# Using ORBLink to bridge Lisp and Java

A comprehensive discussion of the issues involved in bridging Java and Lisp using ORBLink requires in a certain sense full discussion of the installation and use of Java ORBs.

Fortunately, there are several good books on CORBA and Java available, for example, Programming with Visibroker, by Doug Pedrick, Jonathan Weedon, Jon Goldberg, and Erik Bliefield, Wiley, 1998.

A tutorial walking through a Lisp-Java application is available here.

## Java applets and CORBA

You can use CORBA to connect a Java applet to Lisp, but doing so is more complicated than hooking up a Java application to a Lisp program. The reason it is more complicated is that a Java applet imposes security restrictions on network connections. The nature of these security restrictions tends to be highly enterprise-dependent, depending on such variables as:

1. The exact version of the browser your users are using, and what Java ORB you want to use.
2. The security configuration of the browser.
3. The version of JDK you are using; whether you are using the Java activator
4. The firewall configuration at your site.
5. Whether internet or intranet access is desired.
6. Should the applet be usable to remote users who will tunnel through their own firewall?

   There is no "one perfect solution" for all applications at this time. In general, for example, the you can use http tunnelling (using, for example, the Visigenic tunnelling tools) to allow internet applet users to tunnel through their own firewalls, but this often imposes an unacceptable performance overhead for things like callbacks. Browsers tend to support different versions of the JDK as well; of course, if you are willing to use the Java plug-in, things can be somewhat simpler.

   However, if you have control over the browser configuration and are running within an intranet so that firewall configuration is not a problem, hooking up to an applet is much easier. Still, we suggest you begin by getting your application working correction as a Java application and only later addressing the more subtle security and browser issues that are required to get an applet solution to work reliably.