Building a fluent API (internal DSL) in Java

In this post I am going to sum up things I have learned while creating a fluent API (or internal DSL) in Java. I'll talk about the search API I created for my current position: it's not a toy problem, it's a real problem, which has a significant amount of complexity. Because of that complexity, you get to see techniques and ideas that you don't usually see in toy examples. I am not including the full source, which (if you really want) you can access on the project's site. The model First, I need to tell you a little bit about the problem I am trying to solve. IRMIS, the tool that I am developing, needs to keep track of all the components of a particle accelerator and their relationships. For example, you want to keep track where a particular card is, how is it getting power, and how messages from the control system are addressing it. The GUI, for example, would display something like: Each component can be part of multiple hierarchies (control, housing, power), can have multiple children in each, can have multiple parents in each (though 99% of the time it has one). Each component has also a type and a set of properties: public interface Component { ... ComponentType getComponentType(); Set getParents(RelType relType); Collection getChildren(RelType relType); Map getProperties(); } It has a bunch of other stuff too, but to we can limit our attention to this. Each relati...

Date: February, 04 2010
Url: http://www.java.net/blog/carcassi/archive/2010/02/04/building-fluent-api-internal-dsl-java

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