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

Building an Autocomplete Service in GWT screencast Part 3: Getting the Server code to send a basic response

Rene — Mon, 17 Jun 2013 12:20:11 +0000

In this screencast of my series on building an autocomplete service you will learn how to implement a Server servlet in GWT such that autocomplete queries receive a response. In this video the response will always be static and very naive. It will be up to the fourth part of this series which will follow already this week to make the server to something meaningful with the query. This part is rather created to see how the server is supposed to be invoked and what kind of tools and classes are needed. So see this as a preparation for the really interesting stuff.

If you have any questions, suggestions and comments feel free to discuss them.

Create a Screencast in Ubuntu with recordmydesktop and do Soundengineering and post production

Rene — Fri, 17 May 2013 18:36:55 +0000

I promised to create some screen casts for the autocomplete service with GWT based on neo4j. After I have created all the screencasts I had to go through quite some hassle in order to do so.
So let me share my experience and toolchain in order to produce a somewhat accaptable screen cast. I am still not happy with the quality of the results and if you have any suggestions feel free to tell me.
First of all you download and install recordmydesktop. Once this is done you can just do a screencast by calling the following line.
recordmydesktop --quick-subsampling --full-shots --no-shared --v_bitrate 2000000 --on-the-fly-encoding
bear in mind that you should have at least a dual core processor if you really want to do video encoding on the fly.
After creating this screencast I realized that my audio and video tracks where not in sync. Even worse. I realized that the video track was always a few seconds shorter than the audio track. At the end of the video when the audio wasn’t finnished yet the last video frame would just be displayed. This might be alright on a 20 second screencast but some of my screencasts where up to 14 minutes and that really sucked! because speaking and video would just not be synchrone anymore.
In another screen cast that I did today I had the problems with the sound not being loud enough so Here is the stack of software that works fine with corrupt .ogv files produced by recordmydesktop.
After searching quite a while and trying several programms (pitivi, Avidemux,oggtools(!),…) that all crashed on the .ogv file that came out of recordmydesktop I reallized that with ffmpeg2theora I could actually extract the audio and video files seperately. to do so just enter:
ffmpeg2theora video.ogv --noaudio ffmpeg2theora video.ogv --novideo
The problem was the Audiofile. I was able to play it with my Audioplayer but again not able to open it with any editing software but oggconvert!
With this little tool I was able to open the corrupt .oga audio file and save it to an .ogg file (with vorbis audio codec!).
Now after I had a non corrupted audiofile I was able to adjusting the speed of the audiofile adjusting it to the length of the recoreded video with audacity. Easy instructions how to do this are available at http://wiki.audacityteam.org/wiki/Change_Speed Audacity also provided the options for me to amplify the volume of the sound.
Finally I had two files of the same length just need to merge them again. The oggTools again failed to help me on this but there is pitivi which is able to do the job.
So you see if one keeps patient one will reach his goal. Some of the screen casts are already published and more will come. So far I hope you enjoyed reading my experiences and solutions
by the way on wikipedia there are quite some tutorials on how to edit ogg videos.
http://commons.wikimedia.org/wiki/Help:Converting_video

Please help me to realize my Web science massive open online course

Rene — Wed, 01 May 2013 09:59:57 +0000

I am asking you for a big favor in this blog post! You can help me to achieve one of my childhood dreams:
I am an enthusiastic teacher and love to share information (as you might have seen by reading my blog) Over the last month I have designed a structure for an online course on Web Science together with a short video. In this blog post I will introduce the course to you but I am also asking you to vote for the course since only 10 of the 250 courses that applied for the fellowship will be sponsored and thus be realized.
So please go to https://moocfellowship.org/submissions/web-science an learn more about the course and vote for it. You can find almost all details of the course in this blog post.

Why creating such a cours?

The web has become important to its 2.3 billion users. Yet only a small group of people understand the processes that take place on it and quickly steer its development into new directions.

Novelty of the subject

Web Science is an upcoming academic field. Much information about the web already exists online, but no course that comprises all of it.

High value for every web user

The MOOC would be of high value and of relevance for anybody using the web e.g:

A programmer who is building the next web application
A company deciding their web strategy
A judge who has to decide a case regarding net neutrality or copy right infringements
The Government as well as public authorities which have to make decisions on how to regulate the web
…

The web is the right place to learn about the web

The web itself is the best platform to educate people about the web since you can always point directly to the object of study. By creating a MOOC we will be able to aggregate, organize and filter much of the available information.

Integration within our institution

The MOOC will be a core element for the web science lecture of our web science master program. The goal is that students will work with the material provided by the MOOC and the instructors will replace classical lectures with public Q&A sessions. Additionally the Web Science lecture of 2013/2014 will serve as an internal testing of the MOOC such that the improved MOOC can launch on iversity in 2014.

Course content

This MOOC consists of ten lessons divided into three parts.

Lesson 1 – 3: Foundations of the web
Lesson 4 – 7: Theoretical results of web user behavior
Lesson 8 – 10: Web & society

Lesson 1 & 2: History of the Web & Web Architecture

You will understand the historical development of the web and see how the cold war in combination with advances in technical developments led to the Internet Protocol suite.

On each Layer you will know one protocol and understand how these protocols build an open, inter operable and decentralized system. Furthermore you will learn about the domain name system and find out why the concepts of URI and Hypertext were crucial for the success of the web.

Lesson 3: Structure of the Web

You will learn about the six degrees of seperation and understand concepts like small world networks by studying ‘the other’ Milgram experiment. You will be able to use power law distributions to describe the structure of the web, its content and its users.

Lesson 4 & 5: Micro and Macro behavior of web users & Social Network (Analysis)

You will be introduced to theories from Microsociology and see how applying them to the behavior of people on the web leads to macro structures such as:

Analyzing social network data from the Koblenz Network Collection using Octave you will gain a deeper understanding of social theories and social networks.

Lesson 6 & 7: Information Retrieval & Recommender systems

Completing this section you will understand the basic architecture of a (web) search engine. You can name the fundamental (non technical) difficulties one has in order to create a good information retrieval system. You will learn about the connection to recommender systems that are (not only!) used by large web shops to increase cross selling.
You will be able to discuss the danger of such algorithms like the relevance paradox and the filter bubble.

Lesson 8: Trust and Security

You will learn how third parties act as trust providers on the web and how this issue is related to markets with asymmetric information. You will see that trust issues in the online word differ from the offline problems. You will know of ways like cryptography, secure communication and certificates to resolve trust issues and how those techniques can even lead to a new currency.

Lesson 9: Web Economics

You will know of e-commerce models like online shopping & auctions as well as online advertising and marketing. You will be able to interpret and apply metrics for web analytics such as

Lesson 10: Web Governance and Web Ethics

Finally you will understand the important role of institutions like W3C, IETF and ICANN . You will use your understanding of the web architecture to discuss and explain the connections between

Net neutrality
Piracy and copy right infringement
Internet censorship and the freedom of speach

So please go to https://moocfellowship.org/submissions/web-science an learn more about the course and vote for it.

Building an Autocompletion on GWT screencast Part 2: Invoking The Remote Procedure Call

Rene — Tue, 12 Mar 2013 07:25:00 +0000

Hey everyone after posting my first screencast in this series reviewing the basic process for creating remote procedure calls in GWT we are now finally starting with the real tutorial for building an autocomplete service.
This tutorial (again hosted on wikipedia) covers the basic user interface meaning

how to integreate a SuggestBox instead of a textfield into the GWT Starter project
how to set up the neccessary stuff (extending a SuggestOracle) to fire a remote procedure call that requests suggestions if the user has typed something.
how to override the necessary methods from the SuggestOracle Interface

So here we go with the second part of the screencast which you can of course directly download from wikipedia:

Feel free to ask questions, give comments and improve the screencast!

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.