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Jasper notes

Jasper is a bi-directional interface between SICStus Prolog and Java. It is currently built on top of the JNI together with the C-Prolog interface, and hence makes use of the native keyword in Java. As a result, a Prolog-enhanced Java-program can not be used in an applet, for example.

Requirements

To use Jasper, you need a JNI-compatible Java-implementation installed on your system. Jasper has currently only been tested and verified with Sun's JDK 1.1.x, which can be downloaded from

http://java.sun.com/products/jdk/1.1/

Jasper should be able to use any Java-implementation as long as it is JNI-compatible. However, the configure-script makes some assumptions about the locations of header files and libraries which may not be valid for other JDK's than Sun's own. So, if configure fails to locate the correct header files and libraries, it may be necessary to manually set the values of JAVAINC and JAVALIB. See `INSTALL' for information on how to do this. In general, if you manage to get Jasper working on a platform it is not know to work on (or if you don't), please let us know by sending a mail to sicstus-support@sics.se.

Under `$SP_PATH/library/jasper/examples' there are a couple of examples on how to use the Java-interface.

If you want to call Java from Prolog, you must also make sure that library(jasper) (the Prolog library module) was installed correctly.

The interface can be used in two different ways, depending on which language is used at toplevel. Either SICStus is loaded as a runtime-system into Java:

% java JasperTestClass

or Java can be loaded into SICStus as a foreign resource:

% sicstus
SICStus 3.7: Mon Mar  2 19:22:44 MET 1998
| ?- use_module(jasper).
...

Runtime requirements

When using Java as toplevel application

The path to the SICStus library must be included in CLASSPATH (see the documentation of your Java implementation for more details about how to set this variable). For example, under UNIX:

% java -classpath $CLASSPATH:/usr/local/lib/sicstus37/library Class

or under Windows:

% java -classpath "%CLASSPATH%;c:\Program Files\sicstus37\library" Class

Also, the runtime linker must be able to locate the SICStus runtime kernel. This is usually handled automatically when running SICStus, but when Java is used as toplevel application, the system will usually not know where your SICStus application resides.

Under UNIX this is handled by setting the runtime linker search path variable (usually LD_LIBRARY_PATH) to contain the path to the SICStus runtime kernel (`libsprt37.so'), and by setting SP_PATH to point out the location of the Runtime Library.

Under Windows, `sprt37.dll' must be located in one of the placed the runtime linker searches in; the same directory as the executable, the current directory, or the directories specified by PATH (which includes the system directories).

When using SICStus as toplevel application

The runtime linker must be able to locate the Java runtime kernel (`javai.dll' or `libjava.so'), according to the same rules as above.

The classpath variable is taken from the environment variable CLASSPATH which therefore must contain the correct value.

Availability

Jasper is currently only available on Solaris 2.x (SPARC and x86 platforms) and Windows.
Be wary when using terminal-I/O routines in Java code called from within Prolog. Due to conflicts in signal-handling between SICStus and some Java engines, this may crash the process.

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