Webcomic №9

Webcomic №9

The instable position isn’t obvious for the outside observer. No progress possible.

Webcomic №8

Webcomic №8

People, who are careless on their way up, are likely going to build barriers, they cannot overcome.

Using GPG-Agent with opensuse 11.3 and zsh

GnuPG Logo I’m a supporter of mail encryption since I started using free software. At least, I sign all my own mails, with the exception of mails to people, who don’t know what an *.asc file is and might not open my mail for this reason.

By the way, my public gpg key fingerprint is:

F6A9 332D AA28 625E 59A8 F758 7BF6 0F4A 861B C3A3

I’m also involved in the CAcert project. If you want to get “assurced”, don’t hesitate to contact me, if you are in Berlin.

There is just one problem. If you want to sign all your mails, you have to type your hopefully long passphrase at least once[^1] for every single mail. If you get some encrypted mails from your friends, you have to type your passphrase for viewing mails, too. That’s not so nice. So were the gpg-agent invented, which task is to cache your passphrase for a given time, but it didn’t work for me - until today.

I followed the tutorial from the opensuse SDB with no success. Please note, that you might need to change the pinetry-qt to pinetry-qt4.

The solution, which works for me, was to copy the mentioned line to ~/.zprofile instead of .xinitrc, as I am using the awesome zsh.

Announcing Kubeplayer (youtube w/o flash)

Hello Planet KDE, hello RubyCorner

Earlier this year I started writing a KDE application using the Ruby programming language. Coming from the web development, I am no expert at all in C++. So I decided to give KDE development a try using the Ruby bindings for KDE 4 called korundum4.

It wasn’t as easy as expected. Unfortunatly the korundum4 project didn’t got very popular by now, so I found a lot of bugs on the way. Now, three months later, all the bugfixes are included in the last stable KDE. The idea, of just copying the project folder and starting the app without the need of any further setup1, becomes finally true.

Announcing Kubeplayer

Screenshot of Kubeplayer

I started a kind of clone of the well known Qt-based Youtube player Minitube. When starting the development, I had in mind to support Vimeo and maybe some other online video platforms, too. The app should integrate itself better into the KDE workspace, and lately I had the idea of turning it into a mobile app, too. It was possible to get a much cleaner and shorter code, not only because of the nice KDE KIO classes, but also by using Ruby.

Let’s Try It Out In Less Than 1 Minute!

Ok, to be fair, I have to admit, this is only possible using a recent Linux OS2 with korundum4 and Ruby 1.9.x preinstalled.

To give Kubeplayer a try, you just have to checkout the repository, and start the application.

git clone git://git.kde.org/kubeplayer
ruby kubeplayer/kubeplayer

That’s it. You can also install kubeplayer using CMake. Installation works like you would it expect it from a CMake based C++ application.

If you get an error related to json, you are probably using an Ruby version prior to 1.9.x. In this case you have to install rubygems via you distribution package manager. Then you can use Ruby’s own package manager to install the missing dependency.

gem install json

Get Involved!

Not everything is done by now. Youtube works in the most a lot of cases. The GUI needs a lot of small improvements. I even thought about a maemo/meego port, paid for an N900 on eBay, but unfortunately got duped :(. So the mobile development has to wait.

After all, the project is still quite young, the code is very short, nice and clear. If you ever felt like trying to develop for/with KDE, the barrier is now quite low.

  • You don’t have to deal with a KDE development environment. Just clone the repo and you are done. Since yesterday, you can find the project in playground.
    git clone git://git.kde.org/kubeplayer
  • You don’t need to know C++.
  • You don’t have to compile anything at all!
  • You can use the shiny new git infrastructure of KDE.

Take a look at the code base. There are not many files at all. Summed up, there are less then 1000 lines of code (including rare comments). For an already functional multimedia application, this is really few.

├── CMakeLists.txt
├── kubeplayer
├── lib
│   ├── CMakeLists.txt
│   ├── kubeplayer.desktop
│   ├── kubeplayer.rb
│   ├── List.rb
│   ├── MainWindow.rb
│   ├── provider
│   │   └── youtube
│   │       └── Youtube.rb
│   └── Video.rb
├── main.rb
└── README.rdoc

How does the future of Kubeplayer look like? I have already a lof of ideas, what could be done. Maybe you have also many, but different ones. What about:

  • allowing the use to login and comment on all supported video platforms
  • make flash needless on netbooks by providing an optimized app
  • create a scripted KPart to fetch youtube pages and open the video using kubeplayer
  • let the user download the videos (in a video library)
  • make it possible to share supported video platforms with the plasma media center team

So what do you think, can Kubeplayer do for you? What can you do for Kubeplayer?

Kind regards,

  1. This isn’t 100% true. You need to have korundum4 installed, but most distros seems to ship this package by default. On opensuse it is called “ruby-kde4”. ↩︎

  2. As KDE and Ruby is also available for many other OS, Kubeplayer is actually cross platform. ↩︎

Making Of ruby-stocks Plasma DataEngine

Hello Planet KDE, hello RubyCorner

Since I wrote my last Blog post much time has past. After my last exam last Friday I just started to do some hacking on KDE. As it should be something simple for the beginning and something useful, too, I decided to provide a new plasma dataengine for retrieving stocks information.

I used ruby, because plasma hacking with ruby is freaking awesome and totally easy. Let’s prove it!

How To Use It

Simple Plasmoid made with Ruby Before diving into the development process, you probably want to test the final result yourself. First you have to download the plasma package. Then you can install it easily with the plasma package manager.

plasmapkg -t dataengine -i plasma-dataengine-ruby-stocks-v1.0.zip

You won’t need to be root for that. You should get a success response afterwards.

As there is by now no plasmoid to display the provided data, you have to use the plasmaengineexplorer to test the engine. Call this program on your shell and look for ruby-stocks. You have to type in a stocks symbol like GOOG (Google) or NOK (Nokia) to get the information. Is is also possible to just call:

plasmaengineexplorer --engine ruby-stocks --source NOK

You can remove the engine with this short command:

plasmapkg -t dataengine -r ruby-stocks

How To Create It

I started with a look on the plasma ruby examples and copied the inital construct from the given time data engine example. There was also an attempt to create a stocks engine with C++. The code is available in the playground.

The most time took the clean implementation of the cvs data parsing.

If you want to start yourself with a ruby based dataengine, I recommend to start with the time engine example, too. Do not change the given file structure, which should be:

├── contents
│   └── code
│       ├── main.rb
│       └── …
└── metadata.desktop

The top directory gets packaged into a zip for distribution.

Let’s take a look on the main.rb. There a some important things you have to be aware of, when you want to use ruby for plasma dataengines:

  • when you name your engine “ruby-stocks” (see metadata.desktop), you have to name the top module RubyStocks. Otherwise your engine will fail.
  • Plasma looks for a class called Main in that module, which have to inherit from PlasmaScripting::DataEngine
  • make sure, that you implement the member methods: sourceRequestEvent and updateSourceEvent

As both methods should do the same in my example, I used an method alias. If you ever did a plasma dataengine using C++ you have noticed, that it is a straight forward port from C++ to ruby. There is hardly something different.

# file: 'main.rb'
# kate: remove-trailing-space on; replace-trailing-space-save on; indent-width 2; indent-mode ruby; syntax ruby; replace-tabs on; replace-tabs-save on; space-indent on;
require 'plasma_applet'

# the dictonary replaces the ruby hash as we need an ordered hash. only ruby 1.9 uses ordered one.
# when ruby1.9 is the default version, we can switch back to native ruby hash
require 'dictionary'

module RubyStocks
  class Main < PlasmaScripting::DataEngine

    # the url needs to be extended by the stock ID at the end of the string
    # format code: http://brusdeylins.info/projects/yahoo-finance-api/
    DATA = Dictionary[
      "j1" => ["market capitalization", Float],
      "p2" => ["percent change", String],
      "s0" => ["symbol",String],
      "d1" => ["last trade date", Qt::Date],
      "t1" => ["last trade time", Qt::Time],
      "c1" => ["change", Float],
      "o0" => ["open", Float],
      "h0" => ["days high", Float],
      "g0" => ["days low", Float],
      "v0" => ["volume", Float],
      "a2" => ["average daily volume", Float],
      "l1" => ["last trade", Float],
      "c4" => ["currency", String]

    SOURCE_URL = "http://download.finance.yahoo.com/d/quotes.csv?f=#{DATA.keys.join}&e=.csv&s="

    def initialize parent, args = nil
      super parent

      # don't update faster than once a minute
      setMinimumPollingInterval 60000
      # dafault update rate is 10 minutes
      setPollingInterval 600000


    def updateSourceEvent source
      request_url = SOURCE_URL + Qt::Url::toPercentEncoding(source).data.strip
      job = KIO::storedGet KDE::Url.new(request_url), KIO::NoReload, KIO::HideProgressInfo
      job.connect( SIGNAL( 'result( KJob* )' ) ) do |aJob|
        parseCSVLine source, aJob.data

      return false

    def parseCSVLine source, dataByteArray
      $stderr.puts "ruby-stocks plasma dataengine: retrieved data: " + dataByteArray.data
      dataArray = dataByteArray.data.strip.split ","
      if dataArray.size >= DATA.size
        DATA.values.each do |aValue|
          data =  dataArray.shift
          unless data =~ %r{N/A}
            if aValue[1] == Float
                data.gsub! /B$/, "E6"
                data.gsub! /M$/, "E3"
                setData source, aValue[0], data.to_f unless data == "N/A"
            elsif aValue[1] == String
              data = data[1..-2]
              setData source, aValue[0], data unless data.empty?
            elsif aValue[1] == Qt::Time
              setData source, aValue[0], Qt::Time.fromString(data, '"h:mmap"')
            elsif aValue[1] == Qt::Date
              setData source, aValue[0], Qt::Date.fromString(data, '"M/d/yyyy"')

    alias sourceRequestEvent updateSourceEvent



The second file you need is the metadata.desktop.

# file: 'metadata.desktop'
[Desktop Entry]
Name=Stocks Data Engine
Comment=Stocks Data Engine powered by Yahoo! Finance (real time delayed by around 15 minutes


X-KDE-PluginInfo-Author=Robert Riemann
X-KDE-PluginInfo-Category=Online Services

# Icon=alarmclock

What Comes Next?

The engine should be quite usable by now. I plan to create a plasmoid which lets you search for a company name to get the stocks symbol and then shows some important numbers (like the weather widget, but without these nice graphics).

After that I want to create a second plasmoid which just shows a chart from Yahoo! Finance. The most work will probably be to create a settings dialog similar to the one you find here below the chart.

What do you think? Would you use a stocks plasmoid? What do you expect it to display? Why didn’t you have already used ruby to create a dataengine? :wink: And after all, how do I get this engine into KDE trunk?