GWT + database connection in Servlet ContextListener – Auto Complete Video Tutorial Part 5

Rene — Mon, 24 Jun 2013 11:44:47 +0000

Finally we have all the basics that are needed for building an Autocomplete service and now comes the juicy part. From now on we are looking at how to make it fast and robust. In the current approach we open a new Data base connection for every HTTP request. This needs quite some time to lock the data base (at least when using neo4j in the embedded mode) and then also to run the query without having any opportunities to use the caching strategy of the data base.
In this tutorial I will introduce you to the concept of a ContextListener. This is roughly spoken a way of storing objects in the Java Servlet global memory using key value pairs. Once we understand this the roadmap is very clear. We can store objects like data base connections or search indices in the memory of our web server. As from what I currently understand this could also be used to implement some server side caching. I did not do any benchmarking yet testing how fast retrieving objects from context works in tomcat. Also this method of caching does not scale horizontally well as using memcached.
Anyway have fun learning about the context listener.

If you have any suggestions, comments or thoughts or even know of some solid benchmarks about caching using the ServletContext (I did a quick web search for a view minutes and didn’t find any) feel free to contact me and discuss this!

Building an Autocompletion on GWT screencast Part 1: Getting Warm – Reviewing remote procedure calls

Rene — Tue, 19 Feb 2013 09:11:29 +0000

Quite a while ago I promised to create some screencasts on how to build a (personalized) Autocompletion in GWT. Even though the screencasts have been created for quite some time now I had to wait publishing them for various reasons.
Finally it is now the time to go public with the first video. I do really start from scratch. So the first video might be a little bit boaring since I am only reviewing the Remote Procedure calls of GWT.
A litte Note: The video is hosted on Wikipedia! I think it is important to spread knowledge under a creative commons licence and the youtubes, vimeos,… of this world are rather trying to do a vendor lock in. So If the embedded player is not so well you can go directly to wikipedia for a fullscreen version or direct download of the video.

Another note: I did not publish the source code! This has a pretty simple reason (and yes you can call me crazy): If you really want to learn something, copying and pasting code doesn’t help you to get the full understanding. Doing it step by step e.g. watching the screencasts and reproducing the steps is the way to go.
As always I am open to suggestions and feedback but please have in mind that the entire course of videos is already recorded.

screencasts – Data Science, Data Analytics and Machine Learning Consulting in Koblenz Germany

GWT + database connection in Servlet ContextListener – Auto Complete Video Tutorial Part 5

Building an Autocompletion on GWT screencast Part 1: Getting Warm – Reviewing remote procedure calls