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.
Jasper is available on the following platforms:
http://java.sun.com/products/jdk/1.1/
http://java.sun.com/products/jdk/1.1/
Jasper should be able to use any Java-implementation as long as it is JNI-compatible. Doing this, however, requires a source distribution since the Jasper-module needs to be built. Refer to the source code installation instructions for more details.
Using Jasper from applets: Since Jasper relies on calling
methods declared as native, Jasper cannot be used from within an
applet. This is due to a security-restriction enforced on applets; they
are not allowed to call native code.
Note: Be wary when using terminal-I/O routines in Java code called from within Prolog. This is known to crash the Prolog process on some configuration.
The interface can be used in two different ways (but see the section on "limitations" above), 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). ...
When calling Java from Prolog, a foreign resource must be created using
splfr, as described in the User's Manual. This resource must be
linked with the JVM (javai.dll or libjava.so). Under UNIX,
splfr automatically detects that a Java method is called and
passes the correct flags to the linker. Under Windows, however,
splfr takes an additional option -java=JAVADIR to indicate
that the resource should be linked with the JVM. Also, the Java and
Jasper link-flags need to be specified explicitly as a +l option
to splfr.
% splfr simple simple.pl -java=c:\jdk1.1.5 +dynamic \
+l c:\jdk1.1.5\lib\javai.lib %SP_PATH%\library\jasper.lib
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. If you are unsure of what
to set these variables to, a look in the SICStus start-script can be
helpful.
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).
Under UNIX, the SICStus start-script sets LD_LIBRARY_PATH and
CLASSPATH to their correct values, so there is no need to set any
environment variables manually.
Under Windows, the runtime linker must be able to locate the Java
runtime kernel `javai.dll', according to the same rules as above
(i.e. for `sprt37.dll'). The classpath variable is taken from the
environment variable CLASSPATH which therefore must contain the
correct value.
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