jueves, 29 de noviembre de 2007

New process scheduler for linux

There's a new "completely fair scheduler" for linux. I'm eager to see some benchmark or interactivity improvements over the old one.

miércoles, 28 de noviembre de 2007

IBM JDK tools

I'm not the only one with problem in the lack of profilers for the PPC64 IBM's Power platform.

Disable Explicit Garbage collection

You can disable explicit garbage collection (System.gc) by using the following switch:


This week in various stress tests, many Stop the world collections are triggered by ServiceMix. This switch disables this behavior.

Stay hungry, Stay foolish

Google's architecture

Following with the technical video sessions, I'm fascinated by the clear introduction to Google's architecture in this video.

GFS, MapReduce and a modified version of Linux are the base of the empire :)

JBoss stupid configuration errors

Why on earth the JBoss people doesn't warn about connection pooling? The stale connection are very common. What happens when the server has a smaller timeout time for the connection than the application server?
Answer: the connection becomes stale. It doesn't work anymore. Some drivers such as jTDS or DB2 jcc have this behavior.
The best thing you can do is add the following tag to your datasource XML:

<check-valid-connection-sql> SELECT 1</check-valid-connection-sql>

The SQL statement can be anything useful to you. Be sure not to do something crazy such as a join. The only requirement is that the SQL must execute OK, otherwise JBoss creates a fresh connection.

martes, 27 de noviembre de 2007


Today I researched WS-Discovery. This is a protocol of the WS-* family and is very similar to a p2p architecture. But instead of using a propietary or binary messages to discover peers or services it uses XML and SOAP.
I don't agree that the WS-* stack is bloated, the interoperability is great, when you have communicated two applications written in two completely different languages such as Java and ASP, then you know that Web Services are paradise.
If you complain about bandwidth just use compression, and if you don't understand the protocols, do your homework :)
Returning to the subject of my post, WS-Discovery identifies clients and services. The clients send multicast "probe" SOAP messages asking for services. Then the services answer in unicast to the client, using WS-Addressing to indicate the client the service address. Also services can say hello or goodbye to the whole network in a multicast way. All in all it is a very simple protocol and really useful in mobile enviroment where connectivity is limited.
A good way to dynamically obtain a SOA service catalog too.
AFAIK there is no Java implementation, but a .NET one in Windows Vista, but i haven't checked it out yet. Perhaps it's a good addition to Apache Muse.

lunes, 26 de noviembre de 2007

Open Source Code metrics

A few months ago, I found Ohloh. The Ohloh site checks out an open source project code and display several useful metrics like LOC count, the number and geographical location of developers, and an estimated project cost based on an average programmer salary. Check out the Ohloh page for one of my favorite project ServiceMix
You can also embed the metrics into your blog like this from the Shoal project:

Microsoft Surface

Es increible lo que se puede hacer con un touch screen, sin mouse y sin teclado. El Microsoft Surface no es solamente eso, sino que tambien es multi-touch como el iPhone y tiene 5 camaras para reconocer objetos.
Quiero uno!!!

Youtube architecture and scalability

I'm fascinated by the talk given by Cuong Do about the YouTube architecture, its issues and maturity phases. The trick for getting the mysql replication faster is an incredible example of lateral thinking.

It blows my mind!

Architect forum from Microsoft

I've been invited to join an architect forum organized by Microsoft. Fortunately is open minded and technology agnostic not Microsoft centric.
Kudos to Martin Salias and Ezequiel Glinsky for the great discussion topics. Highly recommended to attend if you are a software architect.

OSWorkflow book review

The book is selling well and getting positive reviews both from peers and reviewers like Geertjan

Java application clustering made easy

Ever wanted to share the state and emit signals between two applications? and how about a variable number of application instances? you know how hard it is to do it efficiently, in a multicast way, etc.
And how about recognizing an instance failure? All those features are hard to write and harder to test.
Shoal comes to the rescue. This framework derived from the GlassFish project, provides cluster communication, join and failure signals, messaging and data sharing.