Diving into an Infinite Ocean

New home for Derquinse Commons API documentation

2012-02-10T19:13:00.001+01:00

One of the main issues in Derquinse Commons is the lack of documentation, including the lack of a stable home for the Javadoc-generated documentation.

From now on, and thanks to the wonderful GitHub pages service, you can find the API docs at http://apis.derquinse.net/derquinse-common.

Non-API docs are still missing, and I hope to be able to write some soon.

Derquinse Commons now in Maven Central

2012-01-21T13:26:00.002+01:00

One if the best features in Maven is dependency management. Even with its known problems it is a great step forward and many other build systems reuse Maven's repository structure.

One of the essential parts of this vision is the Maven Central Repository, your one stop shop for most of the dependencies in your projects.

Publishing to Maven Central has always had its requirement set (you can find an updated list here), one of them being that the repository must be self-contained. That is, no artifact may depend on another artifact that is not part of the repository.

Back in 2008, when I started both derquinsej and lucis, this requirement was fulfilled with no problem and synchronization with Central was provided thanks to Sourceforge's SSH access.

However, as time passed, some projects such as Hibernate starting publishing its artifacts in external repositories and many other interesting projects were hosted in repositories different of Central, such as Java.net. So, for future projects Central Publishing was not an option and I prepared an external repository for my own projects.

Fortunately, the situation has improved a lot:

Now many interesting external repositories, such as JBoss and Java.net, are synchronized back in Central.
Central navigation and search has been enhanced.
Sonatype provides a repository for open source projects with the option of being published in Central. The process is very well documented and the response is fast and great (kudos to Juven Xu).

So, from now on, you can find Derquinse Commons in Maven Central.

Follow up to Maven Release Plugin version problems

2012-01-12T21:09:00.000+01:00

In a previous post, I warned about some bugs that caused the Maven Release Plugin to generate wrong tag versions. While those bugs are still opened today, the real culprit was MRELEASE-697 which is fixed in version 2.2.1, which can be used safely.

Lucis upgraded to Lucene 3.5

2011-12-09T19:24:00.001+01:00

Well, at last the jump was made, and based on the previous 2.9.x branch, the migration to Lucene 3.5 has been done with version 3.5.2 now available in central. Apart from the migration work, the most significant changes include:

Writer configuration suppliers, to deal with the fact that certain Lucene objects, such as merge policies, can't be shared.
Managed readers, not based on the new searcher manager, but integrated with the lucis store architecture.

A Lucis branch for Lucene 2.9.x

2011-09-21T07:11:00.000+02:00

As a said in the previous entry, the upgrade to Lucene 3.x may take longer than expected, so to provide an evolution path, a branch based on Lucene 2.9.x has just been released (version 2.9.5, based on Lucene 2.9.4).

It is not a mere recompile. Use of deprecated methods has been removed and the new collectors has been put in use.

A Lucis update

2011-09-16T19:59:00.000+02:00

After a too long period of inactivity at last we have a significant update to Lucis. The migration to Lucene 3.x has been put on hold to work on some more important changes (and I don't know if it will happen before the move to Lucis' successor project). So, to avoid confusion, version numbering has changed so that the first two numbers match those of the Lucene version used.

I have just released version 2.4.31 (should be in central soon), the main changes being:

Reindexing indexes can now hold a checkpoint.
Reindexing indexes can know decide to skip a run.
Cancellation policy for index services has been defined, using interruptions, providing graceful shutdowns. As always for all your java concurrency-related questions, go to the source.
It is know possible to use external executors.
Many more tests.

Also, as of this version, the javadoc is no longer uploaded to the repository, as it can be built from source, but the relevant parts are online for your reading convenience.

UPDATE: Already in Central.

Stick to version 2.0 of Maven Release Plugin

2011-08-20T19:30:00.000+02:00

As reflected on bugs MRELEASE-694 (related to MRELEASE-689 and MRELEASE-691), there are some problems generating the release version numbers (like maintaining SNAPSHOT). This may bite without notice if use non-interactive mode. These bugs are still open as of version 2.2.1.

It's a nice coincidence that because of another bug, the Maven Eclipse Plugin warns you if you use a Maven Release Plugin version other than 2.0 :)

Revisiting Lucis

2011-05-22T13:52:00.000+02:00

The lucis project is a key component of an increasing number of web sites. However, it is starting to show its age. Rushed into production in the summer of 2008 it included some "incorrect" decisions that were to be mended in its successor project, which was also going to include all the important updates. So lucis algo received small evolutions.

However, as the first release of conquiris is delayed again and again, and the number fo projects using lucis increases far more than expected, it is clear that a new impulse was needed.

So today, I've released version 0.0.31 (which should be in Maven Central in a few hours). The only (but fundamental) change is the upgrade from Lucene 2.4.1 to 3.1.0. As the new Lucene version already breaks backwards compatibility, I've gone the whole way and removed use of (now) deprecated parts of Lucene. So this version of lucis is totally incompatible with the previous stable one (0.0.29).

I hope to post about the changes real soon now.

As I said, the "only" change is the Lucene version, so this release won't be integrated in Port@l and GeNews until more improvements are added.

New Look

2011-05-21T22:28:00.000+02:00

Three years after the First Post, I've decided to give this blog a new look, maybe as a first step in posting more often.

So, I've turned to the Blogger Template Designer, chosen a clear and simple one, removed most ads, and converted code snippets to Gist.GitHub.

I hope you like it.

Great presentation for entrepeneurs

2011-03-06T19:31:00.000+01:00

From Zero to a Million Users - Dropbox and Xobni lessons learned

View more presentations from Adam Smith

Gist.GitHub Gadget

2011-01-23T17:47:00.000+01:00

Some months ago I wanted to embed some code snippets stored in Gist.GitHub in some Google Sites-based documentation, just to find that you cannot use the script tag directly. So, I decided to wrap the embedding code in a Google Gadget. You can find it here.

Port@l 3.0 en la LSWC

2010-11-28T18:31:00.001+01:00

Sé que voy con un poco de retraso, pero más vale tarde que nunca. Sólo comentar que el pasado 27 de octubre participé en mesa redonda "Soluciones Web Avanzadas" dentro de la Libre Software World Conference, con una breve presentación sobre Port@l 3.0. Podéis encontrar la presentación aquí embebida y en el siguiente enlace.

Port@l 3.0 en la LSWC

View more presentations from andresrc.

Permgen problems and Running Eclipse on Java 1.6 update 21

2010-07-14T21:05:00.000+02:00

See this post. Reposted here for future reference.

New Home...

2010-07-06T23:46:00.000+02:00

... for this blog (sort of) and my common Java libraries.

Some months ago I bought the domain derquinse.net and started a new incarnation of my common Java libraries, now called derquinse-commons, hosted on Google Code, and based on Google's guava-libraries.

But is hasn't been until recently that I have configured this blog to use the new domain, and performed the first releases (in plural, as the different subprojects are now released independently), which may be found in the Maven Repository (that, as of now, will not be synchronized with Central as there are dependencies that are not part of it). Right now, I've released:

derquinse-commons-base 1.0.0: Base libraries.
derquinse-commons-orm 1.0.1: Base object/relational libraries.
derquinse-commons-orm-hib3 1.0.1: Hibernate 3.5 implementation of the ORM module.

Besides some common POMs. The collections module will be next, with Hierarchy and friends.

Stay tuned.

El Androide Libre sortea un Nexus One

2010-05-06T08:34:00.001+02:00

Pues lo dicho, el blog en español dedicado a Android El Androide Libre sortea un Nexus One. Podeis encontrar las bases en el siguiente post.

Chirp 2010: Scaling Twitter

2010-04-17T13:56:00.002+02:00

Check out this SlideShare Presentation. Really interesting.

Chirp 2010: Scaling Twitter

View more presentations from John Adams.

Trees in Relational Databases

2010-01-25T17:39:00.000+01:00

The presentation below by Lorenzo Alberton is one of the best references I've seen on how to model a tree in a relational database:

Trees In The Database - Advanced data structures

View more presentations from Lorenzo Alberton.

It is perfectly known that relational databases are not the best repository for tree-like (or even graph-like) data structures, but there are many times that you have no other chance, so it's good to know your options.

Is it time to go stackless?

2009-12-12T20:48:00.001+01:00

As a follow-up on Guy Steele's post on tail recursion referenced on my last one and Cook's paper, there's another interesting post by Gilad Bracha that made me wonder: is it time to go stackless?

The stack, as an optimization for call convention is deeply rooted into greatly extended instruction sets. But now, with the amounts of RAM and CPU power available and the really cheap short-lived object allocation time in modern VMs, I think we could afford it, at least for high level languages.

Back in my Python days, I remember Stackless Python, an implementation of this programming language with support for continuations, generators and coroutines.

And this would be only the beginning...

Tail calls in OOLs

2009-12-07T11:25:00.000+01:00

Yesterday's paper is also related to a very interesting post by Guy L. Steele Jr. on the need of tail calls on object-oriented languages. A rather polemic issue with strong proponents (such as Guy) and detractors, like Guido Van Rossum, Python's creator.

I'm sure more interesting contributions will follow.

Readings on Dec 6th 2009

2009-12-06T20:33:00.001+01:00

Today's reading has been "On Understanding Data Abstraction, Revisited" by William R. Cook. It has really been an eye-opener on the differences between abstract data types and objects, and it have helped me understand the implication of the different approaches taken by different programming languages.

Highly recommended.

Lucene 2.9.0

2009-10-25T12:14:00.003+01:00

A few weeks ago Lucene 2.9.0 was released. The list of changes is impressive, and it's certainly an interim release paving the way to release 3.0, where I suppose many of the now deprecated methods will start to disappear.

One of the most interesting changes for me is LUCENE-1382, which will greatly simplify checkpoint management in lucis.

Looking forward to 3.0.

Functional dependencies

2009-09-05T17:00:00.002+02:00

Regarding papers, yesterday's read was Type Classes with Functional Dependencies by Mark P. Jones.

Quite interesting.

CUFP 2009 Keynote

2009-09-05T15:05:00.003+02:00

Bryan O’Sullivan is one of the authors of the book Real World Haskell, and he's given the keynote at CUFP 2009.

CUFP 2009 Keynote - Real World Haskell

View more documents from Bryan O’Sullivan.

I really liked the presentation.

Papers

2009-09-05T14:36:00.004+02:00

Over the last years I've become an avid reader of papers. As the time goes by, I start to have heaps of PDF files scattered through multiple files and computers, unable to find anything.

A few years ago I read in Ars Technica about Papers, a software package that seemed to fulfill all my paper archiving needs :). However, it wasn't until last month that I gave it a try and I only regret not having donde so earlier. Its matching capabilities, search engine and spotlight integration are really wonderful. It is really the iTunes of academic papers.

Highly recommended.

Counting and Grouping Queries in Lucene

2009-07-28T20:41:00.011+02:00

When using a Lucene index to look up some information you have access to some querying facilities not found in other kind of repositories. However, in a classical trade-off, you lose some features such as the aggregate queries easily performed in relational databases.

Anyway, if you need to perform this kind of operations, they may be easily implemented using hit collectors. So, I've included in lucis two simple operations, counting and grouping results:

The LucisQuery object is used to decouple index control policy (when to open and close it, etc) from the queries themselves.

The counting query just needs the Lucene query to perform and the (optional) filter to apply. The result holds the number of documents found and the time the query needed.

For the grouping query you must provide the list of field names you want to group by (in order) and the query result is the same that the counting query plus the root group (the one corresponding to the first field name), where a group is something like (partial API showed, see the source):

So, for each collected value of the provided field you get a child group which itself contains the groups representing the nested fields. The number of hits in a group may not be equal to the sum of the hits in the children groups if any of the fields is multivalued.