JSR 211 defines the Content Handler API (CHAPI). The basic concept idea is that MIDlets can be launched in response to incoming content (files). Modern mobile phones can receive content using SMS, infrared, Bluetooth, e-mail, and other methods. Most content has an associated content type. CHAPI specifies a system by which MIDlets can be launched in response to specific types of content.
In the Java ME Platform SDK Content Handlers are integrated in a project as application descriptors. Content Handlers you define are packaged with the application.