Dr. Drej's thoughts

Lombok – Why is it nice?

drdrej — Tue, 20 Oct 2009 09:45:16 +0000

Florent Ramière wrote a nice article about the advantages of lombok, an annotation compiler to build getter and setter of a class. Nice extension! I’ve never used it, but i love it

http://blog.springfuse.com/2009/10/project-lombok-must-have-in-your-java.html

Thoughts about ORM – Part 2

drdrej — Mon, 19 Oct 2009 15:34:02 +0000

pui… some additional links about ORM. and the discussion doesn’t arrive the end-point.

http://www.crazymcphee.net/x/2009/10/19/orm-is-dead-meme/

http://blog.schauderhaft.de/2009/10/18/hibernate-problems-alternative/

Thoughts about ORM

drdrej — Sun, 18 Oct 2009 13:40:11 +0000

i’ve found a fresh and nice “pro-orm” blog entry… and many good comment

AQula vs. similar frameworks

drdrej — Mon, 29 Jun 2009 20:58:04 +0000

i’ve found a good comparsion of different frameworks related to AQuLa’s concept:

http://source.mysema.com/display/querydsl/Similar+frameworks

i plan to play with some of them in the next days…

Why AQuLa?

drdrej — Mon, 29 Jun 2009 13:09:20 +0000

there are different solutions to handle queries in java. before hibernate was born jdbc was the most popular way to get data from the database. after some simplifications (query-templates with string-replacements based ond text-formatting-libs) a new star was born: “hibernate”. as a flagship of the orm-community he promised an easier way of handling a database in java. the main idea of ORM is to map an object-graph to a relational database.

hibernateis and other ORM-candidates are a nice solution, but they are not perfect. a good explanation of some problems with hibernate can you find here: http://incubator.apache.org/empire-db/empiredb/hibernate.htm

so what is wrong with hibernate & co.?

here some points in a short maner:

hibernate is object-driven. every operation (select, insert, delete, update) is based on the object. an object is full mapped to the database. the way of mapping is not flexible as possible. thats mean that the database-design is strongly influenced by the object-graph.
hibernate allows to create your own selects formed in a special query-language called HQL, but they are hard to maintain, because they are strings.
1. so you need to learn a new query-language.
2. queries as strings aren’t type-safe.
alternatively you can use the criteria api, but (for me) the code is not so readable. queries formed over the criteria-api aren’t readable.
the load is not effektive. bevore you delete an object, you must load it. sounds strange.

i think they are enough arguments to play with an idea to implement a new way of query-mapping. the new solution should be more readable, better to maintain, to train as less as possible.

in the best case queries are formed in simple java and then transformed to a query-language like SQL (or another one). the main focus of the aqula-project is the maintainance and testability of a database-query (f.e. SQL) inside of java.

Aqula is born

drdrej — Wed, 24 Jun 2009 14:26:50 +0000

After playing a while with my experimental project dbox4j (replacement for prevayler, distributed in-memory stores etc.) i’ve realized that i need a query-language directly integrated into java and later transformed into another sql (or another query-language used to query the database).

there are allready some candidates in the fre world i’ve found:

http://www.h2database.com/html/jaqu.html
https://squill.dev.java.net/
http://source.mysema.com/display/querydsl/Querydsl
http://quaere.codehaus.org/
http://code.google.com/p/liquidform
http://josql.sourceforge.net/
http://joist.ws/
http://www.jequel.de/
http://incubator.apache.org/empire-db/empiredb/empiredb.htm
http://code.google.com/p/dreamsource-orm

i will analyze them and than decide what i will do with “aqula”. in the meantime i will register this project on kenai and maybe write down some reasonings about AQuLa.

Andrej meets Flex

drdrej — Thu, 04 Jun 2009 13:36:15 +0000

Some days ago i’ve started with Flex. I’ve downloaded the Flex-Builder Version 3 and started with a small funny project – a game. Last time when i’ve tried to do something with flash is over 5 years ago. So my first imression after this long period: ActionScript 3.0 is good. It’s a strange feeling (I’m a Java-Nerd), but i like it. I like the mixture of multimedia possibilities of the flex-sdk, and the syntax of the language is ok. For JS-Freaks it shouldn’t be a problem to learn ActionScript.

How to organize projects?

drdrej — Wed, 18 Mar 2009 10:43:13 +0000

I’ve decided to organize my projects in a more-mobile-style.

My principles:

all parts (ide, server, database, project-sources) of a project should be stored independed from a used computer.
changes from one system to another one should be fast and simple to minimze the costs of a change.
data should be as mobile as possible.

These principles led me to the following structure:

local maven repository is stored on an online-drive. for this purpose i use http://zumodrive.com. they have a fast and stable integration into the windows os.
source-code, eclipse-ide, archiva, tomcat are stored on an SD-Card.
every project is a set of eclipse-projects and is stored in an own workspace.
environment variables are set in command line scripts.
paths are relative.

Subsumption:

i’ve no idea about how to install databases like oracle or mysql as a portable application. this still remains an issue.
my SD-card is a little bit too slow.
clear structure
independent from used hardware
fast changes between systems

… and I like it