Welcome to TechScreen

Welcome to the TechScreen site. This side shall support the exchange of knowledge in the domain of Web Engineering and related aspects. As a side effect, this side is used for research on knowledge management technologies. User can pose challenges in the problem domain and can participate in quizzes. Further a bibliography about arcticles in different related domains is continously extended. Finally, questionnaires on different issues are provided. To be able to participate you need an account and a password from TU Wien's TISS system.

Optimizing SQL Queries

In a typical university course, performing an SQL query was always a fast thing. However, when you are working on a project that grows over time, you at first might not give the performance of a query much thought. As the project grew, I had complex queries and lots of records in the database, distributed over many tables. What I didn't expect, was that from one day to another, the performance of the page went from zero complaints to constant user complaints (the page loads too slowly). As I found out way later, the bottleneck comes suddenly. It does not build up.

PHP's mail() vs PHPMailer

As I had to build an online platform that started as a very small project, I was not concerned with using anything other than PHP's built in mail() function to send simple e-mails to the users - and it worked great! However, as the platform got larger, the requirements got larger too. Before long I was messing around with headers in the php mail() function to include attachments in e-mails etc. Turns out, adding the PHPMailer functionality makes the whole process a lot cleaner and easier to maintain as the project grows.

Building frontend fails with various (function undefined, etc.) errors

Now happening already two times in my career and spending some time with it, I find it worth telling my problem in this topic. After coming into a new company or to a new (existing) project you try to build the source code to start working on new features. A lot of times it happens that you receive error messages which do not happen on the colleagues work stations. Usually long working employees also fail to detect the root cause of this error. It actually comes from a differend node/npm version and errors from the build are very misleading.

CSS Styling a button does not yield the desired outcome

When trying to incorporate a new page into an existing website with corporate styling, I came to a problem which was hard to detect (for me). A newly created button should have a slightly different position and edge rounding than all other styled buttons as it comes from a different context. Whatever I've done, I never got the correct styling, like magically ignored by the browser. Learning about the developer console I digged deep into the css styling and found out that a <div> from a container forced its own styling on the button.

XML Parsing Library in a JIRA Plugin does not work

When developing a JIRA Plugin and trying to parse XML data from external sources and displaying it, the parsing with the commonly used Woodstox library failed with the following error: javax.xml.stream.FactoryFinder$ConfigurationError: Provider com.ctc.wstx.stax.WstxInputFactory not found Debugging took a considerable amount of time as the library was actually added into maven but was not available once installing the plugin in JIRA. The problem relied in OSGi class loading and a problem with the xml parsing library architecture which has its root in an IBM architecture decision.

How to mock a new instance

Which kind of possibility do we have in order to mock a new instance in the class which we want to test.

what is the mainly characters of Object oriented programming language

Nowadays, the concept of the Object oriented programming becomes more and more popular. What is the mainly characters of it?

What is the most important difference between H2 and PostgreSQL

During the software implementation, it is always difficult for us to decide which one of the database should we use as the technology stack. Especially for the database. So what is the mainly difference between H2 and PostgreSQL.

[Quizzes][Knowledge Management] - Typo in Question

Is there a typo in "Question 10" of "Portals and Content Management Systems" where the question reads "A kind of partite is realized in DRUPAL by ..." ?

Error 504 - Gateway Timeout

This error appears when your connection is to slow or when so many people try to acces to that server.

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