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.

Nested data table in JSF

After certain period the project manager proposed the change of the fields of an object that should be visible in a Primefaces dataTable. The new introduced field was of the type java.util.List with any number of elements. The representation of the values was not solvable in the dataTable as it does not support nested cells. After unsuccessfully fixing of the problem, I needed to represent data in the panelGrid element.

Angular Application UI Testing

Testing UI of an application can be automated with the Selenium testing framework. The problem by testing of an Angular5 application were random assigned indexes to IDs of HTML elements after each application start (e.g. myid-4), which prevents finding elements by id using Selenium web driver. The finding elements had to be changed and set to finding elements by xpath.

Parsing hyphenated words in PDF

In developing of a program for parsing elements of PDF files my task was to develop a feature of “dehyphenation” - a function that merges hyphenated words. The naive approach is to search for hyphens on very last place of each page line and match it with the first word in the next line containing text. This approach would not only exclude the case when the hyphen appears as a last char of a page, but also the case of column page layout, where the matching candidates can be above the text object.

How to test GPS in an Android app

In 2012 I was member of an university project, actually a student project, for the lecture 'Mobile Computing'. The idea was to to get a better accuracy with a "cluster" of android driven GPS smartphone instead of using a professional GPS receiver. Back in the days android was different than it is nowadays. One of hardest issue was to collect GPS data without having a real GPS transmitter. One way was to build the app, copying the app to a phone and then find out is the GPS module working or not, which was fun in some way but that it was a really stupid idea.

Using local ressources in JSP pages

For an internally (no internet access) used webservice based on JSP pages all CSS and JS files had to be included locally. Solution: to achieve this JSTL can be used (<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>) which allows to refernce and load the locally included files, like for example: <link href="<c:url value="/resources/static/css/bootstrap.min.css"/>" rel="stylesheet">

Running a war as a Windows service

For a project a web service packaged as a war file had to be run on a server as a windows service. To be able to do the easily a third party tool was used: https://nssm.cc/ In order to make this possible first the service has to be created: //CMD// nssm install SERVICE "PATH_TO_JAVE_EXE" "-jar service.war" //CMD// And then to let the service be run it is important to tell the service the directory the service has to run in, by: //CMD// nssm set "SERVICE" AppDirectory "PATH_OF_WAR_FILE" //CMD//

Spring boot: starting a camunda process

For a project we had to develop a spring boot webservice including the camunda rest engine to controll the process. When including and starting the camunda process by the autowired capablity we had the problem the just a empty process was launched, not using our deployed process definition. Solution: To tackle this problem we used spring boots EventLister annoation to know when the application had fully deployed the proce

Dependency injection with dagger

We used dagger for dependency injection and had the problem when using @Singelton an a subcomponent. When we tried to compile, we always got an error. The main componeten also used the @Singelton.

Testing with MonkeyRunner

We used an automatic Gui Testing tool for android apps. We had a emulator for an tablet running on an laptop and tried to test our app. The problem was that the runs were sometimes successful and sometimes not with the same code.

Dealing with circular reference in Java

In an uni project we had a complex data structure with 2 circular references. We built an android app with a maven spring java backend using docker. The problem was that we could not load all the informations in an entity with cicular references. In this cases we always only got null if we tried to get the correct values from our backend.

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