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README The Java(tm) Runtime Environment JRE 1.1.8 Updates to these release notes will be posted on the Java Software website: http://java.sun.com/products/jdk/1.1/README-update.html ----------------------------------------------------------------------- CONTENTS Overview of the Java Runtime Environment - Introduction - The Java Runtime Interpreter - Required vs. Optional Files - Win 32 Files - Optional Files - Solaris Files - Optional Files Bundling and Running the Java Runtime - Bundling the Java Runtime - Runtime Documentation ======================================================================= Overview of the Java Runtime Environment ======================================================================= ----------------------------------------------------------------------- Introduction ----------------------------------------------------------------------- The Java Runtime Environment is the minimum standard Java Platform for running Java programs. It contains the Java virtual machine, Java core classes and supporting files. The JRE includes all of the non-debuggable .dll or .so files plus the necessary classes from the JDK software to support a runtime-only program. The JRE does not include any of the development tools (such as appletviewer or javac) or classes that would pertain only to a development system. The JRE can be invoked from the command line by using the jre tool (see the following section). On Windows platforms, the jre tool will ignore the CLASSPATH environment variable. For both Windows and Solaris platforms, the -cp option is recommended to specify an application's class path. This version of the Java Runtime Environment contains a JIT compiler. The JIT compiler is enabled by default on the Win32 JRE. To disable the compiler, you can use the -nojit option of the Java runtime interpreter (see following section). The Symantec JIT compiler is copyrighted (c), 1996-1999, by Symantec Corporation. All rights reserved. The Win32 version of the JRE has an installer suitable for use by end-users. This gives software developers the option of not bundling the JRE with their applications. Instead, they can direct end-users to download and install the JRE themselves. An installer is not available for Solaris versions of the JRE. Developers should bundle the JRE and an installer with their Solaris applications. Licensees, developers, and independent software vendors who distribute the JRE with their Java programs must follow the terms of the JRE Binary Code License agreement, which includes these terms: - Don't arbitrarily subset the JRE. You may omit only the files listed below as optional. See the section entitled Required vs. Optional Files. - Include in your product's license the provisions called out in the JRE Binary Code License. Comments regarding the JRE are welcome. Please send them to jre-comments@java.sun.com. Due to the large volume of email received each day, Java Software usually cannot respond to your email personally. The JRE is a product of Sun Microsystems, Inc. ----------------------------------------------------------------------- The Java Runtime Interpreter ----------------------------------------------------------------------- The jre tool invokes the Java Runtime interpreter for executing Java applications. The tool is available in the Win32, Solaris-Sparc, and Solaris x86 downloads of the JRE. The syntax for the jre command is: jre [ options ] classname <args> The classname argument is the name of the class file to be executed. Any arguments to be passed to the class must be placed after the classname on the command line. An alternative version of the tool, jrew, is available for Win32. The jrew command is identical to jre, except that a console window is not invoked. The syntax of the jrew command is jrew [ options ] classname <args> On Windows platforms, the jre tool will ignore the CLASSPATH environment variable. For both Windows and Solaris platforms, the -cp option is recommended to specify an application's class path. Options for the jre and the jrew commands are as follows: -classpath path Specifies the path that jre uses to look up classes. Overrides the default classpath. -cp path Prepends the specified path to the default classpath that jre uses to look up classes. -help Print a usage message. -mx x Sets the maximum size of the memory allocation pool (the garbage collected heap) to x. The default is 16 megabytes of memory. x must be greater than or equal to 1000 bytes. -ms x Sets the startup size of the memory allocation pool (the garbage collected heap) to x. The default is 1 megabyte of memory. x must be greater than 1000 bytes. -maxe<size> Sets the maximum size of each expansion of the heap when more memory is required. Example: jre -maxe2097152 MyClass -mine<size> Sets the minimum size of each expansion of the heap. Also sets the minimum size of free object space in the heap. Example: jre -mine1048576 MyClass -maxf<float> Sets the approximate percentage of maximum free heap. Example: jre -maxf0.60 MyClass -minf<float> Sets the approximate percentage of minimum free space in the heap to give control over the rate of preallocation performed when heap space is expanded. Example: jre -minf0.35 MyClass -noasyncgc Turns off asynchronous garbage collection. When activated, no garbage collection takes place unless it is explicitly called or the program runs out of memory. -noclassgc Turns off garbage collection of Java classes. By default, the Java interpreter reclaims space for unused Java classes during garbage collection. -nojit Don't invoke the Just In Time bytecode compiler. The virtual machine directly interprets bytecodes, without converting them to native code. -ss x The -ss option sets the maximum stack size that can be used by C code in a thread to x. The default units for x are bytes. The value of x must be greater than or equal to 1000 bytes. -oss x The -oss option sets the maximum stack size that can be used by Java code in a thread to x. The default units for x are bytes. The value of x must be greater than or equal to 1000 bytes. -v, -verbose Causes jre to print a message to stdout each time a class file is loaded. -verify Performs byte-code verification on the class file. Beware, however, that java -verify does not perform a full verification in all situations. Any code path that is not actually executed by the interpreter is not verified. Therefore, java -verify cannot be relied upon to certify class files unless all code paths in the class file are actually run. -verifyremote Runs the verifier on all code that is loaded into the system via a classloader. verifyremote is the default for the interpreter. -noverify Turns verification off. -verbosegc Causes the garbage collector to print out messages whenever it frees memory. -DpropName=value Defines a property value. propName is the name of the property whose value you want to change and value is the value to change it to. For example, the command java -Dawt.button.color=green ... sets the value of the property awt.button.color to "green". ----------------------------------------------------------------------- Required vs. Optional Files ----------------------------------------------------------------------- Licensees must follow the terms of the accompanying LICENSE when redistributing the JRE. The following sections contain lists of the JRE files for both Win32 and Solaris platforms that may optionally be excluded from redistributions of the JRE. All files not in these lists of optional files must be included in redistributions of the JRE. In the case of the Win32 JRE, the native code C runtime library, msvcrt.dll, is located in the Windows system directory. The location of this directory varies on different operating systems, but is usually - winnt\system32 on Windows NT - windows98\system on Windows 98 - windows\system on Windows 95 The msvcrt.dll file should be included in redistributions of the Win32 JRE. ----------------------------------------------------------------------- Win32 Optional Files and Directories ----------------------------------------------------------------------- All font properties files in the lib directory other than the default lib\font.properties file are optional, and vendors may choose not to include them in redistributions of the JRE. In addition, the following may be optionally excluded from redistributions: bin\javakey.exe Executable for Javakey, the Java Security Tool bin\rmiregistry.exe Executable for rmiregistry, the Remote Object Registry Tool bin\symcjit.dll JIT compiler lib\i18n.jar Character conversion classes and all other locale support ----------------------------------------------------------------------- Solaris Optional Files and Directories ----------------------------------------------------------------------- The symbol '<sys>' used in the pathnames of this section stands for the 'sparc' directories in the Solaris-SPARC JRE and the 'i386' directories in the Solaris-x86 JRE. The Solaris version of the JRE uses a threads implementation called "green threads". Files providing support for green threads are in the directories lib/<sys>/green_threads and bin/<sys>green_threads. Another implementation of threads called "native threads" is available in the Solaris Native Threads Pack. If the Solaris Native Threads Pack is installed, its files will be in the directories lib/<sys>native_threads and bin/<sys>/native_threads. With the exception of the optional files listed below, you must include either the entire set of green threads files, or the entire set of native threads files, or both entire sets, when redistributing the JRE. All font properties files in the lib directory other than the default lib\font.properties file are optional, and vendors may choose not to include them in redistributions of the JRE. In addition, the following may be optionally excluded from redistributions: bin/javakey Shell script for launching Javakey, the Java Security Tool bin/rmiregistry Shell script for launching rmiregistry bin/<sys>/green_threads/javakey Executable for Javakey (green threads) bin/<sys>/native_threads/javakey Executable for Javakey (native threads) bin/<sys>/green_threads/rmiregistry Executable for rmiregistry (green threads) bin/<sys>/native_threads/rmiregistry Executable for rmiregistry (native threads) lib/i18n.jar Character conversion classes and all other locale support lib/<sys>/green_threads/libXm.so Symbolic link to Motif runtime library (green threads) lib/<sys>/native_threads/libXm.so Symbolic link to Motif runtime library (native threads) lib/<sys>/green_threads/libXm.so.3 Motif runtime library (green threads) lib/<sys>/native_threads/libXm.so.3 Motif runtime library (native threads) ======================================================================= Bundling and Running the Java Runtime ======================================================================= ----------------------------------------------------------------------- Bundling the Java Runtime ----------------------------------------------------------------------- Information relating to redistributing the Java Runtime Environment with your applications can be found in the JRE Notes of Developers web site. http://java.sun.com/products/jdk/1.1/runtime.html This release of the JRE for Win32 comes with its own installer that makes is suitable for downloading by end users. Java application developers have the option of not bundling the JRE with their software. Instead, they can direct end-users to download and install the JRE themselves. Solaris versions of the JRE do not have an installer. Software developers should bundle the JRE and installer with their Solaris software. When bundling the JRE with application software on Solaris, the following points should be considered: 1) It is suggested that the JRE be installed in its own subdirectory (referred to below as <runtime-dir>). Include all the the required files listed above in the bin and lib subdirectories of <runtime-dir>, following the same directory hierarchy and relative placement of files. The internationalization files marked optional can be included for language localization support. 2) It is suggested that all application-specific classes be placed in a directory other than <runtime-dir>. Application-specific classes may be individual .class files, .jar files, or .zip files. An example directory structure might look like the following: <app-dir> ________________|___________ | | | bin lib <runtime-dir> | | ________|________ app.jar | | bin lib | | 3) If native code support is required, then the native library must be located in LD_LIBRARY_PATH on Solaris or the executable search PATH on Win32. The best way to do this is to install the native libraries in either <app-dir>/lib/<sys> on Solaris or <app-dir>\bin on Win32. LD_LIBRARY_PATH (on Solaris) or PATH (on Win32) should then be set to include these directories. 4) The application can be invoked by using the jre command-line tool, using the -cp option to specify the application's class path. In the example directory tree above, for example, the command might look like this: <app-dir>/<runtime-dir>/bin/jre -cp <app-dir>/lib/app.jar <classname> Information on the jre command-line tool can be found in the section "The Java Runtime Interpreter" above and on the Java Software web site. For Solaris: http://java.sun.com/products/jdk1.1/docs/tooldocs/solaris/jre.html For Win32: http://java.sun.com/products/jdk1.1/docs/tooldocs/win32/jre.html Source code for the jre tool can be found in the Win32 JDK 1.1.8 directory tree in the jdk1.1.8\demo\jre\win32 folder. For the Solaris JDK 1.1.8, jre source code files can be found in the jdk1.1.8/demo/jre/solaris directory. ----------------------------------------------------------------------- Runtime Documentation ----------------------------------------------------------------------- Runtime documentation is any documentation that an end-user might need after they have installed a Java program that runs on the JRE. We supply the following runtime documentation: - Each property file contains comments that describe what the file is useful for and how to modify it. - awt.properties file - KeyEvent uses it to print out properties of key events, usually for debugging purposes. This might be used by a GUI debugger that needs to print out events. - fontprop.html file has a web page describing how to add fonts to the runtime. This document is part of the JDK documentation, and is located both in the JDK documentation download bundle and at the JavaSoft website: http://java.sun.com/products/jdk/1.1/docs/guide/intl/fontprop.html ----------------------------------------------------------------------- Copyright (c) 1997-2000 Sun Microsystems, Inc. 901 San Antonio Rd., Palo Alto, CA 94303 USA. All rights reserved.