Just-in-time (JIT) compilers are a kind of client software built into the browser and designed to overcome the severe performance limitations of the Java Virtual Machine, Sun Microsystems' original client software for running Java applets. They work by compiling or translating Java code to native machine code as it is downloaded from the Net. Native machine code is written for a particular platform and is therefore easier for the computer to read and execute than Java code.
Initially, however, only Windows 95 and Windows NT users will be able to get the improved Java performance in the new version of the browser, called Navigator 3.0 beta 5. Company officials did not return calls by press time to say when Unix and Mac versions of Navigator 3.0 would feature the JIT compiler.
A number of vendors, including Microsoft, IBM, and Symantec, are developing JIT compilers promising to improve performance by as much as ten times. Asymetrix also recently posted to its Web site a souped-up Java engine, called SuperCede VM, although the software is not technically a JIT compiler.
Instead of writing its own, Netscape licensed its JIT compiler from Borland International, and the company hopes that its version released for the first time in beta version today will set the standard for the market.
Microsoft expects to post a new beta version of Internet Explorer 3.0 with the company's own JIT compiler next week.
"Navigator was the first volume platform that Java was delivered on," said Kim Polese, part of the original Java team at Sun and now CEO of Marimba, a Java developer. "The JIT compilers are delivering C++ comparable performance. I think this is extremely significant."
Netscape has added a number of other features to beta 5, including frame border control, multicolumn text, strike-out and underline text, and new directory buttons. A complete list of new features is available on the Netscape's Web site, while the browser itself is available for download from the company's FTP site.
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