Sun Microsystems Inc’s JavaSoft unit has quietly created a pure distributed Java mechanism called Java RMI, Remote Method Invocation, for connecting Java clients with servers that bypasses Corba and the requirement for developers to learn Interface Definition Language. Developers we spoke to said Corba is different enough from Java to make a separate distributed environment necessary if Sun is to realise its Java ambitions. Remote Method Invocation uses what JavaSoft describes as a lightweight TCP/IP-based remote procedure call protocol called Doors ORB for connecting to Java servers. Server programs define remote objects in Java and bind them to URL Universal Resource Locators. Client applets resolve the Universal Resource Locators to receive Java client objects. When the applet invokes the client object, the call is transmitted to the Java object on the remote server. Doors ORB is derived from Sun Labs’ Spring Doors inter-process communication architecture, but is not the same implementation that features in Solaris 2.5. The Doors ORB is also the initial default ORB for use with the alpha release of Java Interface Definition Language which will tie Java applets to the Corba 2 world once an IIOP module is added. Java Interface Definition Language is based on the Java ORB and SunSoft’s Joe suite will connect Java Interface Definition Language to Neo ORB. JavaSoft is seeking third parties to develop modules to connect Java ORB to other ORBs. Alpha releases of Remote Method Invocation, which runs on any Java Development Kit-compatible virtual machine, and Java Interface Definition Language, are up on JavaSoft’s Web site. Client run-time environments enabling Java applets to use Java Remote Method Invocation will be bundled with a future release of the Java Development Kit. The server side run-time environments and development tools will be offered as separate products.
