JavaXPCOM allows for communication between Java and XPCOM, such that a Java application can access XPCOM objects, and XPCOM can access any Java class that implements an XPCOM interface. With JavaXPCOM, a developer can talk to XPCOM or embed Gecko from a Java application. JavaXPCOM is very similar to XPConnect (JavaScript-XPCOM bridge), and uses XPIDL . Install this package if you wish to access XPCOM objects from Java or the other way around. . This package also provides the JavaXPCOM interfaces sources.