10 Interfacing .NET and Java

SICStus Prolog supports two different ways of interfacing a Prolog program with a Java client, and one for interfacing with a .NET client.

For .NET and Java there is PrologBeans and for Java there is Jasper. PrologBeans is the recommended package unless you have special needs and are interfacing with Java in which case you may consider using Jasper.

Jasper is “tightly coupled” with Prolog, which means that everything runs in the same process (the necessary code is loaded at runtime via dynamic linking). PrologBeans, on the other hand, is “loosely coupled”, which means that the client code runs in a different process from the Prolog code. In fact, the client program and the Prolog program can run on separate machines, since the communication is done via TCP/IP sockets.

Advantages of Jasper:

• Jasper is bi-directional. Callbacks are possible (limited in levels only by memory), and queries can backtrack.
• Jasper is normally faster than PrologBeans.

Advantages of PrologBeans:

• Since the client program and the Prolog program run in separate processes, there is no competition for memory between the virtual machine of the client (.NET or JVM) and the Prolog Abstract Machine. This means that PrologBeans works well with large applications.
• Distribution over a network is a no-brainer when using PrologBeans. The application is distributable from the beginning.
• PrologBeans has support for user session handling both at the Java level (with support for HTTP sessions and JNDI lookup) and at the Prolog level. This makes it easy to integrate Prolog applications into applications based on Java servers.

PrologBeans is described in PrologBeans, and Jasper is described in Jasper.