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.

Deep Learning classification too slow for real time service

Problem: The classification time of a trained neural network was too slow on average for a real time service. Solution: 1. Build additional, less complex models with faster inference times (eg. SVM, Decision Trees) to handle the most common requests very fast and efficient. 2. Distill the neural network (https://arxiv.org/pdf/1711.09784.pdf, https://arxiv.org/abs/1910.01108) into a smaller faster model. 3.

Write to database too slow for REST service

Problem: The request response time for a REST service we provided was too slow. Solution: Return data to API customer first and persist data later. Solution explanation: The runtime analysis showed that the write operation to the database was the slowest part of the API call. The solution for speedup was to write the data to the database AFTER returning the response to the client. While this increases the risk of having "old" data in the database for another call, that needs this data (very improbable case) it improves the response performance significantly.

Find Tech Stack for Social App Startup

Problem: Find a software framework for a small social app startup with little in house technical expertise to create a relatively simple app for Android and IOS fast, with little cost but scalability. Solution: Use Vue-Native, Google Firestore and Google Cloud Functions. Solution Explanation: The biggest/cheapest group of developers is assumed to be web developers. They are assumed to know HTML, CSS and Javascript.

No Content being Loaded in Single-Page Web Application

A single-page web application was being served by a web server and was supposed to interact with another web server to load content like posts, comments and ratings. Although the web application could be loaded and the overall structure was visible, no content was being displayed. Looking at the console with Firefox's inspector tool revealed that the request to the other web server, an API proxy, was blocked by Firefox because the request was cross-origin and the other web server did not explicitly allow such a request.

Search Entity by Current Version as well as Previous Version

A search function for a management software was supposed to be able to lookup a customers data by searching with their address. Addresses can change and if for example a customer moved and thus their address changed, it should still be possible to find said customer with their old address. This functionality was required for some other entities as well, so implementing it generally was favorable. Instead of explicitly modeling for every such entity that it can have multiple values over time, I used an extensions for the Hibernate persistence framework called Envers for auditing tables.

No Updates after Switching View Many Times

A single-page web application was getting push updates via SSE. Each view used a different SSE resource from the same endpoint. After a certain amount of navigations via the main menu, no updates would be displayed anymore. This problem seemingly did not occur reliantly at first but as it turned out it would occur exactly after the seventh view changes (navigating 7 times via the menu). Every time a view is opened, its controller requests the respective SSE resource to get updates for the view. I was able to confirm this behavior on the API proxy which logged every request URL.

Bad performance with nested classes and large amount of data when using Hibernate

In my JEE application, I am using the Hibernate framework as the ORM mapper. Initially, the performance was very good. However, as more and more data is gathered during the lifetime of the application, the performance is getting worse and worse. The data model is rather complicated, and the entities are nested. Are there configuration options, that could help to improve the performance?

Values not updated in the GUI frontend of a JEE application using the Apache Wicket framework

I am using the Apache Wicket 6.0 framework as the GUI framework in my web application. I have the following problem: after changing the data, the value displayed in the text field does not change according to the data that has been entered respectively calculated after entering it and pressing a button to perform a calculation. Unfortunately, I have to refresh the site. Why does this behavior occur?

Configuration of a database connection in a JEE application

I intend to create a JEE application with tomcat as the webcontainer. I will use postgresql as a database, and will use Eclipse as IDE. Where can I configure how to access the database?

Increase website visibility in search engines

I want to increase my website visibility in google search engine, so that users finds my websites faster and correct keywords they use in google search guides to my pages. My pages are also rapidly changing because of new information. So I want google search to be up to date what is on my websites.

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