Reusable enterprise metadata with pattern-based structural expressions

An essential part of modern enterprise software development is metadata. Mainstream metadata formats, including XML deployment descriptors and Java 5 annotations, suffer from a number of limitations that complicate the development and maintenance of enterprise applications. Their key problem is that they make it impossible to reuse metadata specifications not only across different applications but even across smaller program constructs such as classes or methods. To provide better enterprise metadata, we present pattern-based structural expressions (PBSE), a novel metadata representation that offers conciseness and maintainability advantages and is reusable. To apply PBSE to enterprise applications, we translate PBSE specifications to Java annotations, with annotating classes automatically as an intermediate build step. We demonstrate the advantages of the new metadata format by assessing its conciseness and reusability, as compared to XML and annotations, in the task of expressing metadata of J2EE reference applications and a mid-size, commercial, enterprise application.