AgentBase for SICStus Prolog

AgentBase for SICStus Prolog
Swedish Institute of Computer Science
http://www.sics.se/isl/agentbase/

Jeval - Java Evaluation for SICStus

Jeval is a package that enable SICStus developers to make full use of the strengths of Java (GUI, networking, etc). Using jeval it is possible and easy to develop the core functionality of the application in prolog and the user interface in Java.

Different Modes - Single/Multi user

The jeval package allow the user to decide if the prolog or the Java code should be the server. When prolog acts as server jeval can handle multiple users (connections) to the application. When Java is the server only one user/GUI can be handled.

Scripted Java Code

Jeval uses the BeanShell scripting package to implement the execution of Java code from prolog. The syntax of BeanShell scripted Java is close to Java and the most obvious difference is that you do not need to declare variables. In Java you would write

String str = textField.getText()

to make the variable str contain the text of textField. In scripted Java you would write

str = textField.getText()

For more information about the syntax, etc of BeanShell please look at http://www.beanshell.org.

Using Single User Jeval

Jeval in single user (single gui) mode is good when you have one or several prolog processes running and you only need one GUI.

Initialization

jeval:jeval_init. - initializes Jeval to use jasper (an automatically started Java in the SICStus)
jeval:jeval_init(+Mode, +Import) - initializes Jeval in one of the following modes:
- jasper - use jasper for Java communication
- jasper(ClassPath) - use jasper for Java communication and with the specified class path
- client - connect to Jeval server at default port
- client(+Port) - connect to Jeval server at specified port
- client(+Host,+Port) - connect to Jeval server at specified location
Import is a list of Java packages to import.

Executing code

jeval:jeval(+JavaCode) - Executes the Java code in the argument JavaCode
jeval:jeval_result(+JavaCode, -ResultAtom) - Executes the Java code in the argument JavaCode and binds Result to the result of the execution. This predicate blocks until the Java execution is complete.

single user example

Using Multi User Jeval

Multi user Jeval is an excellent choice when you have an application that is used by multiple users and need a more interactive user interface than a html-based web interface. In this case prolog acts as a server and users typically connect through applets via a web-browser.

Initialization

jeval_server:register_applet(+Context, +Module) - ...

Executing code

jeval:jeval(+User, +JavaCode) - Executes the Java code - JavaCode - in the client associated with User
jeval:jeval_result(+User, +ResultName, +JavaCode) - Executes the Java code - JavaCode - in the client associated with User. The result will be delivered via a callback to client_result(+ResultName, +ResultAtom, +User)

Callbacks

client_connected(+Host, +User) - ...
client_disconnected(+User) - ...
client_event(+Event, +User) - ...
client_result(+ResultName, +ResultAtom, +User) - ...

multi user example