t is often beneficial to allow users extend your software with their own logic. With the rise of dynamic languages on the JVM it is also much more easier to do than ever before. In this session we will share our experience in creating Groovy authored user plugins interface.
After a brief introduction to domain specific languages (DSLs), their relevance to user plugins and how they can be easily implemented in Groovy, we’ll look at more user-friendly, but developer-challenging type of DSLs, which support plugins written both in Groovy or Java.
Good public API design is another very important aspect - while the APIs have to be broad enough to allow interesting functionality, internals should stay close to allow changes and further development. Exposing APIs to the world come with great responsibility - once ublished they can’t be changed without a price, so it is important keep backwards compatibility in mind.
Another very important aspect is security - you let strangers into your chambers, and you better be ready. Leveraging security mechanisms is essential to establish proper sandboxing and protect your application from malicious or faulty plugins.
Finally, we will cover another very important and nontrivial aspect of user plugins exposure - the classpath isolation when your plugins require dependencies. We will compare different solutions like establishing classpath hierarchies, OSGi, JBoss modules and the long-awaited Project Jigsaw.