Architecture & Design

A type-safe named query design approach for JPA

The MVC pattern implemented with java swing

MVC Pattern Basics
The MVC pattern describes a way to organize the components of a graphical user interface. Therefore it must cover all aspects of a user’s interaction with an application.
If we take an analytic look at a graphical user interface we will understand why the MVC pattern is composed of the 3 elements model, […]

Separation of api and implementation

In every project you have to deal with apis and their implementations. While a lot of projects separate the api from it’s implementation through different java packages (mostly named internal or impl), I want to show you another approach and tell you why this approach makes more sense. I call this other approach “implementation […]

Simplify service layer design using bean validation – jsr-303

Some weeks ago I wrote a blog about Pros and cons of service layer designs. While that blog addresses the service layer design with pure java, this blog is about a service layer design using java bean validation as defined by jsr-303. Both strategies that I have discussed in the Pros and cons of service […]

Impact of proxy on equals and hashCode

A lot of frameworks create proxies  to apply aspect oriented programming or the lazy loading pattern.

Hibernate for example uses cglib or javasissit to create lazy loading proxies. The famous springframework mainly uses java proxyies created via java.lang.reflect.Proxy.newProxyInstance(ClassLoader, Class<?>[], InvocationHandler) or cglib as well.
Therefore it is important to know exactly how proxies work and the […]

Pros and cons of service layer designs

A service layer is a common approach in enterprise applications to encapsulage application specific use cases. So when I talk about service layers I mean the service layer pattern as described in the “pattern of enterprise application architecture” book by Martin Fowler.
While the pattern describes the responsibility of a service layer from a high […]

Handling complex object state with design

Some APIs that implement a complex object state management often violate the single responsibility principle and make the usage very difficult. When you do all aspects of the complex state management in one inferface the interface’s methods must be invoked in the chronological correct order. Such APIs are hard to understand and to integrate. What […]

Impact of native sql queries on hibernate’s second level cache

Anemic vs. Rich Domain Models

There are a lot of discussions about rich and anemic domain models. Some developers tend to praise the anemic model, because of it’s simplicity while other blame the anemic model for it’s simplicity and they pray for the rich domain model.

In this blog I want to show both models, the advantages and disadvantages that […]

The difference between pojos and java beans

Java Beans and Pojos are often used and misunderstood terms. Some think that a pojo is a java bean and vice versa. In fact it is not. There are differences that matter.
The pojo
If you want to know what a term really means you have to find the source context in which the term has been created. […]