quicklook – Project Hosting on Google Code

Quick Look is a package to collect system statistics and output pretty graphics and (X)HTML pages. It allows system administrators to have a quick look on the status of their systems, without going for a more advanced (and heavier) solution.

Quick Look currently shows…

CPU and memory usage

Load average and process spawning rates

I/O operations

Network traffic rates

Tracked network connections

A static demo is available at http://www.carlos-rodrigues.com/projects/quicklook/demo/.

via quicklook – Project Hosting on Google Code.

Java HttpClient and Load Balancer bad interactions

Working for a very big customer, I found a very nasty interaction between Sun HttpClient (JDK 1.4) and Http  Load Balancers.

In a complex network environment, sometimes you can experience low level TCP/IP comunication errors, because sometimes HttpClient get confused and hangs.

The bad behavior of Sun HttpClient is well known: some guys suggested me to use the Axis Web Client. Anyway you can solve the issue adding these three parameters to the JVM launch line

-Dsun.net.client.defaultConnectTimeout=5000
-Dsun.net.client.defaultReadTimeout=5000
-Dhttp.keepAlive=false

The first two parameters set globally the socket timeout to 5 seconds.
The last parameter forces the JVM to avoid reusing http connections when doing http request.

To be honest, http.keepAlive=false is not always effective and could have huge performance impacts, so be very carful adopting it.

But if you stick on the two sun.net.client.default*  properties (doing some tests) you can solve the issue.

References

From Java Plug-in Control Panel:

[…]
Networking properties description:

sun.net.client.defaultConnectTimeout

sun.net.client.defaultReadTimeout

These properties specify, respectively, the default connect and read timeout values for the protocol handlers used by java.net.URLConnection. The default values set by the protocol handlers is -1, which means there is no timeout set.

sun.net.client.defaultConnectTimeout specifies the timeout (in milliseconds) to establish the connection to the host. For example, for http connections it is the timeout when establishing the connection to the http server. For ftp connections it is the timeout when establishing the connection to ftp servers.

sun.net.client.defaultReadTimeout specifies the timeout (in milliseconds) when reading from an input stream when a connection is established to a resource.

For the official description of these properties, see Networking Properties.

[…]

A very good hosting provider

After my past experience with bad hosting provider, I am happy to say I have find a very good hosting service.
If you need VPS hosting, Rimuhosting is a very good choice.

After about two years with Rimuhosting, I can summarize their feature here:

  • They have a very good  entry-price for a virtual hosting
  • System aministrator has a very prompt response: on every issue I get support in 24 hours, also on Sunday
  • Rimuhosting uses a Xen virtualization mechanism which is very effective. I have tried other virtualized solution, which are worst.
  • Java hosting works well, without problems.
  • The default Bandwith is very huge (30GB). There is also  an automatic backup and a remote web-based shell out-of-the-box.
  • You can choose between high-end Linux distribution  (like Red Hat enterprise) and free one.

Dynamic languages troubles

I have read http://www.manageability.org/blog/stuff/chandler-failure and I think it is very danger way of exposing concepts.

In the article pointed out, the quite dead Chandler project is compared to the multi-billion Eclipse project. And then a too easy analysis is done against dynamic languages, where Java is the absolute winner.

I will try to fix some of the things said there, and to add also my two cents here :)


 

First of all, I use Java a lot, but I am also a fan of dynamic languages. Every tool has its place in the world, and I will avoid some holy war here. 

Anyway, it is important to understand major differences between very distant projects.

 

First of all, Eclipse is a very huge project, developed by IBM and based from the beginning with a very strong hype on plugin modularization.

The effort pushed inside Eclipse is very huge and come also from the San Francisco Project. Other IDEs (like JBuilder and Together) stops fighting Eclipse years ago, and eventually failed even to sell their stuff.

 So there are no similar example to Eclipse in Python/Ruby/Perl world. Even in PHP is hard to find a so huge and well designed program. And the languge here is less important: a company big as IBM can also code in PL/I all its stuff, without so much pain :)

Second, PHP is very successful language, even if a bit too insecure, at the present time.

PHP Language has poor support for modules and so on, but project like Drupal, Joomla and other are full of plugins, quite easy to write.

RubyOnRails is falling down because nobody is understanding why PHP should be abandoned for Rails.

Java architectural model is very well written and Sun worked very hard to it. Java Hot Spot VM is derivered from the Self dynamic language,  and has inside technology difficult to develop in an open source project.

Surely Dynamic languages are strong when there is the one-man-band paradigm: sharing works in Smalltalk was  a bit complex in early days.

Put Perl, python and ruby have a strong modularization concepts, and so this issue is often solved.

I have tried Zope and I think it is weak because:

  • Zope is user is non-existent. Zope user is a super-skilled web master which wants a web CMS without writing so much code.
  • Zope product upgrade is a nightmare
  • A stuck Zope Product can destroy your work. So hosting Zope is a problem
  • A lot of Zope basic objects (like cache accelerators and so on) are poorly minded: they works only on RAM, and are not thinked well. Drupal 5 has more strong theory for this issue, and Drupal is poor PHP code.
  • Zope use a proprietary database, when a simple SQL database with a relational mapper can do the same thing…think twice before reinventing the wheel!
  • Every major Zope releases breaks a lot of the API. This is the most stupid thing you can do as open source developer.

Chandler failed because they tried a very difficult business: calendar software is a very difficult area to address. All operating system (including possibly C/64 :-) has now a huge set of Personal Information Manager software (PIM), and LDAP solves sharing issue for big companies

Even Ximian Evolution is near death.

And your bigger competitor is Microsoft Exchange and… yes… old Unix.

Dynamic lanuages has many lacks, and difficult refactoring is a problem but… remember frefactoring tools was INVENTED under SMALLTALK!

IT is a place where you must be careful… isn't it?