jlaunch Home Page

Introduction

Java applications aren't standalone programs, but run by a Java interpreter. As a consequence, you can't configure a Java chess engine application directly as a engine under a chess GUI, but you have to configure the Java interpreter program java.exe as chess engine. Typical pathes for the Java interpreter program are:

• <JDK install dir>\bin\java.exe
  e.g.: C:\j2sdk1.4.2_04\bin\java.exe
• <JRE install dir>\bin\java.exe
  e.g.: C:\Program Files\Java\j2re1.4.2_04\bin\java.exe

What Is jlaunch ?

jlaunch is a native C program for Windows, that is similar to the Java JDK/JRE java.exe command. # The program uses the function JNI_CreateJavaVM of the Java Invocation API to create a JVM in the current process.

The function JNI_CreateJavaVM is loaded at runtime via LoadLibrary/GetProcAddress from the choosen jvm.dll file.

You can find more details about JNI (Java Native Interface) at

• http://java.sun.com/j2se/1.4.2/docs/guide/jni/index.html

Usage

Copy the jlaunch program into the directory of your Java chess engine and create the proper jlaunch.properties file (see examples properties files below).

Why To Use jlaunch ?

Usually the chess GUIs use the directory, where the program is located as the working directory. In case of a Java chess engine application this would be under the JDK/JRE installation path and not where the files of the Java chess engine are located. With jlaunch located in the same directory, you can address other files (e.g. engine specific opening books) relative to the location of your Java chess engine application.

jlaunch Properties File jlaunch.properties

jlaunch reads the configuration data from the properties file jlaunch.properties. The format of lines in this file is:

    key=value

Lines, that begin with a hash (#) in the first column are handled as comments.

Properties

• fullJvmPath
  Full path name of the jvm.dll to use. By default the most recent Sun Java JRE (or JDK) found on your machine will be used.
  You have to use this property, whenever you want to force the usage of a certain JRE/JDK.
  The full path name of the file jvm.dll is typically one of the following:
  • <Java install dir>/jre/bin/client/jvm.dll
    (JDK 1.4.2)
  • <Java install dir>/jre/bin/server/jvm.dll
    (JDK 1.4.2)
  • <Java install dir>/jre/bin/hotspot/jvm.dll
    (JDK 1.3.1)
  • <Java install dir>/jre/bin/classic/jvm.dll
    (JDK 1.3.1)
• mainClassName  (the only mandatory property)
  Name of the Java main class.
• classPath
  The directories and JAR files, needed to run the Java application. Default: . (i.e.: use for classes in the current directory)
• jvm.arg0, jvm.arg1, jvm.arg2, ...
  (max. number of Java options: 20)
  JVM Options, i.e. options for the JVM to start.
  This options are passed to the JVM at the JVM creation.
• app.arg0, app.arg1, app.arg2, ...
  (max. number of Java application options: 20)
  Java application options, i.e. options for the Java chess engine.
  This options are passed to the Java application's main method.

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Software Environment

jlaunch runs under Windows 2000 and Windows XP (other Windows versions aren't available for me so I don't know, whether jlaunch will run). The minimum needed Java version is Sun Java 1.2 but I strongly recommend to use either Java 1.3.1 or even better Java 1.4.2. The upcoming Java 1.5 is also suported.

Hint
Microsoft Java is more or less compatible to Sun Java 1.1.4 and therefore not supported.

jlaunch - Java Application Launcher Program

• jlaunch 1.1.0 for Windows 2000/XP (09-JUN-2004)
  (size: 26K)

Licence

 jlaunch - Java launcher for Windows 2000/XP.

 Copyright (c) 2004 Manfred Rosenboom
 All rights reserved.

 This program is FREEWARE.

 You can redistribute it as long as you don't charge for it, or include
 it in a product which is distributed for profit. It is forbidden to
 change, split, copy, sell, disassemble or produce any changed form of
 this program release without the written permission of the author.

 This program is distributed in the hope that it will be useful, but
 WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Java Chess Engines

Ready to use property files for various Java chess engines.
Just rename the desired file to jlaunch.properties.