Posts

2013

Adding HTML5 Microdata to DokuWiki
HTML5 , Microdata
HTML5 is the new standard for webpage markups. It comes with some pretty cool new features like media support etc. But one of the best things is the Microdata support! Read more...
Implementing State Machines with Java Enums
Domain-driven Design
Often we need to implement State Machines to encapsulate object behavior depending on a given object state. This can be cumbersome as it often leads to a lot of interfaces and implementation classes, and persisting such an object state often leads to problems, as we would need to implement a Hibernate custom type for instance to solve it. Read more...
MVC revised or what are the alternatives?
Modernization , Web
A simple overview about the MVC pattern and its alternatives Read more...
Enterprise Scala Beans or Scala on a JEE application server
Enterprise , Interesting , Scala
Once i was thinking about writing Enterprise Java Beans(EJBs) with the Scala programming language. This should be easy as Scala greatly incorporates with existing Java code bases. But let's create a small test to verify this! Read more...
Maven, Scala and AspectJ(AOP)
AOP , Interesting , Scala
Recently i was thinking about combining AspectJ and Scala in one project. Of course we can argue that functional programming addresses a lot of issues we are trying to solve with AspectJ, but that is not the point. AspectJ is a Bytecode manipulation framework, not a Java code manipulation thing. So why not implement cross cutting concerns like security or transaction handling with AOP/AspectJ in a Scala project? For this short example, i am using AspectJ 1.6.11 and Scala 2.10.1. Read more...
Using Scala with JPA 2.0
Enterprise , Interesting , Scala
Recently i was thinking about persisting Scala classes with JPA. I tried to set up a mixed Java/Scala project, using Java code to do the JPA stuff and using Scala to create the entities. For a more complex example, i decided to persist a master/detail association to test if the Scala collections can be persisted, too. For the test i am using Scala 2.10.1 and the Hibernate 4.1.10.Final EntityManager as the JPA 2.0 vendor. Read more...
Using Scala in legacy applications
Interesting , Legacy , Scala
Often we are enhancing and working on Java legacy applications. But time moves on, and new programming languages like Scala become popular. But one question arises: is it possible to use Scala in Java based legacy applications? Read more...

2012

An overview of current NoSQL databases
Database , Interesting , NoSQL
This summary is taken from the book 'Seven Databases in Seven Weeks' Read more...
How to avoid server round trips by using pretty URLs
JavaServerFaces(JSF) , Performance , Web
Unnecessary server round trips are a common cause for slow application performance. Unfortunately application frameworks like JSF(Java Server Faces) are forcing developers to do so. For instance given the following URL processed by a JSF Implementation: Read more...
Using and enhancing Hibernate Search
Enterprise , Modernization
www.hibernate.org is a very cool and mature Java Object-Relational mapping tool. Using Hibernate we can easily persist or reconstitute Java Objects to or from a relational database like MySQL, PostgreSQL, SQLServer or Oracle. Read more...
Displaying simple animated graphs with JavaFX 2.0
Interesting , JavaFX , User Interface
JavaFX is quite cool. The scene graph concept is quite powerful, combined with visual effects like animation, shadows or motion blurring can create very nice looking user interfaces. Read more...
Logging made easy
Enterprise , Logging , User Interface
In modern, distributed applications logging is a key requirement. But the problem arises if we try to track down an error using different log files on different servers. This is often a problem, depending on the business organization, access rights and other political forces. Read more...
Building CDI support with AOP and AspectJ
AOP , Dependency Injection , Enterprise , Modernization
This explains how to use emulare CDI with AOP and AspectJ Read more...
The Onion Architecture
Domain-driven Design , Enterprise , Modernization
Often we develop complex business driven applications. While we design our application, it's architecture and it's layers, we often feel to use a traditional approach to define the layers. Here is a short structure of what i mean: Read more...
Enriching legacy applications with CDI
Dependency Injection , Enterprise , Legacy , Modernization
There are a lot of applications out there. Some of them are legacy, others are in their maintenance phase. While we are developing new applications, we can use the coolest new technologies, think about good design and other stuff. But what about the software maintenance phase? Often, due to lack of time and other constraints, we cannot do everything perfectly, we need to move some refactoring or even re-engineering to the maintenance phase. Read more...
Putting your objects into context or why overwriting toString() can be evil
Interesting
Often we need to display Java business objects in the user interface. The easiest way is to overwrite the toString() method and give back the String representation of the object. This seems to be easy, but it is an evil temptation. Read more...
The law of leaky abstractions
Interesting
Personally i really like Joel Spolskys law of Leaky abstractions. Every architect should read and understand his article. Here is a summary of this law taken from Joel's Website and Wikipedia. Read more...
A first touch with NoSQL, graph databases and OrientDB
Enterprise , NoSQL
I was thinking about the current way we often store data in relational databases like MySQL, PostgreSQL or Oracle. We are using object-relational mapping frameworks like Hibernate, enriching Java classes with JPA annotations and are hoping that the mapping framework does everything for us the right way. Read more...
Thread tracking or how to know who causes an error
AOP , Logging , Threading
Often we are developing applications for multi-user environments. Classic examples are web applications or web services. This also means that technical or business exceptions can occur at the same time for different users. But how do we know you causes which exception? Read more...
How to embed Hystrix into existing Spring applications
Modernization , SpringBoot , Web
Netflix Hystrix is a very powerful framework to build fault tolerant and resilient applications. It provides common implementations for patterns like Timeout, CircuitBreaker and others. It also comes with nice monitoring capabilities using the Hystrix Dashboard or even JMX. Read more...
Enterprise search with Apache Solr
Enterprise , Search , User Interface
It you want to build a enterprise search engine, you don't have to reinvent the wheel. You can use open source engines like Apache Lucene or if you have just one day to implement it Apache Solr. Solr is a full blown enterprise search server, which comes with a lot of bundled plugins like meta-data and content extraction from a very common set of document types with Apache Tika , search highlighting, fragmented search and also similarity search for search results. This is a short tutorial how to create a search application within one day. Read more...
Software defect detection with AOP and JSR-303 / JSR-305 / JSR-308
AOP , Interesting
For many years common runtime exceptions like NullPointerException or ClassCastException are haunting poor Java programmers. This often leads to repetitions in the source code for checking method arguments for nullness. This is violating the DRY(Don't repeat yourself) principle. The Java Community Process created JSR-305 to address this issue. Unfortunately this JSR didn't become part of the official Java languages, but tools like FindBugs or IDEs like IntelliJ are offering static code analysis to find such NullPointerExceptions at compile time. Read more...
Domain-driven Design - Overview and building blocks
Domain-driven Design , Modernization
There are a lot of excellent blogs out where about Domain Driven Design and what it's all about. I prefer Wikipedia for a short introduction. If you want to know more about the principles behind DDD, you can also consult the GRASP Patterns or the SOLID Patterns. Here is a summary of DDD (also taken from Wikipedia). Read more...
XML Resourcebundles and how to make I18N refactoring safe
I18N , XML
Java Resourcebundles are cumbersome. Without good IDE support, you are lost. It is hard to maintain the different property files, keep them in sync and take care of correct character encoding. And even if you manage all this, you still have the resource keys hard coded in your source code. It is very hard to detect where your resource keys are used. Read more...
Reusing domain objects to create query specifications
Database , Enterprise
How to reuse domain objects to create query specifications Read more...
Swing Databinding with Mogwai DataBinding
Databinding , Swing
While you are developing Java Swing based applications, you need a mechanism to bind Java objects to Swing widgets. Project mogwai.sourceforge.net provides a very simple but powerful framework called DataBinding to help you with this task. Here is an example. Read more...