Microsoft Win32 Virtual Machine for Java

The Microsoft VM for Java ships with the retail version of the Internet Explorer 4.01. This release of the SDK for Java provides this VM in a stand-alone form, to be installed on the retail version of the Internet Explorer 3.02 (or later). It supports the following:

• Enhanced JIT performance and reduced working set requirements

• Enhanced interpreter loop performance

• JDK 1.1 Support

  The Microsoft Virtual Machine for Java supports a number of JDK 1.1 defined enhancements, including Serialization, Reflection and Inner classes.

• Java and COM

  The SafeArray class now has public methods to access array data.

  COM custom marshalling provides better control of how data is passed in and out of the virtual machine.

• ActiveX and Java Beans Support

  Any Bean is exposed as an ActiveX control and any ActiveX control is exposed as a Bean.

  Auto-IDispatch now uses introspection to expose the necessary public classes and variables.

  ITypeInfo is provided on a class automatically and a type library can be persisted for a class.

  Event sourcing and sinking is supported.

• Package Management Features

  The Java Language Package Manager is used by the VM to efficiently organize Java packages. For more information on this feature, please read the SDK documentation on Package Management.

  The current method of installing and using Java packages consists of storing all the classes in a zip file and then appending this file to the CLASSPATH registry key. When the VM needs a class, it searches each CLASSPATH entry. The CLASSPATH can become filled with references to packages that are old or unused, or different versions of the same package. It is also difficult to know which packages are needed and which are not. To address these and other concerns, the Java Language Package Manager is used to organize Java packages. The Java Package Manager offers:

  • Version Control. Package version numbers are tracked, allowing Java programs and installers to intelligently update the system.
  • Namespaces. Entire applets and applications can be installed in namespaces to avoid conflicting with identically named packages and classes from other vendors.
  • Improved Security. Instead of having to fully trust all installed classes, the package manager stores the allowed permissions of each package, as verified by Authenticode.
  • Signing. Through Authenticode signing, the package manager can ensure that only the vendor that installed a package can update it.
  • ActiveX Bean Support. ActiveX Beans in Java packages can be automatically registered by the package manager.
  • Ease of Use. Web pages can install packages without having to alter the CLASSPATH or require a reboot.

  When a Java package is installed in the Package Manager, the original archive file is removed and the classes are stored internally. Thus, developers need to use the clspack command (described in the tools section) to generate the ZIP files used by Java compilers. All of the standard Java packages shipped with this version of the VM are installed in the Package Manager, including the AFC classes.