few examples. Login Page You find the templates for login, logout and the user agreement in the folder Services / init / default In our …
Attribute or Property?
Sorry, not yet translated
Rails ActiveRecord: count, length or size?
The object oriented database layer “ActiveRecord” offeres three different methods to determine the number of objects: count(), length() und size(). Alle drei Methoden liefern das gleiche Ergebnis. Was nehmen wir wann? Warum ist es überhaupt wichtig? Nimmt man die falsche Methode, dann erzeugt unsere Ruby-on-Rails-Anwendung überflüssige Datenbankabfragen oder braucht mehr Speicher als eigentlich nötig. Die …
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LwUIT 1.5: upgrade experiences
Sorry, this article is only in german. As it is quite old, I don’t think I will tranlate it to english.
Ilias Skins
Custom adaptation of a web-based learning management system (Translation in progress) Ilias is a so-called learning management system (LMS), ie a system for web-based education programs. It is a very comprehensive system. It integrates not only the content in online courses but also communication capabilities such as forums, chat and mail. When an organization like …