Java ME on Symbian OS: Inside the Smartphone Model

Chapter 11. Integration of Java ME and Native APIs

In Chapter 10, we discussed the architecture of the Java ME subsystem on Symbian OS – the subsystem binaries, the Java Application Management System (AMS), the CLDC-HI virtual machine (VM), interaction between the VM and AMS and the integration with Symbian OS architecture, platform security and Symbian C++ programming idioms.

Now that the monolithic and so-very-abstract entity of the Java ME subsystem on Symbian OS has been broken into smaller and more concrete entities, and the interaction between them has been explained, a question that should be asked is – when an application invokes a given Java API method, does it go outside the Java ME subsystem into the native Symbian OS services? Or is it handled internally and independently, in the Java ME subsystem only? In more technical terms, how do Java ME APIs map to the native Symbian OS APIs?

For example, given a Java ME API, such as JSR-135 Mobile Media API (MMAPI), is the multimedia content played by the Java ME subsystem itself? Or does it use the native multimedia subsystem and delegate the playing and recording of content to the native Multimedia Framework (MMF)? Another example is the Generic Connection Framework (GCF) – does the Java ME subsystem have its own HTTP implementation? Or does it use the native Symbian OS Application Protocols subsystem, which contains components for using the HTTP protocol, and associated utilities? Assuming that the Java ME subsystem makes use ...