Architecture of Jcapi

The whole architecture of Jcapi is based on the native Common ISDN API (CAPI 2.0) for any platform or system architecture. The vendor of the ISDN device should offer an application level CAPI, usually a shared library (e.g. capi2032.dll for Win32-systems).

Since a CAPI shared library cannot be loaded directly from a Java application, it needs to be "wrapped". This is done by the jcapi20 shared library which links the vendor specific CAPI library dynamically and offers a Java Native Interface for Java access.

Thereby this library builds a bridge over two gaps between platform independent Java applications and ISDN devices: First, it gives access to the native coded driver including direct memory access and second, it replaces the platform specific CAPI 2.0 by an Java Native Interface identical for all platforms and systems.

Since this wrapping feature is only possible for native coded programs, the library has to be built for all platforms seperately; but keeping it small and simple minimizes the extend required.

This layer is designed to extend the Common ISDN Application Programming Interface (CAPI 2.0) to the Java Virtual Machine (JVM) as an additional platform. Therefore it has to be certified by the CAPI Association.

The CAPI interfaces described above are implemented by this layer. The CapiException class lies somewhere in between: It belongs to the CAPI specification but is already an implementation.

The CAPI 2.0 is a "low level" interface with the need of special know-how of the ISDN protocols and data structures. It is not designed for application programmers who don't want to deal with "bits and bytes". The ISDN layer offers a more simple and "Java like" API.

There are standards defined for Java communication APIs like stream I/O. These APIs are implemented for ISDN communication within this layer.