I’ve been using Vimeo Desktop Uploader for over a year. It is simple tool written in Adobe AIR which allows batch upload of videos to Vimeo. From time to time, when I try to run application, it hangs with “Loading” message. Restarting application does not help. Unauthorizing application either. I searched for similar problem on Vimeo Help Forum and found this topic. Looked promising so I’ve follow the advice and deleted vimeo files in ~/.appdata/Adobe/AIR/ELS/ on my Ubuntu. But that didn’t help. After application authorization on Vimeo it was still displaying “Loading” message forever.

But than I thought that it is a good track and decided to clean entire AIR . I’ve deleted ~/.appdata/Adobe/AIR/ directory. And that was it! I could use Vimeo Desktop Uploader once again.

Lately I have problems with free space on my /home partition on my laptop. The problem is that I have nothing else to delete. The only option would be to buy a additional USB hard disc (I find it cumbersome) or buy a new, bigger hard drive for my laptop and exchange it with my current one.

When I was checking space left on my hard drive (using df command) I’ve noticed that

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lukas@acer:~$ df -h
Filesystem Size Used Avail Use% Mounted on
...
/dev/sda3 126G 117G 2,5G 98% /home

Reserved Block Count on partition

I found an explanation (using Google ofcors) that some percent of blocks on each partition is being reserved to reduce system defragmentation, allow root login for maintenance and to allow Linux system logging facility to function properly in case of lack of free space on partition. It is called Reserved Block Count and it is set to 5% of partition size by default.

You can check current Reserved Block Count value using dumpe2fs command

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lukas@acer:~$ sudo dumpe2fs /dev/sda3 | grep "Reserved block count"
dumpe2fs 1.41.12 (17-May-2010)
Reserved block count: 1653590

Block size of my partition is 4096 (it can be checked using dumpe2fs command). So reserved space on my partition is about 6,3 Gb and equal missing size from hd command.

How to change Reserved Block Count
Reserved Block Count for given partition can be changed using tune2fs command

Code block

sudo tune2fs -m 0 /dev/sda3

where /dev/sda3 is your file system identifier

-m option sets the percentage of reserved file system blocks (in this case it is being set to 0%)

Then I’ve checked again free space in my system:

Code block

lukas@acer:~$ df -h
Filesystem Size Used Avail Use% Mounted on
...
/dev/sda3 126G 117G 8,8G 94% /home

I have additional 6Gb on my home partition!

Is it safe?

You can disable Reserved Block Count (by setting the percentage of reserved filesystem blocks to 0%) safely on not-system partitions (such as /home partitions). You shouldn’t do this on partitions used by root (especially / and /root) and on partitions used by OS for logging and storing temporary files (e.g. /var and /tmp).

Today I’ve upgraded Ubuntu on my laptop to Ubuntu 10.10 (Maverick Meerkat) Release Candidate. Everything went smoothly. Ubuntu downloaded all needed packages and upgraded system. I had no problem during startup nor during work with new Ubuntu. Thou when I tried to launch my Chromium browser I shut down immediatly after startup. I tried once again, this time lauching browser from Gnome Terminal.

I got followin message:

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OpenOffice path before fixup is '/usr/lib/openoffice'
OpenOffice path is '/usr/lib/openoffice
Attempting to load the system libmoon
Segmentation fault

I found following bug in Google and I’ve followed last note saing “Uninstalling libmoon solved the problem”.

So I’ve uninstalled libmoon and then I could lauch Chromium browser.

Atlassian has aquired Bitbucket.org, a hosted code collaboration site for Mercurial distributed version control system.

What is more important for developers, from friday Bitbucket will offer a free account for five developers and unlimited numer of repositories (ideal for small teams). Comparable account on github.com (popular collaboration site for Git, main Mercurial competitor) would cost us $7 per month.

I hope that github will soon offer comparable free account. I’m using Git and don’t wan’t to switch to Mercurial.

After successfully installed Rails I’ve created clean project using

Code block

rails new helloworld_project

command and installed sqlite3 gem.

When I tried to start application I got error dialog box with message:

“The program can’t start because sqlite3.dll is missing from your computer. Try reinstalling the program to fix the problem.”

Another confusing error…

Luckily I was able to fix this quickly.

First I’ve downloaded sqlitedll zip from http://www.sqlite.org/download.html site, and then I’ve put sqlite3.dll to my ruby installation bin directory.

Then I was able to successfully launch my rails application.

Lately I’ve changed computer to new one and I’ve lost my Rails installation. Today I decided to recreate my environment. My computer is behind a HTTP proxy so I’ve knew that I will have some problems with installing Rails using gem installer.

Of course running command

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gem install rails

didn’t work.

I received following error message:

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> gem install rails
ERROR:  http://rubygems.org/ does not appear to be a repository
ERROR:  Could not find a valid gem 'rails' (>= 0) in any repository

I’ve created .gemrc file in my home directory and specified http_proxy option and added following line

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http_proxy: http://proxy_ip:proxy_port

into it.

But that didn’t help. I was a little bit confused because it was the way I did it last time (very long time ago thou).

I’ve tried to use -http_proxy in command line but gem could not understand this option (why, if documentation say it is a proper way to configure proxy?!). Then I’ve tried last option mentioned in documentation (-p as a shortcut of -http_proxy option) and, surprisingly, it worked.

I have to remember that: use

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gem install -p http://proxy_ip:proxy_port rails

next time.

In Ubuntu 10.04 Indicator applet replaced separate applets in taskbar (e.g. sound applet, battery applet, network applet). Its main purpose was to unify messages being shown to user.

Personally, I do not like this solution. First of all I can not switch back to previously used applets. There is also problem with space between icons in applet. For example distance between other elements in my taskbar (e.g. clock and Pidgin icon) is less than between indicator applet icons (which looks strange on my desktop). Moreover I use only web interface to my Gmail account so I don’t need envelope icon for Evolution/Thunderbird events. Having unused icon in taskbar is irritating, but I managed to remove it.

I executed following command:

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sudo aptitude purge indicator-me indicator-messages gwibber

Then I removed Indicator applet from by taskbar and then added it once again.

Today I discovered cool extension for Chrome browser: Speed Dial.

It replaces new tab page with your predefined visual bookmarks. Pretty straightforward but can save a lot of time entering once again Gmail or Google Reader address in browser.

Today I’ve upgraded Ubuntu on my laptop to 10.04 version release candidate. Update went smoothly. After 10 minutes I had all packages downloaded. After another 20-30 minutes all packages were installed and after restart I had new Ubuntu release installed.

The only thing that was annoying me was a default window button layout. Minimize, maximize and close buttons were moved from right to left.

After a minute Googling for solution I found it. I had to run gconf-editor (ALT+F2 to open Run command window) and then change settings for apps->metacity->general->button layout property from

maximize, minimize, close:

to

:minimize,maximize,close

Colon position is most important: it determines buttons position in window bar.

Changes were applied immediately and I had good, old buttons layout.

Some time ago I decided to familiarize with Google App Engine capabilities. Lately I read a document about GAE Java SDK version capabilities. I was surprised that a big part of JEE stack is supported e.g.: JPA and JSF. That moment I decided to make simple JSF-based demo application.

Google App Engine

Google App Engine (GAE) is a hosting service which allows you to run your web application in Google data center infrastructure. GAE is responsible for scalling and assuring accesibility of your application. At this moment Python and Java runtime environments are supported. Using GAE is free up to certain limits. Free version is limited to 1,300,000 requests, 1Gb of outgoing and 1Gb of ingoing bandwidth daily. It is not much but should be sufficient at the begining. You can read about GAE quotas and billing here.

Prerequisites

I’ve used SpringSource Tool Suite 2.3.0 but you can use any Eclipse from version 3.3 to 3.5. You will also need to get and install Google Plugin for Eclipse. I’ve used Software Update feature to install plugin but you can download and install it by hand. For details read official Google App Engine documentation.

Create Google Web Application project

Basically I’ve followed instructions on Configuring JavaServer Faces 2.0 to run on the Google App Engine Using Eclipse page. First I’ve created new Google Web Project by selecting File->New project->Other->Google->Web Application Project.

Then I’ve downloaded following libraries into war/WEB-INF/lib folder:
- Unified Expression Language libraries: el-api-1.1.jar and el-impl-1.1.jar
- JavaServer Faces libraries: jsf-api.jar and jsf-impl.jar
- Apache Xalan libraries: serializer.jar, xalan.jar, xercesImpl.jar, xml-apis.jar, xsltc.jar

TIP: I’ve downloaded xalan-j_2_7_0-bin-2jars.zip version and extracted needed Xalan libraries.

Next thing to do was to copy JavaServer Faces Tag library definition. I’ve downloaded Mojarra source distribution and copied jsf_core.tld and ui.tld files from jsf-ri/conf/share directory into war/WEB-INF directory.

That I’ve updated appengine-web.xml file and added <sessions-enabled>true</sessions-enabled> tag

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<?xml version="1.0" encoding="utf-8"?>
<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
 
<application>simpleloancalculator</application>
	<version>1</version>
	<sessions-enabled>true</sessions-enabled>
 
	<!-- Configure java.util.logging -->
	<system-properties>
		<property name="java.util.logging.config.file"
                      value="WEB-INF/logging.properties"/>
	</system-properties>
</application>
</appengine-web-app>

and JSF faces-config.xml and web.xml files with default content

faces-config.xml

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<?xml version='1.0' encoding='UTF-8'?>
<faces-config xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"
version="2.0">
<application>
	<locale-config>
		<default-locale>en</default-locale>
	</locale-config>
</application>
</faces-config>

web.xml

Code block

<?xml version="1.0" encoding="utf-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <display-name>Wildstar Technologies, LLC. Google AppEngine JSF 2.0
        Template</display-name>
    <description>
        Template JSF 2.0 application configured to run on the Google
        AppEngine for Java.
      </description>
    <!--
        ***** GAE 1.3.0 appears to handle server-side state saving. *****
    -->
    <context-param>
        <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
        <param-value>server</param-value>
    </context-param>
    <context-param>
        <param-name>javax.faces.DEFAULT_SUFFIX</param-name>
        <param-value>.xhtml</param-value>
    </context-param>
    <!-- GAE Bug 1506 JSP 2.1 API but 2.0 Implementation -->
    <context-param>
        <param-name>com.sun.faces.expressionFactory</param-name>
        <param-value>com.sun.el.ExpressionFactoryImpl</param-value>
    </context-param>
    <context-param>
        <description>
          Set this flag to true if you want the JavaServer Faces
          Reference Implementation to validate the XML in your
          faces-config.xml resources against the DTD. Default
          value is false.
        </description>
        <param-name>com.sun.faces.validateXml</param-name>
        <param-value>true</param-value>
    </context-param>
    <!--
        ***** Accommodate Single-Threaded Requirement of Google AppEngine
    -->
    <context-param>
        <description>
          When enabled, the runtime initialization and default ResourceHandler
          implementation will use threads to perform their functions. Set this
          value to false if threads aren't desired (as in the case of running
          within the Google Application Engine).
 
          Note that when this option is disabled, the ResourceHandler will not
          pick up new versions of resources when ProjectStage is development.
        </description>
        <param-name>com.sun.faces.enableThreading</param-name>
        <param-value>false</param-value>
    </context-param>
    <!-- Faces Servlet -->
    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>/faces/*</url-pattern>
        <url-pattern>*.jsf</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>30</session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>index.xhtml</welcome-file>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list>
</web-app>

Then I’ve created index.jsp file which basically redirects all request to welcome.jsf page.

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<html>
<head>
	<title>Initial Redirect Page</title>
</head>
<body>
	<% response.sendRedirect("welcome.jsf"); %>
<body>
</html>

welcome.xhtml file prints welcome message using <h:outputText /> JSF tag.

Code block

<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
       "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets">
<h:head id="head">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Welcome to JSF 2.0 on the Google AppEngine!</title>
</h:head>
<h:body id="body">
	<f:view contentType="text/html">
		<p><h:outputText value="You are now up and running with JavaServer Faces 2.0 on the Google App Engine."/></p>
	</f:view>
</h:body>
</html>

When I’ve tried to run my project I’ve got following exception:

java.lang.NoClassDefFoundError: javax.naming.InitialContext is a restricted class. Please see the Google  App Engine developer's guide for more details.
at com.google.appengine.tools.development.agent.runtime.Runtime.reject(Runtime.java:51)
at com.sun.faces.config.WebConfiguration.processJndiEntries(WebConfiguration.java:578)
at com.sun.faces.config.WebConfiguration.<init>(WebConfiguration.java:114)
at com.sun.faces.config.WebConfiguration.getInstance(WebConfiguration.java:174)
at com.sun.faces.config.ConfigureListener.contextInitialized(ConfigureListener.java:161)
at org.mortbay.jetty.handler.ContextHandler.startContext(ContextHandler.java:530)
at org.mortbay.jetty.servlet.Context.startContext(Context.java:135)
at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1218)
at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:500)
at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:117)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:117)
at org.mortbay.jetty.Server.doStart(Server.java:217)
at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
at com.google.appengine.tools.development.JettyContainerService.startContainer(JettyContainerService.java:188)
at com.google.appengine.tools.development.AbstractContainerService.startup(AbstractContainerService.java:147)
at com.google.appengine.tools.development.DevAppServerImpl.start(DevAppServerImpl.java:219)
at com.google.appengine.tools.development.DevAppServerMain$StartAction.apply(DevAppServerMain.java:162)
at com.google.appengine.tools.util.Parser$ParseResult.applyArgs(Parser.java:48)
at com.google.appengine.tools.development.DevAppServerMain.<init>(DevAppServerMain.java:113)
at com.google.appengine.tools.development.DevAppServerMain.main(DevAppServerMain.java:89)

I’ve double checked all settings and library dependencies but couldn’t figure out the source of this exception. Then I’ve Googled this article. I’ve followed instructions on this blog (thanks Josh) com.sun.faces.config.WebConfiguration class in under my project. Content of this class can be found here.

After that I was able to run my project.

Demo of my application.

Source code with all required libraries.